Engine failure in Vy climbout
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Engine failure in Vy climbout
This post relates to a discussion a few weeks back, but I can't find the right one now. One of the things under discussion was what happens if the engine fails while in a Vy (or similar) climbout - i.e. will you stall before you have time to react.
I set up the following experiment: set full takeoff power, trim for Vy, let things stabilise, pull power.
As I expected, nothing bad happened. The airspeed went down to to about 80 knots (Vy in my plane is 90) but by then the nose was pointing downwards and I was picking up speed again.
I didn't try it at Vx - maybe next time. But I'd expect it work much the same.
Someone will no doubt say that this isn't realistic - the real-life case is the pilot hanging on desperately to the yoke trying to maintain a visual climb attitude. And they may be right. There's no need to flight test that one, there's no doubt about what will happen...
(Oh, and someone will criticise my grammar, and several people will accuse me of irresponsibility for daring to try something so risky, and others will go on to accuse me of trying to incite inexperienced pilots to kill themselves. And to all of you I say, a plague on all your houses, or less poetically <invective of choice> off).
I set up the following experiment: set full takeoff power, trim for Vy, let things stabilise, pull power.
As I expected, nothing bad happened. The airspeed went down to to about 80 knots (Vy in my plane is 90) but by then the nose was pointing downwards and I was picking up speed again.
I didn't try it at Vx - maybe next time. But I'd expect it work much the same.
Someone will no doubt say that this isn't realistic - the real-life case is the pilot hanging on desperately to the yoke trying to maintain a visual climb attitude. And they may be right. There's no need to flight test that one, there's no doubt about what will happen...
(Oh, and someone will criticise my grammar, and several people will accuse me of irresponsibility for daring to try something so risky, and others will go on to accuse me of trying to incite inexperienced pilots to kill themselves. And to all of you I say, a plague on all your houses, or less poetically <invective of choice> off).
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Personally, I think you've done well to practice a potential failure scenario. Well done.
Now go do it for Vx next time.
I did the same in the Pitts for the same reason - but more specifically because of the extreme nose-high attitude of a Pitts on climbout. Same result - it was a non-event and very easy to keep things perfectly together, in so far as a drill is just that.
Now go do it for Vx next time.
I did the same in the Pitts for the same reason - but more specifically because of the extreme nose-high attitude of a Pitts on climbout. Same result - it was a non-event and very easy to keep things perfectly together, in so far as a drill is just that.
Big difference between Vy and Vx as Vx is typically less than 10 knots above power off stall. In addition if you are at Vx you will be typically close to the ground and in a steep nose up attitude. When you try the test try it at altitude and assume the engine has failed at 100 AGL. I think you will be surprised at how far the nose has to go down and how fast the 100 feet disappears .....
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It was me who did the test a few weeks ago. I was equally surprised to see that nothing bad would happen, regardless how hard I tried.
Whether to simply let the nose drop of its own accord, or to use a 1/2G pushover, or a 0G pushover all didn't matter. I was fully established in a Vbg glide *before* any altitude loss would occur.
The only thing that could conceivably considered "bad" was when I deliberately tried to maintain the attitude and let the aircraft stall. That lead to a loss of about 400 feet before being established in a stable Vbg glide. But it took three to four seconds from loss-of-power to the stall, so you should have plenty time to think "oh ****".
What did not work at all was simply releasing the stick and let the aircraft sort itself out. After having lost well over 1000 feet in a speed/attitude oscillation I called it quits.
Whether to simply let the nose drop of its own accord, or to use a 1/2G pushover, or a 0G pushover all didn't matter. I was fully established in a Vbg glide *before* any altitude loss would occur.
The only thing that could conceivably considered "bad" was when I deliberately tried to maintain the attitude and let the aircraft stall. That lead to a loss of about 400 feet before being established in a stable Vbg glide. But it took three to four seconds from loss-of-power to the stall, so you should have plenty time to think "oh ****".
What did not work at all was simply releasing the stick and let the aircraft sort itself out. After having lost well over 1000 feet in a speed/attitude oscillation I called it quits.
