Propeller free Sonex...

[rbarber]

All,

As many of you know already, I had my propeller fly off near Sioux Falls, SD. In hopes of saving someone some grief, the attached file is a short write up of the incident, as well as some analysis of the failure.

Regards,
R.
Robert E Barber
N157SX-Sexy Hexy

Propeller loss on a Sonex.pdf

(792.1 KiB) Downloaded 714 times

[builderflyer]

Oh no.......a new reason to worry! Very glad you got it down safely, Robert.

Art,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,Jab 3300 #261

[kevinh]

Great write-up and very useful and wise.

[Jim B]

Robert
Thanks for sharing your incident.
Jim

[lpaaruule]

Thanks for the info.

I'm not sure that there is anything actionable I should do though. My prob flange cap screws were installed with loctite 620. Replacing them at some time interval might risk twisting the heads off.

I'll have to think about this.

[x3 skier]

Thanks for the write up. One thing comes to be mind, which probably highly unlikely, is the use of some lower quality bolts. As an old accident investigator, that would be one thing I would require to be checked. If you can get an analysis of the bolt material, it would be well worth while.

Cheers

[peter anson]

Hi Robert, great job getting it down safely. I've got the brains trust thinking about this problem but I suspect your idea of changing the bolts every few hundred hours is the only practical solution. The parts manual specifies plain washers under the bolts. It might be better to use a couple of Belleville spring washers to prevent the bolts from loosening. Looks like a prop removal is in my future.

Peter

[kevinh]

Thanks for the write up. One thing comes to be mind, which probably highly unlikely, is the use of some lower quality bolts. As an old accident investigator, that would be one thing I would require to be checked. If you can get an analysis of the bolt material, it would be well worth while.

Yah - I'm not anywhere close to being a ME, but that is a very interesting theory.