912 ULS changes tone

Re: 912 ULS changes tone

by Steve Halter » 14 years ago

Steve Halter

2 11 0

I have a 3 blade Nueform prop that does the same thing, I was told its the prop adjusting to the rpms...

Re: 912 ULS changes tone

by Roger Lee » 14 years ago

Roger Lee

131 5.38k 5.44k

Prop loading from a very slight rpm change you may not see, wind changing through the prop at different angles, descending or ascending slightly.

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Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

Re: 912 ULS changes tone

by Robert Comperini » 14 years ago

Robert Comperini

0 22 12

The batteries in your ANR headsets getting low? ;)

(just a little humor)

Re: 912 ULS changes tone

by Allen Rogers » 14 years ago

Allen Rogers

1 1 0

Interesting... I've sent an email to my prop manufacturer (WarpDrive) to get their take. The interesting thing is that I've flow with this prop/engine for about 200 hrs before the issue started. At first it was less common but now has become more common.

Re: 912 ULS changes tone

by Richard DeHaven » 12 years ago

Richard DeHaven

2 26 23

I am having exactly this issue in my Sting Sport, right now. In my case, I am quite convinced that it is exhaust-tube (and pulse) resonnance (and sometimes, associated high-frequency vibration)from my #3 cylinder exhaust, which cracked about 15 hours ago. We welded it three times and each time the weld failed; most recently, we welded a sleeve-wrap around the bad area. The sleeve is holding, so far, much longer than just the welds alone, but it (and doing the welding, without gas-purge inside) has surely messed up the gas expulsion characteristics (like throwing boulders into a little stream) harmonics on this stack. I am waiting for a factory replacement of that part--but it is a long row to hoe (i.e., a real problem with the manufacturer and its US distributor that I better not go off on, here...).

My point is: You may have a cracked exhaust part someplace--or some exhaust part has developed harmonics, getting ready to crack. These cracks can be very small and hard to see; on my #3 tube, you needed a magnifying glass to see it well...