Control Linkages and Safety Wire

[macrafic]

Just wondering what the general thought is out there about using safety wire on the control linkages. Some of the places where this might be considered include the bolts that hold the ailerons on the wings, the nuts that hold the rod end bearings on the aileron pushrods (both the aileron and the bellcrank ends), flap attachment, elevator pushtubes, etc..

The plans don't specificaly call out for safety wire in these places. Is anybody aware of any incidents of control loss in the past? Has anybody found any loose connections during annuals?

 

[MontanaMike]

Safety Wire

Just my 2c worth, an A&P who was overseeing some of my work suggested that I replace any critical friction nuts with castle nut and cotter pin bolts. I E-mailed Vans for their opinion, which came back promptly, "Build to Plans", and the comment that there are hundreds (he might have said thousands) of RV's flying and built to plans and they are just fine. Since that response, Vans has had me open my tanks and safety my fuel pickups. So I have ordered castle nuts/pins/bolts for all my "critical' and "rotating" assemblies. It makes me feel better, anyway. My only other concern is control jamb nuts. I think I will try to find a way to safety them prior to inspection/flight.

MontanaMike
RV-6 Canopy/Panel/Ebay Follies
N918MB Reserved

 

[dan]

The hardware in question doesn't rotate. Nylok nuts work just fine. If the hardware itself rotated, you betcha...lock it up. But it doesn't.

 

[briand]

You can buy keyed rod ends, rod end locking devices (w/safety wire hole) and drilled jam nuts, or you could just use what you have. I agree they are not needed the rod end can't turn more than a few degrees so there is no way they can unscrew. Where I work most of the rod ends are set up for being lockwired but that is because we don't want the installer misadjusting the rod ends. It doesn't prevent readjustment 100% but it sort of screams to the mechanic; hey, I'm set, leave me alone. Most listen, but you almost always know when they don't because the part comes back for readjustment. BTW, if its aftermarket that just cost them about $400, if its Boeing we eat it.