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There must be strong similarities to winch lauch failures with gliders. e.g. you are climbing at a very steep angle, relatively close to stalling speed & then all motive power is suddenly removed.
The remedial action is then to lower the nose as quickly as possible (to about 30 degrees nose down is taught) and then WAIT until the required flying speed (normally approach speed with addition for for windspeed) comes back before returneing to a more normal attitude and then either a) landing straight ahead if possible or b) if landing ahead is not an option because you're too high, turning and re-assessing the options for a safe landing.
Just lowering the nose to a normal (or best glide attitude) means that it takes a much longer time to restore flying speed.
(Please note that option b is not necessarily a good idea in a powered aircraft)
It's educational watching how quickly airspeed is lost during the process of getting the nose down from over 45 degrees up to 30 down. It's also educational to see how long it takes to get back to a safe manoevring speed even when the nose is pointing quite steeply downwards.
The big no-no in the process is to start turning before the airspeed is restored as the glider is then being invited to spin at low level. Glider instructors get quite upset about that!
Also it's a very good reason for not rotating too quickly (i.e while still too low) into the full climb during a winch launch, because by the time you've got the nose down and airspeed restored, the ground has already intervened in the process.
The remedial action is then to lower the nose as quickly as possible (to about 30 degrees nose down is taught) and then WAIT until the required flying speed (normally approach speed with addition for for windspeed) comes back before returneing to a more normal attitude and then either a) landing straight ahead if possible or b) if landing ahead is not an option because you're too high, turning and re-assessing the options for a safe landing.
Just lowering the nose to a normal (or best glide attitude) means that it takes a much longer time to restore flying speed.
(Please note that option b is not necessarily a good idea in a powered aircraft)
It's educational watching how quickly airspeed is lost during the process of getting the nose down from over 45 degrees up to 30 down. It's also educational to see how long it takes to get back to a safe manoevring speed even when the nose is pointing quite steeply downwards.
The big no-no in the process is to start turning before the airspeed is restored as the glider is then being invited to spin at low level. Glider instructors get quite upset about that!
Also it's a very good reason for not rotating too quickly (i.e while still too low) into the full climb during a winch launch, because by the time you've got the nose down and airspeed restored, the ground has already intervened in the process.
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You should not simply stall just because the engine has failed - in any flight regime - because the aircraft will continue flying at the trimmed speed.
It is the trim that sets the flying speed. The engine merely affects the rate of climb
It is the trim that sets the flying speed. The engine merely affects the rate of climb
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Considerably less extreme than the glider example, winch launches are a bit special (and unnatural 
) Even the pitts doesn't climb as steeply as a winch launch, and the glider has a lot less inertia. As the OP says, it's a bit of a non event in a 'standard' piston single really.
) Even the pitts doesn't climb as steeply as a winch launch, and the glider has a lot less inertia. As the OP says, it's a bit of a non event in a 'standard' piston single really.
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With all this, some will question why instructors emphasise so much getting the nose down in the event of an EFATO if it does it itself. The truth is that in the event of a real failure there are many pilots who's brain does not function quite as they would like in a real emergency and having the training to lower it will stop them sitting there pulling the nose up and trying to hold the climb attitude.
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During last fall's flight test program with a highly modified (and draggy) Cessna Caravan, it became necessary to reduce the published Vy, to obtain the minimum required climb rate to pass certification. Because of the added drag, Vy reduced a little = less drag, so better rate of climb.
Once I declared this, Transport Canada said fine, but that means that your target speed at 50 feet will now be the lesser speed to be declared Vy, and therefore I was required to demonstrate an EFATO from 50 feet, at that lower speed. This was not required for the lower yet Vx (thank goodness!).
At my new Vy, this was only just achievable, and was indeed to most scary thing I did during all of the test flying for that program. I had to admit that a few times, it was necessary to add power on the way down to make it work (and adding "a bit" of power in a Caravan is not as easy as it sounds).
