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Mount ELT to F-729A Bellcrank rib?

grayforge

grayforge

Well Known Member
I've searched and see lots of discussion mounting the ELT on the Vans mount attached to the J-Stiffeners, baggage compartment floor, etc...

But no mention of attaching to the Bellcrank rib. Seems this is a strong location, with the aluminum angle across the top and pretty convenient to get to.

Any reason not to mount it here?

Thanks!
Russ
 
Because its purpose is for mounting and operation of the bellcrank and any other use that may interfere with that operation may induce great bodily harm or death should such other use interfere with the proper operation of the bellcrank :eek:
 
I see what you're saying, but if the ELT tore loose in a crash, the bellcrank is no longer useful.

I suppose the ELT could stress the rib over time and cause it to fail... but the same could be said for the 2+ lb auto pilot servo lots of folks rivet to the same rib.
 
There is no rule preventing use of the belcrank rib. However the warning about interference with flight controls should be considered. My 406 instructions specifically demanded a mount that would withstand high G loads. It was 9 G's from any direction, I think. BTW, mine is in the cabin, not in the tailcone. If you use good practice like AC43-13, a good mount can be made for nearly any position, close to control systems or not. Good practice should lead you towards incorporating the bulkhead into the plan, not just the belcrank rib.
 
Yeah, there are lots of changes we do to critical areas on our experimental aircraft: alternate rudder and aileron stops, closing the ends of control surfaces for enhanced aerodynamics, installing 6 cylinder engines, installing variations from the planned fuel system, etc.

My thinking is not "I can't touch this since it's critical", it's "While this is critical, what can safely be done with it?"

If a mechanical engineer said "Adding 1.8lbs to the bellcrank rib would cause undo stress here." Then I'd be happy with moving on.

But probably not to the location shown in the plans where the ELTs seem to tear off in a crash. :)
 
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