It should be obvious that your channel is not intended for the lowest common denominator. Thank you for helping those with a curious mind be, well curious.
Thanks! But it might be remembered that "should be obvious" is one of those phrases like "common sense". Oh, I get it from all quarters... but your comment helps me keep on.
@@AgentJayZ It should be remembered also that for any course of study there are prerequisites- stuff you have to understand prior. Else be "lost in space."
Back in the late 60's while stationed in Germany working on RF4C's /J79's had several flame out's reported by pilots at different altitudes. Couldn't duplicate on trim pad until it was determined the rear seat throttle was not rigged properly. Back seat pilot while operating the engine was unintentionally shutting down the engine. "Not a flame out for sure but scary for pilots" Fortunately all returned to base . The good part of this story, that I hadn't thought about for many years, was all the run up time on trim pad trouble shooting a non Flame Out Situation. Best of memories working on RF4C's and J79-17's. Great Video's Thank You
I appreciate the explanation of this in great detail. I remember learning about how to recover from flameouts and relight when I was going through the documentation of the F-8 Crusader. According to the flight manual, the most common causes of a flameout are by flying at an excessive angle of attack at either a very low speed or at a very high altitude. Doing this can cause the compressor to stall, which can be extremely violent feeling alongside potentially the sound of a loud bang, followed by a flameout. On the J57 used by the F-8 the restart RPM range is 17% - 30%
@@AgentJayZ Please note I did not fly the F-8, but am extremely knowledgeable on the majority of it's flight and development aspects having done extensive research on it. The US Navy is actually extremely detailed on aircraft characteristics in their flight manuals
Thankfully on most modern airliners, FADEC will attempt an auto-relight when N2 falls below a specific threshold. Us lazy pilots can't react fast enough to throw on the ignitors that quick. If the N2 falls too low for an auto relight, then we'll look at the QRH for the appropriate restart procedure. Thanks again for all your insight, love your videos!
I'm the sort of pilot that leave their engine on the ground when they launch. Still I love your content and learning stuff I will never need and watch you assemble stuff that I would likely break on first touch. Thank you for inviting us to your shop!
On several airliners including the 737 series, there is a "continuous" setting on the ignition switches which is typically used on takeoff/landing as well as operation through rain, presumably for the reason you mentioned about having to catch a flameout quickly.
That is standard operating procedure on practically all gas turbine propulsion engines when operating in visible moisture, a wet runway, or heavy turbulence. It is in the aircraft flight manual. I have seen it save a TPE-331 engine from flameout when it ingested a chunk of ice that built up on the inlet lip due to failure of anti-ice on that engine. The chunk was no issue until descending into warmer air, loosening it from the lip. Aside from worrying about the outcome and being focused on watching the slow motion trainwreck in progress, nothing really changed. We knew what was coming and wondered if the compressor would be damaged enough to lose the engine. It was on an SA-227 and we could see the lip and the compressor inducer but when it broke loose we saw the cloud of powdered ice but didn't notice any instrumentation indication other than a very short dip in torque. That tells me the relight was almost instantaneous. The inducer was slightly damaged and had to be replaced but otherwise had no noticeable impact on performance.
As a young tech in the CAF my 1st posting to Cold Lake was during the early years of the CF5 Freedom Fighter. I did much of my OJT (On the Job Training) on that type. For some reason flameouts on CF5's were quite common, good thing it's a dual engine bird as it gives the pilot time to relight while the other engine keeps him flying. Seems like at least weekly we'd have a 1 bell alarm which meant inflight emergency, usually a CF5 with a flameout. IIRC it may have something to do with them hanging an afterburner on the J85. Or the fact the duals were used in training not only our own fighter pilots but also those from other NATO countries like Dutch & Norwegian. No doubt that training included single engine flying & other emergency procedures which a rookie might pooch causing a flameout. Don't recall many double flameouts & few accidents as most relights were successful or if not the pilot was able to return to base with single engine. There was at least one double flameout where the crew was unable to get a relight & decided to eject which they did safely. Don't recall the details exactly, the engines might have still run at idle because it kept gliding along until it landed itself on a frozen lake. I believe they recovered & rebuilt it! I'm sure that accident will be well documented in one of the Flight Comment magazines. One of the pilots was Jock MacKay who was our OC at Base Flight when I was there. We had Pinocchio, DC3 with CF104 radar grafted to the nose which he flew regularly. Also T-33's & a couple CH-135 Twin Hueys. The venerable J85 continues to power our amazing Snowbirds & their Tutors, no afterburner though. The J79 in the CF-104 hardly ever seemed to flameout, the common cause being bird strike or as in one case a 20 mm round from the Vulcan cannon being ingested by the aircraft that fired it after ricochet off the target, exciting low level strafing..... The pilot ejected safely & the investigation confirmed the cause finding blue paint from the inert projectile on damaged compressor blades.
friend of mine was a flight engineer on a SAR c-130. In his re-cert the instructor gave him a 4 engine, and primary electrical failure over a city. his answer was to have the pilot mut max pitch on one engine, push the nose down. he then re opened fuel the the engine and fire the igniters with what little power was left. he then ised the engine generator to restart the other 3 engines.
Nice that you feature a Sabre Orenda power plant for this session. My Dad was an Airframe Tech (RCAF) on them during the Cold War, fond memories. He was fortunate to be part of a number of the teams winning the Guynemer Air Gunnery trophy. You might find a search on that interesting. The Canadians won the trophy a number of years running. Top Guns back in the day. ;) Couldn't help but notice the BMW GS in the background.... Yours? I own a couple boxers myself, including a 1981 R80G/S. I purchased it new on my 1st tour to Germany with the Canadian Forces. Still own the old girl. Added a cruiser, R1200C decades later.
The guys like Mentour pilot have videos on this. The issue is usually feed valves from the various tanks. It seems they are manually operated at the tank, so your screwed if this is the issue anyhow.
The TF-30's were reasonably high-tech for their day but they were a bit bothersome in that you couldn't rapidly change the throttle without risking flameout. That was a reasonably common occurrence in the Tomcats. When they upgraded to the GE F110 engines, those had no such throttle restrictions and the Tomcat really began to become the fighter/interceptor that it was really meant to be. However at low airspeed and in burner, you could create really bad adverse yaw if you had flameout or had a burner blow out, and that could very easily be unrecoverable.
