MD-87 Crash Houston UPDATE 9 Nov. Flight Controls
HTML-код
- Опубликовано: 8 ноя 2021
- LINKS: UPDATE NYSB PRELIMINAEY REPORT! www.ntsb.gov/investigations/P...
NTSB: www.ntsb.gov/investigations/A...
Just Planes: • Some Planes can POWERB...
Servo Tabs: • Servo Tab | Pilot Tuto...
Theme: "Weightless" www.arambedrosian.com
Patreon: www.patreon.com/user?u=529500...
PayPal: www.paypal.com/paypalme/juanb... 
Наука
Excellent video. A few more things to add here. The hyd power you mentioned for these elevators is designed to push the elevators down during a deep stall situations and can only be fully tested in flight. Also, for the viewers not savvy enough to comprehend this old reliable technology, the geared tab linkage shown on the video is connected to the tabs via a push rod that ran inside the elevators. Also, these elevators were statically balanced nose heavy, which is why when the airplane is parked, the elevators are full ANU.. This provided feedback on the yoke as airspeed built up during takeoff, fairing the elevators with the horz stab. The PF should have felt this feedback. No feedback, RTO..
The DC8 used the same identical system, (minus the stall had boosted system) but because of the size of the elevators, an elevator gust lock was installed, and operated from the cockpit by the FO. I spent many years of my life exclusively rigging flight controls on both DC9/MD80s, and all series of DC8s from -55s, thru -70s. Wonderful old school tech. Thank God for the rain in your area. Great show.
He mentions that the control tabs are hydraulically assisted, which is technically not true. The only hydraulic actuation of the pitch control moves the actual elevator, not the control tabs. And that hydraulic power is only activated in a deep-stall recovery.
@Zack Cawvey - Complicated? Nope. Quite simple. It uses aerodynamic forces to amplify and assist pilot applied forces, requiring no hydraulics whatsoever. You can control a 100,000+ aircraft with no electric or hydraulic systems, so works when those systems fail. The controls aren't much heavier than a C172. The only hydraulics in the pitch system is the powered elevator, but that system is virtually never used, except in a deep stall recovery, which has also almost never occurred in a DC-9 or derivatives. If you want complicated, then you want fly-by-wire. One nickname for the DC-9 is "direct cable", as in DC. Cables through pulleys to control tabs. Doesn't get any simpler.
damn good expert
Fully concur with your statement. As a retired senior engineer from McDonnell Douglas / Boeing, I would much rather fly on an MD 80 any day over a 737 for safety.
@@tomjoseph1444 Great additions to the systems discussion. I agree with the simplicity of the system. If you want to talk about possible paths of failures in today’s aircraft, think about tin whiskers.
Juan, Another excellent explanation. I currently fly a DC-9 30 series airplane as a contract pilot. On each flight, just prior to engine start, we do a jammed elevator check with a crew chief out in front to visual check the elevators when we push the yoke full forward. ( Altnernate and Aux hyd pumps on) pretty cheap insurance against trying to rotate with a jammed elevator. .
Thanks David!
I don't think that that proves that the elevator is not jammed down. The hydraulic power only pushes the elevator down when more than 10 degrees of tab are commanded. (20 year DC 9 Captain)
@@leeoldershaw956 ... Well, I suppose that if the elevator doesn't happen to be fully down already, the downward movement of the elevator when the hydraulic boost kicks in would be an indication that it is not jammed. If no movement happens, that would be an indication that is is either jammed or that it is already fully down, in which case (which would be exceptional) I suppose you can bring a ladder or a platform cart and move the elevator by hand (I have done that myself, I mean moving the elevator by hand, not bringing a ladder, the plane was in maintenance so it already had a platform at the tail).
It looks like in the case of gust loads that cause the balance (servo) tab linkage to go overcenter and jam the elevator, this occurs when the elevator is forced quickly down.
In this case, the hydraulic system elevator assist won’t show you anything since it’s function is to push the elevator down (where it’s already jammed).
For a contract flight crew, a very long pole with a cushion on the end used to physically push the elevator up is really the only assurance you have to know that the elevator is not jammed AND.
I'm a mechanic for an airline that flew one of the newer MDs of the v2500 variety. We had a crew that seemingly lost elevator control about 100 ft from the ground on landing. A quick thinking pilot threw the throttles forward to force a flare...the crew was pretty spooked.
