The fact that voice recorders are constantly getting overwritten in all these incidents lately, in the age of NAND in the TBs taking up virtually minuscule amounts of mass and volume, is absolutely ridiculous.
No, that is by design. Not necessarily out of ill will, but imagine pilots talking trash while on cruise could be called out weeks or months later for it. Not relaxing if you have a vindictive manager on your back. Maybe the data needs to be encrypted with a public key after some time (maybe 1-2 hours) with the only private key able to decrypt it held by the FAA or something - and every cockpit recorder has their own, unique public/private key pair. That way, only the FAA (or relevant national authority) can open the recorder data and they’ll only do so for serious events. Yes, you want a lot of redundancy in the storage and limited lengths of encryption snippets to reduce the chance of decryption failure due to memory errors and reduce the amount of damage if such an error occurs. PS: The recorders need their own dedicated power system so they keep working even if the plane gets a total blackout. And because you will want a beacon to find them easier after a crash, say, into the ocean. SOFAR bombs may be a problem due to explosives and airplanes, but certainly would have helped, if not disabled, to find Malaysia 370 - but sabotage and evil intent cannot be overcome with safety equipment designed for honest actors.
@@advorak8529 there are already laws on the books that prevent the airlines ie managers etc from listening to CVR recordings not to mention they don't have the equipment to do so (the NTSB toyed with recommending changes in legislation to let airlines routinely monitor CVR conversations on nominal flights to check if pilots were obeying sterile cockpit rules, etc. in 2010 but it never went anywhere- as far as I know, the pilots union said absolutely not, but even the airlines themselves weren't interested as the extra labor involved to listen to millions of hours of conversations a year would be ridiculous), plus their are also laws against retaliation/discrimination against someone by their employer for what they said in a private conversation even if they did, not to mention ALPA would make sure that never happened and would raise holy hėll if they ever did. Everywhere else in the world has had 25 hours minimum for decades, and the benefits FAR outweigh any nebulous concerns about privacy that really don't actually exist in reality.
@@advorak8529 Plenty of people are recorded for the entire shift every shift and in much less important rolls than a pilot. If a shelf stacker, checkout person, servo attendant etc etc can handle it a pilot can
@@halmc8109 1) They should be on before engine start(if that is what you mean by light the torches. 2) No way are you going to see an exchange program. The paperwork(and by extension time) that would be required on each exchange is a show stopper. Then there is the whole chain of custody issue if the recorder is ever needed in an investigation.
I had some incredible instructors in the USAF. When you do these breakdowns it really reminds me of the quality airmanship passed down to us and expected by us. I have immense respect for instructors like yourself. I always enjoy the nostalgia.
I second that. It's not difficult to see why for years the majors only looked at you if you had cut it as a military pilot. I knew an F.E. on 737s, former USAF, who was not impressed by the training he received at EAL (Eastern). He said he saw more in a sim-check for the C-141 in 15 minutes than he did through months of training at Eastern--and EAL was hardly unique,
@@andredarin8966On 9 May 2012, a demonstration flight directly struck Mount Salak in Indonesia, killing all 45 on board (Sukhoi personnel and representatives of various local airlines). The TAWS was ignored by the pilot. The subsequent investigation concluded that the flight crew was unaware of the presence of high ground in the area and ignored warnings from the terrain warning system, incorrectly attributing them to a system malfunction. The captain of the jet was Alexander Yablontsev (57), a former Russian combat pilot, test pilot, and cosmonaut. He had been involved in the Buran space program, and was the pilot for the first flight of Superjet 100 in 2008.
I love aviation and I know just enough to be dangerous to humanity. However, I am an engineer and spent my entire career in nuclear power, which which is complex . I watch your channel frequently. You do ask for input on occasion, but this video was very much different. You did something that is rare on RUclips. I am extremely impressed. I don’t know how many people noticed. You stated when you did not have details of the max rotor system and asked for help from the professionals that watch your channel. You did not bloviate. You’re confident enough that you knew your limits and asked for data. That requires maturity, common sense, and confidence. I salute you, sir. I got to add a dig. Go Navy.
I only flew the 737 100/200 (guppy series) for PEOPLExpress in the early 80s. I was dispatched once from Florida to Newark with a YAW DAMPER INOP MEL. Holy shit! Even though we were restricted to a lower altitude by the MEL, the passengers in the back sure knew it was not a normal flight by the tail swishing around. I couldn’t feel it up front at cruise altitude, but I REALLY noticed the difference when I was hand flying and we went skidding right through the final approach course… and I realized that because of inop Yaw Damper I had to use the rudder pedals just like in a Cessna , which 737 pilots never do. It was an eye opening experience.
@@sharedsailing4787With different fuselage lengths the rudder moment arm changes, that suggests that the yaw damper needs to be tuned to the aircraft model. Is that a mechanical or electronic change?
@@BrianMorrison Electronic. The Stall Management Yaw Damper control unit uses information from the Air Data Inertial Reference Unit accelerometers to judge the amount of yaw and apply the correct rudder deflection to counter the yaw. That's how the 737-Max does it. The first models of the 737 didn't have ADIRUs, so it was less precise.
We check the SMYD computers at least every A check, which I think is about every 500 flight hours. We check the rudder system in every way. Each hydraulic system. The proper fault warnings when the yaw damper disengages. The standby system for proper operation. Measure the rudder movement at the tail measured against a permanent index plate mounted near the bottom of the rudder. We look for a minimum displacement when switching between systems (so the actuators aren't fighting each other. It's actually quite an exhaustive series of tests through the (SMYD) Stall Management Yaw Damper computers 1 and 2.
Ah, PEOPLE Express! Those were the days. A lot of duct tape to hold up food trays and keep the overhead luggage compartment doors closed. But what did you want for $29 from Newark to Boston.
As a flight attendant of 28 years, responsible for the 737 in all of its iterations, thank you for this . I guarantee we will hear nothing of this in our annual training . I will share it with my co hearts . A very well done presentation.
@@johnnunn8688 I’ve been on everything all the way back to the 200. Right now my company has 4 models . Perhaps I would have said current if had know you were going to be so particular.
Thanks Juan. As a retired 30k hour heavy jet captain, I find it absolutely bizarre that cockpit voice recorders have not been able to record literally many tens of hours, and should have been able to do this for many years. 30 mins, or in this case just two hours is ridiculous. Even my phone can do that- it’s inexcusable.
Electrical Engineer here with a bit of ground experience on USN experimental aircraft engine runs, and an Airworthiness certificate. I always go to Juan since the dam issue in Northern Cal above Sacramento. I really appreciate Juan's take, and contribute to Blancolirio Patreon. Re this topic about lack of voice recorders...maybe the major carriers and manufacturers...just don't want to know ! Like Jack Nicholson said in that court scene with Tom Cruise.
I have a Garmin GPS 4k/audio and video and it will literally record everyday for two months with 6hrs driving everyday min. That is in a dashcam half the size of a pack of ciggies and a decent size SD card. How they don't have something similar is beyond me. They should have dash cams as well
Watching this, I realized what a great FAA Administrator Juan would be. Knowledgeable, committed, and truly focused on getting things right. Juan wouldn't need to fire the incompetent ones, they would just quit out of fear.
One of the things we do in simulator training is a Dutch Roll demo at high altitude. We disarm the Yaw Damper and turn off the autopilot. The results of displacing the rudder in this condition causes a Dutch Roll that can be really dramatic in swept wing jets and hard to recover. Props to the pilots in this case who managed to recover from this incident.
I experienced a total loss of the PCU in a SWA 737-200 on a flight from SAN to PHX. At touch down we lost all hydraulics of the A,B, and Stby system. They claimed that it was not possible to loose all hydraulics through the PCU, but it did occur. This occurred around the time of the crash of the United 737 that crashed in Colorado Springs from a PCU fault.
It was potentially a problem with Airbus too. A potential problem was identified where both Yellow and Green hydraulics could be lost if the fluid was lost in one system and the PTU just ran until it failed trying to make up the pressure. So a mod was done that when fluid was lost in one system the PTU would time out and shut down before it caused the other system to fail also.
This is a very strange occurrence, I’ve been doing maintenance on the 737 NG for about 25 years at this point, as well as the max from it’s beginning stages when we got it at our fleet. The system is identical in both aircraft. The fact that the standby power control unit was causing this issue or was said to cause this issue is very interesting to me. The standby Rudder power control unit it gets alternate hydraulic power from the standby hydraulic pump. The standby hydraulic pump supplies power when system A or system B flight control switch is in the standby Rudder position. Also interesting thing to note is that the standby Rudder shut off valve, on the standby hydraulic system module controls the pressure to the standby rudder power control unit. The system works automatically when the standby pump supplies pressure to the PCU. My best guess is that if the PCU was actually the thing that was causing the Dutch roll, it might’ve been a malfunction within the standby rudder shut off valve where it was sending uncontrolled fluid to the unit. But that’s very unlikely, forgive my assumption, but it seems to me that this might have been induced by human error and in doing so trying to correct themselves caused the Dutch roll. But once again it’s an assumption wait for the NTSB report.
"On Jun 13th 2024 The Aviation Herald learned that two ribs, that the stand by PCU is being mounted to, were damaged as well as the mounts of the stand by actuator. A temporary repair was done in Oakland replacing the damaged PCU, the aircraft was then ferried to Everett to replace the damaged ribs."
They have not said, but I think so much force was applied by the captain to regain straight and level flight, that damage to the structure mentioned by you occurred.