If I remember correctly the TF-30 was also fairly sensitive to angle of attack. Combine that with the throttle sensitivity issue and you have an absolute nightmare for a carrier-based aircraft that may need to go from near idle power to full blowers to abort a landing. The wide spread of the Tomcat's engines only exacerbates the yaw issue during a low-speed flameout, it's no wonder they switched to the F110 as soon as they could.
Windmilling restart is a thing in airliners. You need to go pretty fast, but e. g. the the A330 has a procedure for it under "All Engine Flameout", It lists an optimal windmilling restart speed of 300 knots indicated, or Mach 0.82, but it's possible. Above 25,000 feet windmilling restart is the only option, as the APU can only be started below that altitude. Pitch angle for 300 knots is, according to the manual, roughly 2 degrees nose down. Which sounds like little, but is actually quite unusual in an airliner.
@@Kalimerakis Flaps increase the effective angle of attack of the wings, meaning you actually fly with a lower pitch angle than with retracted flaps at the same speed. On final approach the main reason for the higher pitch angle is really the low speed. But you are right, most jet airliners fly the approach slightly nose-high.
A&P here. The first gig I had was on FedEx C-208's. Had the PT-6/114A. They had a FCU emergency bypass (I think that is what it was called....it has been a long tim...but was absolutely a bypass, there was only one FCU). It was basically a separate throttle control held in idle by break away wire. If that wire was broken, we would have to do a bunch of checks. Never had that issue though. Honestly, I have no idea how it worked. Would be interesting to see if you had a PT-6 in the shop...unless that was just a specialty FedEx addition.
One good example of an engine flame-out in Hollywood is from Behind Enemy Lines. He didn't reduce throttle to eliminate the fuel vapor stream exiting the engine 😬
I read in some book about a Mirage III pilot who had an engine flamout doing some maneuver with a high G load. Perhaps in older fighters this could be an extra factor to be taken care of during the flight. Or perhaps these older jet engines were more sensitive to changes in intake airflow.
I was in an Airbus that had a flame out. A few minutes after takeoff the right engine flamed out and the entire plane very quickly yawed noticeably. Moments later the entire right side of the plane had a huge red flash and what I assume was all of this fuel reigniting as the engine restarted. The pilots must’ve been pretty busy because they didn’t say anything for several minutes. When they got on the intercom they said they were talking to maintenance on the ground and deciding if we were going to go back home or continue on the trip. Everything must have checked out OK because about 10 minutes later he got back on and said that we would be continuing on our way across the country. At first he said the passengers flying on the second leg of the trip would continue in this same plane as scheduled but when we got to the gate he made the announcement that they would be switching aircraft so I assume whatever had happened warranted getting an inspection or maintenance done on the engine. Very memorable. I believe it was a bird strikes that caused it.
May I suggest an alternate definition of the term "flameout". One of my powerplant instructors in A&P school stated that the only reason the hot gases move to the aft or exhaust end of the engine is due to the fact that the airflow from the compressor is pushing it that way. If at any time that airflow is disrupted, the flame in the combustor may now be at a higher pressure than the air in the compressor. This would result in the hot gases and flame to leave the combustor and travel through the compressor. Hence a true "flameout" where there is fire outside of the combustor.
A lot of people would call that a surge, resulting from a compressor stall. What I am calling a flameout is when the flame goes out. The combustion process stops and there is an instant loss of power. Sometimes this can be caused by a compressor stall, but there are other causes.
What you describe is usually referred to as a "surge". A compressor stall almost always results in a surge, often with actual flames coming out the front of the engine, accompanied by a loud bang, but a "simple" flameout (when the flame goes out) is usually due to fuel starvation.
A lot of people, including me and everyone I worked with at R-R, would call that a surge. A stall condition in a compressor can often result in an engine surging, with a loud bang and flames coming out of the intake, as the flow through the compressor breaks down and suddenly reverses. However, this does not necessarily result in a flameout: the engine can surge repeatedly until it is shut down or the stall condition clears. I distinctly recall being at JFK many years ago, waiting for my flight back to LHR. During one take-off, an engine (of a DC-10?) surged three times: the very loud bangs could clearly be heard across the airport and inside the terminal building. A classic incident of repeated engine surges, following a bird strike, can be viewed elsewhere on RUclips. Check out 'Thomsonfly 757 bird strike'. The incident happened at Manchester (England), back in 2007. The pilot called a Mayday (very calmly) and came back in for an emergency landing.
why turbine jet engines suffer flame out when the fuel supply is reduced too quickly? assume all components are all in optimal condition. would it relates to something like minimum fuel mass flow rate requirement at the RPM at that instance? for self-sustain
Uh, they don't. One of the things we test and set up after an engine has been overhauled is specifically the throttle response in decreasing the power to idle. If the engine shuts off with a one second throttle movement from max to idle... we adjust the fuel control and test it again, until it doesn't do that. No matter what the pilot does with the throttle, the main fuel control is the one in control of the fuel.
@@AgentJayZ Thanks for your informative and practical response. I understand the whole system including the operator or pilot would try their best to prevent this from happening. But I probably didn't express my original question clearly. I was trying to know in very theoretical or simplified ideal condition, when the fuel supply is reduced, would it cause flame out , if the answer is yes, what could be the possible reason (Refers to the actual fuel fed into the chamber is quickly truly reduced, regardless any other linked control systems) I appreciate if you could give some thoughts. : )
I gave you the answer. After overhaul the engine is tested for proper function before being accepted as serviceable for aircraft use. A very important step in that setup is ensuring that a rapid reduction from full power to idle by the pilot does not cause flameout. We do that with mechanical adjustments to the fuel control so that, whatever the pilot does, he can not shut off the fuel. Unless he decides to purposely command the engine to stop. This involves moving the throttle lever around a large positive gate... going from ground idle to shutdown. The pilot would never chose ground idle while in the air, as there is a higher detent at what is called flight idle. From flight idle to any significant thrust is 2-3 seconds. From ground idle it will take over ten seconds to start making any real thrust. To deliberately select fuel cutoff in flight is an option I guess, but it's like putting your car in Park while driving down the freeway. Your phrase "regardless of any other linked fuel system" is a fantasy "what if", it's completely meaningless and impossible. The pilots are very skilled, like a race car driver or MotoGP rider, and when they want idle, they select idle. If they really want to select ground idle... they can do that, and they understand the risks they are taking. If they really want to shut down the engine in flight, they can do that, but it is almost impossible to do that by accident. See a recent Blancolirio video for a case of the almost impossible possibly happening.
