PA-44 prop feathering check
05-27-2009, 06:05 PM
#1
On Reserve
Thread Starter
Joined APC: Jun 2007
Posts: 16
PA-44 prop feathering check
When doing a prop feathering check in the PA-44 you should not get a drop of more than 500 RPMs. If the RPMs drops more than that what is the likely cause? I have heard two things. 1.) the nitrogen charge in the unfeathering accumulator is under-serviced or, 2.) the nitrogen pressure in the prop hub has been over-serviced. From what I understand either way you might have difficulty unfeathering the engine? Just looking for any thoughts on the subject.
05-27-2009, 07:15 PM
#2
Gets Weekends Off
Joined APC: Aug 2008
Posts: 999
I think the drop of 500 rpm is more of a technique problem. If I do the prop check and do it very very slowly, i can get a much much higher drop than just 500 rpm.
The issues that you bring up have nothing to do with unfeathering accumulator. The prop governor is what controls the prop rpm while the engine is running, not the unfeathering accumulator. The unfeathering accumulator is only part of the equation when the engine is not providing pressure for the governor (when the prop is feathered and engine is not running)
The issues that you bring up have nothing to do with unfeathering accumulator. The prop governor is what controls the prop rpm while the engine is running, not the unfeathering accumulator. The unfeathering accumulator is only part of the equation when the engine is not providing pressure for the governor (when the prop is feathered and engine is not running)
05-28-2009, 12:07 PM
#3
pants on the ground
Joined APC: Jan 2007
Position: back seat
Posts: 1,358
I agree with 250.
Flew the pa-44 for my ticket but lived in the be-76. in the be-76, the poh stated that 'you should not allow the rpm to drop 500 rpm' meaning you hand control over the rpm drop. hope this helps.
Flew the pa-44 for my ticket but lived in the be-76. in the be-76, the poh stated that 'you should not allow the rpm to drop 500 rpm' meaning you hand control over the rpm drop. hope this helps.
05-29-2009, 06:00 AM
#4
Flying Farmer
Joined APC: Jul 2006
Position: Turbo-props' and John Deere's
Posts: 3,160
It's hard on the engine is what it's doing! Low power settings, no forward momentum, and going to a low-RPM setting, makes it run rough, and since low power=lower oil pressure, takes a little more time to get that prop back to low-pitch.
Does not have anything to do with the unfeathering accumulator. This procedure is synonimous with any other piston twin that I know of.
Does not have anything to do with the unfeathering accumulator. This procedure is synonimous with any other piston twin that I know of.
06-04-2009, 07:29 PM
#7
Gets Weekends Off
Joined APC: Sep 2006
Posts: 926
Originally Posted by ZnCrO4
Many newer piston twins (Seneca V and G58) the feathering check is completed at 1500 RPM per the AFM.
I don't think that the Seminole checklist referred to above states that the RPMs should never get below 500 RPMs, but rather that they shouldn't be allowed to fall below 500 RPMs.
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