[SkyKing]

Hew,

Not too much to worry about, but the AD does cover the 336 models, 337's, and the P-models as well, but with different affectivity times as to when the inspections are to begin.

The purpose of the AD is to detect cracking of the wing front and rear spar lower caps, front spar web and web doubler, in the vicinity of where the struts attach to the wing. The inspection process involves using an eddy current probe and dye penetrant, as well as the old eyeball. Of course, if any cracks are discovered, the parts must be replaced before the airplane is returned to service. So far, I've not heard of anyone having to replace the subject parts, but given the prices Cessna has been charging lately for things, this could be a rather EXPENSIVE proposition.

Cessna Multi-Engine Service Letter ME78-2 addressed the issues on February 13, 1978, so this is not something new for Skymasters. However, the original AD that came out was 73-04-03 with a later amendment, 76-10-11, and then the current amended AD, which is 78-09-05.

The affectivity and "compliance timetable" are based on the type of aircraft operations and total time in service by model. For example, non-pressurized Skymasters are generally not affected by the current amended AD until 5,000 hours total time in service have accumulated, and the initial inspection must be accomplished within 25-hours time in service after the effective date of the AD, with 500 hour repetitive inspections.

Since the P-model has a beefier airframe and generally isn't subjected to low-level contour operations like pipeline patrol or police patrol work, the P's aren't affected until 10,000 hours total time in service. And then, within 25-hours time in service after the effective date of the AD, and the same 500 hour repetitive inspections.

Mind you, this is my read of the AD, and like anything else, it would behoove the reader to check out the facts and actually obtain the necessary paperwork from Cessna and the FAA to get the straight skinny.

So, there is something to be said for searching out a pristine, low time airplane. Personally, I've never heard of a 337 having cracks as per the AD, so I think this boils down to Cessna doing a "CYA" Operation with the FAA's blessing, i.e., "cover your _ _ _ " type of thing. But that's my personal opinion based on other known facts. In any event, the AD is issued for safety reasons, and it is a mandatory thing.

Overall, I'd say the Skymaster, at least the later model P337 series have a minimal number of AD's to comply with, as compared to other airplanes. Ever look at the AD list on a Piper? Yikes.

Hope this helps.

SkyKing