On 5/25/2025 9:44 PM, Samuel Ajayi via KRnet wrote:
I have never heard of stretching of AN bolts, let alone one on a
critical component such as a prop. Were that the case, every one of
the spam cans on the ramp ought to have replaced their prop bolts a
few times by now. Most of them are flying with the same bolts they
left the factory with.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Yes, bolts do stretch when "pulled in tension" as in tightening down the
nut. Normally a "critical" bolt is stretched (tension-ed) to a greater
length (thousands of an inch) than it will see in service so it does not
cycle under load and cause it to fatigue / crack. Have you ever bent a
piece of metal back and forth until it breaks?
As it is rather difficult to measure the "stretch" of a bolt accurately,
we use a torque value instead in in/lb, ft/lb, etc. which is a close
approximation and a much more convenient method. The bolt loading areas
that we encounter with thing like prop bolts on a wood prop , 15 - 18
ft/lbs are certainly not critical. When you get in to areas like engines
that see high stress values the numbers start to get more critical.
Follow the instructions and all will probably work out.
Larry Flesner
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