Emergency procedure: Power Loss in Flight

[Ulysse]

My POH states :

Power Loss in Flight:
Fuel selector SELECT OTHER TANK
Throttle    FULL FORWARD
Mixture        FULL FORWARD
Propeller    FULL FORWARD
Magneto/Starter Switch    Verify on BOTH
High Fuel Boost Pump    ON

Then, in other sections where power loss is mentionned, the rule is to cut off mixture and slowly advance.

I do not understand why the procedure regarding mixture setting is different.
 

 

[201er]

3 hours ago, Ulysse said:

My POH states :

Power Loss in Flight:
Fuel selector SELECT OTHER TANK
Throttle    FULL FORWARD
Mixture        FULL FORWARD
Propeller    FULL FORWARD
Magneto/Starter Switch    Verify on BOTH
High Fuel Boost Pump    ON

Then, in other sections where power loss is mentionned, the rule is to cut off mixture and slowly advance.

I do not understand why the procedure regarding mixture setting is different.
 

 

If you burn a tank dry in flight while cruising LOP and then switch tanks, it will still flame out. Won’t restart that lean so you have to slowly advance the mixture.

[aviatoreb]

Why throttle full forward?  Wouldn't something closer to mid throttle like closer to how you start it on the ground be better?

[N201MKTurbo]

Just switching tanks usually gets the job done.

[PeteMc]

I know the POH says to push everything in, but don't, at least at first.  Just switch the tank and give it a few (agonizing long) seconds.  If you're running LOP, then as @201er said, push the mixture in a bit to get in the rich side of peak.

If the engine doesn't start, then slowly push the mixture all the way in and then slowly push in the throttle.  If the prop has stopped, bring the throttle back more to the middle and use the starter.

 

 

Edited April 28, 2022 by PeteMc

[201er]

1 hour ago, PeteMc said:

I know the POH says to push everything in, but don't, at least at first.  Just switch the tank and give it a few (agonizing long) seconds.  If you're running LOP, then as @201er said, push the mixture in a bit to get in the rich side of peak.

If the engine doesn't start, then slowly push the mixture all the way in and then slowly push in the throttle.  If the prop has stopped, bring the throttle back more to the middle and use the starter.

Just realized we're talking about a K model. Letting a tank run dry at high altitude can be disastrous as there won't be enough air for a relight without the turbo. Hence why POH probably recommends to give it all the throttle you've got. But, don't be quick to go full throttle down low and be prepared for a surge.

[Fly Boomer]

OP never said anything about switching tanks.  I think the question was about power loss.

[Hank]

Nobody has said anything about pitching for best glide, either. How quickly do you want to descend???

[jaylw314]

3 hours ago, 201er said:

Just realized we're talking about a K model. Letting a tank run dry at high altitude can be disastrous as there won't be enough air for a relight without the turbo. Hence why POH probably recommends to give it all the throttle you've got. But, don't be quick to go full throttle down low and be prepared for a surge.

Nah, all POH's I've seen say something similar.  I don't know that it would be "disastrous" at high altitude since you've got plenty of time and altitude to glide, descend, troubleshoot and, if needed, wait to a lower altitude to restart the engine, unless you're over the Himalayas  

The POH is just for the plane.  The pilot still needs his own engine-out emergency checklist, like "Airspeed, Best landing spot, Cockpit checks, Communicate".  The POH stuff is only a part of that, and not the first thing.

For OP, @Ulysse, the checklist you listed is probably the "power loss during takeoff or climb" and is intended to include both partial and complete power loss.  In either case, there's no time for separate checklists, it's a balls-out, everything forwards, throw the kitchen sink checklist.  There should be a subsequent checklist that is "power loss in flight" and has a more limited and specific scope. 

I think the one you're looking at is the "Air Restart" checklist, which assumes that you've FOUND and corrected the cause of your power loss (presumably a fuel problem).  Now, you have the time and space to do the restart correctly and safely, which includes mixture at idle, mags both, little throttle (mine says 1/4 throttle), then advance mixture gradually.  That way, you don't get a massive afterfire from unburnt fuel, which your exhaust system won't enjoy

Edited April 28, 2022 by jaylw314

[carusoam]

Yikes!

Gents…

For TC’d pilots…

 

Know your turbo restart procedures!

Know that once the turbo spools down, re-starts get challenging…

Turbo failures, lost intake hose couplings… anything that lets the MP equal outside pressure…

 

Know what the restart altitude for your engine is…

Have this in your plan when flying over mountains…

 

This is a nice topic for transition training… from NA to TC….

It goes much deeper than NA engine restart at altitude…

Mixture pulled back, and sweep forwards… is hunting the mixture that will re-light the fire…

If all is mechanically well… the fire re-lights and turbo spools back up… and mixture calls for more….

