Loading…
12
Why does nobody talk about using feeler gauges on cowl fasteners instead of just torque specs
I used to torque every camloc and dzus fastener to spec and call it done, until a senior guy at our hangar in Spokane walked me through why that misses the real problem. He grabbed a .003 feeler gauge and showed me that on a 737 engine cowl door, two fasteners reading perfect torque were actually sitting proud because the sheet metal had worn. He pulled a flashlight out and pointed at the light leaking through a gap no bigger than a business card, and that gap was throwing off the whole panel fit. We re-shimmed four fasteners and the door sat flush for the first time on that airframe. I had been signing those off for two inspection cycles without catching it. Now I keep a gauge in my shirt pocket, but I'm wondering if anybody has a better field check for worn camloc seats before they cause a bigger issue down the line.
1 comments
Log in to join the discussion
Log In1 Comment
elizabeth_king18d ago
Carry that logic one step further and check the seat depth itself before you even bother with the gauge. A camloc that reads good torque but has a wallowed out hole is still going to let that panel move under vibration, and the feeler gauge only tells you the gap is there, not why. Try pressing the stud down with your thumb and watching for any spring back, a worn seat will let it drop lower than the ones around it. If you find one that sits deep, pull the receptacle and look for the classic oval shape where the cross pin has been eating into the metal. I started marking those spots with a paint pen during inspections so the next guy knows to watch them instead of just re-torquing and walking away. That way you catch the wear before it turns into a fastener that won't hold at altitude.
5