C182 CSU/governor failures
 

Hi guys,

I'm currently trying to complete my C182 endorsement questionnaire. But i am yet to find out (in the POH) where it talks about failures of the CSU.-- "If the oil pressure to the propeller dome is lost, does the propeller go into coarse or fine pitch?
I have read on other forums that most GA single engine aeroplanes props would revert to fine pitch, is this the case with 182s??
Any thoughts on this would be greatly appreciated!

cheers

It's in the POH. Here you go:
CESSNA MODEL 182T NAV III GFC 700AFCS
PROPELLER
SECTION 7 AIRPLANE AND SYSTEM DESCRIPTION
The airplane has an all metal, three-bladed, constant speed, governor regulated propeller. A setting introduced into the governor with the propeller control establishes the propeller speed, and thus the engine speed to be maintained. The governor then controls flow of engine oil, boosted to high pressure by the governing pump, to or from a piston in the propeller hub. Oil pressure acting on the piston twists the blades toward high pitch (Iow RPM). When oil pressure to the piston in the propeller hub is relieved, centrifugal force, assisted by an internal spring, twists the blades toward low pitch (high RPM).

Thankyou on behalf of the originator,Mr 'C',....For the POH reference.

However, I am left 'wondering' why the lad's instructor, the 'endorsing pilot', couldn't answer this without the lad resorting to PPRuNe and all of its 'vagaries'....??

To 'brief' this info used to be 'par for the course'....
Cheers

If the POH doesn't tell you, look up the part number for the propeller and grab the manual for that from the manufacturer's website. The C182 POH I just looked at said it uses the McCauley C2A34C204.The manual for that propeller is on McCauley's website. The key information is this:

The C200 and C400 series propellers are constant speed type. They are a single-acting unit in
which hydraulic pressure works against the forces of springs and the natural centrifugal moment
of the rotating blade to provide the correct pitch for engine load. Hydraulic pressure causes the
blades to move toward high pitch (decreasing rpm). The springs and centrifugal moments urge
blades toward low pitch (increasing rpm).

Obviously if you take away the hydraulic pressure, there's no force driving towards high pitch and so the propeller will go to low pitch.

Or more likely it was homework, and rather than wait until tomorrow to ask the instructor (or whenever) they thought someone on PPRUNE can likely help.

What about the next bit Jason? What happens when it goes full fine? ;)

I had this in a C182H at night about 20 years ago.
Heading into Bankstown on a 40-something degree summer's night the oil temp went through the roof (pressure was ok) and the prop went to full fine.

Had to pull the MAP back to about 18-20" to avoid overspeeding the engine, and we were getting about 80 kts IAS.

Not a fun night. Still don't know what caused it and the same aeroplane did it to 3 or 4 other pilots over a period of years.

Depends on what kind of failures you are referring to.

For the 182 (and most singles) the loss of oil pressure would cause it to go to fine pitch, and a failure of the speeder springs in the CSU would cause it to go to coarse pitch.

Multi engine pistons generally work in the reverse (I'm not exactly sure why, but assume it has something to do with the feathering function).