 

PP thoughts only, not a TC’d pilot…

Best regards,

-a-

 

[A64Pilot]

Theses aren’t Diesel’s, why won’t they restart at any altitude the aircraft is capable of? High altitude and no boost you want to be pretty lean to restart, at the flight levels with no boost full rich is going to be awful as in maybe flooding rich. If you lose the boost and were LOP, you won’t be when all that boost is gone. It’s just like being at an high altitude airport, but way moreso of course

Finally if there is a restart max ceiling, it will be in the POH, what does the POH say about restarts?

If an engine quit because the tank ran dry, selecting the other tank will have it running again remarkably quick, just a few seconds, if it doesn’t come back real quick then it wasn’t the tank.

Lastly even at high altitude the prop will keep windmilling, if your 110 kts indicated or so and it stops, something is wrong inside the engine, if the engine quits and you don’t re-trim she will pitch down and maintain trim speed pretty much.

Edited April 28, 2022 by A64Pilot

[PeteMc]

Mine basically says if you don't catch it while the Tubo is still spinning, take a quiet ride down below12K and try again.

At altitudes above 12000 feet engine restart will take 13 seconds or longer when switching from an empty fueltank to a full fuel tank.
1. Throttle - Full Forward.
2. Low Fuel Boost Pump - On.
3. Fuel Selector - other Tank.
4. Mixture - Full Rich.
5. Magneto/Starter Switch - Check Both On.
6. If Engine Starts - Retard throttle as MP approaches 40 in. Hg. Boost Pump Off.
7. If engine does not restart - Attempt restart procedure with high boost pump on.
8. If engine does not restart - Descend below 12000 ft and repeat.

[carusoam]

7 hours ago, A64Pilot said:

Theses aren’t Diesel’s, why won’t they restart at any altitude the aircraft is capable of? High altitude and no boost you want to be pretty lean to restart, at the flight levels with no boost full rich is going to be awful as in maybe flooding rich. If you lose the boost and were LOP, you won’t be when all that boost is gone. It’s just like being at an high altitude airport, but way moreso of course

Finally if there is a restart max ceiling, it will be in the POH, what does the POH say about restarts?

If an engine quit because the tank ran dry, selecting the other tank will have it running again remarkably quick, just a few seconds, if it doesn’t come back real quick then it wasn’t the tank.

Lastly even at high altitude the prop will keep windmilling, if your 110 kts indicated or so and it stops, something is wrong inside the engine, if the engine quits and you don’t re-trim she will pitch down and maintain trim speed pretty much.

Similar to diesel… but opposite…

The CR of the TC’d planes makes it a bit more difficult…

And the low MP of the TC not working….

Getting a fuel ratio that will burn is the challenge…

 

As PeteMc points out above… waiting for the MP to find 12k’ ft… may find the tops of some mountains rising before the engine comes to life…

Then, with a damaged TC… it may not be a lot of power once started…

This makes TN’d engines a bit more user friendly… 

 

PP thoughts while reading about TCs and what works for my situation…

Best regards,

-a-

[PeteMc]

I was trying to find some documentation on restarting at altitude, but can't.  So maybe I'm making it up....  But I seem to remember in some course or conversation that if the engine doesn't restart on it's own soon after switching tanks, the best option if you are in high terrain is:

• Throttle Half Open

• Mixture Lean, then advance slowly

• Continue to advance slowly until engine starts

Also, hopefully you would have noticed Induction Icing earlier, but don't forget to pull the Alt Air.  The issue may not be just fuel.

 

[Ulysse]

19 hours ago, jaylw314 said:

the checklist you listed is probably the "power loss during takeoff or climb"

no, it is under POWER LOSS - IN FLIGHT (RESTART PROCEDURES) after the takeoff and climb section.
Then under the turbocharger failure section, under "complete loss of engine power", the procedure to restart is the same except that this time the mixture is supposed to be cutoff and slowly advanced until restart. confusing
Also, how do you determine that you have a turbocharger failure? drop of MP? any other sign? does a failure on the hot side have the same effect as a failure on the cold side?
 

[A64Pilot]

1 hour ago, PeteMc said:

I was trying to find some documentation on restarting at altitude, but can't.  So maybe I'm making it up....  But I seem to remember in some course or conversation that if the engine doesn't restart on it's own soon after switching tanks, the best option if you are in high terrain is:

• Throttle Half Open

   

• Mixture Lean, then advance slowly

   

• Continue to advance slowly until engine starts

   

Also, hopefully you would have noticed Induction Icing earlier, but don't forget to pull the Alt Air.  The issue may not be just fuel.

 

That is a logical procedure, and this is why.

Half throttle is plenty to restart and being at half your at low enough power so no huge surges etc should occur

Mixture lean to start with and slowly advance reduces possibility of flooding, wetting plugs so they won’t fire and after fires etc

Just a thought I assume not, but do you guys have pressurized mags?

Just think in 1934 Wiley post took a 1920’s R-1340 radial to 50,000 ft. I’ve been trying to find info on the motor, but haven’t been successful

 

Edited April 29, 2022 by A64Pilot

[A64Pilot]

40 minutes ago, Ulysse said:

no, it is under POWER LOSS - IN FLIGHT (RESTART PROCEDURES) after the takeoff and climb section.
Then under the turbocharger failure section, under "complete loss of engine power", the procedure to restart is the same except that this time the mixture is supposed to be cutoff and slowly advanced until restart. confusing
Also, how do you determine that you have a turbocharger failure? drop of MP? any other sign? does a failure on the hot side have the same effect as a failure on the cold side?
 

