The prop governor controls within a range and should hold a
steady rpm within that range. When the run-up is done at
say, 2400 rpm the prop should be cycled to the minimum rpm
and allowed to stabilize for a few seconds to check that the
governor is working properly. On a multiengine airplane the
prop should be reduced to just outside the feather detent
and allowed to run for several seconds to be sure that the
prop isn't feathering at the minimum governed speed [usually
2000 rpm on most piston engines]. If the prop control is
not rigged properly the prop will feather too soon. Then
the prop feather check should be done.

Most props have a certain amount of internal leakage to keep
warm oil circulating in the prop hub, but several cycles on
a cold engine/prop will assure that the prop does reach
proper operating temperatures.

In very cold temperatures, I like to vary the rpm every some
often to be sure the prop is functioning, but normal
internal flow should make this mostly an unneeded habit.

Remember, on a single-engine reducing rpm send oil to the
prop and on a multi, reducing rpm/feathering drain oil from
the prop.


--
James H. Macklin
ATP,CFI,A&P

--
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But government sees it as an obstacle to be overcome.
some support
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"Dudley Henriques" wrote in
message
ink.net...
|
| "Frode Berg" wrote in message
| ...
| Hi!
|
| I was told by my mechanic to only pull the prop handle
until I could
| audibly
| hear a slight pitch change to establish that it was
working.
|
| However, the aircraft manual says it should be cycled
completely, and on a
| cold engine three times to make sure oil is applied to
the governor, or
| the
| pitch mechanism.
|
| Can someone elaborate on this?
|
| What is recommended?
|
| Thanks,
|
| Frode
|
| POH rules of course, but aside from that, I always liked
to exercise a prop
| through several cycles, especially when cold, just to get
everything nice
| and warm and fluid up there.
| Dudley Henriques
|
|