We found that, what looks to be in your drawing "surface follow up link" but could be slightly different on this MD, has a piece of metal that touches the end of both the "follow up link" and the control output and it pivots about a bearing, 1 ea for left and right. This bearing on one of the sides was seizing and consequently binding the yoke and inducing a split, putting the plane also into manual reversion.
Haven't seen or heard of anything like that before or after but figured I'd share 🤙
Very Interesting Thanks for the information. I never worked on this style of DC9/MD80's mostly airbus and boeings I worked on. I am not sure about the 727 I do not think they have a different system.
Thank you for the info Juan. It’s fascinating. 🎸
Juan, I Live 2.15 miles south of the runway threshold at Houston executive. I have been following this crash closely. The day of the accident I recall walking out in the backyard and seeing the tower of smoke. I remember thinking I hope that wasn’t the airport. Conversations with members of the community and reports in local media indicate that this aircraft was too large to be hangered at the airport. The aircraft spent most of its time under the “World’s largest arrival canopy” exposed to the elements. In the weeks leading up to the incident we had several storms pass through that carried strong straight line winds. I do believe there is merit to the idea that the dampers were overstressed prior to the incident. Please keep up the good work and keep us informed.
Hasnt something almost exactly like this happened before? A storm came through and the gusty winds forced an actuator over-center or something?
Never flew any of the DC-9 variants, but did fly the DC-8 for about 3 years. We did an elevator check on the takeoff roll--the FO, regardless of who was flying the leg (the captain was guarding nose tiller) momentarily pushed forward on the yoke at 80 knots which resulted in the nose dropping, and verified proper elevator control. This was a result of the 1970 JFK TIA crash (11, all crew, onboard, no survivors). The investigation found that a piece of asphalt had lodged between the elevator and horizontal stabilizer, which jammed the elevator. Interestingly, other types do not use that procedure.
Yup, 20yrs of '80kt checks' on the Diesel-8 here. If this thing has the same system as the DC-8, then how,.....why,.....why would you take off without ensuring the elevator is functioning by simply pushing forward on the yoke? Bob the nose and press on or return to the ramp. The habit's so ingrained that I push on the wheel as my car accelerates through 80mph.
Very interesting. Thanks for the imput. I never worked on a DC9/MD80 style plane. Mostly Airbus and Boeing's. I cant really remember but I think the 727 has a different system and the Elevators operate by cable and control tab. By Hydraulic
I was involved in the crash investigation representing the Port Authority. A true case of something that the designers never thought about.
Well that 80 knot check is a bit more meaningful than what we do now!
@@kaveman9 Then what?
Still a miracle nobody perished! Thanks for the review
Juan: Local Houston TV stations are reporting that NTSB investigators have said that your theory is exacly right. The geared tab drives on both sides were found to be "overcentered" and bent and that both elevators were jammed in the trailing edge down position.
The amount of pro's in the comment sections is astounding. Mr Brown, you've got some audience helping out. Thank you!
This is similar to the rejected takeoff that happened at Jfk with a Chautauqua Airlines Erj-145 about 10 years ago. The plane had experienced strong gusty winds the night prior. The elevator is moved by mechanical cables and the controls are locked by a mechanical control lock in the cockpit. The winds had caused the cables to be jerked to the point that they had broken.
During the before takeoff control check, there was no indication that anything was abnormal. Thankfully the flight took off on the 14,000' runway, so the crew was able to stop on the runway after aborting above Vr with no losses.
That incident caused an AD to be issued by Embraer to retrofit all Erj-145s with electric gust locks that engage pins directly into the elevators to prevent stress on the control cables.
I remember picking up the empennage of a dc-9 off the runway at Edwards AFB. When it sheared upon landing during an emergency landing for FAA cert!
That landing had a vertical sink speed of about 16 fps vs the design limit of 15 fps, so they got their structural analysis about right : )
Thank you for the update, as an aircraft mechanic I'm always interested in what to potentially look out for. 👍👍👍👍👍❤🇺🇸
After your first video about this accident showing the tire skid marks on the departure end of the runway and grass up to the aircraft I asked a family friend (retired) who flew DC 9/ MD80s and he drew a similar conclusion .
