Caught a loose torque stripe on a 737 flap actuator yesterday

I was doing a routine walk-around at DFW and spotted a torque stripe that had shifted about 1/4 inch from its original position, which means someone either forgot to tighten the bolt or didn't mark it right. That kind of oversight could lead to a control surface issue mid-flight if it came loose enough. Has anyone else run into torque stripes that looked fine from a distance but were actually way off?

3 comments

3 Comments

ray_williams1mo ago

That bit about a "lazy torque stripe that's still in place but misaligned" is spot on, @gibson.morgan, but I gotta push back a little on the idea that the paint was applied after the job was half-assed. More often than not, I see guys who properly torque the bolt but then paint the stripe across the washer and nut without checking that the line actually lands on the same faces it started on, so it shifts when the bolt doesn't move. The point is you can't trust the stripe until you verify the hardware hasn't backed off, which means looking at the gap between the bolt head and the surface, not just the paint.

gibson.morgan1mo ago

That 1/4 inch shift is exactly the kind of thing I used to brush off as just paint peeling. I figured if a torque stripe looked basically intact from a few feet away, it was fine. But after I saw a bolt on a cargo door hinge that had backed out almost a full thread with the stripe still looking mostly straight from a distance, I totally changed my mind. Now I get right up close and actually check if the line is still perfectly matched up with the hardware edges. A lazy torque stripe that's still in place but misaligned is a huge red flag because it means the bolt never got the right torque or it slipped. It's way too easy to miss on a quick walk around if you're not specifically looking at the stripe alignment instead of just its presence. Good catch on that actuator, man.

angelarivera1mo ago

The way you said "a lazy torque stripe that's still in place but misaligned" really hits the nail on the head. I've seen so many guys just glance at a stripe from five feet away and think it's okay, but the whole point is the alignment, not just the paint being there. If the stripe is still perfectly in line but the bolt is loose, that's a major problem because it means someone probably painted it after they half-assed the job. I actually had a similar thing happen on a flap track fairing once, where the stripe looked straight from the ground but when I got up close the bolt head was sitting a little proud of the washer. The paint had been applied so it still looked like the line matched, but it was basically just a fake mark. Your point about getting right up close is the only way to catch this stuff, and it's something a lot of new guys don't get until they see a bolt that's actually backed out.