The manuever was akin to autorotations, in that prompt and considerable "down" control was required, with the intent to accelerate, and then an agressive flare at the bottom. This required considerable practice, and was very stressful in a new plane, which was supposed to be landed nose low to prevent a groundstike of the payload.
We all agreed that the maneuver could be done, on the premise that the aircraft did not have be undamaged after landing, just no one hurt. That would have been doable.
The popularity of STOL kits also brings this to the forefront. Whether it is an EFATO, or simply an approach flown rather slowly, the very real hazard is there. In the early days I remember finding that my STOL C150 would very happily glide at 50 MPH, rather than 60+ stated in the flight manual. This was fine "up there" but very risky close to the ground. You could approach the ground power off at 50 MPH, but you had no inertia left with which to flare. Just slamming into the ground unarrested was a very real risk. Again, akin to the autorotation, where if you have not built up rotor RPM for the flare, you're just going to hit the ground.
Though flight training should teach the basics of this, the "fine points" are sometimes not understood by the instructor, and not taught well. In general, many aircraft will fly certain maneuvers at speeds less than the flight manual stated speed, but if the engine quits, you will no longer have the margin to maintain safe flight for the FAA's pilot who is flying without applying "unusual skill, attention and strength".
Though never to be published, for my Caravan program, I was required to fly a Vref -5 circuit. From liftoff to touchdown at my new speeds -5 knots. I did it, but the stall warning was sounding through most of it. That was the required margin between "normal skill and attention" and what I should be able to demeonstrate with my total of 40 flight test hours on type!
Once I declared this, Transport Canada said fine, but that means that your target speed at 50 feet will now be the lesser speed to be declared Vy, and therefore I was required to demonstrate an EFATO from 50 feet, at that lower speed. This was not required for the lower yet Vx (thank goodness!).
At my new Vy, this was only just achievable, and was indeed to most scary thing I did during all of the test flying for that program. I had to admit that a few times, it was necessary to add power on the way down to make it work (and adding "a bit" of power in a Caravan is not as easy as it sounds).
The manuever was akin to autorotations, in that prompt and considerable "down" control was required, with the intent to accelerate, and then an agressive flare at the bottom. This required considerable practice, and was very stressful in a new plane, which was supposed to be landed nose low to prevent a groundstike of the payload.
We all agreed that the maneuver could be done, on the premise that the aircraft did not have be undamaged after landing, just no one hurt. That would have been doable.
The popularity of STOL kits also brings this to the forefront. Whether it is an EFATO, or simply an approach flown rather slowly, the very real hazard is there. In the early days I remember finding that my STOL C150 would very happily glide at 50 MPH, rather than 60+ stated in the flight manual. This was fine "up there" but very risky close to the ground. You could approach the ground power off at 50 MPH, but you had no inertia left with which to flare. Just slamming into the ground unarrested was a very real risk. Again, akin to the autorotation, where if you have not built up rotor RPM for the flare, you're just going to hit the ground.
Though flight training should teach the basics of this, the "fine points" are sometimes not understood by the instructor, and not taught well. In general, many aircraft will fly certain maneuvers at speeds less than the flight manual stated speed, but if the engine quits, you will no longer have the margin to maintain safe flight for the FAA's pilot who is flying without applying "unusual skill, attention and strength".
Though never to be published, for my Caravan program, I was required to fly a Vref -5 circuit. From liftoff to touchdown at my new speeds -5 knots. I did it, but the stall warning was sounding through most of it. That was the required margin between "normal skill and attention" and what I should be able to demeonstrate with my total of 40 flight test hours on type!
Someone will no doubt say that this isn't realistic
What did you do during your simulation? I suspect you reduced the power to idle.
There is a BIG difference in a real engine failure. Has the prop siezed? Is it windmilling? Have you still got take off flap selected?
Trim will be affected by a stopped or seized engine (much more nose down... meaning lots of nose up trim..which may run out).
By throttling back to idle you still have a little residual power (put simply somewhat like feathering) which reduces drag. It can be nothing like the real thing!
