I always thought torque wrenches were bulletproof until one cost me a day of work

I've been an A&P for about 12 years and I always assumed my torque wrenches were good to go as long as they clicked. Last month I was doing a flap track rebuild on a 737 at a shop in Tulsa and I kept snapping bolts on the gearbox mounts. I checked the manual, checked the bolt spec, everything looked right. After the third one snapped I grabbed a different torque wrench from the tool crib and it clicked perfectly at the same setting. My old one was about 15 ft-lbs off at the lower end of its range. I sent it out for calibration and sure enough it was way out of whack. Now I'm sending all my click-type wrenches out every 6 months instead of yearly. Has anyone else had a wrench go bad without any signs of damage?

2 comments

2 Comments

aarons369d ago

Yeah click-types can drift without you noticing. That's why I send mine out every 4 months now. Saved my ass on a gearbox job last year.

carr.willow9d ago

Reminds me of how my car's oil life monitor started lying to me around 50k miles. Digital stuff gives you a false sense of precision when the sensors are just guessing half the time. People trust the readout without thinking about drift. Feels like the same issue with any calibration over time, whether it's a torque wrench or just the mpg display in your dash.