Lycoming O-320-H2AD

[RyanB]

Im sure this has already been addressed on here, anyways, i assume all the 172N's as far as ones in the rental fleet have had the modifications necessary to fix the cam and lifter issues it once had. Can anyone confirm this and fill me in on what is wrong with this engine?

 

[MAKG1]

Every 172N that has passed a legitimate annual has had that AD serviced.

However, I believe it's not a modification, but an inspection regime.

Cams don't just spall instantly. That's not an "engine blowed up" process. They slowly disintegrate until the valves don't open anymore. And while this is going on, they put lots of bits of steel in the oil, which gets trapped in the filter and can be identified with a magnet.