TIL a torque wrench calibration chart is basically useless if you drop the thing once

So three years ago I was torquing down a main landing gear wheel on a 737 at a hangar in Tulsa, and my coworker handed me his torque wrench without saying it got dropped off the stand the day before. I used it anyway because I was in a hurry (stupid me, I know). Got the lug nuts all set, signed off, and the plane did two flights before a pilot reported a wobble on landing. Turned out I under-torqued half the nuts by like 30 foot-pounds because that wrench was way off after the drop. My lead had me redo the whole job on the ramp in 95 degree heat while the crew watched. Now I shake every torque wrench before I use it and check the calibration sticker. Has anyone else ever chased a problem for days only to find out it was a tool you trusted that let you down?

2 comments

2 Comments

patricia_green211mo ago

I used to be one of those people who thought torque wrenches were pretty much indestructible, you know, just a big hunk of metal. Then my neighbor borrowed mine to put new tires on his truck, dropped it on the concrete, and handed it back without saying a word. Next thing I knew, I was chasing a weird vibration in my own car for two weeks, replacing control arms and bushings that were perfectly fine. Finally took the wheel off myself and checked the lug nuts with my other wrench, and every single one was off by at least 20 ft-lbs. Never assumed they're tough again, that's for sure.

elliot451mo ago

A torque wrench dropping onto concrete from a truck bed isn't enough to knock it 20 ft-lbs out of spec. Those tools are built with hardened steel internals, and a drop like that would take a lot more force than gravity from waist height to mess with the calibration. More likely your neighbor was already cranking them on with an impact gun and just used the torque wrench as a final check, or the wrench was never calibrated right to begin with. I've dropped my Craftsman click-type onto a garage floor more times than I can count and it still checks out within a couple ft-lbs on my beam-style tester. The real lesson here is you should be verifying your tools' accuracy once a year either way, not assuming one drop killed it.