I’m a little puzzled that the standby actuator and mount could get damaged. Normally hydraulic system A and/or B would be powering main rudder PCU and the standby actuator would basically just be along for the ride so to speak. The primary Yaw Damper uses system B hydraulics so I’m wondering if they were on standby rudder power or was some part of the system on MEL or ?? It’ll be interesting to see what the NTSB investigation reveals.
Hey Juan. I thoroughly enjoy your videos and all the in-depth research you do. I just watched the video about the 737rudder issue that happened recently. I am a tech instructor for both the A-320 and B737 Max for an airline. To answer your question, the Max uses the same rudder control system as the NG. Incidentally, after the RSEP (Rudder System Enhancement Program) which was mandated in the early 2000's, a new main PCU was installed (I did a few of them while I was turning wrenches). That said, the classics then had the same type of rudder system as the NG and the Max after the modification was incorporated (RSEP). The Force Fight Monitor was a big part of this upgrade. The Force Fight Monitor is installed in the main rudder PCU and once it detects a difference of 3600 psi for a minimum of 5 seconds (one system pulling one way while the other system pulls the other way), it will automatically turn on the standby hydraulic pump and activate the standby PCU which will control the rudder. One disclaimer is that I DO NOT work for the airline that had the problem but am aware of it via the news and your channel. Hope this helps and keep your awesome content coming!
Is it possible that one of the PCUs or hydraulic systems was MEL'd, and then a failure of the other left the airplane without the yaw damper? Or is that not an MEL item on the 737?
Such a strange story. Dutch roll felt by the pilots at Fl34. Failure of yaw damper? Pilots regained control per FAA but cause structural damage to the ribs, standby pcu damaged- what does that even mean- physical damage to standby pcu-how does that even happen. Pilots then continue flight like nothing never happened. But something serious did happen. Can’t wait for the NTSB report. Ribs of airframe structurally damaged. Incredible.
@@gailcates8826 inadequate supporting structure for the PCU. Which in itself is saying something-the PCU is a pretty robust piece of equipment & given it's role in primary control of the aircraft-one would tend to question the basic design of the structure itself........
@@stevenrobinson2381 Yessir! Think of it as a tug-of-war type event. The system A servo valve pulls one direction while system B pulls the other creating an actual pulling force between the system servo valves of greater than 3000 psi. Also, when there are rudder inputs made from left to right and vice versa, the point where the rudder changes direction makes a pressure bump but it's so short-lived that it's not considered a force fight. That's why it is set up to require a period of five seconds minimum in which it would be an actual force fight. Hope this helps clarify it
Old enough to have flown a C141. Lol. Didn't fly it, but I jumped out of one a few times in airborne school. I think my class was one of the last to do that. I remember it was a long shuffle back to the jump door. All the way! De Oppresso Liber!
It is a problem with the Rudder Yaw Damper. Had it happen to me on a B737-500 over Palms Springs at FL330 enroute from LAX to CLE. Lost 6000' before getting aircraft back to straight and level. Thank God for my Navy aerobatic training.
@OfficialBlancoliriogt it's your channel. Do as you wish. It's my experience. Had a B737 U.S. Air Check Airman in the JS when this happened. My F.O. the Check Airman, and myself were all in agreement about what we experienced.
What a great example of human factors. We, as humans, can take some very limited information and make absolute conclusions based on the most fallible and ever changing element of our psyche called MEMORY. Only time, investigation and forensic reconstruction offers any hope of a certain cause to this event. Your post is a perfect example of how we all process information to fit our views to resolve any internal conflicts.
@justu2bnit17 you sound like an NTSB clown who initially blamed Captain Sully for ditching in the Hudson. In the incident I described, after passengers were deplaned in CLE, the aircraft was towed to the hangar, doors closed, hidden from sight. FAA investigators questioned the First Officer but never the Captain. Guess why...
@@johnwatson9518 Wow.. another quick to judgement response.. from your Navy aerobatic training that you were able to utilize in a B737-500, do you remember the phrase “all thrust, no vector”? My point is that a professional should know enough to know when they don’t know enough. The news outlets do a great job of spreading sensationalistic unverified drama. They need no help from professional aviators such as yourself.
For all you fellow aviation geeks out there, according to William Cook in his book The Road to the 707, the yaw damper was invented by Ed Pfafman, an engineer at Boeing during the flight testing of the XB-47 - the USAF's first swept wing jet bomber. The test pilots noted a continuing Dutch Roll in '47 and Ed came up with a solution. Brilliant guy. A yaw damper has been standard equipment on swept wing jets ever since.
The yaw damper has come a long way: the early ones were mechanical (mass and spring) devices, and now they are electronic, part of the flight control computers.
Some of the engineers at NACA, the predecessor of NASA, worked on similar systems, including pitch dampers and special systems to help control buffeting. One of those guys was Christopher Kraft, who later became the Chief Flight Director at NASA.
correct ,,dutch rolls have been happening for years on aircraft and at high altitude and your are correct about the yaw damper,,,gyro,,,it will correct this no big deal.
Good job explaining the 737 rudder PCU systems which the yaw damper is integrated with. Couple of things: I’m a retired 737 Mx guy and worked on them both in airline world and when I was at Boeing working 737 safety. The NG and MAX rudder PCU systems are identical. The only changes to flight controls of course was the MCAS and FBW spoilers. When I hear things like PCU was damaged, I think ok was Mx working on the system prior to this flight or previous flights? These units are located in the tail section. So damaged, how? Then hearing structure issues? Was the jet ground damaged and not reported? These systems are extremely reliable on the 737NG/MAX. FYI, manual reversion is a requirement during for Mx test flights and Boeing production flights… in my many years of experience very seldom did we encounter any problems from that test. Going to be an interesting NTSB report. Thanks Juan
I have 36 years on the 737 by itself and four years being on the 737 Max, I haven't seen any differences in this rudder system, I believe it's the same on the 737 Max as it was on the earlier model 737 's . I've seen if the input rods on the main rudder PCU are out of rig it will induce the force fight monitor system to kick on the stby rudder pump on and thus the stby rudder actuator and life goes on., Why the damage to the stby rudder actuator I have no idea, never seen this kind of issue before, hope this helps.
Love your content Juan. I'm an ARFF firefighter for an airport in Ohio and happened across your channel shortly after I started. Love the videos you do on aircraft incidents since it is something I could possibly be involved in responding to..
In the MAX the MCAS IS a function of the Speed Trim system which itself a function of the (SMYD) Stall Management/Yaw Damper system. (SYMD) It is composed of 3 systems. Yaw Damper, Elevator Feel Shift and Speed Trim (MCAS is a function of the Speed Trim system in the Max) The Max has slight changes to the RSEP (Rudder system enchantment Program) And a small change to the Yaw Damper system indication.
I read somewhere that 3 ribs were damaged including the one or two the PCU is attached to and that is why it was being ferried to Washington, for repairs. Apparently SWA has a contract maintenance facility there.
@@cavsh00ter Built (final assembly) in Renton Washington, with major fuselage structures supplied by Spirit Aerosystems of Wichita. Some will eventually be built in Everett Washington but that new assembly line is still a way off.
Juan, Found you many years back during the Orville Dam disaster. What a pleasant surprise to hear you announcing the STOL drags today, June 15th, at the Columbus Air Show. Thanks for your interest and good work! Long time subscriber, Dave Columbus, Ohio
Check out films of the time lag on the Tesla Cybertruck fly-by-wire steering system. Then shake your head very slowly. Do make sure you have your hands to either side of your head to stop the possibility of any interference cycle where you might get into a loop and shake your own head off!
@@COIcultistNon-issue when driving at speed. Those demonstrations are done when stopped. Also the electric steering requires much fewer input turns lock-to-lock
Hi Juan. My dad was in charge of all maintenance at Rickenbacker AFB in 72-75. They had 12-b52s and 12-kc135s and a few ardvarks F111s that I knew about when I was 9-10 yo. Going to work with your dad was really special back then. FYI. Dad was also in charge of the base renaming from Lockbourne to Rickenbacker. Of course we all loved Eddie. But the usaf frowned when Eddie’s Eastern Air sort of took over the celebration event. Life and times remembered. One 60 yo usaf brat. Always and forever.
I searched for the most recent "dutch roll" videos as soon as I saw it in the news, and wasn't disappointed. That being said, the algorithm also provided another video next to yours: "how to roll a dutch" by a guy who didn't really look like an aviation expert, but definitely knows how to fly high. Thanks Juan, amazing content as usual!
Regarding the voice recorder, at least 10 years ago, I bought an Olympus hand held digital voice recorder for around $60. It would store about 16 hours in stereo CD quality or 128 hours mono at dictation quality. The chips to do this are ridiculously cheap. I get that it has to be shock, heat, and electrically hardened. However there is no reason that the voice recorders not store dozens of hours of audio.
