Had a packed bearing nearly take out a gearbox on a 737 yesterday

I was doing a routine wheel change at our hangar in Atlanta and noticed a slight discoloration on the main landing gear trunnion. Pulled the bearing and found it was dry as a bone with metal shavings starting to pile up. One more flight and that bearing would have seized, turning a 2-hour job into a full gearbox swap. Anyone else ever catch something small like this before it turned into a weekend-killer?

2 comments

2 Comments

beth_hunt3d ago

... yeah, caught a similar thing on a hauler once, not a plane but a semi, and let me tell you that noise when a bearing goes is something you don't forget... sounds like the truck is trying to eat itself. I'd rather spend two hours swapping a bearing than two days wrestling with a gearbox, that's for sure. Must've been a real nice feeling spotting that discoloration though, like finding a crack in the windshield before it turns into a spiderweb... nobody wants that weekend project.

gracecarr3d agoMost Upvoted

Man, that bearing noise description is spot on, Beth_hunt. I had an old riding mower once that started making this low growl every time you turned left. Thought it was the belt or something simple. Turned out the bearing in the front wheel hub was totally shot, and it had worn the axle down to almost nothing by the time I figured it out. Ended up having to weld a whole new piece onto it, which took way longer than just swapping the bearing would've if I'd caught it sooner. You're dead right about the weekend project thing too, sometimes fixing one thing just leads you down a rabbit hole.