Hey JayZ. Great video! Saravanamuttoo (2017) says that compressor surge appears due to incidence, causing a drop in pressure at point 1, while point 2 doesnt decreases fast enought, what causes a back flow (point 2 -> point 1). Aungier (2000) says that a longer intake lenght can let the air rearrange itself, decreasing the incidence effect. With that, i have some doubts.. 1)One of the reasons we dont see high incidence in airline jets its because its engines doesnt has enough intake lenght to withstand high incidence? 2)The purpose of inlet guide vanes is to allow high flow velocities because without it, relative velocity would be high, leading to high relative mach numbers. But, can inlet guide vanes prevent compressor surge too? Its really hard to find papers about intakes. Can you talk about it?
Yes you can. Most APUs cannot be used at cruise lvl and will require the aircraft to descend before starting. This is also the same for relighting an engine in flight.
In a multi engine jet, usually there's an ability to use bleed air from one engine to engage the starter on the other engine. On those, things get really scary when all the engines flameout. How do you know if you can use this option? It's actually easy. The manual will describe using cross-bleed air to start another engine once one engine is running and you've disconnected the start cart. If there's no section in the manual describing this, you probably can't use bleed air to restart an engine.
Yes it can, from the two sources of power the APU makes. A typical airliner engine will be fitted with an air turbine starter - literally a small compressed air powered turbine bolted to a driveshaft turning the core of the engine. These are used because they make way more power for their size and weight than electric motors, and can be kept spun up for as long as you need, provided you have the compressed air supply to drive them. Whereas an electric starter motor can only be run for a limited time before its windings overheat, and if that happens you may need to wait for up to an hour for them to cool down before you try again, which obviously isn't ideal. Some early turbojets did use electric starters - the dome shaped section sticking out of the front of the engines on a B47 bomber (as an example) are aerodynamic fairings covering the starter motors, which are bolted to the front of each engine. Anyway, the APU is often the same model of small gas turbine engine as is used in ground power "start carts" - they usually have far larger compressor stages than they need to run themselves, so bleed air from the engines own compressor is the source of the compressed air they make. The APU will also drive a couple of electrical generators, one to make 28 volts DC and another to make 115 volts, 400 Hz AC for the two electrical buses on the aircraft. Older aircraft may only have the low voltage DC system, but most modern airliners have both. The APU might also drive some auxiliary hydraulic pumps to maintain hydraulic pressure for control surfaces and raising/lowering the landing gear, in case the main engines cannot be restarted. To start the main engine needs compressed air and electrical power to run the igniters in the engine combustion chambers. The APU can supply both - there will be compressed air lines running between the APU and every other engine on the aircraft, as well as cross-feed compressed air lines between the engines. So if you can get one of the main engines started using air from the APU, that engine will most likely then take over starting duties for the other engines, since each engine will also have bleed-air ports on its own compressor stage to supply air for starting any of the other engines. The other purpose of the bleed-air ports on the engines is to supply air for cabin pressurisation, though this usually goes through a heat exchanger to cool it first since the compressed air from the engines (or from the APU) would otherwise be far too hot to pump straight into the cabin. On much older aircraft with piston engines, the cabin pressurisation air came from the turbochargers or superchargers on the engines, since these are still just compressors.
OK question. You mentioned compresser rpm and engine rpm Can you tell me the difference between compressor RPM and engine RPM or are they both the same thing?
In a single shaft engine, the compressor and the turbine are on the same shaft. If they are not turning the exact same speed... well, we have some really big problems...
One rare reason for an engine flameout occurred in 1982 to British Airways Flight 009. In the middle of the night on the London to Aukland NZ route (with various stops along the way) 009 flew into a volcanic ash-cloud. Aside from spectacular electrical discharge effects and sand-blasting to the exterior of the airplane, the volcanic particles played havoc in the engine hot section where the silicate (i.e. glass) based material melted in the combustor section, then solidified in the HP and LP turbine sections. All four engines flamed out. Steadily losing altitude, the pilots made plans to ditch at sea. After losing some 25,000 feet of altitude, were able to restart all four engines (only three would continued ops), and limped to Jakarta for an emergency landing. I must believe British Airways made a change of fresh underwear available to the passengers.
And during all that the Captain found the time to reassure the passengers in classic British fashion: "Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them going again. I trust you are not in too much distress."
The BA009 event has been discussed more than once on this channel and I've added my comments in the past, because I saw some of the components from one of the engines laid out at Derby, some weeks later.
@@grahamj9101Are you the same Graham that used to perform design work with RR? I've always stated that your input on the channel discussion threads was invaluable. I used to hang-out here under user name Jangle2007.....until youtube insisted on a new name. During the past several years my attention has been drawn outside youtube to deal with work and family related matters, so I imagine I've missed a lot of AgentJayZ critical content and context. On point, I've seen poor quality images of used turbine parts after getting worked by volcanic ash. I couldn't make heads or tales of it. I must believe that volcanic ash is highly destructive to metal parts, especially those that rotate at high speed?
It has happened of 2 other instances since then. In 1989 A KLM 747 was approaching Anchorage International and flew in to volcanic ash cloud from Redoubt. Lost all 4 engines and was able to get 2 restarted after falling from FL250 to 13-thousand to regain control before getting the remaining 2 relit. This event was the impetus of the creation of the Alaska Aviation Weather Unit and Anchorage Volcanic Ash Advisory Center which I work for. We are one of only 9 VAACs in the world. Just when you think you're done hearing this given the danger it happened AGAIN THIS YEAR! A well advertised/warned volcanic ash cloud from the Russian volcano Bezymianny erupted to over 40 thousand feet and rapidly drifted into US airspace. Despite a controller asking a 747 cargo crew if they wanted a reroute they declined and maintained course, literally Leroy Jenkins-ing it into the cloud. I don't know every detail but my understanding is at least 3 of the 4 engines overheated and the plane Pan-panned into Anchorage without the degree of damage from the BA or KLM incidents. Truly a FAFO moment. Doubt that captain flys for that airline anymore.
