wrote:
I was recently talking with my A&P/IA friend about my upcoming annual on my PA-28-180. He said
that there's some particularly disturbing news regarding manufacturer's service bulletins that can
*require* compliance even for Part 91 operators.

The one that brought is up is SB643B from TCM regarding Bendix mags. Basically, it's a the
normal 100-hour inspections, impulse coupling inspections, etc. The kicker is that it also says mags
must be overhauled every 5 years from previous overhaul, or 4 years from the date put in service.

Normally, a Part 91 guy would say, "Service Bulletins aren't mandatory, so I don't need to do
it." TCM added the magic phrase at the beginning of the SB which says: "The following information
constitutes the manufacturer's Instructions for Continued Airworthiness..." Those magic words appear to
make it a mandatory legal requirement as per the FARs.

Has anyone run into this already? The mandatory 4-year overhaul of mags seem excessive for most
owners. The precidence it sets essentially allows a manufacturer to issue an "AD" without oversight by
the FAA and public comments, etc.



Yes and the FAA has already come out stating what we all believed in the
first place. A manufacturer cannot force a part 91 operator to replace
on a certain schedule no matter what the wording of a service bulletin
or any other documents by the manufacturer.