Dead Foot, Dead Engine? ...maybe

Captain

Captain

Final Approach
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So I had my first engine failure in just over 10,000 hours of flying the other night. We were enroute to KSUA and at FL270, going over 330 kts in cruise when it happened. I ended up diverting to KPBI for longer runways and better crash rescue services. I did declare an emergency.

A little background. A P180 has a power lever and a condition lever for each PT6 engine. They are both linked to the fuel control unit and propeller governor through linkages and use a bit of PFM to operate and control the engine. Basically, in flight, the power lever controls fuel to the engine and the condition lever controls prop pitch. That changes a bit on the ground and for start but that doesn't really apply here except the condition lever is also the fuel cutoff in the bottom detent.

I've seen a cell phone video the mechanic took the following day and it's pretty obvious what happened. The linkage from the power lever became detached to the FCU.

So, while flying in cruise the right engine just accelerated to max power, over the normal cruise torque limit. The plane yawed firmly to the left and I immediately looked to the engine gauges to see the right engine over torqued. I pulled the right power lever back to lower the torque and that had no effect even going to the stop. So with the power lever all the way back at idle and the engine still in an over torque I was forced to pull the condition lever back to cutoff.

That's when the 'dead foot dead engine' saying went through my head...but wait..my left foot is dead. That's odd. I'm about to pull the right condition lever to cut off and my left foot is dead. I looked again at the stack and confirmed...'yup, it's the right engine' I said to myself and pulled it back to cutoff.

The right engine quit when the fuel was cut off and it went to feather. After that everything was as you'd expect. We continued and landed in PBI as uneventfully as you could expect having an engine failure. Talked to the Fire Rescue folks (nice guys and I've even taken my boys to their facility for a tour and a ride in the Dragon), gave some info to the airport manager rep and that was that.

Thought I'd pass this along as a possible alternative scenario to what we have ingrained in us during our ME training.
 
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Yep, because your engine 'failure' was atypical in that it didn't fail to produce power, it was producing too much so your 'dead foot' would be opposite until you got it shut down.
 
Seeing how I fly and train SEL. I take it when you loose an engine in a twin you shut down the engine on the side your foot is not pushing on the rudder peddle.

Good job reading the situation and not going into default mod so to speak. I always say listen to the airplane, its talking to you.

I learned this lesson about 40 hrs after soloing. Lost reduction unit and prop on a Brand New airplane. This was something little tiny compared to anything you folks fly, I am ashamed to even mention it. But I did learn a lot from it. It happened in a Legal eagle at 1000' Landed in a corn field, the corn was about 2 inches tall. I have a pic somewhere of my airplane in the field. If I find it I will post it.

I envy all you who fly the bigger birds and also have a lot of respect for those who do. MEL is out of my pay grade. Yeck a 172 is out of my pay grade. Sucks to be me..LOL

Tony
 
uuuuhhh, I fly behind a pair of O-320-A1A
A massive overpower condition on one side is not something I train for
For me it is dead foot/dead engine
Or more factually, dead engine versus less dead engine
Must be nice to have your problems Captain - well, as long as I am not paying the fuel bill that is.
 
My limited time with turbo prop twins ,was forget dead foot dead engine. Verify before any shutdown feather.
 
Interesting story. It's not often you hear about "I have too much power" emergencies.
 
frfly172 said:
My limited time with turbo prop twins ,was forget dead foot dead engine. Verify before any shutdown feather.
Click to expand...
I was also taught to forget about dead foot dead engine when I went to initial in the King Air. The rudder bias which kicks in when one engine fails could fool you. This is probably true of any airplane which has an automatic assist to the rudder during engine failure.
 
Dang Captain what a weird failure mode. The linkage to the FCU, was it broken or fastner missing? Also any repercussions on the over torque. Some manufactures give a time verses amount of over torque limitation. These are - 66 engines, correct?

I am curious about your statement about condition levers. Am I reading your post correctly that condition levers control prop pitch? On the P&W's I am familiar with "not in beta" pitch (RPM) is controlled by the prop control (blue). The condition lever shuts fuel off and on. On some models you can go past start to allow a higher ground RPM for example when doing a generator assist start. Usually an extra 15% Ng or so. You return condition levers to start for take off and normal ground proceedures. I am not familiar with the P180 at all. Have they somehow deleted the prop control lever? :dunno:

Edit: After writing this, it seems like way way back in the deepest recesses of what few functioning brain cells I have, I think the P180 does have some kind of un natural (;)) control levers. Anyway I am curious. Oh, and good job!
 
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My turbine time is limited to single and duel engine helicopters but an over speed was always something we worried about and probably more than a failure...although we could always lock out the FADEC and fly it manual throttle it was a *****...
 
frfly172 said:
My limited time with turbo prop twins ,was forget dead foot dead engine. Verify before any shutdown feather.
Click to expand...

