Was dead wrong about torque wrenches for smaller bolts until a crack in a flap track proved it

Spent 8 years thinking I could just feel it on bolts under 15 ft-lbs. Been doing it that way since my A&P days. Then last month on a CRJ700 in Denver, I got called out for a flap track bolt that had a hairline crack in the lug. Lead mechanic asked me what I torqued that little one to. I said 'felt right.' He pulled out his Snap-on digital torque wrench and showed me I was 4 ft-lbs over. That crack was from years of me and probably other guys doing the same thing. Now I use a beam style for anything under 20 ft-lbs and I actually check the table. Has anyone else caught themselves guessing on small hardware and gotten away with it?

2 comments

2 Comments

dylan2651d ago

Felt right" is the universal language of people who have never had to explain a bolt failure to an FAA inspector. Yeah I did the same thing for years on those little AN3 bolts, figured a snug plus a grunt was close enough. Then a buddy of mine snapped a valve cover bolt on a Lycoming and spent a Saturday afternoon drilling and easy-outing it out of the case. Bet that "feel" cost him a six pack and a ruined weekend. Torque wrenches are cheap, engine cases are not.

the_evan1d ago

Used to think I could get by with the old "calibrated elbow" method too. Your story about the valve cover bolt hits home, never had to drill one out of a Lycoming case but I can imagine the pain. You're right though, torque wrenches are cheap insurance and I finally bought one after a friend stripped a critical bolt on his project.