windmilling propellers

[virgo]

I cannot convince a non-aircrew colleague of mine that on large supercharged piston engines with constant-speed-propellers, if you lost an engine during cruise due to fuel starvation, it would continue to windmill at the selected rpm with accompanying boost (manifold pressure) and oil pressure. The only indication of the engine failure -if you missed the initial hiccup of parameters - would be the falling cylinder-head or coolant temperature and yaw and decay of airspeed.
Can anyone point me in the direction of getting written confirmation of this ???

[PPRuNe Pop]

I have to think about this a bit, but you would not want a windmilling prop! It needs to be feathered (so that its blades are edge on to the wind) because of drag. Apart from the correct drills sequence this the first most important action.

[virgo]

Thanks Pop............Yeah, we all know that !
My point is that if you had a somewhat sloppy (or very tired) flight-crew, it's quite possible to miss the moment of engine failure and as a result of the characteristics described, they can continue flying around for some time before the penny drops that they've lost an engine.
Please don't say it couldn't happen...........it has !

[DH106]

That seario assumes no pitch stops that would prevent the CS units driving the prop into the beta range for windmilling.

[stevef]

Apparently this situation would reveal itself with the Cessna 336/337 twin (centreline thrust push/pull configuration) if the rear engine failed. Obviously there would be no yaw to alert the pilot as to the reason for reduced performance.

[GOLF_BRAVO_ZULU]

I recall being told by an ex Shackleton AE that a Griffon would often fail in the air with no clues from the the RPM indicator. The only immediate clue was the loss of boost pressure. It seemed logical at the time but did I remember him wrongly?

[DH106]

Depends on how the boost was achieved - on an exhaust driven turbocharger you'd see a boost loss, but on a mechanically driven supercharger should maintain the boost as it's all still turning at the same speed. Was the Griffin turbo- or supercharged?

[stevef]

Shack's Griffon - single-stage, two-speed, mechanically supercharged, I believe.
I agree that CHT is the best indication of a failed governed engine (discounting yaw & a/s ) as Virgo says.

[Rory57]

Does this not depend upon how the propeller controller functions? It seams reasonable to expect the control mechanism to react to the reversed torque, even to "auto-feather" I don't know anything about propeller control mechanics, any Rotol / Hamilton Standard experts out there?
Some piston engines have torque metering, to directly indicate what is going on.

[Herod]

Similar to the Cessna 337, the BN Trislander had a centreline-thrust engine. If it failed, there was no indication until the CHT and oil temp dropped. I know; it happened to me. There was a light which would indicate a loss of RPM on take-off; can't remember the figure. It caused consternation during taxy since the passengers could see this light winking, above a sign saying "No2 Engine Failure" :O

[sixtiesrelic]

A DC4 pilot told me in the sixties, that the first indication you have if you arent watching the engine instruments carefully, is a decrease in airspeed of about ten knots.
Sounds like it happened.

[virgo]

Thanks everyone for your inputs........it's nice to have some confirmation.

These youngsters aren't quite as knowledgeable as they sometimes think they are !