Stop torquing spark plugs with a torque wrench in 100 degree heat

I just pulled five plugs out of a Lycoming last week where the threads were stretched from being torqued hot, which throws off the readings and can crack the housing. The spec is 300 inch-pounds cold, but every third plane that comes through my hangar has someone who torqued them after a run-up and now I'm helicoiling the head. How do you guys handle torque values when the engine is still warm from taxiing?

3 comments

3 Comments

charlies3713d ago

Did a buddy of mine learn this the hard way with his O-360? He torqued plugs after a short taxi job, next flight one cracked the ceramic and cost him a top overhaul.

morgan.jason13d ago

Man that sucks, I feel for your buddy. Had a similar thing happen on a Continental IO-470 where I torqued the plugs cold and the first run after a quick reposition cracked two of them. Cost me a cylinder removal and a lot of cussing at myself lol. Now I only torque them after the engine's been run and fully heat soaked, even if it's just a short taxi.

fionam1113d ago

Actually, torque after heat soak even with just a taxi - that's the only safe way.