I also watched Dan Gryders video where he stated this aircraft rotated..flew then crashed ...this is exactly why I watch your channel..a measured and well thought out analysis is better than a guess..thanks Juan for another informative video
Really good info for us low hour pilots
I didn't know about such elevator system in DC-9/MD-80s... The more I watch this video, the more I like my good old Boeing 737!
😀
I do miss however how these models went vertical on take off!
I can't imagine the feeling of pulling back on the yoke, expecting to climb, and getting NOTHING as you hurtle down the runway at 170 MPH! Can't be a good experience! Thank God everyone walked from this one. They all must've hit the ground running so to speak, thanks to a great crew.
Glad to see that rain gauge keep filling up lately! You guys needed a big break! Glad you finally got it.
Way better then pulling up in the air and nothing ....
I lost elevator on r/c plane it did a nice nose dive into the ground ,
@@cardboardboxification This is true!!
V1…Vr rotate…Houston, we have a problem! Brake!!! Nice job here!
Thank You for an excellent and technically informative video.
I worked for McDonnell Douglas when the last MD-87 rolled off the line. American Airlines brought it to St. Louis and parked it so we could All see it. The DC-9 MD 8O series were great airliners, for their time.
As a fellow nor-cal resident, your note about the rain makes me very happy.
Nor-cal is the only area of Cali that seems to be still sane. So beautiful, and good people. I hope to make my way west in a few years, Texas is old hat.
This rain is glorious!:-) 🖖
I've seen that blowback maneuver happen before. I used to work as a ground handler at my local airport, and the company I worked for had a contract with a courier service that flew 727s. Pilot had a brainfart and failed to stop when signaled to do so. Because of this lapse of judgement, they didn't have enough room to turn around to exit the ramp area we worked from, and there wasn't a tug able to get there to push him back. Out came the buckets and they backed up. My biggest takeaway was that I was glad I wasn't marshaling that night, and that my boss was. The argument between him, the aircrew, and my boss' boss was EPIC. But there were 15 of us ground handlers that saw the boss cross his wands and the plane kept rolling.
As always Juan, you are providing technical crash analysis in a very understandable manner. Great job! Carry on, Sir!👍👍👍🙂
In all my years of fascination with aircraft of all types, I never knew about tab-driven free-floating elevators. Very interesting!
I've heard of aircraft that were taxiing behind the mad dog calling ground or the tower to notify them that the elevator is broken on the aircraft in front of them because the 2 elevators did not align up
Marty you are everywhere ;) back to work you are so close!
Very similar to the DC8. There was a TIA DC8 crash at JFK caused by a jammed elevator in Sep 1970.
The ailerons are the same concept thru the entire dc9/ 80 fleet too. The only difference is there is a bus cable connecting the ailerons to help but a small control tab moves the control surface.
Same here!
Thanks for taking the time to show us the test videos- they’re really helpful for a simpleton like myself. Good work, JB 🤙🏼
Nice work! Those test clips, along with the jam comparison photos really tell the story. Will be interesting to see the final NTSB report.
Thank you, Juan, for your usual excellent analysis commentary on all A/C accidents! I was a US Navy pilot transitioning into an old Navy jet, the A-3D (all three dead in Navy slang) an aircraft similar to the Air Force B-66, except the AF models had retrofitted ejection seats. The Navy kept putting that safety feature off thinking they would all be retired (or crashed) and replaced by A-6 or AF-18s. I was doing a simulated engine out approach to a wave-off/go-around, added power on the port engine, pushed hard on the rudder pedal and broke the rod that actuated the upper part of the rudder. Loss of flight control, stall, leveled wings and rode it in. The Navy's fix was real simple---no single engine wave-offs. Which resulted in NO SINGLE ENGINE landings attempted, just bail out in the event of a single engine failure. Very bad airplane design.
Very detailed breakdown of the initial root cause. Very familiar with the MD80 from my years at AA. It had a lot of unique engineering. Thanks Juan and safe travels ✈️
Thanks for another great and informative video! On another note, I like your theme music so much that I purchased Aram Bedrosian's album.
