Thru Bolts: NDT or NOT?

[efrench]

I am doing an owner assist field overhaul on an o-360. The question came up regarding the thru bolts. I can't find anything definitive regarding NTD inspection. As far as I can tell, these are not on the mandatory replacement list but is NDT inspection required? Can someone reference a SB that lists those items that are required to be yellow tagged during overhaul? Thanks.


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[Jeff J]

I think the question is: Are through bolts “stressed” bolts? All stressed bolts get replaced whether on the list or not.

[Steve Pierce]

Are you not sending the crankcase out for overhaul? I have seen no NDT data on through bolts but have always sent my crankcase out for v overhaul when overhauling an engine.

[efrench]

Are you not sending the crankcase out for overhaul? I have seen no NDT data on through bolts but have always sent my crankcase out for v overhaul when overhauling an engine.

I'm getting a replacement case from the supplier (salvage/yellow tagged), not sure if it will include the thru bolts or not. So, I disassembled and sent all of the normally expected parts for yellow tag inspection. I overlooked the thru bolts on the parts, but that raised the question.

Jeff asked a valid question as to whether the bolts are stressed or not. In my very limited thinking and total ignorance, I am expecting that they would not be as stressed as the cylinder base bolts, however maybe more ability to stretch? This is a mission of academia more than anything else.

Thanks


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[efrench]

Spoke to BJ's Custom Engine today and learned that the thru bolts are normally magnafluxed. They indicated that on a replacement case, the fixed thru bolts (2) should come with the new-to-me case and should be certified with the case. So, I'll ship the floating bolts (4) to go along with the rest of the parts. Maybe not specifically lined out, but as Jeff pointed out, this is a stressed item and a failure could be not conducive to a quality Aviating experience.


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[Steve Pierce]

Good to know, thanks.