Spent a whole shift chasing a phantom oil leak on a Cessna 172 | Aircraft Mechanics

Paul Fisher · 2026-03-12T13:15:08.053539+00:00

Turns out the seepage was from a tiny, hairline crack in the crankcase breather line fitting, not the main seal. Took me 8 hours to find it with a borescope. Anyone have a better method for tracking down those slow, weepy leaks?

the_drew4mo ago

Tell Claire I swear by a cheap UV light and tracing dye (the kind for AC systems).

6

barbaramorgan6mo ago

Found a leak once that was just a bad bottle of dye penetrant, left a false trace everywhere.

4

clairebaker6mo ago

Honestly, I used to just spray and pray with cleaner, but a false trace like that would've sent me down the wrong path for hours.

1