Looking at FOM 2 (Max vs NG), it is almost identical with respect to Yaw Damper architecture and operation (with minor variations in some of the older NG tails). One of the first lessons when I learned to fly the 727 (from a Boeing trained demo/test pilot) was that the rudder pedals on large jets are not to be confused with rudder pedals on a “regular” airplane. They became ENGINE OUT pedals once the aircraft is airborne (+ crosswind pedals). Fighting (helping?) the turn coordination of the Yaw Damper could result in PIO and in some cases aggravate dutch rolling tendencies. Think feet on the floor (of course you will still guard the pedals with no pressure) unless you are controlling for X-wind or engine out- PERIOD. This lesson is very often missed today… The 72 had a more aggressive sweep than the 73. It was more challenging in a x-wind (dutch roll tendency) and had 2 split rudders and 2 yaw dampers. The dutch roll recovery maneuver in the sim was… aggressive? Lol. Feet on the floor and snapping maximum aileron/roll spoiler input opposite the roll. High altitude made it much worse, although I know someone who lost one of the yaw dampers and he said the approach was yaw unstable even with the one working. At the expense of cruising speed, the 73 is more stable (less sweep) and has very limited dutch rolling tendency (provided the pilot understands what the rudder pedals are properly used for- see the above paragraph). Unfortunately, the 737 (all variants) still require the Yaw Damper to be reengaged with every IRS alignment.
737 pilot's Dad speaking. Son says, "Just aileron inputs to turn, don't touch the rudder pedals" The yaw damper takes care of turn coordination. Pilot input upsets the precise coordination. Need the rudder for landing...
@@j_taylor From FCOM Vol 2 "Either yaw damper is capable of providing dutch roll prevention, gust damping and turn coordination. Yaw damper operation does not result in rudder pedal movement. The pilot can override either main or standby yaw damper inputs using either the rudder pedals or trim inputs."
Thanks for the honorable mention of the C-141. I'm sure you remember the C-141A flew along in a tiny dutch roll movement and when the plane was lengthened (with air refueling added and designated a C-141B) that the slight dutch roll was eliminated with a new digital yaw damper. A more stable feel of the aircraft was a welcome change. Keep up your great analysis THANKS !
Juan, I watched your call of the STOL races at RENO (streamed online LIVE) and really enjoyed your work on that! It brought the excitement while making the races very approachable for someone like me who hadn't seen that type of racing before. Your fine work was understandably overshadowed by the tragic mid-air that same afternoon, but I wanted to let you know what a great job you did! They're lucky to have you.
It's really crazy that in 2024 cockpit voice recorders are just 2 hours and aren't archiving their data after flights are completed - is it a union thing?
I need to thank Juan for this one. I thought I was old until he mentioned if you're old enough to remember flying the C141. All the sudden I feel young again! Kudos Juan!! haha
@@Largecow_Moobeast Why would you have them stop investigating after two weeks? That sounds like a perfect setup to slow roll the investigation (sorry out sick) until your 2-week deadline arrives.
I just had to look it up: "Dutch Roll was the term used for skating repetitively to right and left on the outer edge of one's skates. By 1916, the term had been imported from skating to aeronautical engineering."
As a passenger in a 777 on climbout from Shanghai Pudong I experienced a dutch roll due to wake turbulence from a 747 ahead of us. It damped down quickly but left us passengers wondering until the flight deck informed us what had happened. It wasn't frightening but was certainly out of the ordinary and felt like an evasive maneuver.
As a previous KC135 guy, I lived with Dutch roll, esp in the A model which didn’t have a dedicated yaw damper. When you lost the rudder axis on the autopilot, it became a, long flight crossing the Atlantic or Pacific. The R model incorporated a full time yaw damper which was a godsend. I’m kind of surprised this would happen on a modern day jet.
In your next video about this incident you might want to discuss recovery from Dutch Roll. In the 2010’s I was flying a cargo DC-9-10 into hot, high elevation airports in Mexico. The -10 series had a short fuselage, no LE slats, and an anemic yaw damper system - all aggravating its wing’s known tendency to Dutch Roll. Training in recognition and recovery from Dutch Roll was absolutely necessary to fly that airplane - not so much now with the more modern airplanes. So, maybe a couple minutes on recognition and recovery would be good refresher for some viewers. I’ve since immigrated to NZ and all my sailplane buddies here try to “tall poppy” me with comments like, you airline guys don’t know how to use the rudder….I just smile and chuckle every time I hear that old trope. 🤣
I wish I knew you were in Columbus! I worked on those KC-135’s you see on the ramp! I live close by and would have liked meeting you in person! Long time subscriber of your channel!
Spent 12 years on the C-141B as a maintainer. Don't recall many Dutch roll issues as porpoising issues w AP engaged. Thanks for using proper terms as well. So many would call it a yaw dampner, and it would drive me crazy. Anyway. Really appreciate your posts. 👍✈️
Former Crew Chief on a USAF KC-135 (59-1507) and experienced firsthand in the late 80s a Dutch roll on a TDY trip. Not a good feeling I must say. Subsequent local sorties pilots were experiencing the same on this particular jet. Boeing came up to Loring AFB (our home base) and started changing out parts. Aircraft was grounded for a while but eventually the Red X's were signed off and the jet flew again without anymore incidents. Crazy times. Kudos to the test pilots and Boeing engineers.
@@ajs1691 I honestly don't know. The story around the flightline was Boeing changed out a lot of stuff over a month or so and then one day it no longer did Dutch Rolls. Yeah. I'm sure Boeing knew, but by that time i was transferred to another tail number 58-0093 and the jet in question 1507 went to Tinker for the R-mod conversion.
Back when the 707 was fairly new, Brannif was taking delivery of a new aircraft . It was a test flight with Boeing test pilots, and Brannif pilots. The pilot flying the plane induced a Dutch roll which ended up tearing off the engines, and resulted in a catastrophic crash. Luckily only a few people died.
You should add that the test pilot was fairly inexperienced and at that portion of the test, they had disabled the yaw damper (as a part of the test flight) which heightened the effects experienced.
From the pilot perspective, during dutch roll the nose inscribes a figure-8, usually in a very small area (plus or minus 5 degrees, dissipating if you stop fighting it if the aircraft has favorable dynamic stability characteristics, which most of them do - by law.
Once more Mr. Brown great information we have trusted for straightforward explanations to so many aviation difficulties these days. After hearing this one on the news my first thought was the Yaw Damper and or rudder faults of previous 737 crashes and handling problems. Thanks for the ever-increasing roll you play in bringing these cases to ours and the aviation world's attention.
Little bit off topic, but we had an "uncommanded yaw motion" in the CRJ-200 once, which calls for basically turning off the yaw damper as I recall. Assuming the design is similar in less degrees of authority given to it, I suppose the pcu controlling it just went wacky? It certainly got our attention, felt like someone kicked the rudder to the floor while on climb out.
Hi Juan, thanks for the in-depth post and explanation. If anyone has ever seen or been in a larger aircraft while the pilot is getting aerial refueling training, you've seen or experienced dutch roll. During this evolution, the pilot often causes the dutch roll via a PIO or pilot induced oscillation while trying to stay in position behind the tanker. Remember that, Juan? Cheers!
I remember at least 20 years ago, experiencing an inflight upset which I now know to have been a "Dutch Roll", in a British Airways 737 on decent into Heathrow. As I recall, we only experienced a couple of oscillations, which never the less were quite disconcerting. The pilot later claimed that the disturbance, as he described it, had been due to wake turbulence. Unfortunately, there was no Blancolirio around at the time to dissect the incident!!
Juan, it's funny that you correctly state it's a "damper, not a dampener. We're not trying to get things wet by dampening them". Then you you go on to say that it dampens the yaw. LOL, gotcha! It "damps" the yaw.
As soon as you mentioned the trouble with the PCU, it reminded me if the three incidents in the 1990s with the 737’s, where the PCU caused two bad crashes and one incident with another plane, which was able to land safely.
Hi Juan, not much difference is shown in the rudder systems description in the FCOM between the Max and NG. The only change I see is that although on both types, rudder authority is reduced by 25% above approximately 135 knots (system works the same in the air and on ground), on the Max this limit is removed if it senses a difference in engine speeds (failure, shutdown etc.)
The maneuver practiced by students is not really a "Dutch roll." In a true Dutch Roll the roll and yaw are out of phase: the plane is rolling one way, but yawing the opposite. By the time the plane's dynamic stability brings the yaw into line with the roll, the plane has already rolled back the other way, and the yaw is still contrary to roll. In the practice maneuver the idea is to not let the nose move: it should remain fixed, i.e. NO yaw, while the plane rolls side to side. An uncoordinated turn is more akin to a Dutch Roll, in that initially yaw is opposite roll.
I used to have one RC Model that would Dutch Roll quite well. To enter the Dutch Roll, it would need to be climbing on 3/4 throttle with a high alpha, nose up configuration. Then any quick blip of the aileron would set it off on the Dutch Roll, and decrease the rate of climb. To exit the roll all that was needed was to release the back pressure on the stick, to push the nose back down. I always flew this with the model heading away from me, as I wanted to see the aircraft. The period of the oscillation was about once every two seconds, so no rudder control was attempted.
Dispatching in the Jurassic/Classics with the damper MEL’d in Summer was nauseating. We had a PCU adventure or two that took the factory to ground the aircraft till the tail units were changed out. Like today, it’s always on the QT.
“Dual concentric” rudder PCU design was found to be the probable cause of the two hull loss accidents (UA585, N999UA, 1991-03-03, Colorado Springs and US427, N513AU, 1994-09-08, Pittsburg). As a result, the PCU was completely redesigned (initially a modified dual concentric PCU, then a ground-up redesign) and a retrofit "Rudder System Enhancement Programme" was initiated, and then mandated under Airworthiness Directive 2000-22-02 R1. All 737s in service today will have the new design fitted and there should be no in-service airframes with a dual-concentric PCU in operation.
@@mikemicksun6469 I thought the PIT loss was due to flying too low of an airspeed for the configuration and went below inflight minimum control speed. I'm probably wrong.
