Can A&P do impulse-coupling AD?

[Ernie Martin]

There is a 500-hour recurring AD on our Bendix magnetos to check the impulse-coupling. Does anyone know if an A&P can do this if he has the Service Bulletin, or do the magnetos have to go to a specialty shop?

Ernie

[big al 08]

yes and have had it done and thank you for the info on the hoses. rick

[Skymaster337B]

What AD number is that? I think I have different mags, but just wanted to check.

[Kim Geyer]

Ernie
The AD you are thinking of is AD 96-12-07 which was superceeded AD 05-12-06 and it no longer applies to bendix / TCM magnetos on Continental engines. But you still have a recomended 500 hr. inspection.
Kim

[Ernie Martin]

Kim:

I subscribe to Adlog, so I get AD updates. But I don't remember getting AD 05-12-06, so I'm under the impression that AD 96-12-07, including the 500-hr recurring inspection of the impulse-coupling assembly, still applies to the Bendix mags on my engines. I called Adlog, they faxed me the 2005 AD and it seems to cover only magnetos installed on Lycoming 540-series engines, not our IO 360 engines. In any event, the 500-hr recurring inspection is still required under the new AD. Am I reading this wrong?

Also, in your fleet, do your A&Ps do the impulse-coupling inspection or do you send them out to a magneto shop?

Thanks,
Ernie

[Kim Geyer]

Ernie
Thats one of the problems with Adlog systems. the new AD didn't apply to your aircraft so you didn't get AD 05-12-06 which does superceed 96-12-07.
Kim

[Kim Geyer]

Let me tell you I've done the AD a bunch and no we don't have to do it anymore. Basically the new AD takes the place of the old one. Although its not required anymore it sure ain't going to hurt anything to look at them now and then, being we had 2 mag failures causing us to pull the engines.
Cessna sez to check TCM service Bulletin 643 and they want you to do a 500 hr inspection of the whole mag and overhaul it ea. 4 years.
Kim

[Ernie Martin]

Kim:

I'm hoping you're right, I'm rooting for you....

But forget Adlog, I've read the AD and it seems applicable only when these magnetos are installed on Lycoming series 540 engines, and even then the 500-hr impulse coupling inspection is still a requirement. I'm at an impasse here. Any further info would be most welcome.

Ernie

[Kim Geyer]

Ernie
You are right the AD now only applies to those mags installed on lycoming engines. If you read AD 05-12-06 at the begining it sez this AD superceedes AD 96-12-07 that means take the place of.
I have the Feds and other assorted gov. officals looking at our aircraft records sereral times a year and believe me if I was wrong they would let me know.

[Ernie Martin]

Kim:

OK, I see that, where it supersedes AD06-12-07, but Table 2 still requires repetitive inspections every 500 hours -- not recommended, but required. Am I reading this wrong?

Thanks for your help,
Ernie

[Kim Geyer]

Ernie
This AD only applies to mags on those Lycoming engines listed.
The repetive inspections only apply to to those Lycoming engines listed in the AD. The TCM service bulletin 645 does apply to all mags with impulse couplings.

[SteveG]

After reading both AD's it seems clear enough that the new AD only applies to those Lycoming 540 models listed and that our Continental 360's no longer require inspection. The AD goes on to say that compliance with SB643b and MSB645 is still highly recommended. Which then begs the questions: What service life is actually being experienced with our engine/mag combination and is there a significant difference between the riveted and snap ring couplings? From those operators who have inspected their mags since the '96 AD, what percentage have failed the 645 tolerences? SB643 goes on to say that all mags, regardless of application, must be replaced or overhauled every five years regardless of hours in service, which I suspect nearly no Part 91 operator is complying with. Its hard to know if this is a real problem or a Continental CYA bulletin. Obviously the FAA must have felt the 500 hr. interval was overkill for engine/mag combinations other than the Lyc. 540 to have recinded the applicability yet they say they expect that all operators will voluntarily comply with the manufacturer's SB. I'd be interested to hear about any real world in service experience anyone else can share.