Appreciation post: the old torque wrench method I learned in Long Beach

Back in 2009 I used to just click the wrench until it stopped and call it good, but then a line chief in Long Beach showed me how he backs off and re-torques every fastener twice for thermal stability. Now on turbine fan blades I do the full sequence with a dial indicator too, and it adds maybe 20 minutes per fan but the vibration readings stay cleaner. Has anyone else switched to a two-pass torque routine since the newer composite fans started showing up?

2 comments

2 Comments

the_holly19d ago

Wait, doesn't the dial indicator add more variables than it removes on a hot fan disc? I've seen guys chase a couple tenths and end up chasing their tails all shift, but torque is torque once it clicks.

davis.adam18d ago

Whoa, hold on, @the_holly, you're telling me you've watched guys burn a whole shift on that thing? That's wild. I mean, I've seen the needle dance around like a meth-head on a hot plate, but I always figured it was just my crappy technique. Chasing two tenths on a fan disc that's gonna heat-soak the moment you walk away, that's pure madness. You're right though, once that torque wrench clicks, the fastener doesn't care about the last thousandth. You'd think the dial would settle things, but it just gives you a new, fancier way to second-guess yourself.