Great episode, Juan. I read those articles but never really understood what Dutch roll was (I’m not a pilot, obviously) This is why I always eagerly wait for your videos.
Hi Juan! I've followed you for sometime now but never posted a comment. Just wanted to thank you for everything you've taught me. Every episode is like being in a classroom. You have great clarity and objectivity and you really are a great teacher. Whenever an aviation incident occurs I don't watch or read any other media about it, I just wait for you to give us the facts. I also enjoy the Husky flights and the Dad time you share with us when your son is with you. Always look forward to your next post. Thanks again!
Hi Juan the content on this channel is great I,m no aviation expert just an enthusiast but flying back from Faro in Portugal last on a Jet 2 737 don’t know the model i could have swore the aircraft did the same mid flight only for about 60 seconds.
welcome to Columbus. great to see you at the airshow. what a performane by tne thunderbirds. thank you for explaining dutch roll . i always struggled with that
Juan, 11k hour NG/MAX driver here, unfortunately or fortunately depending on your perspective, I’m inclined to posit human error on this one. One of the pilots “stuffed” a rudder accidentally and either the YD was overwhelmed or they (the pilot) tried to override the YD to correct his/her misstep. Similar to loss of control of Lantam 787, with inadvertent seat movement. FWIW.
The usual explanations don't mention how the Dutch Roll gets started up at cruise. I'm very grateful for Brownie's mention of turbulence as one possible cause. Thanks for sharing another possible cause. Lucky that the plane was designed and assembled well enough that she was able to continue flying and land safely.
Did they lose altitude or declare an emergency and why would that cause damage to the PCU? If they knew why it happened why would they report it to the NTSB as a unknown cause?
Hate to say this, but it does seem like our entire language has been going the way of Boeing's quality control. Many reasons I suppose, but a bit disappointing to see it all in one's own life-time.
Airplanes do not develop extreme dutch roll if the yaw damper is working properly. Therefore there was either a malfunction or the yaw damper was not engaged. The damage nobody is talking about probably involves the vertical tail structure which can fail if the maneuver continues to get more severe (diverge) . The biggest risk is encountering turbulence at high altitudes above FL370. I suspect that the difficulty occurred above this altitude and the pilots were descending to aid in recovery as they are usually taught since pilot recovery is extremely difficult using manual flight control inputs. Yes, once upon a time C-141 pilots were demonstrated dutch roll during training. They however turned the yaw damper back on to recover and were not required to demonstrate proficiency in making a manual recovery.
OK for @blancolirio or whoever can offer an informed answer this question: With in mind the fact that so many commercial planes are now connected to the internet, why don't the voice and data recorders simultaneously stream to the FAA or airline's HQ? In addition to redundancy (should the stream fail or the black boxes not be able to be found), this would make the info immediately available with full history except when there was a drop in the stream. This wouldn't replace the recorders, but it seems like a no brainer to have it in place for the reasons stated above.
The Air Force lost a KC-135 back in 2013 due to a Dutch Roll event. Got so bad part of the aircraft broke off. Investigation found insufficient training.
*insufficient training to recognize a Dutch roll condition. All three aircrew were all under 30. I was at Fairchild when the news broke that we lost them and it hit pretty hard.
I was a crewchief on a KC-135R that arrived the day before and was parked beside the mishap jet. It was very sad and disturbing the next day when we found out what had happened.
Split-rudders on the 747 and 772 make the issue manifest itself a bit differently ... but, then there is the chance that one of the rudders could hard-over...something that used to happen on -200B from time to time! Those were fun...😳
Great reporting Juan. I instantly thought of the hard over rudder losses with USAir and the United on final to COS. I’m more concerned with more Max mysteries. I think you mentioned that the primary PCU was not the failed unit. When Boeing was trying to certify the 707 in either Europe or the U.K. They required Boeing to add a boosted rudder. Look up American flight 1 in the early 60’s departing out of ISP (NY) bound for LAX.
So funny you brought up the C-141! I was a jumper on a C-141 Starlifter and we got the crazy figure 8 roll! By the time it was done I was extremely eager to jump out of the aircraft! I was young and it was scary!
Re: "Boeing has lost our trust". A guy I was talking to once told me something one of his NCOs in the Army had told him: "Trust is like a drinking glass. If you break it, you might be able to glue it back together, but it will never be the same."
@@agamemnon7461the only thing saving Boeing is that there’s such a massive backlog of narrow-body planes that airlines can’t simply switch to Airbus. It’s also why airlines haven’t cancelled 737MAX orders, because then they’d go to the back of the line for BOTH Boeing and Airbus.
Excellent report Juan! I retired from your airline almost 20 years ago and I'll admit it I have used damper and dampener interchangeable over the years I'm going to blame it on dyslexia.
Great report Juan. Very helpful but also a bit alarming. Those two fatal rudder hard over crashes were nothing short of horrific. No pilot on Earth wants to see a repeat of those nightmarish incidents. What could cause the secondary PCU to have sustained damage? Wasn't the yaw damper ON during flight to help prevent the roll in the first place?
Excellent & puzzling report Juan as usual! This happening at altitude is ominous to say the least, the USair outside of Pittsburgh PA as I recall passed through wake turbulence from the aircraft in front on approach. I'm hoping that this is solved quickly & reported correctly! Something initiated the rudder problem but what was it??
![[Part 2] SEVERE SMOKE IN COCKPIT | Panic Moments in Icing Conditions!](/img/1.gif)
The fact that voice recorders are constantly getting overwritten in all these incidents lately, in the age of NAND in the TBs taking up virtually minuscule amounts of mass and volume, is absolutely ridiculous.
No, that is by design.
Not necessarily out of ill will, but imagine pilots talking trash while on cruise could be called out weeks or months later for it.
Not relaxing if you have a vindictive manager on your back.
Maybe the data needs to be encrypted with a public key after some time (maybe 1-2 hours) with the only private key able to decrypt it held by the FAA or something - and every cockpit recorder has their own, unique public/private key pair. That way, only the FAA (or relevant national authority) can open the recorder data and they’ll only do so for serious events.
Yes, you want a lot of redundancy in the storage and limited lengths of encryption snippets to reduce the chance of decryption failure due to memory errors and reduce the amount of damage if such an error occurs.
PS: The recorders need their own dedicated power system so they keep working even if the plane gets a total blackout. And because you will want a beacon to find them easier after a crash, say, into the ocean. SOFAR bombs may be a problem due to explosives and airplanes, but certainly would have helped, if not disabled, to find Malaysia 370 - but sabotage and evil intent cannot be overcome with safety equipment designed for honest actors.
@@advorak8529 there are already laws on the books that prevent the airlines ie managers etc from listening to CVR recordings not to mention they don't have the equipment to do so (the NTSB toyed with recommending changes in legislation to let airlines routinely monitor CVR conversations on nominal flights to check if pilots were obeying sterile cockpit rules, etc. in 2010 but it never went anywhere- as far as I know, the pilots union said absolutely not, but even the airlines themselves weren't interested as the extra labor involved to listen to millions of hours of conversations a year would be ridiculous), plus their are also laws against retaliation/discrimination against someone by their employer for what they said in a private conversation even if they did, not to mention ALPA would make sure that never happened and would raise holy hėll if they ever did. Everywhere else in the world has had 25 hours minimum for decades, and the benefits FAR outweigh any nebulous concerns about privacy that really don't actually exist in reality.
Doesn't the European agency EASA demand 25h recording time for the voice recorder?
Us too cheap for that?
@@advorak8529 Plenty of people are recorded for the entire shift every shift and in much less important rolls than a pilot. If a shelf stacker, checkout person, servo attendant etc etc can handle it a pilot can
@@halmc8109 1) They should be on before engine start(if that is what you mean by light the torches. 2) No way are you going to see an exchange program. The paperwork(and by extension time) that would be required on each exchange is a show stopper. Then there is the whole chain of custody issue if the recorder is ever needed in an investigation.
I had some incredible instructors in the USAF. When you do these breakdowns it really reminds me of the quality airmanship passed down to us and expected by us. I have immense respect for instructors like yourself. I always enjoy the nostalgia.
I second that. It's not difficult to see why for years the majors only looked at you if you had cut it as a military pilot. I knew an F.E. on 737s, former USAF, who was not impressed by the training he received at EAL (Eastern). He said he saw more in a sim-check for the C-141 in 15 minutes than he did through months of training at Eastern--and EAL was hardly unique,
@@andredarin8966On 9 May 2012, a demonstration flight directly struck Mount Salak in Indonesia, killing all 45 on board (Sukhoi personnel and representatives of various local airlines). The TAWS was ignored by the pilot.
The subsequent investigation concluded that the flight crew was unaware of the presence of high ground in the area and ignored warnings from the terrain warning system, incorrectly attributing them to a system malfunction.
The captain of the jet was Alexander Yablontsev (57), a former Russian combat pilot, test pilot, and cosmonaut. He had been involved in the Buran space program, and was the pilot for the first flight of Superjet 100 in 2008.
Like you not like yourself 😊
Was at the Columbus Airshow today and I thought that voice sounded familiar. You and all the announcers did a great job today.
Thanks!
My sister was there, I saw a selfie of her and Juan. I asked her to ask Juan what "goat rope" meant!
@@blancolirio
Did you Also, hear about the SWA incident in Hawaii
@@justanotheraviator2357
Good Q, and that's what I thought this was going to be about.
