What would you do?

Salty

Salty

Touchdown! Greaser!
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Salty
I heard this story today, don’t really believe it, but let’s assume it’s true...

O-360 with constant speed prop suddenly over revs during cruise to 3500 rpm. Pilot flies to nearest airport 15 minutes at this rpm, attempts to land and ends up going off the runway and striking prop. I’d be tearing the engine down anyway, but...

if this happened to you, what would you do? I mean in the air when the rpms went up.
 
What does the POH say to do in that situation?
 
Lycoming mandatory service bulletin 369R covers what to do about an overspeed.

Overspeeds do occasionally happen. In the time I've been maintaining airplanes and overhauling engines I've only been involved in one overspeed case which occurred when the prop governor drive gear broke. The engine had to come apart to fix the governor drive anyway, so pushing the inspection was easy. That engine was enough of a mess anyway it just ended up getting overhauled.
 
If possible I'd reduce throttle until the RPM dropped into the safe range and limp into the nearest airport, assuming that altitude could be maintained at that power setting.
 
mondtster said:
Lycoming mandatory service bulletin 369R covers what to do about an overspeed.

Overspeeds do occasionally happen. In the time I've been maintaining airplanes and overhauling engines I've only been involved in one overspeed case which occurred when the prop governor drive gear broke. The engine had to come apart to fix the governor drive anyway, so pushing the inspection was easy. That engine was enough of a mess anyway it just ended up getting overhauled.
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I agree, but what would you do to keep it running until you get back on the ground?
 
A few years ago I had an over speed with my IO-540 due to my prop gov self destructing. I was out practicing instrument approaches when it happened. I opted to fly 20 min home in the DC SFRA rather than land at one of the nearby airports. Glad I did as I had no idea at the time exactly what had happened or that an over speed had occurred. It ended being a $30K inspection and replacement of the prop, and both alternators. There is a Lycoming SB that covers this. Hartzell has one too.
 
Salty said:
You own it.
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Priorities:

1) Get it to the airport. (Reduce RPM, if possible, using throttle, mixture, etc).
2) Do as little damage as possible. (Kill the engine at the appropriate point on final to be sure of making the runway, while minimizing the chances of an over-run).

Alternately, belly it in blaming a huge distraction. Then let the insurance company deal with it. ;-)
 
I guess the variable here is whether the overspeed can be controlled. You would think that reducing throttle or mixture would resolve it most of the time. I mean, even if you had to cut fuel mixture to get it slowed down you could probably keep modulating the fuel to provide intermittent power until you had a runway made. If you’re thinking the engine/prop is going to come from together and there’s no way to control it, move fuel selector to “off” and find a field I guess.
 
kyleb said:
Priorities:

1) Get it to the airport. (Reduce RPM, if possible, using throttle, mixture, etc).
2) Do as little damage as possible. (Kill the engine at the appropriate point on final to be sure of making the runway, while minimizing the chances of an over-run).

Alternately, belly it in blaming a huge distraction. Then let the insurance company deal with it. ;-)
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Well, adding belly skin replacements and 6 -12 months on a jig, plus 337s and double the insurance premium due to the 200k claim doesn't sound worth it.
 
Not just the engine, but the prop.

Overspeed prop is a concern. I would consult the prop manufacturer.
 
Salty said:
I heard this story today, don’t really believe it, but let’s assume it’s true...

O-360 with constant speed prop suddenly over revs during cruise to 3500 rpm. Pilot flies to nearest airport 15 minutes at this rpm, attempts to land and ends up going off the runway and striking prop. I’d be tearing the engine down anyway, but...

if this happened to you, what would you do? I mean in the air when the rpms went up.
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Set course for VERY long runway, declare emergency, make the airport, fly a practice approach, go around, set up to land at the 1000' marker, kill the mixture. glide for landing.
 
Geosync said:
Well, adding belly skin replacements and 6 -12 months on a jig, plus 337s and double the insurance premium due to the 200k claim doesn't sound worth it.
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Sounds like time to rent is here. That’s the price of owning a fine aircraft. If you had been renting all along this would never have become an issue. Now the answer it to rent, period. I guess the powers that be do not want you to own, period. OK then, let them carry the liability. The other option is to stop flying. Unless you have discretionary income or wealth out the wazoo. Then of course, you can do whatever you want.
 