So appreciated, with your pedigree and presentation skills these are the only analysis’ of air crashes that mean anything to me.👍
GREAT REPORT! "as usual" Thanks for all of your hard work and the "time" you give up to make this Channel a living classroom! If just ONE person learns and avoids an accident with the wealth of information you present to Aviation, it makes it all worth while!
Your videos are superb. Add in all the additional information from aircraft professionals in the comments, and you have the number one source for accurate news and analysis of aircraft incidents on the internet. What an incredible channel.
The DC-8 elevator control system was essentially the same as that on the -9. After a fatal accident with the -8 involving a jammed stab, an "elevator position indicator" was installed on the instrument panel. This allowed the pilots to check for actual movement of the elevators after esufficient airflow had been established over them to permit such, usually around 80kts. I'm surprised that; 1) the DC-9/MD-80 series of airplanes didn't get the same mod, and 2) that the airplane was ever certified in the first place without the crew having some positive method of assuring proper movement of the elevators prior to flight.
Juan, many thanks for clearing this up for us. I enjoy your debriefs about these incidents. You make clear and succinnct explanations which help us determine just what has happened. I have to say, you make these comments about previous incidents and the eventual reports that are made by the NTSB (when they actually attend these crash sites) but it seems that the FAA then either sit on their hands or otherwise do nothing about these incidents. Why was nothing apparently done about sorting out this cearly percived problem? It is the 737 Max, all over again!
Excellent update. I've been hoping that you would give us this latest information regarding this crash. Please, keep up your great work. Thank You
Excellent as always! Having maintained MD-80s for almost ten years, I've found this video fascinating!
Thanks for the updates.
So fortunate that only the plane was lost.
That rain in the background looks amazing!
Informative as usual. Happy you're getting the much needed weather.
Nice summary Juan. I'm a big MD80 fan. I knew the guy who designed the control tab for the B36. Great guy, rest his soul.
Absolutely incredible, thank you Juan for the clarification and education regarding the functionality of this system
Beyond an excellent video. You are amazing in describing accidents causes where all of us amateur airplane enthusiast understand . Always waiting for your reports on all aviation subjects and all other subjects you report. Thanks Juan.
Thanks for the info, JB. Best wishes from Australia.
Another excellent presentation, thank you Juan. BTW your explanation of the MD-80 elevator system is much better than mine ever was...and I spent eight years driving them!
Thanks for the update Juan this explains a lot but wont know for sure until the investigation is over great job Juan.
There was a similar accident at teterboro with a Challenger bizjet. The pilot pulled and the airplane did not rotate. The pilot rejected late, went through a border fence and into a warehouse. It turned out that the flight controls were fine. The airplane was loaded beyond its forward cg limit.
Great job Juan. As a "classic" DC-9 Captain (-10,-31,-51) it energized the grey cells to recall a lot. Your explanations are complete and understandable and I guess that is why we enjoy your videos so much. Keep up the good work.
This reminds me of a Trans States Airlines EMB-145 that had an undetected cracked torque tube, resulting in very little elevator authority. At Vr, the captain pulled back on the yoke and the nose came up extremely slowly on runway 19L at Dulles. There was concern that they wouldn't clear the trees at the far end of the very long runway. We were fortunate to have one of our finest captains at the controls. She remained cool and flew the airplane back to a landing using stabilizer trim. She should have received some kind of medal, but she never made a big deal about it and few people knew that it ever happened.
Incredible, thank you for sharing that. Frank was RIGHT! LoL
Besides those trees, another potential problem with the takeoff could have been tire failure as speed continued to increase without a liftoff.
When did this occur? Tried searching and couldn't find anything about this.
I worked on F/A-18 C & D aircraft years ago. If memory serves me correctly, our aircraft had feedback from all of the flight controls to indicate actual position. Not just the commanded position. I take it as many of the much larger commercial aircraft do not have this type of feedback system? While still performing preflight checks the pilot would always perform a “wipeout” to verify that all flight control surfaces were functional. The ground crew were watching as well for any abnormalities.
I haven’t been in the aviation world in almost 20 years aside from working on my part 107 for UAV lately. I was brought to your channel from “Practical Engineering” RUclips channel. And I have been binge watching your content ever since. Love the channel.
I want to add my compliments to the others here. You explained this in a manner that I can understand despite having no training at all in these matters. Thanks for another highly informative video.