The blades in an axial flow compressor are miniature wings. In both cases, stall is when the airflow separates from the wing, typically on the trailing edge of the low-pressure face (top of the wing or "backside" of the blade). When this happens, the higher pressure air from the other side curls around to fill the vacuum instead of going where it's supposed to. The wing keeps moving, but loses lift and drops. The compressor loses pressure gain from the stalled stage and the airflow becomes abnormally turbulent, possibly propagating the stall to successive stages.
Skip: yes they do. When an aircraft flies slowly, and does not reduce angle of attack of the wing, it will stall. The wing stops producing lift, and it will fall out of the sky.
Although the latter may lead to the former, e. g. if the autopilot tries to maintain altitude with the engines out, it will fly it right into the stall. At which point the autopilot will disconnect and dump the plane, which has departed controlled flight, into the laps of the pilots.
Hello Sir, I hope you're doing well. As I watched your videos during my study as an aircraft engineer, and I am interested in joining your team, is there any chance I can contact you, Sir
Gas turbine (and Diesel) engines always run "lean". There's an excess of air which brings the flame temperature, say 3500 f, down to something the metal engine parts can handle. More fuel means the flame is larger in comparison to the amount of air going through which increases temperatures.
A turbojet is quite different from a piston engine. From the viewpoint of a turbine engine, 2-strokes and 4-strokes are exactly the same, with no differences in what they do or how they do it. Fuel type also does not matter. A Sabre Jet, a Starfighter, and an F-35 can burn heating oil, diesel, Jet A, 87 octane pump gas, Race gas, 100LL avgas, ethanol, methanol, and pure nitromethane just fine, with no adjustments needed to anything.
I turned up the maximum fuel adjustment on my injector pump on my 80 series diesel too high and melted the piston tops and I cracked a piston due to the excessively high combustion temperature which showed up as higher EGT. I didn't back off in time. So same for kerosene. expensive lesson.
Does having a two-stroke engine stop on a RC airplane count as a flameout? If so, I've experienced many flameouts. I was able to safely land the airplane each time (landing in a lake is still a safe landing right?). One of my RC airplanes had an onboard starter. I would occasionally kill the engine while in the air just so I could restart the motor airborne. People observing were very surprised to hear the motor die and then restart. Thanks for another interesting video AgentJayZ.
If you run out of fuel in mid air. Either it leaked out or some idiot did not understand the kg/lb conversion and under filled the fuel tanks. You will get a flame out.😂
Well, shutting off the fuel is the most common cause, but when I say flameout, I am talking about the combustion process stopping even though their is fuel flowing. The only time fuel starvation happens when the throttle is not at idle is when the aircraft actually runs out of fuel. I'm not really talking about that case here either. Both the examples I give that happened in our test cell were caused by accidentally shutting the fuel off. The flameout I have in mind during this discussion happens in flight, when there is plenty of fuel in the tanks, and the throttle is set to anything between flight idle (84% rpm) and takeoff power (105% rpm).
In Soviet era jets, there is a rocket stove connected to the top combustion chamber for cockpit heat. Easy for the pilot to simply add cigarette butt and vodkas to relite. Russians are so practical.
We're talking about a movie, and the story was based on the engine having a compressor stall and flaming out. It should have been possible to fly on one engine, but hollywood.... I'm not kidding, but expecting Top Gun to have technical accuracy makes you the joke here.
@@AgentJayZ The A model of F-14 Top Gun use TF30 notoriously prone to flame out caused by inlet airflow disturbance i.e. in high alpha maneuver, or sudden throttle command. F-14 is capable to fly and land on one engine, but because of the spaced engine it will cause significant yaw on flameout. This yaw have caused loss of airframe combined with low altitude and low recovery time.
So now we've moved from once in a million to once in a billion. Outside the scope, man. Next step: is the world just a dust speck... Horton hears a who...
It should be obvious that your channel is not intended for the lowest common denominator. Thank you for helping those with a curious mind be, well curious.
Thanks!
But it might be remembered that "should be obvious" is one of those phrases like "common sense".
Oh, I get it from all quarters... but your comment helps me keep on.
@@AgentJayZ It should be remembered also that for any course of study there are prerequisites- stuff you have to understand prior. Else be "lost in space."
Back in the late 60's while stationed in Germany working on RF4C's /J79's had several flame out's reported by pilots at different altitudes. Couldn't duplicate on trim pad until it was determined the rear seat throttle was not rigged properly. Back seat pilot while operating the engine was unintentionally shutting down the engine. "Not a flame out for sure but scary for pilots" Fortunately all returned to base . The good part of this story, that I hadn't thought about for many years, was all the run up time on trim pad trouble shooting a non Flame Out Situation. Best of memories working on RF4C's and J79-17's.
Great Video's Thank You
I appreciate the explanation of this in great detail. I remember learning about how to recover from flameouts and relight when I was going through the documentation of the F-8 Crusader. According to the flight manual, the most common causes of a flameout are by flying at an excessive angle of attack at either a very low speed or at a very high altitude. Doing this can cause the compressor to stall, which can be extremely violent feeling alongside potentially the sound of a loud bang, followed by a flameout. On the J57 used by the F-8 the restart RPM range is 17% - 30%
Thanks for this. Always good to hear from people who were there.
@@AgentJayZ Please note I did not fly the F-8, but am extremely knowledgeable on the majority of it's flight and development aspects having done extensive research on it. The US Navy is actually extremely detailed on aircraft characteristics in their flight manuals
Thankfully on most modern airliners, FADEC will attempt an auto-relight when N2 falls below a specific threshold. Us lazy pilots can't react fast enough to throw on the ignitors that quick. If the N2 falls too low for an auto relight, then we'll look at the QRH for the appropriate restart procedure. Thanks again for all your insight, love your videos!