Try stopping the engine at altitude with the mixture control, then switch off both mags. You may be quite surprised at the result, and thats probably without the prop actually stopped!
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n5296s - the discussion you refer to revolved around TURN BACK, where in the red corner were the land straight ahead brigade, and in the blue corner, the advocates of a successful turn back. It looked closely at Vx, Vy, and at what altitude a successful turn back with safe landing could be achieved, or not as the case might be.
The situation of what happens at EFTAO, the pilots reaction, and importantly, the aeroplanes reaction, was discussed at great length. Several individuals, including you if I remember correctly, were going to conduct experiments, particular to type.
With respect, pulling the power, at stages of speed/climb, would be a fairly benign incident, height dependent, but it was the input of turn that created the full debate, and discussions as to whether this be a good idea.
The situation of what happens at EFTAO, the pilots reaction, and importantly, the aeroplanes reaction, was discussed at great length. Several individuals, including you if I remember correctly, were going to conduct experiments, particular to type.
With respect, pulling the power, at stages of speed/climb, would be a fairly benign incident, height dependent, but it was the input of turn that created the full debate, and discussions as to whether this be a good idea.
I am posting a section of an article from the latest Transport Canada Aviation Safety Letter which discusses GA stall spin accidents
Quote
The occurrences broke down into three principal groups:
a. stall or spin accidents resulting from aircraft handling (27);
b. stalls or spins following engine failure (9); and
c. stalls or spins resulting from loss of control in IMC (3).
Handling Accidents
Twenty-seven accidents resulted from mishandling the aircraft into an aerodynamic stall. These accidents resulted in 26 fatalities and 16 serious injuries. In two cases, it appears that the engine was not producing full power but the aircraft was capable of controlled flight and the stall was avoidable. In all cases, the stall, which sometimes precipitated a spin or wing drop, occurred at low altitude and at low airspeed. The stalls and spins occurred at a height where recovery was very difficult and probably impossible. Sixteen stalls resulted from turning at low airspeed, 10 occurred in straight ahead flight, and one inverted spin developed when the pilot was practising aerobatics at about 1 500 ft AGL.
Most of the 27 handling accidents happened during the takeoff/initial climb-out or approach phase. There were 13 stalls during the climb-out after taking off and at least six of these occurred during a low speed, low altitude turn. Five stalls, all in turns, occurred during the approach/landing phase, most often on turning base to final. One practice overshoot ended in a stall when the instructor waited too long to take control and the airspeed fell too low.
Unquote
Lowering the nose after a low altitude engine failure, or even a inadvertant loss of airspeed, may sound obvious but in the heat of the moment the accident statistics say pilots are getting this wrong. I firmly believe this is an area where flight schools need to work harder to make sure students have an automatic condition response to lower the nose in the event of a loss of engine power or any stall indication.
Too many pilots are saying "well that will never happen to me", the problem is it IS happening to pilots just like you .......
Quote
The occurrences broke down into three principal groups:
a. stall or spin accidents resulting from aircraft handling (27);
b. stalls or spins following engine failure (9); and
c. stalls or spins resulting from loss of control in IMC (3).
Handling Accidents
Twenty-seven accidents resulted from mishandling the aircraft into an aerodynamic stall. These accidents resulted in 26 fatalities and 16 serious injuries. In two cases, it appears that the engine was not producing full power but the aircraft was capable of controlled flight and the stall was avoidable. In all cases, the stall, which sometimes precipitated a spin or wing drop, occurred at low altitude and at low airspeed. The stalls and spins occurred at a height where recovery was very difficult and probably impossible. Sixteen stalls resulted from turning at low airspeed, 10 occurred in straight ahead flight, and one inverted spin developed when the pilot was practising aerobatics at about 1 500 ft AGL.
Most of the 27 handling accidents happened during the takeoff/initial climb-out or approach phase. There were 13 stalls during the climb-out after taking off and at least six of these occurred during a low speed, low altitude turn. Five stalls, all in turns, occurred during the approach/landing phase, most often on turning base to final. One practice overshoot ended in a stall when the instructor waited too long to take control and the airspeed fell too low.
