Slight performance change after annual?

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drotto

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drotto
I have been primarily flying the family Saratoga SP with a three blade standard prop the last 8 or 9 months, and doing my IFR training. It was brought in for an extensive annual about 1 month ago because it was due for its yearly as well as all the two year IFR certification stuff. Some small issue were fixed but nothing major. Engine compressions were great, all high 70's. The shop did comment that the prop seemed to have many nicks so they filed it. Overall the prop has about 500 hours on it.

Now, I may crazy, but the plane seems a few knots slower than it was before, and the prop seems to be happier at a slightly different RPM. It used to love being at 2300 now it likes about 2400 better. Could the filing of the prop have resulted in these subtle changes? Even the CFI noted that the plane seemed happier at 2400 now, and he was not privy to everything done during the annual. Otherwise it is flying great.
 
Prop balance?

I'd have a new dynamic balance done, one of the best cheap improvements you can make ether way.

Balance and mag timing is something which is often overlooked and rather cheap and easy to have done.
 
Check the rudder trim and make sure that you're flying Cordinator flight and not skidding. Uncoordinated or skidding could cost you three or 4 kn in the toga.

I suspect all the trim was checked and the rudder trim is in a different position then used to.
 
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A minor prop dressing should be unremarkable. Cleaned and rotated plugs and re-timed mags would be more likely contributors.
 
Checkout_my_Six said:
Check the rudder trim and make sure that you're flying Cordinator flight and not skidding. Uncoordinated or skidding could cost you three or 4 kn in the toga.

I suspect all the trim was checked and the rudder trim is in a different position then used to.
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Think you may be onto something here. Now the you mentioned it the ball was slightly shifted to the left, and I had the passing notion that there was a mild left wing dip. The plane has always been so balanced in the past, I have not needed to play with the trim yet.
 
Did they retime it? If so, check that. An airplane can pass the magneto test and not be in time.
 
drotto said:
Think you may be onto something here. Now the you mentioned it the ball was slightly shifted to the left, and I had the passing notion that there was a mild left wing dip. The plane has always been so balanced in the past, I have not needed to play with the trim yet.
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Provided that the trim setting is on your checklist, when you ran your checklist did you notice if it was positioned differently than it usually was?
 
SkyDog58 said:
Provided that the trim setting is on your checklist, when you ran your checklist did you notice if it was positioned differently than it usually was?
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Not sure, the toga uses a twist nob type adjustment so there is not a very clear indication as to where it is set. It really needs to be done during flight.
 
What is the density altitude now compared to when you last flew it? This time of year weather conditions are changing rapidly which can make a big difference on performance.
 
I find it rather difficult to believe that your CFI would not notice if the rudder trim were out of kilter. I mean, either your flying askew or you're pressing on one of the pedals to keep it from doing that, in which case you'd crank the knob to alleviate the issue.
 
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