I'm the sort of pilot that leave their engine on the ground when they launch. Still I love your content and learning stuff I will never need and watch you assemble stuff that I would likely break on first touch.
Thank you for inviting us to your shop!
On several airliners including the 737 series, there is a "continuous" setting on the ignition switches which is typically used on takeoff/landing as well as operation through rain, presumably for the reason you mentioned about having to catch a flameout quickly.
Thanks for this info from the cockpit.
I remember learning about this from TACA Flight 110 - flameout due to rain and hail ingestion and incredible emergency landing beside a river
That is standard operating procedure on practically all gas turbine propulsion engines when operating in visible moisture, a wet runway, or heavy turbulence. It is in the aircraft flight manual. I have seen it save a TPE-331 engine from flameout when it ingested a chunk of ice that built up on the inlet lip due to failure of anti-ice on that engine. The chunk was no issue until descending into warmer air, loosening it from the lip. Aside from worrying about the outcome and being focused on watching the slow motion trainwreck in progress, nothing really changed. We knew what was coming and wondered if the compressor would be damaged enough to lose the engine. It was on an SA-227 and we could see the lip and the compressor inducer but when it broke loose we saw the cloud of powdered ice but didn't notice any instrumentation indication other than a very short dip in torque. That tells me the relight was almost instantaneous. The inducer was slightly damaged and had to be replaced but otherwise had no noticeable impact on performance.
As a young tech in the CAF my 1st posting to Cold Lake was during the early years of the CF5 Freedom Fighter. I did much of my OJT (On the Job Training) on that type. For some reason flameouts on CF5's were quite common, good thing it's a dual engine bird as it gives the pilot time to relight while the other engine keeps him flying. Seems like at least weekly we'd have a 1 bell alarm which meant inflight emergency, usually a CF5 with a flameout. IIRC it may have something to do with them hanging an afterburner on the J85. Or the fact the duals were used in training not only our own fighter pilots but also those from other NATO countries like Dutch & Norwegian. No doubt that training included single engine flying & other emergency procedures which a rookie might pooch causing a flameout. Don't recall many double flameouts & few accidents as most relights were successful or if not the pilot was able to return to base with single engine. There was at least one double flameout where the crew was unable to get a relight & decided to eject which they did safely. Don't recall the details exactly, the engines might have still run at idle because it kept gliding along until it landed itself on a frozen lake. I believe they recovered & rebuilt it! I'm sure that accident will be well documented in one of the Flight Comment magazines. One of the pilots was Jock MacKay who was our OC at Base Flight when I was there. We had Pinocchio, DC3 with CF104 radar grafted to the nose which he flew regularly. Also T-33's & a couple CH-135 Twin Hueys. The venerable J85 continues to power our amazing Snowbirds & their Tutors, no afterburner though.
The J79 in the CF-104 hardly ever seemed to flameout, the common cause being bird strike or as in one case a 20 mm round from the Vulcan cannon being ingested by the aircraft that fired it after ricochet off the target, exciting low level strafing..... The pilot ejected safely & the investigation confirmed the cause finding blue paint from the inert projectile on damaged compressor blades.
friend of mine was a flight engineer on a SAR c-130. In his re-cert the instructor gave him a 4 engine, and primary electrical failure over a city. his answer was to have the pilot mut max pitch on one engine, push the nose down. he then re opened fuel the the engine and fire the igniters with what little power was left. he then ised the engine generator to restart the other 3 engines.
Nice that you feature a Sabre Orenda power plant for this session. My Dad was an Airframe Tech (RCAF) on them during the Cold War, fond memories. He was fortunate to be part of a number of the teams winning the Guynemer Air Gunnery trophy. You might find a search on that interesting. The Canadians won the trophy a number of years running. Top Guns back in the day. ;)
Couldn't help but notice the BMW GS in the background.... Yours? I own a couple boxers myself, including a 1981 R80G/S. I purchased it new on my 1st tour to Germany with the Canadian Forces. Still own the old girl. Added a cruiser, R1200C decades later.
It's a 2007. Still getting used to it. It's a good bike!
Flameouts in the old lear 25 were fairly common. Thanks for vid. My mom liked you too.
The guys like Mentour pilot have videos on this. The issue is usually feed valves from the various tanks. It seems they are manually operated at the tank, so your screwed if this is the issue anyhow.
The TF-30's were reasonably high-tech for their day but they were a bit bothersome in that you couldn't rapidly change the throttle without risking flameout. That was a reasonably common occurrence in the Tomcats. When they upgraded to the GE F110 engines, those had no such throttle restrictions and the Tomcat really began to become the fighter/interceptor that it was really meant to be. However at low airspeed and in burner, you could create really bad adverse yaw if you had flameout or had a burner blow out, and that could very easily be unrecoverable.
If I remember correctly the TF-30 was also fairly sensitive to angle of attack. Combine that with the throttle sensitivity issue and you have an absolute nightmare for a carrier-based aircraft that may need to go from near idle power to full blowers to abort a landing. The wide spread of the Tomcat's engines only exacerbates the yaw issue during a low-speed flameout, it's no wonder they switched to the F110 as soon as they could.
Windmilling restart is a thing in airliners. You need to go pretty fast, but e. g. the the A330 has a procedure for it under "All Engine Flameout", It lists an optimal windmilling restart speed of 300 knots indicated, or Mach 0.82, but it's possible.
Above 25,000 feet windmilling restart is the only option, as the APU can only be started below that altitude. Pitch angle for 300 knots is, according to the manual, roughly 2 degrees nose down. Which sounds like little, but is actually quite unusual in an airliner.
2° does sound very little; i guess usually the flaps keep the nose up on descent
it does still sound like very little tough
@@Kalimerakis Flaps increase the effective angle of attack of the wings, meaning you actually fly with a lower pitch angle than with retracted flaps at the same speed. On final approach the main reason for the higher pitch angle is really the low speed. But you are right, most jet airliners fly the approach slightly nose-high.
