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Hole edge clearance question

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BJC

Well-Known Member
Supporting Member
Joined
Oct 7, 2013
Messages
18,227
Location
97FL, Florida, USA
Reference: Lycoming IO-360-B1E engine and a custom air induction elbow on a Glasair.

I need to attach a 4130 steel brace that runs between between the 1/4" accessory case bolt that is just to the left and below the left magneto, to the 5/16" bolt that attaches the throttle body to a 90 degree elbow between the intake and the throttled body. The brace provides support for the throttle body.

I know that the recommended edge clearance, measured from the center of the hole is twice the diameter of the hole. The strap that I have will not fit if I follow that. The tabs on the strap are 1/8" thick, which is relatively thick for the bolt sizes used. If the in-service throttle body weighed 5 pounds (it is less, but I haven't taken it off and weighed it) then the max load at 6 g would be around 30 pounds. Factor in the mounting angle. a safety factor, some robustness for engine vibration and thermal expansion, call the max load 400 pounds.

Using a yield strength of 60,000 PSI for the 4160 would indicate the need for less than 1/8" of edge metal, or an edge distance of 3/8" and 9/32".

What issues would you anticipate with the reduced edge distance in this application?

Thanks,


BJC
 
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