Lycoming mounting ear nuts

[stringfellow]

I've misplaced the nuts for my 540 mounting ears, so I guess I'm buying new. They are called out in the IPC as STD-596, and Lycoming is quite proud of them . Cheapest I see is $3.64 online (Spruce wants $4.75), and I need 16 of them (double nutted.)

Can I substitute AN316 3/8-24 for this? Is there anything special about the Lycoming variety? I mean, if one was going to pay $4.00/nut, why not make it count? http://smithprecisionproducts.com/pr...-jam-nut-38-24


Thanks.

[BillL]

I "think" your grade 5 AN should be just fine, but you really want to "know".

I think I would be sure by getting several grade 8 bolts from the store, a $4 nut, the AN nuts, and some grade 5 hardware nuts. Oil them all, use a hard, flat washer and torque them to failure for comparison. I believe you will find the AN is just as good as the Lyc nut. But that is me, and I really want to know, with data.

Or just call Barrett for their professional recommendation, or order from them.

[stringfellow]

I did call Barrett on your suggestion. They said they use AN315-6.

[BillL]

Good to hear - Can't go wrong w/BPE.

[johnbright]

AN 316 is thin "shear" nut, not appropriate for this tension application.

I assume titanium is not appropriate.

My real question... what is the locking means?... I would have thought castle nuts.

[stringfellow]

Originally Posted by johnbright

AN 316 is thin "shear" nut, not appropriate for this tension application.

I assume titanium is not appropriate.

My real question... what is the locking means?... I would have thought castle nuts.

My mistake, it's 315 not 316. My reply above referenced the correct AN nut.

Locking means is internal tooth lock washer and torque.