I’m sincerely not laughing or enjoying the illustrated situation in any way. It’s a matter of practicality. Actually, the scenario described sucks! And we are talking about general aviation in the most open and free and resource rich civil aviation country on Earth! There comes a time in our life that favors compromise as opposed to battle because our time here is limited. And IT IS ALL GOOD!
 
Some aircraft performers run their engines well over 3,000 rpm, so I've heard. But to answer the question, I would refer to the prop and engine manufacturer and do what they recommend.
 
PaulS said:
Some aircraft performers run their engines well over 3,000 rpm, so I've heard. But to answer the question, I would refer to the prop and engine manufacturer and do what they recommend.
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You gonna call them from the cockpit?
 
Salty said:
You gonna call them from the cockpit?
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Maybe? lol, realistically, pull the power back, the rpm will drop, if that results in not enough power to make it to a safe landing then, f the engine, it has failed you, run it, with enough power to get to a landing, then be smart and have it reviewed per the manufacturer's instructions. Ain't worth dying over.
 
Geosync said:
Well, adding belly skin replacements and 6 -12 months on a jig, plus 337s and double the insurance premium due to the 200k claim doesn't sound worth it.
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what kind of airplane is this?
 
I'm a little shocked at the responses here. A governor failure is part of my complex or high performance endorsements. Pull the power back and slow the airplane to get the rpm down. Land as soon as practical.
 
Capt. Geoffrey Thorpe said:
Pull the big black knob out?
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That's the first thing I'd try. I have a tough time believing someone would watch the RPM go to 3500 on their O-360 and think boy that's strange, I'd better leave it there and fly it to an airport that way. Why would you do that?
 
Salty said:
if this happened to you, what would you do? I mean in the air when the rpms went up.
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Assuming I’m in the single mentioned and not my plane:
1) pull the prop lever back to see if I can lower it
2) pull the throttle back to see if I can lower it and still fly
3) pull the nose up to Vy and see if that has any lowering effect until I’m over the airport
4) decide on over speeding while landing or dead-sticking it. If I was solo and comfy with the plane probably dead stick. Otherwise when landing assured kill the mixture and slip as needed to dissipate energy to stay on the concrete. Drop plane off at mechanic. Watch checking account shrink.
 
PaulS said:
Some aircraft performers run their engines well over 3,000 rpm, so I've heard. But to answer the question, I would refer to the prop and engine manufacturer and do what they recommend.
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You are correct however they are not stock engines and they are overhauled every 20 to 150 hours depending on how they are operated.
 
My POH says: "

Propeller Overspeed
  1. Throttle -retard to red line
  2. Airspeed -reduce
  3. Oil pressure - check
Warning: If loss of oil pressure was cause of overspeed, the engine will seize after a short period of operation.

4. Land - Select nearest suitable site and follow landing emergencies procedure


My second hand information from those who experienced this, the engine seizes in under a minute. I add the following step to my procedure:

Pull the firewall shutoff.

Reason is that I have heard in most instances the engine will freeze as parts fly thru the case and oil will come out onto the hot engine and fill the cabin with dense white smoke, making visibility inside the cockpit near zero until the smoke/oil steam dissipates.
 
If the throttle doesn’t work you make it a glider, yeah? The part about the hard landing confuses me; even if the pilot couldn’t lower rpm, they can turn the engine off for landing...

Was doing night 180 power off landings (at idle) the other day in a rental and ended up doing a power off takeoff...lol. No sputter, just peace and quiet about 500 feet off the ground on takeoff. Got ‘Er started while gently lowering the nose and turning to clear power lines. (fuel starvation, Piper, gauge showing 1/2 tank)
 
kyleb said:
Priorities:

1) Get it to the airport. (Reduce RPM, if possible, using throttle, mixture, etc).
2) Do as little damage as possible. (Kill the engine at the appropriate point on final to be sure of making the runway, while minimizing the chances of an over-run).

Alternately, belly it in blaming a huge distraction. Then let the insurance company deal with it. ;-)
Click to expand...

Nothing in my POH, but since we're at cruise I'd yank the black knob to idle, yank the blue knob out, and see where the rpms are. If still overspeed, slow until either 65kts or so, or until the rpms are below 2700. If they drop below 2700, add just enough black knob to achieve 2700, then look for a place to land.

I'd certainly not continue to fly at 3500rpm until landing.
 
You can control RPM and power with the mixture, pull it till RPMs drop, yes the engine will stumble a bit, but leaning, no matter how much, won’t hurt the engine, unlike high RPMs.
 
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