| I grounded my plane in January because I saw black oil or grease coming from the prop blade seals on my Aero Composites prop. The prop had also over sped on a takeoff (maybe up to 3,800 RPM for a few seconds and then back to 3,300 for landing). The prop has been in service for 6 years and over 1,000 hours.
Last week I had the prop resealed for $800 by H & S Propeller Shop, Inc in Pontiac, Mi. I was really impressed with the shops work.
Brian, from H & S, told me that one of the blades was hard to remove and was slightly out of round at the hub. We called Aero Composites. After talking to them for a while, we decided that Brian was capable of milling the prop back to the original specs.
The prop went back on yesterday and when first started (with a new alternator belt) the alternator CB (40 amps) tripped even though the alternator switch was not on. After retightening the alternator nuts and making sure that no lines were grounded everything worked just fine.
The props leading edge is still as smooth as silk after over 1,000 hours. The nickel leading edge is just perfect.
Before I had the prop resealed, I tested the max RPM. When I immediately went to full throttle, the engine went right to 2,750 RPM and then stabilized at 2,700. The minimum prop pitch was set to 9°. The max pitch on this prop, stopped by the hub, is 35°.
I asked Aero Composites if I could raise the low pitch of the prop to maybe 12°. They said that, that would be to much and that I would not be able to get full power at takeoff. I had H & S set (with a .050 shim) the low pitch to 10°. Now when I go to full throttle, the engine goes to 2,600 RPM and by 30 KTS up to 2,700 RPM. My hope is that if I have another overspeed, the RPM will not be as high.
Wolfgang worked out some 0° thrust prop speeds. I am including his chart below. From the chart, it appears that to 9° versus 10° will not make any difference at 100 KTS. I am still happy that the stops take control on takeoff rather than the governor. I am also going to check my RPM at 50 KTS on takeoff from now on. This was one of the checks on my C-340 before going to full throttle. Wolfgang calculates the prop slip angle to be between 4° and 6°. Make sure to add this to the 0° thrust prop speeds to calculate the true prop angle.
I now have 5 check lists.
1) before master on: gear handle down 2) before takeoff: standard takeoff checklist 3) at 50 KTS: no more than 2,700 RPM 4) while descending: standard landing checklist 5) before landing: if you see a runway, make sure that you see 3 green lights
Lorn
-- Lorn H. 'Feathers' Olsen, MAA, ASMEL, ASES, Comm, Inst LNC2, FB90/92, O-320-D1F, 1,790 hrs, N31161, Y47, SE Michigan
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