Did some work on the 337 today at my IA shop. He does maintenance for a small but busy flight school. He’s got a few filters but they’re depleting faster than what few come in. He’s already purchased some K&N’s. When the time comes (soon) he’s going to call the FSDO and tell them there’s no choice, will have to use K&N Or ground some flight school and number of corporate planes he takes care of on the field as well as personal aircraft. Busiest airport in the state, so not a small following might back that up. Also, we discussed “owner manufactured” parts solutions allowed by the regs when nothing else available. Alternative is that this be considered owner “manufactured” part solution. I guess you can document it that way.
Found this interesting in Cessna flyers:
https://www.cessnaflyer.org/maintena...lications.html