Trying to grasp the AD for wing spars

[YankeeClipper]

I've read quite a bit about the 78-09-05 AD but am still lost on a few things.

1) Mandatory or not for non-commerical, private owners and operators?

2) Why wouldn't someone want to inspect & repair even if not?

3) What are the ball park costs associated with a) inspection and b) remediation? I read figures up to $60k.

Thanks.

[hharney]

AD's are mandatory. SID's are not mandatory. I think you may be confusing the two.

The wing spar AD is mandatory at 5,000 hours airframe time (3,000 for utility use).

I have heard costs in the $2K to $3K range for the wing spar AD compliance at 5,000 hours

[YankeeClipper]

Obviously I'm a complete neophyte--not only to Skymasters, but to flying. So I can only assume you are referring to inspection only.

The $60k number I saw was actually from an AVWeb article that appears to have quote you about a SID that involved wing removal. Is this a different issue or requirement? Does it not address a risk that could affect all owners?


http://www.avweb.com/avwebflash/news..._201736-1.html

Thanks for the response.

[hharney]

The AD 78-09-05 does not require the wings to be removed. Access is gained to the spar and is inspected using an eddy current device (NDI)

The SID that is referred to in the report from AvWeb is the inspection of the attach points of the wings and struts. Because the process requires the bolts to be removed for inspection the inspection is estimated to be very expensive. In order to remove the bolts that attach the wings, the entire tail and boom assembly must be removed first. This is the only method known that will minimize the potential damage that could occur by performing this inspection. If some kind of jig were to be developed that could support the structure maybe the bolts could be safely removed for inspection. To my knowledge no such device exists.

The AD attached is a walk in the park compared to these SID inspections. Although never taken lightly this AD has been performed on many Skymaster's already and may be best to use an experienced shop for the inspection.

[YankeeClipper]

Really clears things up. Thanks.

So does the SID concern most 337 owners as well?

[Ernie Martin]

SIDs are NOT mandatory for Part 91 operators, which includes private owners in the U.S. Overseas the situation is different. Some (most?) countries consider SIDs mandatory for everyone, some only for commercial operators.

Ernie Martin

[YankeeClipper]

Sorry, I was after whether the issue raised in that SID should concern 337 owners, as in to bother, worry, or raise doubt--as opposed to applicability. With the costs involved, some are inclined to suspect revenue generation, while others might feel there is a genuine risk afoot.

But that was helpful information in any case ... thanks Ernie.

[hharney]

The SID development by Cessna was a proactive approach on their part. It all comes from Congress passing the Aging Aircraft Bill. This document is primarily pointing to the airliners but will eventually catch up to all aircraft. Cessna is just getting ahead of the game you might say.

Bottom line is liability. Cessna never intended that their aircraft should still be flying 50 years after construction. They really don't care about selling parts for the old ones either otherwise they would make the parts. They would in my opinion rather see the aircraft retired. They would like to sell you a new one.

Personally I think we can learn a lot from the SID's. They do identify key areas to inspect and be aware of potential weaknesses of our aircraft. Use them as guides and they may make some sense. I would suggest that everyone that owns a Skymaster buy a copy of the SID's to use along with the service manual. They are available from Cessna through companies like Yingling Aircraft.

[Ernie Martin]

I agree with Herb, and some of the SIDs make sense and should be used as guides, but if we focus on the big-ticket item -- the wing-attach points SID -- there are two additional factors to consider:

1. There is NO indication that there has ever been a problem in the area. If you read the entire SID thread you will learn that Cessna's stated methodology for areas needing SID attention was the FAA Service Difficulty Reports (SDRs, over 35 years of problem reports furnished to the FAA by repair shops, with about 1,000,000 reports, of which 1,773 involve Cessna 337 aircraft), BUT there were no relevant SDRs in this area. More importantly, Don Nieser's Commodore Aerospace has disassembled numerous Skymasters -- some with well over 5,000 hours -- and has never found corrosion or stress in this area.

2. If not done properly -- and that's likely with an inexperienced shop -- the SID may cause more harm than good, putting undue stress in the inspection area.

Ernie