Propeller malfunction
05-06-2009 | 10:06 PM
#1
Thread Starter
New Hire
Joined: May 2009
Posts: 1
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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?
05-07-2009 | 03:18 AM
#2
Line Holder
Joined: Apr 2008
Posts: 95
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From: HS-125
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?
05-07-2009 | 08:30 AM
#3
Prime Minister/Moderator
Joined: Jan 2006
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From: Engines Turn or People Swim
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.
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.
Last edited by rickair7777; 05-07-2009 at 08:46 AM.
05-07-2009 | 12:46 PM
#5
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Joined: Apr 2007
Posts: 946
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From: 747 FO
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.
