Watching guys torque those new composite panel fasteners wrong at the hangar

Been at a regional MRO in Tulsa for about eight months now. I keep seeing mechanics use a standard torque wrench on the new generation of composite panel fasteners, the ones with the blue collar. They crank it to the book spec, hear the click, and move on. The problem is, these fasteners need a slow, steady pull to seat properly in the composite material. If you just go for the click, you can overstress the surrounding area without even knowing. I saw a panel come back for a re-seal job last week because of a hairline crack that started right at a fastener hole. My lead showed me the right way, which is to go about 80% of the torque, back off, then finish to spec in one smooth motion. It adds maybe ten seconds per fastener but saves a huge headache later. Has anyone else run into this with the newer materials, or is my hangar just behind the curve on the training?

3 comments

3 Comments

the_ivan22d ago

Man, I used to be that guy just going for the click. Thought the spec was the spec. Then we had a whole set of panels on a 737 MAX cheek section come back with stress whitening around every other fastener. The NDT guys showed me how the quick jerk from a click wrench can basically shock the composite. Now I do that slow final pull like your lead said, and it makes a visible difference in how the collar sits. Totally changed my approach.

matthew12222d ago

Stress whitening around every fastener" sounds like the composite was trying to send you a message. Honestly, it's wild how a tiny change in technique can stop you from basically shock-treating airplane parts. Guess the spec isn't just a number, it's a whole mood.

iris_rivera443d ago

Yeah, that "slow final pull" thing is key. I mean, @matthew122 is right, it's a whole mood. Letting the tool do the work instead of forcing it makes all the difference.