Snapped the M3x25 special bolt...

[eobie]

How common is this.

[curmudgeon]

During installation or during flight?

Generally, those Jesus bolts are secured by nylock nuts, and should not be overtightened.

[eobie]

In flight... The first time was my fault, had the delay in the gov turned way down. Replaced with a standard m3x25 and that snapped. Found a nice fully shouldered bolt, that's been holding until I get the official replacement..

[curmudgeon]

Jeez.  Hope you were able to auto OK.

There is an older thread on HF about a similar issue with the Whiplash and the lower Jesus bolt.  http://www.helifreak.com/showthread.php?t=493735

[eobie]

Oh yeah auto'd down both times successfully. No damage. Are you guys just tightening it down until you hit resistance?

[curmudgeon]

Yes.  It is my understanding that any lower Jesus bolt that goes though a OWB assembly should only be tightened until you meet resistance, otherwise it can deform the OWB mechanism.

[Chris Sexton]

Oh yeah auto'd down both times successfully. No damage. Are you guys just tightening it down until you hit resistance?

Not only does it deform the hub, but you can stretch the shoulder bolt pretty easy and that can cause failure. The nyloc nut is used so that you can just snug it up and let the nylon do it's job.

[Matt Botos]

These bolts will not break in flight. The only time I have seen them break is during a crash where the rotor head contacts the ground at full RPM.

Make sure you use a shouldered bolt as a replacement, a non-shouldered bolt will not work.

Do not over tighten any of the bolts related to the main shaft, you can stretch them causing a failure. All you need to do is close the gap with the nylock nut.

Hope that helps!

Thanks,

Matt