The American Eagle crash at RDU really points out the verify issue. They feathered a perfectly good running engine because a 'relight' light didn't extinguish after the engine relit. Then the Captain stepped on the wrong pedal to keep control. The last thing on the CVR is my buddy Matt in the right seat saying "Wrong Foot! Wrong Foot!" :(
 
I'd imagine the P180 also has a yaw damper, wonder how much that might mask things.
 
Captain said:
So I had my first engine failure in just over 10,000 hours of flying the other night. We were enroute to KSUA and at FL270, going over 330 kts in cruise when it happened. I ended up diverting to KPBI for longer runways and better crash rescue services. I did declare an emergency.

A little background. A P180 has a power lever and a condition lever for each PT6 engine. They are both linked to the fuel control unit and propeller governor through linkages and use a bit of PFM to operate and control the engine. Basically, in flight, the power lever controls fuel to the engine and the condition lever controls prop pitch. That changes a bit on the ground and for start but that doesn't really apply here except the condition lever is also the fuel cutoff in the bottom detent.

I've seen a cell phone video the mechanic took the following day and it's pretty obvious what happened. The linkage from the power lever became detached to the FCU.

So, while flying in cruise the right engine just accelerated to max power, over the normal cruise torque limit. The plane yawed firmly to the left and I immediately looked to the engine gauges to see the right engine over torqued. I pulled the right power lever back to lower the torque and that had no effect even going to the stop. So with the power lever all the way back at idle and the engine still in an over torque I was forced to pull the condition lever back to cutoff.

That's when the 'dead foot dead engine' saying went through my head...but wait..my left foot is dead. That's odd. I'm about to pull the right condition lever to cut off and my left foot is dead. I looked again at the stack and confirmed...'yup, it's the right engine' I said to myself and pulled it back to cutoff.

The right engine quit when the fuel was cut off and it went to feather. After that everything was as you'd expect. We continued and landed in PBI as uneventfully as you could expect having an engine failure. Talked to the Fire Rescue folks (nice guys and I've even taken my boys to their facility for a tour and a ride in the Dragon), gave some info to the airport manager rep and that was that.

Thought I'd pass this along as a possible alternative scenario to what we have ingrained in us during our ME training.
Click to expand...
Well done. It's always amusing to watch someone get their first engine overspeed failure in the sim. It is a very confusing scenario. :lol:

For those who think the PT-6 is bulletproof, it is not.
 
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Dead Stick said:
For those who thing the PT-6 is bulletproof, it is not.
Click to expand...

Sounds more like an accessory/linkage issue than a PT6 issue to me. I'm still pretty confident in the P&W
 
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Dead Stick said:
Well done. It's always amusing to watch someone get their first engine overspeed failure in the sim. It is a very confusing scenario. :lol:
Click to expand...
Now that I think back (a long ways) I got this scenario during King Air initial on takeoff and I didn't stay on the runway.
 
James331 said:
I'd imagine the P180 also has a yaw damper, wonder how much that might mask things.
Click to expand...

It does have a yaw dampener. I disconnected that after I pulled the power lever back. It's SOP for me to fly the plane with the YD off when single engine. Gives me a feel for the plane.

NJP_MAN said:
Sounds more like a accessory/linkage issue than a PT6 issue to me. I'm still pretty confident in the P&W
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I just saw the plane in the shop. It was indeed linkage that failed. A wire tied nut started working itself loose and two locking washers finally got loose enough to skip teeth and that's what did it.

Turns out there was a bunch of over torque...broke an engine mount. So now they're sending off oil and doing a bore scope I think. They're still early in the process so don't hold me to anything. I took a couple pics I'll try to attach later if anyone is interested.
 
Really? Power lever and condition lever. No prop control on a P180?

I can't imagine the condition lever controlling the prop.
 
On s###. Gear boxes are breath taking expensive. Sounds like you got things under control before everything went to h### in a hand basket. Scary that it broke a mount!! Again, good job! Yes post pictures.
 
kgruber said:
Really? Power lever and condition lever. No prop control on a P180?

I can't imagine the condition lever controlling the prop.
Click to expand...

My thought untill I thought it over, read my post #9.

Edit: Captain how hot did the turbine get? At 270 you had to be temp limited so to make enough torque at that altitude... Did you by chance attempt a feather before getting power reduced? Glad the thing did not grenade on you. It is amazing how quickly things can get into the proverbial hand basket. Glad you and passengers got on the ground safely, that is all that counts. Regardless, the insurance is going to get a work out. That is what the premiums are for.
 
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Do you recall what the ITT was before finally getting it shut down ?



Edit : ^ just saw that post asking about temp as well.
 
Good flying, Captain; and thanks for telling about it. Hope for the owner's sake the engines were on program.
 
I know just about as many pilots who have shut PT6s down for over-torque problems as for low-power/failure problems. Not as uncommon as we'd like to think.
 
