USMCFLYR

Those are less restrictive than the ones in my AFM for a PT6A-60A on the BE-300s we fly.
30 seconds ON - 5 minutes OFF
30 seconds ON - 5 minutes OFF
30 seconds ON - 30 minutes OFF

satpak - what says your book?

Gjn290

Those are for a PT6-114A. Could it possibly be different between higher and lower power rated PT6's?

USMCFLYR

I'm sure that they have to do with the different models, which is why I'd like to know if satpak's is any different since we are flying the same engines.

Gjn290

I can't seem to find this thread after it's been moved without looking under my profile and posts. Shouldn't it be under technical?

Any pc12 drivers that have different limitations than us also?

satpak77

USMC - my information for the B-350 is identical to the above

M696

I have lots of hours flying behind a variety of PT-6's, only thing to add is that during a quick turn there is still a lot of heat in the shut down engine...motoring it for an extra few seconds before adding fuel will result in a much cooler start.

Duksrule

Mine is a -34
30 seconds on 60 off
30 seconds on 60 off
30 seconds on 30 minutes off

Same limit for internal or external power

JohnBurke

Pratt doesn't specify a minimum time, but it is specified on some aircraft, which is ironic; in those cases it's the airframe manufacturer making the specification, and not the engine manufacturer. I have flown aircraft which dictated in the AFM that a minimum of 15 minutes would pass between shut down and start-up, that were powered by PT6A's.

The starter limitations are very different than a limitation between shut-down and re-start.

One area that should be approached with caution are multiple short starts or start attempts, before scavenge pumps have a chance to do their work; a lot of oil can shift to places it shouldn't, and EPA cans can quickily fill, too. This can take place during several start cycles when the engine doesn't reach full speed, or during prolonged motoring.

The best cure to hot engines during quick turns is motoring the engine to cool the gas path before reintroducing fuel. One should always max motor, rather than light off the engine at the minimum Ng anyway, but if the battery is available, motor to the maximum RPM available for the starter and keep it there for a moment to cool the engine before moving the start lever. It's conducive to engine longevity and it produces more consistent, cooler starts.

Gjn290

We know that starting limitations are different then shut-down and re-start procedures.

What would you consider as a quick turn? I would say less than 15 minutes. For checking the oil they use less than 15 minutes to check max hot oil levels and after 15 minutes for checking max cold oil levels.

feltf4

The only limitation I can think of for restarting is you have to motor the ITT down to 150 before introducing fuel again for the restart. Other than that same time limits for the starter apply. PC12.