Prop Seal

On the way back from the coast the other day, I noticed some oil on the windshield. It was so little that it was barely visible unless the light was just right. I took the cowl off and found some more traces of oil, but it was hard to tell where is was coming from. There was some on the very forward edge of the cowl and the spinner. My first thought was it was the crank seal again, but this looked a little different, so I decided just to monitor it for a while. Well, it has become progressively worse and it seems clear that the problem is with the seals where the prop blades go into the hub. So it looks like the prop is due for a "reseal" after only 99 hours.

I really enjoy the catapult-like acceleration the constant speed prop gives me, but it and it's related systems have been such a pain the tush so far, I am left wondering if I should have gone with a cheaper, lower maintenance fixed-pitch prop. Something I'll consider next time.

UPDATE: 06/21/05 - The prop is back from US Propeller. They found a "twisted quad seal" on one of the blades, which was the cause of the oil leak. The reseal cost $503. Even though I bought this prop way back in 2001 (from Van's), Hartzell is going to cover the labor costs, which was $425. I have to hand it to Hartzell for standing behind their work and making things right. My hat is off to you. Thanks!! See pictures of the seal below.

More evidence on every leading edge too; wings, gear legs & empennage.

See the twist in the seal at 3:00? Subtle, but enough to cause a leak.

Something else I had to contend with after the prop returned was the fit of the front plate that the spinner mounts to. The front cylinder on the prop hub torques down to a different spot each time (so explains the prop shop). This means the screw holes in the plate and the spinner no longer line up. So I ordered another front plate from Van's, overnight shipping. While the new part is enroute, I tried indexing the existing plate differently by rotating it 90`. Alignment was worse, which is good, because now I have enough room for nutplates for the new holes. This technique worked fine, and I put the new plate on the shelf for next time.