Great video. The Bristol Brittania had the same tab operated elevators which required aerodynamic force to work. Modern jets have MFD display of control surface movement during preflight checks.
Very insightful. Appreciate the breakdown of the events.
Juan, this is by far the best video you've done since I've been watching the channel! I went from EMB120's direct to 737s and missed the DC9 series, so I found this just fascinating. I wonder if a better elevator lock system would have helped. Then again, taking off with a gust lock system (from an elevator you can't preflight inspect without an elevator [sic]) would result in same problem; a wrecked airplane at V1 failure.
Boy, stopping a 150k lb airliner that has all systems accelerating the aircraft must have been a bitch on a 7k ft runway. Sounds to me that quick-reaction captain should be awarded a presidential medal (but gotta wait for next one on that).
Finally, I'd like to see the storage history of this a/c. If it was in the hangar, what are the chances some physical damage occurred that either over-centered the dampers, or even bent the geared tab push rods? A little far fetched, but it was in that hanger for some time I hear. That is, in the hangar and out of the elements. Good one - thanks!
Thanks for the deep dive Brownie - great job!
Thanks for the update Juan. You are the best.
Very interesting Juan. Thanks for the detailed research. That test was pretty cool.
That just scared the crap out of me. I worked on md 83 and md 90s for about 7 years and never knew this was something that could happen . Not sure any of the certified guys knew either. Just WOW.
Keep up the great work.
Another great video Juan , you really explained that well and we appreciate you 👍🏾
Thank you for all the research and a great presentation, as always!
Our favorite part in your videos is now the Bloncolirio rain gauge update..... You are filled with so much information to share on all kinds of aviation happenings. My wife keeps asking me why you don't work for the NTSB.
That’s Gryder’s bailiwick. Juan’s more like our sgt. Joe Friday…”just the facts…”. Even has a fine looking LAPD Deetective’s fedora.
The hydraulic actuator on the elevator is for if the aircraft goes into a stall. If the pilot give a nose down command more than 10 degree push, the actuators will push the elevators to a full nose down command. During a stall, the elevators don't have enough air flow for the control tab to move the elevator so the actuator will assist the system. Pilots are to test the system before takeoff by pushing the stick nose down and look for the blue indicator light on the overhead panel.
Thanks, Kev. I kept thinking there had to be some way to test those flight surfaces aren't jammed up before takeoff - having to be at speed is not a happy way to do a test.
Juan, thanks again for a quick and clear “ probable cause”. Your explanation are clear and easy to understand for all.
Your channel and a selection of other knowledge aviators are bringing what we used to call Hangar Flying Knowledge to millions vs a few.
Your help is saving untold lives.
Keep it up.
Great job explaining.
Actually, if the elevator is jammed, it wouldn't let the pilot know. The blue light indicates the hydraulic actuator works but it may not push the elevator down. What he was showing of the other plane with the damage, it would never move. The only way someone could verify the jam is to watch the elevators while the test is done. We had to verify when the system was deferred because they didn't get the light. I know we had to do visuals on the plane that encountered high winds before. Never found any problems, I think the dampers did their job on slowing the control surface.
I flew the DC9 -32, and -15, on the UK register in the mid 80’s and early 90’s. My recollection is that following the Trident deep stall crash at Staines, the CAA required a hydraulic stick push system to the elevator, to permit recovery should the elevator airflow be blanked by the wings in a deep stall. ( non UK registered a/c did not have this ). Once the thrust levers were set for take off, the handling pilot would apply full forward control column, to activate the system, and if the stick push light did not illuminate, then the take off would be rejected. Later developments with the MD’s, I have no knowledge.
Juan, you are a pro.
There's no simpler way to put it.
Thanks for you great coverage of A/C accidents.
Excellent presentation!
Always great content.
So much great info in Blanco's videos AND the comment section!! Thx for sharing sir ^_^
Great report and analysis, Juan!
Good job explaining the elevator control on a DC-9. I thought the #1 engine puff of smoke may have been involved. We shall see! Thanks Juan
No it’s not!
@@paullewis6612 assuming the pilot recognized an elevator malfunction, the puff of smoke may have resulted from power adjustments when the decision to abort was made. just speculation, though. I don't have the expertise to know where in the video V1 and V2 would have been.
