Thorp Air Command - T18.net

Not sure how to categorize this one- it's strange. It is not T18 specific, but thought I'd start here...

I'm flying my T18 IO360 with Hartzell CS prop quite a bit- mostly longer trips. I've begun to notice what sounds like an engine beat frequency- like a twin with the engines slightly out of sync. It's roughly 1 beat per second.

It may have been doing this for some time- but I've just recently noticed it, and can't imagine what this could be. Two things rotating at slightly different speeds, I guess. Maybe prop governor?

Anyone ever experience this? Any ideas?

Thanks!

Peter

Check the fuselage gap cover where the wing attaches. These have known to vibrate loose over time and can resonate.

_________________
Bob Highley
N711SH
SN 835
KLAL

Interesting! I never would have thought of that. I'll check, fly, and report back.

Thanks Bob!

Just to close this out...

So, I found the panel under the walking beam had a number of surprisingly loose screws at the outer ends. I tightened those, and took another long trip. The resonance is gone!

Big thanks to Bob Highley for suggesting it might have been something loose causing the issue. I've learned something!

Thanks again, Bob! I owe you a beer!

Peter