Ground loop testing is being skipped way too often on bench work

Honestly, I keep seeing guys in our shop at KSFO skip the ground loop test after a simple LRU swap, and it's biting us on the next flight. A 0.5 ohm difference on the bonding strap can cause a 60 Hz hum on the intercom that the pilot blames on the audio panel, not the install. I know it adds 20 minutes, but I've traced three write-ups in the last month back to exactly this shortcut. Anyone else tracking this on their 737s, or is it just our hangar culture pushing speed over solid checks?

2 comments

2 Comments

faithwalker20d ago

Preach, man. That 20 mins saves way more hassle later.

olivia_bailey20d ago

Wait, 0.5 ohm? That's what you're chasing? Half an ohm on a bonding strap can do that? I've seen guys chase a hum for two days and pull their hair out swapping audio panels and intercoms, and it's just some stupid strap with a little corrosion or a loose screw. You're telling me you've traced three write-ups to that exact thing in a month? That's wild. Most guys will spend an hour backprobing pins before they even look at the bonding strap. And they still won't find it because they're staring at the box, not the ground path. I've seen a 737 with a new audio panel that hummed like a fridge, and the install was perfect, but the strap under the floor had a cracked terminal. Half an ohm doesn't sound like much, but it's the whole damn game on the audio system. You're right to be mad about skipping that test.