Great video, as always. Love the hat. Where could I tell the better half to look for one for Christmas? Stay safe and keep putting out awesome vids! Ever come thru KCLT?
Another informative video, thanks Juan. Must be a huge relief to have had some decent rain, hope the the winter brings plenty more of the wet stuff.
Excellent video. Thanks Juan!
Great stuff Juan, I learn so much from you!!
Another excellent report. I’ve got about 600 or so hours in the 208 but not under that engine. Spot on about feathering and I remember my training with my chief pilot at the time and that’s what he taught me
Another fantastic video. It's great that there was no loss of life in this incident. Even though it's an older airframe, if even one more plane can be saved by what they learn in this investigation, it will be a blessing to those souls on board, who may never know their lives were saved.
Keep it up Juan.
Once again Jaun, a very informith video. I really did not know that is how the DC-9/MD80's tail section works Now wonder Mechanics hated working on these beast. I am former A&P but never worked on a DC9 style plane.
Thanks for the detailed explanation Juan!!
Excellent analysis. Thoroughly interesting , thank you.
NTSB report out today. You nailed it.
Very interesting. Never knew about the elevator/horizontal stabilizer /tab workings on the DC9 (I'm 68 and a pilot). Great work
Thank You for the detailed write up. Amazed such a serious undetectable flaw was never had a mandatory AD against it.
Wonder how many of these issues were picked up during an inspection but never resulted in a accident.
Appreciate this great update. Thank you.
Juan excellent informative commentary! 👏
Thanks for this well documented in-depth explanation of a possible cause. I'm looking forward to the NTSB report to come out so that DTSB can step in and provide the probable cause.
Excellent debriefing Juan.
Nice report. Thank you. Still raining up the road here in Alta.
Thanks Juan. Always a pleasure.🇬🇧
Wow great job finding those load testing videos.
Great video, Juan - well done.
This report and explanation has got to be your Top 3 all time best video ever. Thanks for going the extra mile on this accident.
Which brings up the idea. Is there a better system to setup by the FAA & NTSB to get these findings out quicker than the standard Preliminary Report and Final Investigation 3 years later?
The AD's and Service Bulletins are usually sent to Owner/Operators. The AP Mechanic complies at annual or during FAA Part 121 progressive inspections on Commercial Aircraft.
We as pilots need a quicker system to lookup a specific model or type and related reports. The NTSB Accident/Incident Monthly reports are a great source for pilots but is a database which is not widely used by most pilots. For me it's a great source to read and understand other Pilot Errors that may occur in my everyday flying.
Why not design a system made exclusively for pilots to simply type the Aircraft Tail Number or Serial Number to pull up history.
Thank you so much for explaining how this system works. I crewed B-52Ds which had a similar tab-driven flight control system. I always wondered if the jet was being damaged listening and watching the ailerons and elevators banging up and down in the wind. I guess it was a little more robust in structure, plus it had hydraulically operated spoilers for help in roll control. The later G and H models did away with ailerons all together.
Great reporting as always.
Another great video Juan .
Great research, great explanation. Thank you.
Excellent demonstration!!!...thank you!!👍👍😎
Thanks Juan great explanation
Excellent work! Thanks 👍
Excellent report, as always.
Thank you for the informed update.
I remember taking off from Philadelphia in a DC nine backed up from the terminal with the reverse thrusters. I had never seen a DC nine do that at O’Hare! Something about breaking windows
Excellent technical discussion. Great to hear about the rain! And where can I buy that hat?
Great detailed report Juan…
Ya, Good rain and snow. We are in the southern part still holding our breath. We need to gain moisture in southern California and snow in our local mountains. It is still a relief that the northwest of the United States is getting the needed moisture! Nice also to have you explain with a good insight on the MD 87 overrun/crash as to what is needed to be looked for and into about the runway excursion... So thank goodness no one was killed or had a major injury in this crash!
Very Interesting Juan. Thanks for the technical explanation.
Excellent video, thank you!
Juan, You might want to consider adding another rain gage to your deck railing. The "Stratus Precision Rain Gauge with Mounting Bracket" , available from Amazon, is what professional weather monitors use. It is very easy to read to 1/100 of an inch and can hold up to 11" .
Thanks Juan, safe flights sir!