I love aviation and I know just enough to be dangerous to humanity.
However, I am an engineer and spent my entire career in nuclear power, which which is complex .
I watch your channel frequently. You do ask for input on occasion, but this video was very much different.
You did something that is rare on RUclips. I am extremely impressed. I don’t know how many people noticed. You stated when you did not have details of the max rotor system and asked for help from the professionals that watch your channel. You did not bloviate. You’re confident enough that you knew your limits and asked for data.
That requires maturity, common sense, and confidence. I salute you, sir.
I got to add a dig. Go Navy.
This is a very complicated case, Maude. You know, a lotta ins, a lotta outs, lotta what-have-yous. 😎
I only flew the 737 100/200 (guppy series) for PEOPLExpress in the early 80s. I was dispatched once from Florida to Newark with a YAW DAMPER INOP MEL. Holy shit! Even though we were restricted to a lower altitude by the MEL, the passengers in the back sure knew it was not a normal flight by the tail swishing around. I couldn’t feel it up front at cruise altitude, but I REALLY noticed the difference when I was hand flying and we went skidding right through the final approach course… and I realized that because of inop Yaw Damper I had to use the rudder pedals just like in a Cessna , which 737 pilots never do. It was an eye opening experience.
Yeah I once had 737 with an MEL'ed YD and it was a puke fest in the back. We refused the plane after flying 1 leg.
@@sharedsailing4787With different fuselage lengths the rudder moment arm changes, that suggests that the yaw damper needs to be tuned to the aircraft model. Is that a mechanical or electronic change?
@@BrianMorrison Electronic. The Stall Management Yaw Damper control unit uses information from the Air Data Inertial Reference Unit accelerometers to judge the amount of yaw and apply the correct rudder deflection to counter the yaw. That's how the 737-Max does it. The first models of the 737 didn't have ADIRUs, so it was less precise.
We check the SMYD computers at least every A check, which I think is about every 500 flight hours. We check the rudder system in every way. Each hydraulic system. The proper fault warnings when the yaw damper disengages. The standby system for proper operation. Measure the rudder movement at the tail measured against a permanent index plate mounted near the bottom of the rudder. We look for a minimum displacement when switching between systems (so the actuators aren't fighting each other. It's actually quite an exhaustive series of tests through the (SMYD) Stall Management Yaw Damper computers 1 and 2.
Ah, PEOPLE Express! Those were the days. A lot of duct tape to hold up food trays and keep the overhead luggage compartment doors closed. But what did you want for $29 from Newark to Boston.
As a flight attendant of 28 years, responsible for the 737 in all of its iterations, thank you for this . I guarantee we will hear nothing of this in our annual training . I will share it with my co hearts . A very well done presentation.
ALL of it’s iterations? It first flew 67 years ago!
@@johnnunn8688 I’ve been on everything all the way back to the 200. Right now my company has 4 models . Perhaps I would have said current if had know you were going to be so particular.
Thank you for your service
@@NCrdwlf you said, ‘all’, how am I supposed to take that?
@@johnnunn8688 Nope. Try 57 years ago.
Thanks Juan.
As a retired 30k hour heavy jet captain, I find it absolutely bizarre that cockpit voice recorders have not been able to record literally many tens of hours, and should have been able to do this for many years. 30 mins, or in this case just two hours is ridiculous. Even my phone can do that- it’s inexcusable.
Union issue!
@@bobcookplease care to elaborate.
Or video which the union has fought for years.
Electrical Engineer here with a bit of ground experience on USN experimental aircraft engine runs, and an Airworthiness certificate. I always go to Juan since the dam issue in Northern Cal above Sacramento. I really appreciate Juan's take, and contribute to Blancolirio Patreon. Re this topic about lack of voice recorders...maybe the major carriers and manufacturers...just don't want to know ! Like Jack Nicholson said in that court scene with Tom Cruise.
I have a Garmin GPS 4k/audio and video and it will literally record everyday for two months with 6hrs driving everyday min. That is in a dashcam half the size of a pack of ciggies and a decent size SD card. How they don't have something similar is beyond me. They should have dash cams as well
Watching this, I realized what a great FAA Administrator Juan would be. Knowledgeable, committed, and truly focused on getting things right. Juan wouldn't need to fire the incompetent ones, they would just quit out of fear.
One of the things we do in simulator training is a Dutch Roll demo at high altitude. We disarm the Yaw Damper and turn off the autopilot. The results of displacing the rudder in this condition causes a Dutch Roll that can be really dramatic in swept wing jets and hard to recover. Props to the pilots in this case who managed to recover from this incident.
I experienced a total loss of the PCU in a SWA 737-200 on a flight from SAN to PHX. At touch down we lost all hydraulics of the A,B, and Stby system. They claimed that it was not possible to loose all hydraulics through the PCU, but it did occur. This occurred around the time of the crash of the United 737 that crashed in Colorado Springs from a PCU fault.
Wow you lucky some things on untied 737 sadly those people were killed now we have 737 max almost same thing this crazy why is always 737 🤦🏿♂️
@@wilfordfootball79
It’s not only the 737.
Yikes!
It was potentially a problem with Airbus too. A potential problem was identified where both Yellow and Green hydraulics could be lost if the fluid was lost in one system and the PTU just ran until it failed trying to make up the pressure. So a mod was done that when fluid was lost in one system the PTU would time out and shut down before it caused the other system to fail also.
@@richardlewis4288 "It’s not only the 737."
True. It was a potential problem on the A320 line also but a modification greatly reduces that risk today.
This is a very strange occurrence, I’ve been doing maintenance on the 737 NG for about 25 years at this point, as well as the max from it’s beginning stages when we got it at our fleet. The system is identical in both aircraft. The fact that the standby power control unit was causing this issue or was said to cause this issue is very interesting to me. The standby Rudder power control unit it gets alternate hydraulic power from the standby hydraulic pump. The standby hydraulic pump supplies power when system A or system B flight control switch is in the standby Rudder position. Also interesting thing to note is that the standby Rudder shut off valve, on the standby hydraulic system module controls the pressure to the standby rudder power control unit. The system works automatically when the standby pump supplies pressure to the PCU. My best guess is that if the PCU was actually the thing that was causing the Dutch roll, it might’ve been a malfunction within the standby rudder shut off valve where it was sending uncontrolled fluid to the unit. But that’s very unlikely, forgive my assumption, but it seems to me that this might have been induced by human error and in doing so trying to correct themselves caused the Dutch roll. But once again it’s an assumption wait for the NTSB report.
Appreciate your keen and very well stated hypothesis.
"On Jun 13th 2024 The Aviation Herald learned that two ribs, that the stand by PCU is being mounted to, were damaged as well as the mounts of the stand by actuator. A temporary repair was done in Oakland replacing the damaged PCU, the aircraft was then ferried to Everett to replace the damaged ribs."
Wow!
They have not said, but I think so much force was applied by the captain to regain straight and level flight, that damage to the structure mentioned by you occurred.
Uh oh
@@billrichard4438so he basically warped the structural integrity saving their lives. I mean silver lining is they are alive. Wow.
I’m a little puzzled that the standby actuator and mount could get damaged. Normally hydraulic system A and/or B would be powering main rudder PCU and the standby actuator would basically just be along for the ride so to speak. The primary Yaw Damper uses system B hydraulics so I’m wondering if they were on standby rudder power or was some part of the system on MEL or ?? It’ll be interesting to see what the NTSB investigation reveals.
Saw the headline but decided to just wait until Juan talked about it instead of looking then.
Same.
Just in time!
Literally had an email in my draft to ask him to cover it :-)
Its a pleasure to here a "reporter" actually know what he is talking about
Ditto 😂
Never have I seen modified charades so expertly explain the physics of a Dutch roll. Well done, Juan!⚡👊🏼⚡
Hey Juan. I thoroughly enjoy your videos and all the in-depth research you do. I just watched the video about the 737rudder issue that happened recently. I am a tech instructor for both the A-320 and B737 Max for an airline. To answer your question, the Max uses the same rudder control system as the NG. Incidentally, after the RSEP (Rudder System Enhancement Program) which was mandated in the early 2000's, a new main PCU was installed (I did a few of them while I was turning wrenches). That said, the classics then had the same type of rudder system as the NG and the Max after the modification was incorporated (RSEP). The Force Fight Monitor was a big part of this upgrade. The Force Fight Monitor is installed in the main rudder PCU and once it detects a difference of 3600 psi for a minimum of 5 seconds (one system pulling one way while the other system pulls the other way), it will automatically turn on the standby hydraulic pump and activate the standby PCU which will control the rudder. One disclaimer is that I DO NOT work for the airline that had the problem but am aware of it via the news and your channel. Hope this helps and keep your awesome content coming!
Is it possible that one of the PCUs or hydraulic systems was MEL'd, and then a failure of the other left the airplane without the yaw damper?
Or is that not an MEL item on the 737?
Such a strange story. Dutch roll felt by the pilots at Fl34. Failure of yaw damper? Pilots regained control per FAA but cause structural damage to the ribs, standby pcu damaged- what does that even mean- physical damage to standby pcu-how does that even happen. Pilots then continue flight like nothing never happened. But something serious did happen. Can’t wait for the NTSB report. Ribs of airframe structurally damaged. Incredible.
@@gailcates8826 inadequate supporting structure for the PCU. Which in itself is saying something-the PCU is a pretty robust piece of equipment & given it's role in primary control of the aircraft-one would tend to question the basic design of the structure itself........