MauleSkinner said:
I know just about as many pilots who have shut PT6s down for over-torque problems as for low-power/failure problems. Not as uncommon as we'd like to think.
Click to expand...
Another common issue is oil pressure - too high or too low that requires a significant power reduction to keep the engine from eating itself up. It's a non-issue in twins, but not so much in singles. Problems like this don't show up as engine failures in the statistics, but none the less, that's exactly what they are. Like I said, no engine is bulletproof, not even the PT-6.
 
MauleSkinner said:
I know just about as many pilots who have shut PT6s down for over-torque problems as for low-power/failure problems. Not as uncommon as we'd like to think.
Click to expand...

May be but, at 270 it is going to be hard to over torque with out a propeller problem. If the prop is turning any kind of reasonable RPM, in a cruise range, to get over torque is going to result in PT blades being spit out due to heat. I am not sure a -66 will produce red line torque at 270 at any turbine temperature. If there was some type of auto feather failure or simply an attempt to feather at altitude then all bets are off. If the over torque was enough to break a motor mount you are looking at hub, blades, gear box and at least a PT section. Ouch!!
 
A common over-torque scenario is bearing seizure on the gas generator governor...calls for massive amounts of fuel, and will over-torque at pretty much any airspeed/prop setting.
 
ronnieh said:
May be but, at 270 it is going to be hard to over torque with out a propeller problem. If the prop is turning any kind of reasonable RPM, in a cruise range, to get over torque is going to result in PT blades being spit out due to heat. I am not sure a -66 will produce red line torque at 270 at any turbine temperature. If there was some type of auto feather failure or simply an attempt to feather at altitude then all bets are off. If the over torque was enough to break a motor mount you are looking at hub, blades, gear box and at least a PT section. Ouch!!
Click to expand...


This. The linkage to the FCU is also connected to the beta rod. My suspicion now that I know mounts are broke is that it went into feather and that caused the over torque. I didn't see any other red other than the torque so I'm pretty confident it didn't go over ITT limit and that would support my theory.
 
That makes sense. I am not familiar with the linkage on the P180. I know it is kind of strange compared to a more conventional. No doubt going into feather would wreak havoc. I suspect you will be lucky if the blades, hub and gearbox are OK. Sounds like you did a great job of handling a very weird situation. Keep us advised, I am just curious as to what the final damage will be.
 
Captain said:
A wire tied nut started working itself loose and two locking washers finally got loose enough to skip teeth and that's what did it.
Click to expand...

How did the nut work itself loose if it was wire-tied? Did the wire break? What caused that to happen??
 
And, remember, nobody is counting the PT6 failures in a twin. They just land and get fixed.

The published MTBF for the PT6 is pure fantasy!
 
Jim_R said:
How did the nut work itself loose if it was wire-tied? Did the wire break? What caused that to happen??
Click to expand...

I don't know. I saw the wire tie there but the whole post was loose under the wire tie.


Here are the pics I mentioned. The pink arrow is the post that worked loose. The blue arrow is linkage that goes back to the Beta Rod.

Engclose.jpg


Here is a pic I snapped in the Sim. Notice how there is only a Power Lever and a Condition Lever for each engine. There isn't a props lever per-se as the Condition Lever incorporates that function.

Pedistal.jpg
 
kgruber said:
And, remember, nobody is counting the PT6 failures in a twin. They just land and get fixed.

The published MTBF for the PT6 is pure fantasy!
Click to expand...

Meh, over 5,000 hours flying two of them at a time and this is the first to quit. And it wasn't actually the engine that quit but the linkages. And I flew for Avantair who wasn't exactly know for stellar maintenance!

:)
 
Captain said:
Meh, over 5,000 hours flying two of them at a time and this is the first to quit. And it wasn't actually the engine that quit but the linkages. And I flew for Avantair who wasn't exactly know for stellar maintenance!

:)
Click to expand...

5000 hrs......me too. And two of them quit.
 
Captain said:
....That's when the 'dead foot dead engine' saying went through my head...but wait..my left foot is dead. That's odd. I'm about to pull the right condition lever to cut off and my left foot is dead. I looked again at the stack and confirmed...'yup, it's the right engine' I said to myself and pulled it back to cutoff.....
Click to expand...

daaamn, Captain.....did u stay in a holiday inn express the night before or what!? job well done!!
 
Good job.

Maybe one day you can start a thread about the performance, handling and maintenance of the P180? It's one of those dream planes I've swore I want to own before I die. And the firs generation ones are creeping down in price.. Be good to hear from someone who actually flies them.
 
I suspect the broken part is integral to the fulcrum, that's why the wire doesn't matter.
 
kgruber said:
And, remember, nobody is counting the PT6 failures in a twin. They just land and get fixed.

The published MTBF for the PT6 is pure fantasy!
Click to expand...

I believe PWC says 1 failure per 1 million flight hours. Or something ridiculous like that. Another source says 1 per 200'000 hours.
Sounds like what NASA said about the Space Shuttle pre-Challenger.
 
I'd be suspicious of the 200,000 hr figure as well.
 
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Well, you did the opposite. And it worked! Maybe you should keep it up!!
 
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