Check Composite Spinner Bulkheads....

I was cleaning up Tsamsiyu today for an airshow this weekend, and as I was cleaning bugs off the spinner, I noticed that it seemed a bit loose - it had a definite (small) wobble to it. Further examination revealed that the rear bulkhead of our WW-151 prop spinner appeared to be moving slightly relative to the hub. After removing the top cowl and spinner dome, it became apparent that the six AN4 bolts that hold the bulkhead to the hub were a little loose. I cut all the safety wire and tightened them up, then spent an hour resafetying them (as ad as prop bolts).

My conclusion on this is that the hold the bulkhead to the hub by essentially clamping the composite to the hub. The bolts couldn't loosen - they were wired - but the material probably gave a little. The lesson here is that these bolts probably need to be checked every couple of hundred hours (ours has 300 at this point - and they weren't loose at the last annual) - either the composite is getting crushed, relieving the torque on the bolt, or it is flowing with the same results.

For those without WW props - the prop comes with the spinner and the composite bulkhead - this does not apply directly to Van's spinners.

Paul

Ironflight said:

or it is flowing with the same results.



Paul

Click to expand...

That would be my guess.

Same Here

Found similar issue on Whirlwind spinner for my 200RV prop. Spoke with a knowledgeable person who confirmed that the bolts should be torqued now and then. I was cautioned to NOT torque too tightly, as the fibers in the carbon fiber could be crushed. No specified torque.

My spinner was very noticeably loose after only about 30 hours. Easy to check on every pre-flight walk-around inspection.

Ironflight said:

<snip> or it is flowing with the same results.

Paul

Click to expand...

Paul, can you elaborate on "flowing"? Thanks!

Cheers,
Bob

Myabe not related but worth a read

I good friend of mine had a similar problem with a composite bulkhead and almost lost his prop. Probably not the same issue, it's a Berkut (pusher) with a catto wodden porpeller, but worth a read.
http://www.berkut13.com/ntxspinner.htm

Scott

rvmills said:

Paul, can you elaborate on "flowing"? Thanks!

Cheers,
Bob

Click to expand...

Well, composites CAN be sort of like glass - not really a solid, and actually a liquid. Sure, they seem solid in the short term, but in the long term, they can change shape like a liquid. So if you squeeze down on a composite, it can effectively "flow" away from the pressure points - that means you have to turn the bolt a little every once in awhile to keep a good clamping pressure.