OUTSTANDING response. However-a difference of 3600 PSI ? Considering System A & B as well as Standby operate at 3000 PSI ?
@@stevenrobinson2381 Yessir! Think of it as a tug-of-war type event. The system A servo valve pulls one direction while system B pulls the other creating an actual pulling force between the system servo valves of greater than 3000 psi. Also, when there are rudder inputs made from left to right and vice versa, the point where the rudder changes direction makes a pressure bump but it's so short-lived that it's not considered a force fight. That's why it is set up to require a period of five seconds minimum in which it would be an actual force fight. Hope this helps clarify it
Old enough to have flown a C141. Lol. Didn't fly it, but I jumped out of one a few times in airborne school. I think my class was one of the last to do that. I remember it was a long shuffle back to the jump door. All the way! De Oppresso Liber!
It is a problem with the Rudder Yaw Damper. Had it happen to me on a B737-500 over Palms Springs at FL330 enroute from LAX to CLE. Lost 6000' before getting aircraft back to straight and level. Thank God for my Navy aerobatic training.
@OfficialBlancoliriogt it's your channel. Do as you wish. It's my experience. Had a B737 U.S. Air Check Airman in the JS when this happened. My F.O. the Check Airman, and myself were all in agreement about what we experienced.
What a great example of human factors. We, as humans, can take some very limited information and make absolute conclusions based on the most fallible and ever changing element of our psyche called MEMORY. Only time, investigation and forensic reconstruction offers any hope of a certain cause to this event. Your post is a perfect example of how we all process information to fit our views to resolve any internal conflicts.
@justu2bnit17 you sound like an NTSB clown who initially blamed Captain Sully for ditching in the Hudson. In the incident I described, after passengers were deplaned in CLE, the aircraft was towed to the hangar, doors closed, hidden from sight. FAA investigators questioned the First Officer but never the Captain. Guess why...
Why?
@@johnwatson9518 Wow.. another quick to judgement response.. from your Navy aerobatic training that you were able to utilize in a B737-500, do you remember the phrase “all thrust, no vector”? My point is that a professional should know enough to know when they don’t know enough. The news outlets do a great job of spreading sensationalistic unverified drama. They need no help from professional aviators such as yourself.
For all you fellow aviation geeks out there, according to William Cook in his book The Road to the 707, the yaw damper was invented by Ed Pfafman, an engineer at Boeing during the flight testing of the XB-47 - the USAF's first swept wing jet bomber. The test pilots noted a continuing Dutch Roll in '47 and Ed came up with a solution. Brilliant guy. A yaw damper has been standard equipment on swept wing jets ever since.
The yaw damper has come a long way: the early ones were mechanical (mass and spring) devices, and now they are electronic, part of the flight control computers.
Some of the engineers at NACA, the predecessor of NASA, worked on similar systems, including pitch dampers and special systems to help control buffeting. One of those guys was Christopher Kraft, who later became the Chief Flight Director at NASA.
correct ,,dutch rolls have been happening for years on aircraft and at high altitude and your are correct about the yaw damper,,,gyro,,,it will correct this no big deal.
Good job explaining the 737 rudder PCU systems which the yaw damper is integrated with.
Couple of things:
I’m a retired 737 Mx guy and worked on them both in airline world and when I was at Boeing working 737 safety. The NG and MAX rudder PCU systems are identical. The only changes to flight controls of course was the MCAS and FBW spoilers.
When I hear things like PCU was damaged, I think ok was Mx working on the system prior to this flight or previous flights? These units are located in the tail section. So damaged, how?
Then hearing structure issues? Was the jet ground damaged and not reported?
These systems are extremely reliable on the 737NG/MAX.
FYI, manual reversion is a requirement during for Mx test flights and Boeing production flights… in my many years of experience very seldom did we encounter any problems from that test.
Going to be an interesting NTSB report. Thanks Juan
Which means, that if there is an issue with the PCU, it could also affect the NG. This does look like a quality control-related defect though.
@Stoney3K nothing new for Boeing
I have 36 years on the 737 by itself and four years being on the 737 Max, I haven't seen any differences in this rudder system, I believe it's the same on the 737 Max as it was on the earlier model 737 's . I've seen if the input rods on the main rudder PCU are out of rig it will induce the force fight monitor system to kick on the stby rudder pump on and thus the stby rudder actuator and life goes on., Why the damage to the stby rudder actuator I have no idea, never seen this kind of issue before, hope this helps.
Love your content Juan. I'm an ARFF firefighter for an airport in Ohio and happened across your channel shortly after I started. Love the videos you do on aircraft incidents since it is something I could possibly be involved in responding to..
In the MAX the MCAS IS a function of the Speed Trim system which itself a function of the (SMYD) Stall Management/Yaw Damper system. (SYMD) It is composed of 3 systems. Yaw Damper, Elevator Feel Shift and Speed Trim (MCAS is a function of the Speed Trim system in the Max)
The Max has slight changes to the RSEP (Rudder system enchantment Program)
And a small change to the Yaw Damper system indication.
I read somewhere that 3 ribs were damaged including the one or two the PCU is attached to and that is why it was being ferried to Washington, for repairs. Apparently SWA has a contract maintenance facility there.
Wow!
THATS WHERE THEY ARE BUILT?
@@cavsh00ter Built (final assembly) in Renton Washington, with major fuselage structures supplied by Spirit Aerosystems of Wichita. Some will eventually be built in Everett Washington but that new assembly line is still a way off.
@@benz-share9058, yeah , Spirit is just a bad as Boeing!
SWA has had a contract for MRO services with ATS, at Paine Field, for years.
Brilliant, instructive and crystal clear examination of the phenomenon. Thanks again, Juan. You cranked it out of the park, once again.
Best explanation of a Dutch roll period. Much as gracias Juan.
Juan, Found you many years back during the Orville Dam disaster. What a pleasant surprise to hear you announcing the STOL drags today, June 15th, at the Columbus Air Show. Thanks for your interest and good work! Long time subscriber, Dave Columbus, Ohio
Electrical engineer here. Great explanation, of an unstable system, with phase shift contribution !
Same here. Got a chuckle out of the damping vs. dampening comment!
truly ! excellent! also EE. especially the yaw leading to the roll combined dynamics.
Physicist here. This was very well presented. I am impressed by all the EE's around.
Check out films of the time lag on the Tesla Cybertruck fly-by-wire steering system. Then shake your head very slowly. Do make sure you have your hands to either side of your head to stop the possibility of any interference cycle where you might get into a loop and shake your own head off!
@@COIcultistNon-issue when driving at speed. Those demonstrations are done when stopped. Also the electric steering requires much fewer input turns lock-to-lock
Your explanation of the how the rudder peddles are connected is great! It gives a lot of insight into how these systems work.
Pedals not peddles. Are you AI??
Hi Juan. My dad was in charge of all maintenance at Rickenbacker AFB in 72-75. They had 12-b52s and 12-kc135s and a few ardvarks F111s that I knew about when I was 9-10 yo. Going to work with your dad was really special back then. FYI. Dad was also in charge of the base renaming from Lockbourne to Rickenbacker. Of course we all loved Eddie. But the usaf frowned when Eddie’s Eastern Air sort of took over the celebration event. Life and times remembered. One 60 yo usaf brat. Always and forever.
Oh yeah. Dad was a load master on the c141 and then finally a flight engineer. Much like yourself. Thank you for your service !
Juan, you are the best pilot debriefer on the internet. Keep up the great work!
I searched for the most recent "dutch roll" videos as soon as I saw it in the news, and wasn't disappointed. That being said, the algorithm also provided another video next to yours: "how to roll a dutch" by a guy who didn't really look like an aviation expert, but definitely knows how to fly high. Thanks Juan, amazing content as usual!
That's wild!
Regarding the voice recorder, at least 10 years ago, I bought an Olympus hand held digital voice recorder for around $60. It would store about 16 hours in stereo CD quality or 128 hours mono at dictation quality. The chips to do this are ridiculously cheap. I get that it has to be shock, heat, and electrically hardened. However there is no reason that the voice recorders not store dozens of hours of audio.
Looking at FOM 2 (Max vs NG), it is almost identical with respect to Yaw Damper architecture and operation (with minor variations in some of the older NG tails).
One of the first lessons when I learned to fly the 727 (from a Boeing trained demo/test pilot) was that the rudder pedals on large jets are not to be confused with rudder pedals on a “regular” airplane. They became ENGINE OUT pedals once the aircraft is airborne (+ crosswind pedals). Fighting (helping?) the turn coordination of the Yaw Damper could result in PIO and in some cases aggravate dutch rolling tendencies. Think feet on the floor (of course you will still guard the pedals with no pressure) unless you are controlling for X-wind or engine out- PERIOD. This lesson is very often missed today…
The 72 had a more aggressive sweep than the 73. It was more challenging in a x-wind (dutch roll tendency) and had 2 split rudders and 2 yaw dampers. The dutch roll recovery maneuver in the sim was… aggressive? Lol. Feet on the floor and snapping maximum aileron/roll spoiler input opposite the roll. High altitude made it much worse, although I know someone who lost one of the yaw dampers and he said the approach was yaw unstable even with the one working.
At the expense of cruising speed, the 73 is more stable (less sweep) and has very limited dutch rolling tendency (provided the pilot understands what the rudder pedals are properly used for- see the above paragraph). Unfortunately, the 737 (all variants) still require the Yaw Damper to be reengaged with every IRS alignment.
