IO-550 Airworthiness Directive

Those of us with IO-550N engines need to comply with a new airworthiness directive: 2004-8-10. Some of the cylinders installed on our engines may be from a batch which has been over-hardened, potentially leading to the formation of cracks. If found during inspection, these cylinders need to be replaced before further flight.

I’ve posted details including links to the AD and an ECi service bulletin on the Lancair forum.

I don’t have any word yet on the extent to which this will affect the SR-22 or Columbia fleets, if at all. But it poses a potentially significant safety issue and entails sending 6 cylinders back to Texas. I wonder if there’s any insight from the Cirrus owners on this one at this early stage?


This was discussed on the Member’s forum. The cylinders involved are aftermarket (not TCM) cylinders that would only be found on an engine that was overhauled with the listed ECI brand cylinders…not too likely to have happened to any SR22s in the fleet.




I did not see and could not find by search the post on the Members Forum, but I came to the same conclusion: it is an aftermarket cylinder that is the problem. if you don’t have a new cylinder from that manufacturer you are o.k.

Received the AD today on the cylinders. Cirrus was not named.