PSA: Double check those torque wrenches on turbine blades

I was torquing turbine blades on a Pratt PT6 last Tuesday and my digital wrench read 45 in-lbs, but the old beam style showed 38 in-lbs when I checked it after. Turns out the digital one was off by 7 in-lbs from getting knocked around in the toolbox, which could've been a real problem. Anyone else having issues with digital torque tools drifting over time?

3 comments

3 Comments

oscar74315d agoTop Commenter

Oh man, just a heads up, 45 in-lbs on a PT6 blade seems a bit high. Most PT6 torque specs I've seen are around 30 in-lbs for the base. Might wanna double check that manual before anything else.

hayes.joel14d ago

Yeah good catch @oscar743, that 45 in-lbs had me scratching my head too. It's like when you see someone tighten a gas cap way too hard, just because a little torque is good doesn't mean more is better. I've noticed this pattern all over, people think cranking something down tighter makes it safer or more secure. But with these PT6 blades, going past the spec can actually cause stress cracks or warp the mounting surface over time. Same reason you don't overtighten lug nuts on a car, it warps the rotors and makes things worse. You ever seen someone strip a bolt because they thought "a little more" was the safe route?

vera_palmer14d ago

So do we get bonus points for using two different torque wrenches and still not agreeing on the right number? Sounds like your digital wrench needs a timeout in the corner after getting knocked around like that.