Unfortunate example of a classic VMc crash at low level in a twin.
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Unfortunate example of a classic VMc crash at low level in a twin.
Well, the video speaks for itself.
Pilot let it get to slow and ran out of rudder and with no altitude left to correct, he was toast. Or maybe he initiated a base turn and got to slow there. Anyway, he should have throttled back on the good engine, or/and kept speed up. Look how fast it rolls when it starts. Tragic.
Pilot let it get to slow and ran out of rudder and with no altitude left to correct, he was toast. Or maybe he initiated a base turn and got to slow there. Anyway, he should have throttled back on the good engine, or/and kept speed up. Look how fast it rolls when it starts. Tragic.
Last edited by AdamFrisch; 19th Dec 2011 at 01:59.
What ever they tell you in the book I was amazed by the speed of this... Any report on how, what, where this happened?
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Happened recently in the Philippines - bit more discussion here:
http://www.pprune.org/rumours-news/4...ane-crash.html
http://www.pprune.org/rumours-news/4...ane-crash.html
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One engine sounds as if its wasn't very happy backfiring.
Problem is with alot of folk is they think keeping a knackard engine running is helping matters.
If you are down at flight idle alot of the time this is actually creating more drag than if you had shut the thing down. For my type if your under 10-12% torque you are making matters worse flight idle is 2-6%
Of course with additional drag one side that won't give you the expected climb performance or possibly decent drift down performance and also will give you a significant increase in Vmca. Then they are decending not going to make it so pitch up, feed more rudder which creats more drag which makes them pitch up again until they run out of rudder then wham she rolls on her back and in she goes with more airspeed than the books says your safe doing.
Problem is with alot of folk is they think keeping a knackard engine running is helping matters.
If you are down at flight idle alot of the time this is actually creating more drag than if you had shut the thing down. For my type if your under 10-12% torque you are making matters worse flight idle is 2-6%
Of course with additional drag one side that won't give you the expected climb performance or possibly decent drift down performance and also will give you a significant increase in Vmca. Then they are decending not going to make it so pitch up, feed more rudder which creats more drag which makes them pitch up again until they run out of rudder then wham she rolls on her back and in she goes with more airspeed than the books says your safe doing.
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It's hard to know exactly what's going on here, but he seems to turn into the dead/misfiring engine, which at slow speed is not a good idea. Raise the dead, and then proceed to make an approach that will sustain that wing high. In this case, it seems he should have told them he'd do a right circuit to land or gone straight in.
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I don't think they had any choice in the matter.
You have less than a second to reduce the power on the working engine. It would have been above blue line speed when it happened.
The more power you have in each engine the faster it all happens.
You have less than a second to reduce the power on the working engine. It would have been above blue line speed when it happened.
The more power you have in each engine the faster it all happens.
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Yep your normally Vyse is above Vcma. Maybe blue line is the wrong one as I haven't flown anything with a line for years for me its always V2 and Vyse bugs.
You have more drag on the flight idle engine than if it was feathered which means more yaw with the other one at full chat. This means your Vcma is increased quite dramatically because its worked out with the engine feathered.. The bigger the engines/props the bigger the increase.
You have more drag on the flight idle engine than if it was feathered which means more yaw with the other one at full chat. This means your Vcma is increased quite dramatically because its worked out with the engine feathered.. The bigger the engines/props the bigger the increase.
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As long as you don't get too slow, most twins are pussycats. If an engine quits at altitude or cruise, it's a non event. But down close to Vmca and the ground... In this instance a single would probably have had a safer outcome.
My Vmca is not published, but I tried it recently at altitude and it's around 65-67kts. This is with an unfeathered engine, so potentially slightly lower feathered. I'm guessing around 62kts, maybe. Still, you'd want to keep a good margin above that. My Vyse is 81kts.
Greve - Get a Cessna Skymaster
My Vmca is not published, but I tried it recently at altitude and it's around 65-67kts. This is with an unfeathered engine, so potentially slightly lower feathered. I'm guessing around 62kts, maybe. Still, you'd want to keep a good margin above that. My Vyse is 81kts.
Greve - Get a Cessna Skymaster
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Right...you just cured me from ever wanting to get a twin rating.
Get yourself a TBM850
I was able to fly one "out of the box" with minimal instructor involvement and fly an ILS down to 200ft after the 1.5hr flight.The catch? You need considerably more dosh than for a typical beaten-up piston twin, although the ongoing operating costs will probably be fairly similar
TBM700 prices are coming down, but they are still way above piston twins.
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Yeah, but even with a TBM850 - would you feel comfortable doing a 4hr leg over water? I wouldn't. But I would in a twin.
If I may offer you, dear sir, the very best aircraft ever built - the Rockwell 695, the last of the twin turbine Commanders....
...has a 300kts cruise, a 2100nm range (longest range of any turbine I know of), burning 64gal/hr, can take off and land on any surface. The Dash 10 Garretts have a 5400hr TBO - eat your heart out PT6's, with their puny 2000hr. Not only that, they'll burn less specific fuel per SHP. If you're in a bind they can run on any fuel - diesel or avgas. Try that with a PT6 and they're toast. All this for half the price of a used TBM700. Fantastic aircraft that has true transcontinental capabilities.
If I may offer you, dear sir, the very best aircraft ever built - the Rockwell 695, the last of the twin turbine Commanders....
...has a 300kts cruise, a 2100nm range (longest range of any turbine I know of), burning 64gal/hr, can take off and land on any surface. The Dash 10 Garretts have a 5400hr TBO - eat your heart out PT6's, with their puny 2000hr. Not only that, they'll burn less specific fuel per SHP. If you're in a bind they can run on any fuel - diesel or avgas. Try that with a PT6 and they're toast. All this for half the price of a used TBM700. Fantastic aircraft that has true transcontinental capabilities.
Last edited by AdamFrisch; 19th Dec 2011 at 21:41.
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It's hard to know exactly what's going on here
I opine that a spin entry will happen with much more abruptness than a roll loss of control resulting from poor flying below Vmca. The below Vmca roll would be recoverable up to a point, with a reduction of power on the high side. An incipient spin entry in that aircraft probably requires a whole turn of recovery effort to get out.
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but even with a TBM850 - would you feel comfortable doing a 4hr leg over water? I wouldn't. But I would in a twin.
The other thing is that there are very few 4hr legs over water - unless you are doing an Atlantic run and a pretty direct one. 4hrs is about 1000nm+ at economy cruise.
My Vmca is not published, but I tried it recently at altitude and it's around 65-67kts. This is with an unfeathered engine
Full Power on the live Engine
Failed Engine Windmilling
Critical Engine failed
Flaps in take off position
Undercarriage up
C of G rearmost at MTOW
At Sea Level
If you don't meet those conditions its not VMCA and it doesn't vary.
VMC on the other hand takes into account the element of surprise of a sudden and complete engine failure, with full power on the other engine such that the average skilled pilot can maintain control in straight flight with no more than 5 degrees bank applied towards the live engine.
I don't think that measuring the lowest speed that you can maintain the aircraft straight at altitude is getting close to determining either of these critical speeds.
The film clip is interesting, is the aircraft asymmetric or did it suffer an engine failure in the turn? The rate of roll is more characteristic of a stall that an engine failure in the turn as the base leg power setting would not be sufficient to roll the aircraft so dramatically. If its a stall in the turn, the outcome would not be de-similar in a single. A useful training clip.
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Before it turns it seems to have a very low forward speed for the sound of the engine(s) - a 'high power setting' noise. Would this not indicate that the LH engine was probably windmilling (lots of drag) and the RH was at full power, but speed low due the assymetric power and drag?