So the rudder pedals aren't used to coordinate turns?
737 pilot's Dad speaking. Son says, "Just aileron inputs to turn, don't touch the rudder pedals" The yaw damper takes care of turn coordination. Pilot input upsets the precise coordination. Need the rudder for landing...
@@ianhart356 Thanks for explaining. Yet one more minor difference between a 737 and a sailplane, then. 😀
Thank you for sharing this.
@@j_taylor From FCOM Vol 2 "Either yaw damper is capable of providing dutch roll prevention, gust damping and turn coordination. Yaw damper operation does not result in rudder pedal movement. The pilot can override either main or standby yaw damper inputs using either the rudder pedals or trim inputs."
Thanks for the honorable mention of the C-141. I'm sure you remember the C-141A flew along in a tiny dutch roll movement and when the plane was lengthened (with air refueling added and designated a C-141B) that the slight dutch roll was eliminated with a new digital yaw damper. A more stable feel of the aircraft was a welcome change. Keep up your great analysis THANKS !
Juan, I watched your call of the STOL races at RENO (streamed online LIVE) and really enjoyed your work on that! It brought the excitement while making the races very approachable for someone like me who hadn't seen that type of racing before. Your fine work was understandably overshadowed by the tragic mid-air that same afternoon, but I wanted to let you know what a great job you did! They're lucky to have you.
Thanks!
It's really crazy that in 2024 cockpit voice recorders are just 2 hours and aren't archiving their data after flights are completed - is it a union thing?
I need to thank Juan for this one. I thought I was old until he mentioned if you're old enough to remember flying the C141. All the sudden I feel young again! Kudos Juan!! haha
Love the 30 day deadline for the preliminary report - as stuff like this can't wait 2 years to come out. Thank you NTSB for all you do.
for real, anything related to a Boeing quality concern should be a 2 week SLA.
@@Largecow_Moobeast Why would you have them stop investigating after two weeks? That sounds like a perfect setup to slow roll the investigation (sorry out sick) until your 2-week deadline arrives.
I just had to look it up: "Dutch Roll was the term used for skating repetitively to right and left on the outer edge of one's skates. By 1916, the term had been imported from skating to aeronautical engineering."
Proof that those punk skaters do become aeronautical engineers 😂
As a passenger in a 777 on climbout from Shanghai Pudong I experienced a dutch roll due to wake turbulence from a 747 ahead of us. It damped down quickly but left us passengers wondering until the flight deck informed us what had happened. It wasn't frightening but was certainly out of the ordinary and felt like an evasive maneuver.
Thanks Juan, have been waiting for you to explain this in the only way you can. Have a great time in Dayton.
Yet another excellent description of this event and the related A/C systems. Thanks Juan and keep up your wonderful support of the aviation community!
As a previous KC135 guy, I lived with Dutch roll, esp in the A model which didn’t have a dedicated yaw damper. When you lost the rudder axis on the autopilot, it became a, long flight crossing the Atlantic or Pacific. The R model incorporated a full time yaw damper which was a godsend. I’m kind of surprised this would happen on a modern day jet.
Pretty sure it shouldn't.
In your next video about this incident you might want to discuss recovery from Dutch Roll.
In the 2010’s I was flying a cargo DC-9-10 into hot, high elevation airports in Mexico. The -10 series had a short fuselage, no LE slats, and an anemic yaw damper system - all aggravating its wing’s known tendency to Dutch Roll. Training in recognition and recovery from Dutch Roll was absolutely necessary to fly that airplane - not so much now with the more modern airplanes. So, maybe a couple minutes on recognition and recovery would be good refresher for some viewers.
I’ve since immigrated to NZ and all my sailplane buddies here try to “tall poppy” me with comments like, you airline guys don’t know how to use the rudder….I just smile and chuckle every time I hear that old trope. 🤣
I think that's just a Kiwi thing. You can always tell a Kiwi but you can't tell them anything.
Ok, but unless i've missed something. They were referring to airline pilots. Not nationalities. It's banter between aviation people.
@@davidtaylor351 yes. My reply is just banter too, you supercilious prick 🤣
I wish I knew you were in Columbus! I worked on those KC-135’s you see on the ramp! I live close by and would have liked meeting you in person! Long time subscriber of your channel!
Spent 12 years on the C-141B as a maintainer.
Don't recall many Dutch roll issues as porpoising issues w AP engaged.
Thanks for using proper terms as well. So many would call it a yaw dampner, and it would drive me crazy.
Anyway. Really appreciate your posts. 👍✈️
My favorite bug when I was a flight sim tech on the 141’s, was to pop the yaw damper breaker when they started their decent.
You have a terrible sense of humor. But I bet you got their attention.
@@lisanadinebaker5179 it actually hard to figure out what’s going on, teaches them to fly the airplane while they run the procedures.
Former Crew Chief on a USAF KC-135 (59-1507) and experienced firsthand in the late 80s a Dutch roll on a TDY trip. Not a good feeling I must say. Subsequent local sorties pilots were experiencing the same on this particular jet. Boeing came up to Loring AFB (our home base) and started changing out parts. Aircraft was grounded for a while but eventually the Red X's were signed off and the jet flew again without anymore incidents. Crazy times. Kudos to the test pilots and Boeing engineers.
What was the cause?
@@ajs1691 I honestly don't know. The story around the flightline was Boeing changed out a lot of stuff over a month or so and then one day it no longer did Dutch Rolls. Yeah. I'm sure Boeing knew, but by that time i was transferred to another tail number 58-0093 and the jet in question 1507 went to Tinker for the R-mod conversion.
Amazing how you set down in a hotel room and prepare this. Complex technical subject in your precision language and I easily follow and understand.
Thanks!
Back when the 707 was fairly new, Brannif was taking delivery of a new aircraft . It was a test flight with Boeing test pilots, and Brannif pilots. The pilot flying the plane induced a Dutch roll which ended up tearing off the engines, and resulted in a catastrophic crash. Luckily only a few people died.
yes, there's a youtube video
You should add that the test pilot was fairly inexperienced and at that portion of the test, they had disabled the yaw damper (as a part of the test flight) which heightened the effects experienced.
I learn so much from Juan!
Glad the SWA flight landed without incident
From the pilot perspective, during dutch roll the nose inscribes a figure-8, usually in a very small area (plus or minus 5 degrees, dissipating if you stop fighting it if the aircraft has favorable dynamic stability characteristics, which most of them do - by law.
Once more Mr. Brown great information we have trusted for straightforward explanations to so many aviation difficulties these days.
After hearing this one on the news my first thought was the Yaw Damper and or rudder faults of previous 737 crashes and handling problems. Thanks for the ever-increasing roll you play in bringing these cases to ours and the aviation world's attention.
Little bit off topic, but we had an "uncommanded yaw motion" in the CRJ-200 once, which calls for basically turning off the yaw damper as I recall. Assuming the design is similar in less degrees of authority given to it, I suppose the pcu controlling it just went wacky? It certainly got our attention, felt like someone kicked the rudder to the floor while on climb out.
That must have been really frightening. Glad you knew how to disable the yaw damper in a hurry!
Hi Juan, thanks for the in-depth post and explanation. If anyone has ever seen or been in a larger aircraft while the pilot is getting aerial refueling training, you've seen or experienced dutch roll. During this evolution, the pilot often causes the dutch roll via a PIO or pilot induced oscillation while trying to stay in position behind the tanker. Remember that, Juan? Cheers!
I remember at least 20 years ago, experiencing an inflight upset which I now know to have been a "Dutch Roll", in a British Airways 737 on decent into Heathrow. As I recall, we only experienced a couple of oscillations, which never the less were quite disconcerting. The pilot later claimed that the disturbance, as he described it, had been due to wake turbulence. Unfortunately, there was no Blancolirio around at the time to dissect the incident!!
I've read in "Killer Rays" by Mark Frankel the old Douglas Skyray was also a notorious dutch roller in the groove.
Juan, it's funny that you correctly state it's a "damper, not a dampener. We're not trying to get things wet by dampening them". Then you you go on to say that it dampens the yaw. LOL, gotcha! It "damps" the yaw.
I’m so glad you were here in Columbus Ohio. I watch you all the time. I hope you liked the show.
As soon as you mentioned the trouble with the PCU, it reminded me if the three incidents in the 1990s with the 737’s, where the PCU caused two bad crashes and one incident with another plane, which was able to land safely.
Hi Juan, not much difference is shown in the rudder systems description in the FCOM between the Max and NG. The only change I see is that although on both types, rudder authority is reduced by 25% above approximately 135 knots (system works the same in the air and on ground), on the Max this limit is removed if it senses a difference in engine speeds (failure, shutdown etc.)
Thanks for explaining the dutch roll as evperienced on the 737 as compared to the training manuver I remember from my student pilot days!
The maneuver practiced by students is not really a "Dutch roll." In a true Dutch Roll the roll and yaw are out of phase: the plane is rolling one way, but yawing the opposite. By the time the plane's dynamic stability brings the yaw into line with the roll, the plane has already rolled back the other way, and the yaw is still contrary to roll.
In the practice maneuver the idea is to not let the nose move: it should remain fixed, i.e. NO yaw, while the plane rolls side to side. An uncoordinated turn is more akin to a Dutch Roll, in that initially yaw is opposite roll.
