Debate: torque wrench calibration frequency - yearly or per 100 cycles?

Had a Pratt & Whitney JT8D engine mount bolt snap on me last Tuesday over in Memphis while torquing it down. I always follow the manual and calibrate yearly, but my lead says we should do it every 100 cycles which feels like overkill. The bolt failure was from stress cracking, not a tool error, but now I'm second guessing. How often do you guys actually send your wrenches in, and have you ever had a failure tied to calibration drift?

2 comments

2 Comments

lopez.brooke24d ago

Gotta agree with your lead on this one, sorry. Yearly calibration is fine for most stuff, but high cycle tools like torquing engine mounts on a JT8D take a beating. I've seen wrenches drift after like 50 cycles on the heavy stuff, especially if they get dropped or stored hot. The bolt failure probably wasn't the tool, but having it spot on everytime helps rule that out real quick. Sending it in every 100 cycles is cheap insurance when you're dealing with parts that can kill a whole plane if they let go.

ryang7724d ago

90 cycles on a 3/4" Snap-on and it was reading 15% low. Found out the new guy dropped it off the wing stand the week before and just never said anything. Guess I'll keep double checking my wrenches with a beam style for a while.