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-   -   Propeller malfunction (https://www.airlinepilotforums.com/technical/39765-propeller-malfunction.html)

rs makker 05-06-2009 10:06 PM

Propeller malfunction
 
During the process of relightof one of the engines in a twin engine aircraft, propeller spins up from feathered position (Blade angle ~80 deg) to 100% (prop rpm) as the prop control lever is moved to fine pitch position from feathered position. The engine is yet to be started and there is minimal oil pressure in the system. How did it happen?Any conjecture?

shanKs 05-07-2009 03:18 AM

Depends on the aircraft and some other factors. A lot of piston twins use oil pressure to push the prop hub to low pitch/high rpm. Is it an aircraft with a unfeathering accumulator? Is this turbine or piston? What make and model?

rickair7777 05-07-2009 08:30 AM

It sounds like it has an accumulator to store pressurized oil for pre-start unfeathering. The accumulator would normally be dumped when yoiu take the prop level out of feather.

Some light twins have the accumulator as an option (a flight school would want that option, a private owner might not). This can create confusion when folks learn on one airplane, then go fly another of the same type which did or did not come with the option.

But to be honest...you really should get educated on that sort of system BEFORE you fly a twin.

Ewfflyer 05-07-2009 09:15 AM

What kind of plane is this, there are a lot of details left out here.

Clue32 05-07-2009 12:46 PM


Originally Posted by Ewfflyer (Post 606718)
What kind of plane is this, there are a lot of details left out here.

Not a King Air. Feathering Springs, counter-weights, and a governor that uses oil pressure the N1 driven oil pump makes this scenario impossible. I am having visions of ME training in Seminols 8 years ago flash through my head with rick's post.


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