DirectTo

Within 10 minutes for MAX HOT, first flight of the day for MAX COLD, and motor the engine if more than ten minutes in the -114/-114A. Van AFM 8-17.

bozobigtop

gjn290 is correct. What you don't want to do is to turn the condition lever off by mistake and then shove it out of the off position to low idle. This will torch the combustion chamber for sure.

Ewfflyer

On the TBM'S we have a 60 second starter limitation, so have a little more leeway on motoring.

Shut down hot, sit for a few min, the ITT will rise up to 300+ with no wind. Restart within first 5-15 minutes, I would motor for 20-25 seconds, get below 150, then normal from there. Usually hit 50% by 40-45 seconds, which is usually 5+ seconds faster than the cold start.

Otherwise I've never heard of a time limitation, they preferred to teach the owner pilots to wait until the ITT got to 200 or less just to keep them from coming close to overtemping

JohnBurke

The amount of time that it takes the engine to cool really depends on ambient conditions. Quick turn for an engine is not the same as quick turn for you.

The oil check interval for the engine shutdown varies with the installation. In some aircraft it is 10 minutes and in others 15 minutes. Beyond that the oil level read on the dipstick can be inaccurate, and should be considered unreliable.

JohnBurke

No, it won't.

Low idle, or start position, isn't going to torch the engine. If you move the condition lever to cutoff while motoring, the engine fuel control will terminate fuel flow, and the temperature will begin to decrease. If the engine was spooling on fuel flow, above motoring speed, the engine Ng RPM will begin to droop. If one reintroduces fuel, the engine will begin to accelerate again, but from a lower temperature.

This is actually a method of starting on certain model engines which tend to start hotter; it's sometimes referred to as a modulated start. The fuel is cut off and reintroduced several times during the start. Each time the temperature drops, and the fuel is reintroduced before RPM decay occurs. The engine will not "torch" or hot start by doing that. In fact, it's just the opposite. You're not dumping fuel into the engine and then lighting it off. By moving to cutoff, you're shutting off fuel and reintroducing it.

80ktsClamp

The GE CF34 requires motoring the engine down to 100 ITT prior to turning on the fuel for the next start.

If there is nothing published and you are concerned about how warm the engine is, just motor it a bit longer.

Other GE motors I've flown require no such motoring... just throw the fuel on and good luck!

DirectTo

I don't doubt it works on some engines...but Pratt-specific straight out of the factory checklist:
"If the fuel condition lever is moved past the low idle position and the engine Ng falls below 53%, moving the lever back to the low idle position can cause an ITT over-temperature condition. If the engine has started to shutdown in this situation, allow the engine to complete its shutdown sequence, and proceed to do a normal engine start using the 'starting engine' checklist."

If the manufacturer of the engine says let it shutdown, I'm letting it shutdown.

WalkOfShame

Got over a thousand hours in pc-12s from a past job. Don't remember any specific limitation for time between starts, i.e.-- a shutdown to let pax off or on. The starter duty cycle limitations existed but no of times that I can remember. Of course, there was a limitation for when to introduce fuel on a hot engine (motor it to 150*C ITT I believe).

JohnBurke

I said nothing of letting Ng droop to starter RPM.

Cutting off the fuel and reintroducing it while the engine is running does not cause torching.

During start, if the fuel is cut off and restored, it does not cause torching.

When fuel is chopped, an immediate decrease in exhaust gas path temperature occurs. RPM droop is not immediate.

During an engine start with the starter engaged below 50%, moving the start lever to cutoff and back to idle will not cause the engine to go hot or to torch.

During idle operation, moving the start lever to cutoff and back to idle will not cause torching or an overtemperature condition.

This isn't a checklist issue. It's a know-your-engine issue.

If an engine has been shut down, that's one thing. If the engine Ng RPM hasn't drooped to starter levels, however, there's no reason that fuel can't be reintroduced. Think about it. What do you do in heavy rain, or turbulence or certain kinds of operation. Turn on ignitors? Why? To get a relight? Do you think the engine is going to begin over temping and torching in that case? Flame--no flame--flame.

You stand a substantially higher possibility of going hot during a flame-out and relight, than cutting off the fuel with the fuel control and then reintroducing it.

DirectTo

My apologies, I read your earlier post wrong.