Mentour has a video on this for sure. A specific incident
A&P here. The first gig I had was on FedEx C-208's. Had the PT-6/114A. They had a FCU emergency bypass (I think that is what it was called....it has been a long tim...but was absolutely a bypass, there was only one FCU). It was basically a separate throttle control held in idle by break away wire. If that wire was broken, we would have to do a bunch of checks. Never had that issue though. Honestly, I have no idea how it worked. Would be interesting to see if you had a PT-6 in the shop...unless that was just a specialty FedEx addition.
Pilots noticing the passengers screaming and thinking “we should have been dentists…”
Thanks for your posts they are very interesting
Excellent video!
One good example of an engine flame-out in Hollywood is from Behind Enemy Lines. He didn't reduce throttle to eliminate the fuel vapor stream exiting the engine 😬
I read in some book about a Mirage III pilot who had an engine flamout doing some maneuver with a high G load. Perhaps in older fighters this could be an extra factor to be taken care of during the flight. Or perhaps these older jet engines were more sensitive to changes in intake airflow.
Excellent explanation, thank you.
I was in an Airbus that had a flame out. A few minutes after takeoff the right engine flamed out and the entire plane very quickly yawed noticeably. Moments later the entire right side of the plane had a huge red flash and what I assume was all of this fuel reigniting as the engine restarted. The pilots must’ve been pretty busy because they didn’t say anything for several minutes. When they got on the intercom they said they were talking to maintenance on the ground and deciding if we were going to go back home or continue on the trip. Everything must have checked out OK because about 10 minutes later he got back on and said that we would be continuing on our way across the country. At first he said the passengers flying on the second leg of the trip would continue in this same plane as scheduled but when we got to the gate he made the announcement that they would be switching aircraft so I assume whatever had happened warranted getting an inspection or maintenance done on the engine. Very memorable. I believe it was a bird strikes that caused it.
Aren't Intake Variable Guide Vanes just for that , stalling compressor elimination ? like the j79
Yes. The best way to explain a compressor stall is to show the mechanisms designed to prevent it, which is what I do in the video recommended here.
May I suggest an alternate definition of the term "flameout". One of my powerplant instructors in A&P school stated that the only reason the hot gases move to the aft or exhaust end of the engine is due to the fact that the airflow from the compressor is pushing it that way. If at any time that airflow is disrupted, the flame in the combustor may now be at a higher pressure than the air in the compressor. This would result in the hot gases and flame to leave the combustor and travel through the compressor. Hence a true "flameout" where there is fire outside of the combustor.
A lot of people would call that a surge, resulting from a compressor stall.
What I am calling a flameout is when the flame goes out. The combustion process stops and there is an instant loss of power. Sometimes this can be caused by a compressor stall, but there are other causes.
What you describe is usually referred to as a "surge". A compressor stall almost always results in a surge, often with actual flames coming out the front of the engine, accompanied by a loud bang, but a "simple" flameout (when the flame goes out) is usually due to fuel starvation.
A lot of people, including me and everyone I worked with at R-R, would call that a surge.
A stall condition in a compressor can often result in an engine surging, with a loud bang and flames coming out of the intake, as the flow through the compressor breaks down and suddenly reverses. However, this does not necessarily result in a flameout: the engine can surge repeatedly until it is shut down or the stall condition clears.
I distinctly recall being at JFK many years ago, waiting for my flight back to LHR. During one take-off, an engine (of a DC-10?) surged three times: the very loud bangs could clearly be heard across the airport and inside the terminal building.
A classic incident of repeated engine surges, following a bird strike, can be viewed elsewhere on RUclips. Check out 'Thomsonfly 757 bird strike'. The incident happened at Manchester (England), back in 2007. The pilot called a Mayday (very calmly) and came back in for an emergency landing.
Most modern passenger jets have auto ignition or they reccomend you turn it manually to continuous in some critical phases to prevent flame out.
why turbine jet engines suffer flame out when the fuel supply is reduced too quickly? assume all components are all in optimal condition.
would it relates to something like minimum fuel mass flow rate requirement at the RPM at that instance? for self-sustain
Uh, they don't. One of the things we test and set up after an engine has been overhauled is specifically the throttle response in decreasing the power to idle. If the engine shuts off with a one second throttle movement from max to idle... we adjust the fuel control and test it again, until it doesn't do that.
No matter what the pilot does with the throttle, the main fuel control is the one in control of the fuel.
@@AgentJayZ Thanks for your informative and practical response. I understand the whole system including the operator or pilot would try their best to prevent this from happening. But I probably didn't express my original question clearly. I was trying to know in very theoretical or simplified ideal condition, when the fuel supply is reduced, would it cause flame out , if the answer is yes, what could be the possible reason (Refers to the actual fuel fed into the chamber is quickly truly reduced, regardless any other linked control systems) I appreciate if you could give some thoughts. : )
I gave you the answer. After overhaul the engine is tested for proper function before being accepted as serviceable for aircraft use. A very important step in that setup is ensuring that a rapid reduction from full power to idle by the pilot does not cause flameout. We do that with mechanical adjustments to the fuel control so that, whatever the pilot does, he can not shut off the fuel.
Unless he decides to purposely command the engine to stop. This involves moving the throttle lever around a large positive gate... going from ground idle to shutdown. The pilot would never chose ground idle while in the air, as there is a higher detent at what is called flight idle.
From flight idle to any significant thrust is 2-3 seconds. From ground idle it will take over ten seconds to start making any real thrust.
To deliberately select fuel cutoff in flight is an option I guess, but it's like putting your car in Park while driving down the freeway.
Your phrase "regardless of any other linked fuel system" is a fantasy "what if", it's completely meaningless and impossible.
The pilots are very skilled, like a race car driver or MotoGP rider, and when they want idle, they select idle.
If they really want to select ground idle... they can do that, and they understand the risks they are taking.
If they really want to shut down the engine in flight, they can do that, but it is almost impossible to do that by accident.
See a recent Blancolirio video for a case of the almost impossible possibly happening.
@@AgentJayZ Totally understood. thank you : )
Hey JayZ. Great video!
