Exhaust Stud Torque

[Notatestpilot]

If an O540 engine exhaust stud uses a 5/16-18 thread nut, what is the required torque?
What does the overhaul manual call out?

 

[Bell206]

If an O540 engine exhaust stud uses a 5/16-18 thread nut, what is the required torque?

Lycoming lists torques in the SSP-1776. TCM used to have a Service Bulletin with all the torques but I think they moved them into the M-0 Standard Practices manual which I can't get to link at the moment.

 

[Notatestpilot]

Thank you Bell206!

 

[Stewartb]

There is no specific torque value for exhaust flange nuts listed in the current Lycoming engine manuals I’ve read. That sends you to the standard torque table for 5/16” nuts, which is 17-19 pound feet of torque. Most mechanics I know disregard that and tighten to snug fearing warping of exhaust flanges. That’s why guys lose exhaust nuts. I tighten mine per the standard torque table and use Nord-Lock washers. Mine stay put.

 

[Let'sgoflying!]

maybe this?

https://www.lycoming.com/sites/default/files/attachments/SSP-1776-5%2520Table%2520of%2520Limits%2520-%2520Complete.pdf

 

[Stewartb]

O-540 doesn’t indicate a geared engine.

 

[Notatestpilot]

There is no specific torque value for exhaust flange nuts listed in the current Lycoming engine manuals I’ve read. That sends you to the standard torque table for 5/16” nuts, which is 17-19 pound feet of torque. Most mechanics I know disregard that and tighten to snug fearing warping of exhaust flanges. That’s why guys lose exhaust nuts. I tighten mine per the standard torque table and use Nord-Lock washers. Mine stay put.

Thank you sir. Didn't know about Nordlock. I shall check it out...

 

[donjohnston]

They ain’t cheap, but they work.