Pro tip: check the torque on those LRU mounting bolts, not just the connector pins

I was doing a post-install check on a new comms box in a King Air last week and found all four mounting bolts were barely finger tight, even though the D-sub pins were torqued to spec. The tech before me must have rushed the final step. That kind of thing can cause a real bad day from vibration down the line. How often do you guys actually break out the torque wrench for the hardware, not just the avionics?

3 comments

3 Comments

margaret_lane4d ago

...and that's exactly what I said before I snapped a bolt clean off on a Citation V last month. My face was the exact shade of the "I've made a huge mistake" meme from Arrested Development. The worst part is, I had the torque wrench right there in my hand but thought "nah, it's just a mounting bolt, it'll be fine". So yeah, I get why people skip it - time adds up fast - but my pride took a bigger hit than that bolt did. Now I just leave the torque wrench sitting on top of the unit before I even start, like a reminder to my own dumb brain.

elizabeth_chen2mo ago

Honestly, that seems like overkill for a mounting bolt. If the connector is secure and the unit is seated, those bolts are just there to keep it from rattling around. A good quarter-turn with a standard wrench after it's snug has always been fine in my experience. Pulling out a torque wrench for every piece of hardware would triple the install time for no real gain.

finleybutler2mo ago

Ever sheared one off by going a quarter-turn too far? Asking for a friend who definitely isn't me.