Pro tip: Stop using the wrong grease on landing gear bolts

I spent two years packing landing gear bolts with standard wheel bearing grease because that's what the old guys in my hangar did. Last month a regional airline inspector flagged my work during a spot check and told me to look at the spec sheet. Turns out I needed a specific MIL-PRF-81322 grease for those pins, and my cheap stuff was causing premature wear on the bushings. Has anyone else been using the wrong lube without realizing it?

2 comments

2 Comments

terryallen15d ago

Whoa, hold on a second. I've been using standard wheel bearing grease on landing gear bolts for over a decade and never had a single issue. The spec sheets are written by engineers who don't actually have to turn wrenches in the field. That MIL-PRF-81322 stuff is expensive and hard to find at most local shops. If your bushings are wearing out from a little bit of regular grease, maybe the problem is the bushing material or how you're torquing the bolt, not the lube itself. What kind of aircraft are you working on?

lucas_perez15d ago

The thing about MIL-PRF-81322 is it's a synthetic grease that holds up way better in high load, high vibration areas like landing gear pins. Wheel bearing grease is mostly for, well, bearings that spin. On a bolt that barely moves but has a lot of pressure, the cheaper stuff can get pushed out and dry up faster, leading to corrosion and wear. I've seen it on a few King Airs and Cessna 400 series where guys swore by the old grease but the bushings were egg-shaped after a few hundred hours. Your mileage may vary, but the spec is there for a reason even if it's a pain to find.