I used to have one RC Model that would Dutch Roll quite well. To enter the Dutch Roll, it would need to be climbing on 3/4 throttle with a high alpha, nose up configuration. Then any quick blip of the aileron would set it off on the Dutch Roll, and decrease the rate of climb. To exit the roll all that was needed was to release the back pressure on the stick, to push the nose back down. I always flew this with the model heading away from me, as I wanted to see the aircraft. The period of the oscillation was about once every two seconds, so no rudder control was attempted.
Welcome to CMH Juan. Glad you are in town. Enjoy the air show. I live in a suburb.
Dispatching in the Jurassic/Classics with the damper MEL’d in Summer was nauseating. We had a PCU adventure or two that took the factory to ground the aircraft till the tail units were changed out. Like today, it’s always on the QT.
Great analysis Juan! I have over 6 years and nearly 4K hours on the C-141. Every time I sit in a swivel chair it brings me back.
😂😂
10 years in the 737-800, I never had any of these issues, such a safe, nice flying machine. I miss it now that I am retired!
How is the -800 related to the -MAX8? I presume not at all. Same question regarding -900 and -MAX9?
“Dual concentric” rudder PCU design was found to be the probable cause of the two hull loss accidents (UA585, N999UA, 1991-03-03, Colorado Springs and US427, N513AU, 1994-09-08, Pittsburg). As a result, the PCU was completely redesigned (initially a modified dual concentric PCU, then a ground-up redesign) and a retrofit "Rudder System Enhancement Programme" was initiated, and then mandated under Airworthiness Directive 2000-22-02 R1.
All 737s in service today will have the new design fitted and there should be no in-service airframes with a dual-concentric PCU in operation.
What losses are you talking about the one in Pittsburgh was a servo valve that went past its stop and caused a rudder hard over.
@@mikemicksun6469 Yes. Added detail to my post.
@@mikemicksun6469 I thought the PIT loss was due to flying too low of an airspeed for the configuration and went below inflight minimum control speed. I'm probably wrong.
Great episode, Juan. I read those articles but never really understood what Dutch roll was (I’m not a pilot, obviously) This is why I always eagerly wait for your videos.
Thanks Juan. I was waiting for your input when I saw this on X this morning.
7:58 Rudder PCU's.
I remember that Air Crash Investigation episode,
Im still amazed how such a small device can move a 737 Rudder.
Hi Juan! I've followed you for sometime now but never posted a comment. Just wanted to thank you for everything you've taught me. Every episode is like being in a classroom. You have great clarity and objectivity and you really are a great teacher. Whenever an aviation incident occurs I don't watch or read any other media about it, I just wait for you to give us the facts. I also enjoy the Husky flights and the Dad time you share with us when your son is with you. Always look forward to your next post. Thanks again!
Hi Juan the content on this channel is great I,m no aviation expert just an enthusiast but flying back from Faro in Portugal last on a Jet 2 737 don’t know the model i could have swore the aircraft did the same mid flight only for about 60 seconds.
welcome to Columbus. great to see you at the airshow. what a performane by tne thunderbirds. thank you for explaining dutch roll . i always struggled with that
Juan, 11k hour NG/MAX driver here, unfortunately or fortunately depending on your perspective, I’m inclined to posit human error on this one. One of the pilots “stuffed” a rudder accidentally and either the YD was overwhelmed or they (the pilot) tried to override the YD to correct his/her misstep. Similar to loss of control of Lantam 787, with inadvertent seat movement. FWIW.
The usual explanations don't mention how the Dutch Roll gets started up at cruise. I'm very grateful for Brownie's mention of turbulence as one possible cause. Thanks for sharing another possible cause. Lucky that the plane was designed and assembled well enough that she was able to continue flying and land safely.
Did they lose altitude or declare an emergency and why would that cause damage to the PCU? If they knew why it happened why would they report it to the NTSB as a unknown cause?
Great explanation about why swept wings aggravate the problem!
Thank you, Juan. “Yaw damper,” not “yaw dampener.” I’ve been harping on that one for years.
Now we have to work on irregardless.
@@TheSaturnV Best double negative, a bumper sticker: If you aint a cowboy you aint sh*t.
Observed in Bakersfield Calif.
yeah, like turbIN not ine
If the shocks in your car leak, they become moisturizers. 😇
Hate to say this, but it does seem like our entire language has been going the way of Boeing's quality control. Many reasons I suppose, but a bit disappointing to see it all in one's own life-time.
Thanks for the very detailed explanation of how the system works, Juan!
I can get in flight WIFI for an entire flight across the pacific, but Flight recorders cant stream data in real time to a cloud for storage?
Airplanes do not develop extreme dutch roll if the yaw damper is working properly. Therefore there was either a malfunction or the yaw damper was not engaged. The damage nobody is talking about probably involves the vertical tail structure which can fail if the maneuver continues to get more severe (diverge) . The biggest risk is encountering turbulence at high altitudes above FL370. I suspect that the difficulty occurred above this altitude and the pilots were descending to aid in recovery as they are usually taught since pilot recovery is extremely difficult using manual flight control inputs. Yes, once upon a time C-141 pilots were demonstrated dutch roll during training. They however turned the yaw damper back on to recover and were not required to demonstrate proficiency in making a manual recovery.
Thank you for that very concise description of the Dutch Roll.
OK for @blancolirio or whoever can offer an informed answer this question: With in mind the fact that so many commercial planes are now connected to the internet, why don't the voice and data recorders simultaneously stream to the FAA or airline's HQ? In addition to redundancy (should the stream fail or the black boxes not be able to be found), this would make the info immediately available with full history except when there was a drop in the stream. This wouldn't replace the recorders, but it seems like a no brainer to have it in place for the reasons stated above.
The Air Force lost a KC-135 back in 2013 due to a Dutch Roll event. Got so bad part of the aircraft broke off. Investigation found insufficient training.
Shell 77
Pardon ?
*insufficient training to recognize a Dutch roll condition.
All three aircrew were all under 30. I was at Fairchild when the news broke that we lost them and it hit pretty hard.
I do wonder if it's more difficult to damp the oscillations with all that fuel sloshing around, adding extra inertia to the oscillations.
I was a crewchief on a KC-135R that arrived the day before and was parked beside the mishap jet. It was very sad and disturbing the next day when we found out what had happened.
SW had one on Wednesday 6.19.24 that had issues as for as being to low.
It was coming from Vegas to Oklahoma as well.
Used to practice the Dutch Roll on the B727 simulator. The maneuver was not practiced in the B747 or B777. Glad they recovered safely.
Split-rudders on the 747 and 772 make the issue manifest itself a bit differently ... but, then there is the chance that one of the rudders could hard-over...something that used to happen on -200B from time to time! Those were fun...😳
Great reporting Juan. I instantly thought of the hard over rudder losses with USAir and the United on final to COS. I’m more concerned with more Max mysteries. I think you mentioned that the primary PCU was not the failed unit. When Boeing was trying to certify the 707 in either Europe or the U.K. They required Boeing to add a boosted rudder. Look up American flight 1 in the early 60’s departing out of ISP (NY) bound for LAX.
So funny you brought up the C-141! I was a jumper on a C-141 Starlifter and we got the crazy figure 8 roll! By the time it was done I was extremely eager to jump out of the aircraft! I was young and it was scary!
Looking good, Juan. Haven’t watched you in awhile.😊
Re: "Boeing has lost our trust". A guy I was talking to once told me something one of his NCOs in the Army had told him: "Trust is like a drinking glass. If you break it, you might be able to glue it back together, but it will never be the same."
Starliner? Yeah NOPE.
Except, Airbus is out there grabbing their market share... By the time they regain the market trust, all the nice orders will be filled!
If it ain't Boeing, I ain't going.
@@agamemnon7461the only thing saving Boeing is that there’s such a massive backlog of narrow-body planes that airlines can’t simply switch to Airbus. It’s also why airlines haven’t cancelled 737MAX orders, because then they’d go to the back of the line for BOTH Boeing and Airbus.
Excellent report Juan! I retired from your airline almost 20 years ago and I'll admit it I have used damper and dampener interchangeable over the years I'm going to blame it on dyslexia.
At this point I wouldn’t even be surprised to find out that this is something Boeing has been aware of for while already.
@m.choudry4898oh they know for sure.
Ask any KC135 pilot about dutch roll or damaged PCUs. Its written in blood into our -1 (flight manual) due to SHELL77
Great report Juan. Very helpful but also a bit alarming. Those two fatal rudder hard over crashes were nothing short of horrific. No pilot on Earth wants to see a repeat of those nightmarish incidents. What could cause the secondary PCU to have sustained damage? Wasn't the yaw damper ON during flight to help prevent the roll in the first place?
Loved the 141 Starlifter! Flew on many...luckily none which got into a Dutch roll.
Total "Hull Loss" is a phrase you never want to hear :/
I remember one happened on approach to PIT, Pittsburgh.
Cant believe they recovered this one
Duh
It’s right up there with “Rapid Deconstruction” ie SpaceX jargon.
Or simply W/O for written off. Ugh
Retired C141 wing Stan/eval flight examiner pilot here and I also was a FCF pilot, so I am quite familiar. Great explanation.
Well done Juan. Great explanation. I hear your frustration over AI assisted news, not good!
Excellent & puzzling report Juan as usual! This happening at altitude is ominous to say the least, the USair outside of Pittsburgh PA as I recall passed through wake turbulence from the aircraft in front on approach. I'm hoping that this is solved quickly & reported correctly! Something initiated the rudder problem but what was it??
Keep up the good work. I love your videos. They are the most complete while easy to understand!