Ayamr-Demuth Propeller

[RFazio]

I was told today by one of the local airport hangouts, that there was a problem with Ayamr-Demuth propellers. A certain run of them had balance problems, or the way they were balanced. There was some kind of advisory on a certain serial number range? I'm wondering if anyone has heard of this. My propeller is kind of old now but never been flown. I'm almost ready to fly and am thinking about the prop. It's a 68?D X 78?P and the serial number is 92378. Thanks for any input.

[John Clark]

A search of the NTSB reports came up with these:

http://www.ntsb.gov/ntsb/brief.asp?e...06X01178&key=1
http://www.ntsb.gov/ntsb/brief.asp?e...21X01790&key=1

John Clark
RV8 N18U "Sunshine"
KSBA

[Kyle Boatright]

Originally Posted by RFazio

I was told today by one of the local airport hangouts, that there was a problem with Ayamr-Demuth propellers. A certain run of them had balance problems, or the way they were balanced. There was some kind of advisory on a certain serial number range? I'm wondering if anyone has heard of this. My propeller is kind of old now but never been flown. I'm almost ready to fly and am thinking about the prop. It's a 68?D X 78?P and the serial number is 92378. Thanks for any input.

Why don't you call the manufacturer? That's gotta be a better source of information than airport scuttlebutt.

I got Mike of Aymar-Demuth on the phone right after Oshkosh when I was looking for directions on refinishing my prop.

[breister]

I had no problem with balance on my Aymar-Demuth propeller. It was quiet and smooth, providing 180mph on 6gph.

Right up until...

[RFazio]

Do you know what caused the problem? Was there any damage to the prop prior to the split? Any nicks or cracks?

[breister]

Originally Posted by RFazio

Do you know what caused the problem? Was there any damage to the prop prior to the split? Any nicks or cracks?

No visible nicks or cracks. Looked like brand new, and nearly was. I bought the airplane and it had two "spare" wood propellers, was flying with a Prince prop. I had flown the Prince prop through precip with hail, and had returned it to the factory for refinishing (they also repitched slightly and changed glass for carbon - looked kewl!). Thus, I had what looked like a brand new prop on when I flew to Eleuthera.

In fairness, the point at which the split occurred was fairly thin and only a couple of plys of wood. I suspect one ply was simply imperfect and failed; the remaining / surrounding plys were not strong enough to sustain alone. After all, wood does not grow in a vat and so the "manufacturing process" is uncontrolled.

Nowadays I fly a Hartzell (metal); my ideal prop would be all composite with a nickle leading edge - but they are more expensive than the tried-and-true Hartzell.

[N941WR]

Metal props can fail too.

This is a picture of a friend's Waco UPF-7 after losing 7" of one prop tip. There were no cracks or nicks prior to the flight, it just simply failed.


BTW, that was the Staten Island Ferry parking lot he landed in. Notice the light pole behind the Waco that he had to swerve around. The plane was flying again a few months later.

[breister]

Yes I know. A friend experienced TWO Hartzell prop failures in his Lancair 360 (that's enough that several people here know who I'm talking about...).

The prop / engine combo I have on my 320 has a pretty solid reputation - but if I do experience failure I now know how to recognize the symptom and immediately kill power. But, I agree that metal props are actually more dangerous if they fail - if only because the blades are heavier and therfore more likely to rip the engine off it's mounts.