Saravanamuttoo (2017) says that compressor surge appears due to incidence, causing a drop in pressure at point 1, while point 2 doesnt decreases fast enought, what causes a back flow (point 2 -> point 1). Aungier (2000) says that a longer intake lenght can let the air rearrange itself, decreasing the incidence effect. With that, i have some doubts.. 1)One of the reasons we dont see high incidence in airline jets its because its engines doesnt has enough intake lenght to withstand high incidence? 2)The purpose of inlet guide vanes is to allow high flow velocities because without it, relative velocity would be high, leading to high relative mach numbers. But, can inlet guide vanes prevent compressor surge too?
Its really hard to find papers about intakes. Can you talk about it?
Can you restart and engine in flight using bleed air from an APU ?
Yes you can. Most APUs cannot be used at cruise lvl and will require the aircraft to descend before starting. This is also the same for relighting an engine in flight.
If the airliner has an APU, it is usually one of the sources of power used by the starters on the main engines.
In a multi engine jet, usually there's an ability to use bleed air from one engine to engage the starter on the other engine. On those, things get really scary when all the engines flameout. How do you know if you can use this option? It's actually easy. The manual will describe using cross-bleed air to start another engine once one engine is running and you've disconnected the start cart. If there's no section in the manual describing this, you probably can't use bleed air to restart an engine.
Love your videos, Can APU help to spin the engine and then relight?
Yes it can, from the two sources of power the APU makes. A typical airliner engine will be fitted with an air turbine starter - literally a small compressed air powered turbine bolted to a driveshaft turning the core of the engine. These are used because they make way more power for their size and weight than electric motors, and can be kept spun up for as long as you need, provided you have the compressed air supply to drive them. Whereas an electric starter motor can only be run for a limited time before its windings overheat, and if that happens you may need to wait for up to an hour for them to cool down before you try again, which obviously isn't ideal. Some early turbojets did use electric starters - the dome shaped section sticking out of the front of the engines on a B47 bomber (as an example) are aerodynamic fairings covering the starter motors, which are bolted to the front of each engine.
Anyway, the APU is often the same model of small gas turbine engine as is used in ground power "start carts" - they usually have far larger compressor stages than they need to run themselves, so bleed air from the engines own compressor is the source of the compressed air they make. The APU will also drive a couple of electrical generators, one to make 28 volts DC and another to make 115 volts, 400 Hz AC for the two electrical buses on the aircraft. Older aircraft may only have the low voltage DC system, but most modern airliners have both. The APU might also drive some auxiliary hydraulic pumps to maintain hydraulic pressure for control surfaces and raising/lowering the landing gear, in case the main engines cannot be restarted.
To start the main engine needs compressed air and electrical power to run the igniters in the engine combustion chambers. The APU can supply both - there will be compressed air lines running between the APU and every other engine on the aircraft, as well as cross-feed compressed air lines between the engines. So if you can get one of the main engines started using air from the APU, that engine will most likely then take over starting duties for the other engines, since each engine will also have bleed-air ports on its own compressor stage to supply air for starting any of the other engines. The other purpose of the bleed-air ports on the engines is to supply air for cabin pressurisation, though this usually goes through a heat exchanger to cool it first since the compressed air from the engines (or from the APU) would otherwise be far too hot to pump straight into the cabin. On much older aircraft with piston engines, the cabin pressurisation air came from the turbochargers or superchargers on the engines, since these are still just compressors.
What do you think of the Y2K bike and it's power plant?
It's an Allison/Rolls Royce 250. An extremely successful and reliable turboshaft used in many different helicopters.
OK question. You mentioned compresser rpm and engine rpm Can you tell me the difference between compressor RPM and engine RPM or are they both the same thing?
In a single shaft engine, the compressor and the turbine are on the same shaft. If they are not turning the exact same speed... well, we have some really big problems...
Thanks
One rare reason for an engine flameout occurred in 1982 to British Airways Flight 009. In the middle of the night on the London to Aukland NZ route (with various stops along the way) 009 flew into a volcanic ash-cloud. Aside from spectacular electrical discharge effects and sand-blasting to the exterior of the airplane, the volcanic particles played havoc in the engine hot section where the silicate (i.e. glass) based material melted in the combustor section, then solidified in the HP and LP turbine sections. All four engines flamed out. Steadily losing altitude, the pilots made plans to ditch at sea. After losing some 25,000 feet of altitude, were able to restart all four engines (only three would continued ops), and limped to Jakarta for an emergency landing.
I must believe British Airways made a change of fresh underwear available to the passengers.
ruclips.net/video/8AM6kMayn20/видео.html
And during all that the Captain found the time to reassure the passengers in classic British fashion: "Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them going again. I trust you are not in too much distress."
The BA009 event has been discussed more than once on this channel and I've added my comments in the past, because I saw some of the components from one of the engines laid out at Derby, some weeks later.
@@grahamj9101Are you the same Graham that used to perform design work with RR? I've always stated that your input on the channel discussion threads was invaluable. I used to hang-out here under user name Jangle2007.....until youtube insisted on a new name.
During the past several years my attention has been drawn outside youtube to deal with work and family related matters, so I imagine I've missed a lot of AgentJayZ critical content and context.
On point, I've seen poor quality images of used turbine parts after getting worked by volcanic ash. I couldn't make heads or tales of it. I must believe that volcanic ash is highly destructive to metal parts, especially those that rotate at high speed?
It has happened of 2 other instances since then. In 1989 A KLM 747 was approaching Anchorage International and flew in to volcanic ash cloud from Redoubt. Lost all 4 engines and was able to get 2 restarted after falling from FL250 to 13-thousand to regain control before getting the remaining 2 relit. This event was the impetus of the creation of the Alaska Aviation Weather Unit and Anchorage Volcanic Ash Advisory Center which I work for. We are one of only 9 VAACs in the world.
Just when you think you're done hearing this given the danger it happened AGAIN THIS YEAR! A well advertised/warned volcanic ash cloud from the Russian volcano Bezymianny erupted to over 40 thousand feet and rapidly drifted into US airspace. Despite a controller asking a 747 cargo crew if they wanted a reroute they declined and maintained course, literally Leroy Jenkins-ing it into the cloud. I don't know every detail but my understanding is at least 3 of the 4 engines overheated and the plane Pan-panned into Anchorage without the degree of damage from the BA or KLM incidents. Truly a FAFO moment. Doubt that captain flys for that airline anymore.
