chopjock -
Not sure the specifics, but he was required to comply with the AD and as memory recalls ended up having to replace the entire section in the process. Thankfully my C20B had just been overhauled (to the tune of $190,000.00) by Premier when I purchased my 500 so I had little to do but compressor inspections. Also, I had brand new blades on my ship when purchased, so I was well ahead of the game in regards to really expensive parts. I did go through a tailrotor gearbox after an in-flight chip light, that went to Canada to be overhauled...I think that and a blade grip replacement (had to be done by MD, they flew two guys out to do it) were the two most major items in all the time I had the 500. Beyond that, "regular" maintenance was just way expensive.