Manipulating Throttle Regained Power

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pelmet
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Manipulating Throttle Regained Power

Post by pelmet »

….or at least that is what it sounds like may have happened in a recent incident, I have heard it mentioned previously that different positioning of the various engine controls could result in an power recovery after a failure depending on the circumstances. And while the odds of it being successful might be minimal it could be worth the effort...….

"C-GSFR, a Cessna 172S operated by Southern Interior Flight Centre (1993) Ltd, was conducting
circuit training flights at Kelowna International Airport (CYLW), BC, with 1 flight instructor and 1
student on board. During the second circuit, the aircraft experienced a sudden engine power loss
(Avco Lycoming, IO-360-L2A) during climb out at approximately 200 feet AGL. The flight instructor
took control, declared a MAYDAY and pitched the aircraft forward in preparation for a forced
landing. The flight instructor recovered engine power with throttle manipulation at approximately 75
feet AGL and climbed to 300 feet AGL. A second MAYDAY was declared and the aircraft landed
without incident on Runway 16. ARFF was on standby. There were no injuries and no damage to
the aircraft. The G1000 download indicated a fluctuating fuel flow with a drop to 1.08 gallons per
hour. Maintenance removed the fuel servo (Precision Airmotive Model RSA-5AD1) to inspect for
intermittent operation."
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PilotDAR
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Re: Manipulating Throttle Regained Power

Post by PilotDAR »

Two thoughts:

For carburetted planes (not the 172S mentioned), following a loss of fuel flow in the carb gently pumping the throttle may give you some power, as the engine might run somewhat on the accelerator pump. The primer may also be used this way - I have had occasion to do both. There are a few older carburetted planes which are not equipped with accelerator pumps in the carb, and it is wise to know for the plane you fly.

If you have had an engine failure to the point where sustained flight is not possible, and you have a suitable landing site available, really consider continuing with the forced landing, and not relying on power. If the power returns for reasons you don't understand (Yeah, if you changed to the full fuel tank, you do understand the reason for the power loss), abandoning a suitable landing site to continue, or return to a runway is risky, should the power fail again.

In the mean time, practice forced landings....
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GoinVertical
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Re: Manipulating Throttle Regained Power

Post by GoinVertical »

A throttle sweep, and a mixture sweep, should always be taught as memory items for power loss in a piston.

I've had a fuel injected piston lose power during the climb to the point it would not maintain altitude, but closing the throttle to around half brought it back to life. No problem returning to land.

Turned out to be a partially blocked fuel line, and with higher fuel flows the piece of dirt was becoming lodged against a fitting, where as at lower fuel flows it was loose enough for fuel to travel around it.

Have had similar issues with clogged injectors.
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rookiepilot
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Re: Manipulating Throttle Regained Power

Post by rookiepilot »

GoinVertical wrote: Sat Apr 11, 2020 4:10 pm A throttle sweep, and a mixture sweep, should always be taught as memory items for power loss in a piston.

I've had a fuel injected piston lose power during the climb to the point it would not maintain altitude, but closing the throttle to around half brought it back to life. No problem returning to land.

Turned out to be a partially blocked fuel line, and with higher fuel flows the piece of dirt was becoming lodged against a fitting, where as at lower fuel flows it was loose enough for fuel to travel around it.

Have had similar issues with clogged injectors.
Interesting....good to remember
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pelmet
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Re: Manipulating Throttle Regained Power

Post by pelmet »

Glad I started the thread. Thanks for the input GoinVertical.
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JasonE
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Re: Manipulating Throttle Regained Power

Post by JasonE »

PilotDAR wrote: Fri Apr 10, 2020 7:35 amIn the mean time, practice forced landings....
Very good advice. I did a presentation for our flying club on this topic, only the recently licensed pilots had practiced any in the past 12 months!! I had one in an airframe which I was very comfortable with and had practiced many many times. It saved my butt and was almost a non event, except for the $40K engine repair. :shock:
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jakeandelwood
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Re: Manipulating Throttle Regained Power

Post by jakeandelwood »

Anyone who has ever owned a Chrysler product from the 60's or 70's will have valuable experience in how to use throttle manipulation and the accelerator pump to keep the old pig running especially when cold 😆
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jakeandelwood
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Re: Manipulating Throttle Regained Power

Post by jakeandelwood »

Anyone who has ever owned a Chrysler product from the 60's or 70's will have valuable experience in how to use throttle manipulation and the accelerator pump to keep the old pig running especially when cold 😆
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lownslow
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Re: Manipulating Throttle Regained Power

Post by lownslow »

Depending on the airplane and failure mode, manipulating the throttle can also make your situation irreversibly worse. A friend of mine was in a spot once where he could close the throttle more but not open it. In that situation it’s probably better to discover that at 60% power than at 25%, you know?
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Scuderia
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Re: Manipulating Throttle Regained Power

Post by Scuderia »

There are points at which one should commit to a forced landing and stop mucking around with the engine and trying to regain power. Get rid of air, fuel, and spark -- the last thing I want at 50 feet is a surge of power making me overshoot my landing area, especially if it means going off the end of a runway vs landing on remaining pavement.
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photofly
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Re: Manipulating Throttle Regained Power

Post by photofly »

I can’t help but smile at the implied criticism of the instructor, who, after all, recovered his student, himself, and the airplane to a satisfactory conclusion.
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Scuderia
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Re: Manipulating Throttle Regained Power

Post by Scuderia »

photofly wrote: Sun Apr 12, 2020 6:45 pm I can’t help but smile at the implied criticism of the instructor, who, after all, recovered his student, himself, and the airplane to a satisfactory conclusion.
Sorry, should've been clearer to avoid someone reading into it and seeing that implication. If I wanted to criticize the instructor I would've been direct and said so. In fact it's very likely that they were cutting the throttle to land straight ahead when power suddenly returned.

My comment stands only as general commentary for similar situations.
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pelmet
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Re: Manipulating Throttle Regained Power

Post by pelmet »

Scuderia wrote: Sun Apr 12, 2020 5:58 pm There are points at which one should commit to a forced landing and stop mucking around with the engine and trying to regain power. Get rid of air, fuel, and spark -- the last thing I want at 50 feet is a surge of power making me overshoot my landing area, especially if it means going off the end of a runway vs landing on remaining pavement.
I have read of this happening several times leading to more damage. In those cases, the throttle was not at idle and the engine was not secured.
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