@@flightsimman Great story, had to look up "FAFO".
don't wings also stall but keeps moving?
The blades in an axial flow compressor are miniature wings. In both cases, stall is when the airflow separates from the wing, typically on the trailing edge of the low-pressure face (top of the wing or "backside" of the blade). When this happens, the higher pressure air from the other side curls around to fill the vacuum instead of going where it's supposed to. The wing keeps moving, but loses lift and drops. The compressor loses pressure gain from the stalled stage and the airflow becomes abnormally turbulent, possibly propagating the stall to successive stages.
Skip: yes they do. When an aircraft flies slowly, and does not reduce angle of attack of the wing, it will stall. The wing stops producing lift, and it will fall out of the sky.
@@AgentJayZ An aircraft can stall at any speed if it exceeds the critical angle of attack.
No argument there... I agree with oldtugs.
"We see flame ..... *_and the passengers are screaming"_* 😳
😂😂😂😂
When an aircraft stalls it’s not because the aircraft has stopped moving through the atmosphere. Or the propeller has stopped moving. Lol! 😊
Although the latter may lead to the former, e. g. if the autopilot tries to maintain altitude with the engines out, it will fly it right into the stall. At which point the autopilot will disconnect and dump the plane, which has departed controlled flight, into the laps of the pilots.
Hello Sir, I hope you're doing well. As I watched your videos during my study as an aircraft engineer, and I am interested in joining your team, is there any chance I can contact you, Sir
perfect
Good Morning Sir
Dont kill me but dont EGT readings go down in rich burns? Thats what happens on my RD400 two-stroke anyways.
Gas turbine (and Diesel) engines always run "lean". There's an excess of air which brings the flame temperature, say 3500 f, down to something the metal engine parts can handle. More fuel means the flame is larger in comparison to the amount of air going through which increases temperatures.
@@RallyRat ah! Thank you for that explanation I didnt know that.. very interesting
A turbojet is quite different from a piston engine. From the viewpoint of a turbine engine, 2-strokes and 4-strokes are exactly the same, with no differences in what they do or how they do it.
Fuel type also does not matter. A Sabre Jet, a Starfighter, and an F-35 can burn heating oil, diesel, Jet A, 87 octane pump gas, Race gas, 100LL avgas, ethanol, methanol, and pure nitromethane just fine, with no adjustments needed to anything.
I turned up the maximum fuel adjustment on my injector pump on my 80 series diesel too high and melted the piston tops and I cracked a piston due to the excessively high combustion temperature which showed up as higher EGT. I didn't back off in time. So same for kerosene. expensive lesson.
Francis: you won't find most of those fuels on an air base, but the engines could use them.
Every pilot knows if in case of flameout, you jiggle the keys and when the starter engages, go for broke.
Also remember the profanity. Always helpful!
Does having a two-stroke engine stop on a RC airplane count as a flameout? If so, I've experienced many flameouts. I was able to safely land the airplane each time (landing in a lake is still a safe landing right?).
One of my RC airplanes had an onboard starter. I would occasionally kill the engine while in the air just so I could restart the motor airborne. People observing were very surprised to hear the motor die and then restart.
Thanks for another interesting video AgentJayZ.
Seems like people are constantly applying ICE knowledge to gas turbine engines when they’re completely different.
Neat!
US Airways Flight 1549 or landing on Hudson. Both engines flameout on A320 resulting from hit and ingestion of canadian geese.
If you run out of fuel in mid air. Either it leaked out or some idiot did not understand the kg/lb conversion and under filled the fuel tanks. You will get a flame out.😂
You referring to a certain Gimli Glider??
Ah, I was thinking about air Transat more recently.
@@AgentJayZ ha ha ha, referred to both. LOL.
@@MikeSiemens88 that was some talent on that pilot. Unbeleivable Landing. Especially that last minute move before touch down!
@@jimmyj5557 I spent a few years of my youth in Gimli as Dad was posted there in the early 1960s.
I'd think that the most obvious cause for engine flameout is fuel starvation
Well, shutting off the fuel is the most common cause, but when I say flameout, I am talking about the combustion process stopping even though their is fuel flowing. The only time fuel starvation happens when the throttle is not at idle is when the aircraft actually runs out of fuel. I'm not really talking about that case here either.
Both the examples I give that happened in our test cell were caused by accidentally shutting the fuel off. The flameout I have in mind during this discussion happens in flight, when there is plenty of fuel in the tanks, and the throttle is set to anything between flight idle (84% rpm) and takeoff power (105% rpm).
In Soviet era jets, there is a rocket stove connected to the top combustion chamber for cockpit heat. Easy for the pilot to simply add cigarette butt and vodkas to relite. Russians are so practical.
🎉
1st to combustion can-again .. .. tnx
You can pick up your participation ribbon in the lobby.
Hello.I am vibration inspector
Top Gun? It just went from full afterburner, to full military. Are you kidding?
We're talking about a movie, and the story was based on the engine having a compressor stall and flaming out. It should have been possible to fly on one engine, but hollywood....
I'm not kidding, but expecting Top Gun to have technical accuracy makes you the joke here.
@@AgentJayZ The A model of F-14 Top Gun use TF30 notoriously prone to flame out caused by inlet airflow disturbance i.e. in high alpha maneuver, or sudden throttle command. F-14 is capable to fly and land on one engine, but because of the spaced engine it will cause significant yaw on flameout. This yaw have caused loss of airframe combined with low altitude and low recovery time.
Yeah, so why did Mav punch out?
Rhetorical. It's a Hollywood cartoon.
2nd
Nope.
1st
To qualify for the imaginary trophy, you must watch the video. Time indicates that you have not, and so are disqualified. Thank you.
@@AgentJayZ I will watch the video, I'm just doing homework
All that and then there's volcanic ash... en.wikipedia.org/wiki/British_Airways_Flight_009
So now we've moved from once in a million to once in a billion. Outside the scope, man. Next step: is the world just a dust speck... Horton hears a who...
@@AgentJayZ Heh, didn't mean to suggest that it was in scope, I just happened to read about that incident over the weekend so...
The captain (capt. Moody) has done a few interviews with RUclipsrs on the incident - worth a watch if you have the time.