Unquote
Lowering the nose after a low altitude engine failure, or even a inadvertant loss of airspeed, may sound obvious but in the heat of the moment the accident statistics say pilots are getting this wrong. I firmly believe this is an area where flight schools need to work harder to make sure students have an automatic condition response to lower the nose in the event of a loss of engine power or any stall indication.
Too many pilots are saying "well that will never happen to me", the problem is it IS happening to pilots just like you .......
Last edited by Big Pistons Forever; 28th Feb 2012 at 02:32.
You should not simply stall just because the engine has failed - in any flight regime - because the aircraft will continue flying at the trimmed speed.
In fact, the drop in power could be considered instantaneous, but it will take a finite time for the aircraft to change attitude. During this time, it's airspeed must inevitably decrease and I would have thought that whether this decrease takes it below stalling speed would be very much type-dependent.
My reading is that Pilot Dar's experience tends to confirm this.
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abgd, I have tried this, as I described earlier. Establish the aircraft in a stable, full power, Vy climb, properly trimmed and all. This is about a 20-25 degree nose up attitude. Release the stick altogether and chop the power.
The aircraft got into a wild speed/pitch oscillation and had not sorted itself out after 1000' of altitude loss so I called it quits. However, the aircraft did indeed NOT stall. (Although I don't remember if it got close enough to the stall for the stall warner to go off.)
Furthermore, even though Vbg is equal to Vy in this aircraft, the trim settings were completely different. With full power there is a lot of airflow over the all-flying tailplane, with zero power there is not.
The aircraft got into a wild speed/pitch oscillation and had not sorted itself out after 1000' of altitude loss so I called it quits. However, the aircraft did indeed NOT stall. (Although I don't remember if it got close enough to the stall for the stall warner to go off.)
Furthermore, even though Vbg is equal to Vy in this aircraft, the trim settings were completely different. With full power there is a lot of airflow over the all-flying tailplane, with zero power there is not.
I didn't mean to ignore your test - just to point out that IMO there's not a theoretical justification to think that the aircraft should simply sort itself out. Which I think your post also confirms.
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there's not a theoretical justification to think that the aircraft should simply sort itself out.
Most every plane I fly, I stall - numerous times, and in every configuration. I continue to be amazed at the variations in handling, and "sorting itself out" which I experience. Some are great, a few marginal, and one recent (Italian type certified) one did not enough pitch control available to prevent a stall in certain "normal" configurations. I like to find these little surprises with lots of altitude, and all other things being in hand. EFATO is not the time.
As obviously does the OP
, if you commonly fly one or a few types of aircraft, it is excellent to cautiously experiment (with mentoring, if appropriate). The more you know about what your plane will do, the safer you'll be. There have been remarks about stopped propellers, and the differences in drag. Yes, this is often the case, but I consider this risk to be well down the scale. For my experience, though failures of engines to develop useful power occur, seizures are rather rare. If your skills are good at handling the aircraft with an idled engine, the differences you could experience with a stopped prop will not be so different as to invalidate your skill.
Then there are the really odd situations.... Last week while flight testing a Piper Cheyenne II with an external survey modification, the left main gear decided it was very happy staying in the wing, despite my seletion for it to appear. After the methodical checking of systems, and repeated attempts, but before going to full blown emergency procedures, I decided that a few G's might coax it down.
Though I can happily find a bit more than 2G in a coordintated turn in most aircraft, and anger it closer to 3G by pulling once there - not it a Cheyenne! At speeds appropriate for the gear being extended, and with the flaps up, it gives an unmistakable stall buffet before you get to 2G. Two attempts at that were enough to convince me that fooling around accelerated stalls in a Cheyenne was not for me! Though perhaps it helped, as shortly afterward, the gear presented itself as desired, and it all worked out in the end.
It is easy to see that when something goes wrong, pilots can lose track of the primary role of mantaining controlled flight, and the problems compound. Engine failure during climb would be one of these opportunities. That probably factors well into the points with Big Pistons has presented, with which I completely agree!