Only likely failure modes I’m familiar with are failure of the center section bearing which can cause the turbo to seize and or consume lots of oil as the oil seal is torn up when the shaft is wobbling around. In theory you could burn up the turbine but I’ve never seen it and the cold side could eat some FOD. 

Boost starts dropping or completely goes away, and very likely your losing a lot of oil through the exhaust

[A64Pilot]

54 minutes ago, Ulysse said:

Then under the turbocharger failure section, under "complete loss of engine power", the procedure to restart is the same except that this time the mixture is supposed to be cutoff and slowly advanced until restart. confusing

 

That’s because once the boost goes away, the mixture will be excessively rich, by going to idle cut-off your clearing the engine and by slowly advancing your getting to correct mixture ratio, because who knows what’s that going to be at x altitude and reduced or no boost? Sneaking up on it from the lean side is safest and conservative.

How do you start a hot motor? Same thing.

You can actually flood an engine and wet the plugs so they won’t fire. Anyone with old two stroke motorcycle experience can attest to that. By going to idle cutoff the residual heat should dry those plugs, if they got wet.

Edited April 29, 2022 by A64Pilot

[Will.iam]

4 minutes ago, A64Pilot said:

That’s because once the boost goes away, the mixture will be excessively rich, by going to idle cut-off your clearing the engine and by slowly advancing your getting to correct mixture ratio, because who knows what’s that going to be at x altitude and reduced or no boost? Sneaking up on it from the lean side is safest and conservative.

How do you start a hot motor? Same thing.

You can actually flood an engine and wet the plugs so they won’t fire. Anyone with old two stroke motorcycle experience can attest to that. By going to idle cutoff the residual heat should dry those plugs, if they got wet.

Grrrr damn 2-strokes. Used to have 6 spare plugs with me to change out as i would foul out 2 or 3 every weekend riding. The backwards logic of oil mixing made it worse as i thought if I’m fouling plugs must be too much oil in the mixture so go with a leaner mixture 40:1. But what I didn’t know was the carb jet is designed with a certain viscosity and by me going to less oil i was in effect richening the air/fuel mixture thus wetting the plugs. Once i went to 30:1 i. E. More oil in the gas that cause the jet to meter less fuel oil and I didn’t foul a plug since. More oil less fouling not logical until explained to me as above. 

[Will.iam]

Neighbor had a cessna 140 trying to learn how to land a tail dragger as he had been a trike all his previous flying. He came in one day and bounced big, added power and went around. As he was half way around the pattern the engine was coughing and sputtering he was losing power and thought he might have carb ice so pulled the carb heat verify the fuel selector was on both but the engine got worse and he couldn’t make the runway so put it down in a pasture. When he got out there was fuel leaking out of the cowl. Come to find out when he bounced, the float bowl got stuck down and could not regulate how much fuel was going into the carb and it was flooding the engine. He kept thinking that the engine was starving for fuel. Never dreamed it could be getting too much. Had he pulled to idle-cut off and sweep to rich he might have found a better running mixture to at least get back to the runway instead of landing short. 

[Fly Boomer]

On 4/28/2022 at 3:03 AM, Ulysse said:

Then, in other sections where power loss is mentionned

If you are high, and if the turbocharger stops turning, I would expect MP to precipitously drop from 30-something (whatever you were running) down into the teens.

[PeteMc]

57 minutes ago, A64Pilot said:

Just a thought I assume not, but do you guys have pressurized mags?

Yes, mine are pressurized.

[A64Pilot]

35 minutes ago, PeteMc said:

Yes, mine are pressurized.

OK that of course further complicates restarts at altitude as when the engine quits, Mag pressure goes away and they may not work well without it.

[Will.iam]

16 minutes ago, A64Pilot said:

OK that of course further complicates restarts at altitude as when the engine quits, Mag pressure goes away and they may not work well without it.

One of the main reasons i put a surefly on so if at alt the mag starts arcing due to pressurization failure i can isolate the mag and still run on the surefly that does not need a pressurized housing or if the engine quits and I’m trying to restart it at alt at least the surefly will get the engine running then once i have pressure back reengage the now pressurized mag. 

[201er]

22 hours ago, jaylw314 said:

Nah, all POH's I've seen say something similar.  I don't know that it would be "disastrous" at high altitude since you've got plenty of time and altitude to glide, descend, troubleshoot and, if needed, wait to a lower altitude to restart the engine, unless you're over the Himalayas

 

18 hours ago, PeteMc said:

Mine basically says if you don't catch it while the Tubo is still spinning, take a quiet ride down below12K and try again.

Seems like a pretty disastrous place to have one of those.

But even at sea level, I'm sure it would be disastrous for whatever pants you're wearing in any case