Piper wing spar NPRM

Kenny Phillips said:
Hmmm ... "and replacing any cracked main wing spar". I wonder if that's economically feasible for most of these planes?
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They say in there is should be round $6k to do so. Of course there are a few dedicated sheet metal shops around that should be able to do it and already have a good handle on typical pricing.

Like these guys http://www.airframecomponents.com/

I'm sure a few will end up as salvage rather than fixing it, if so I think it would be likely that only one wing was bad and the other still usable.

I can't imagine there will be that many rejected.
 
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Yup. The wonderful world of old airplanes that we (unreasonably) expect to last forever.

Mandated SDR feedback from the AD inspection findings will likely result in an amended AD to require periodic inspections.

As the fleet ages we will see more of this sort of thing. Cessna has SIDs on eddy-current inspections of spar wing root fittings and strut and strut fittings. We found a cracked strut that way.
 
Cessna has a 10,000 hour single engine eddy current inspection program.

You can purchase it from a Cessna dealer.
 
It appears that many Pipers will only need a logbook inspection and not need this wing inspection based upon the factored service formula that requires 5000 hours. If an inspection is required, the AD estimates roughly $350 to inspect both wings and report. If in the unlikely event the wing needs work, that could be expensive.

Per draft AD, a plane with logbooks that shows no 100 hour inspections can go 17 * 5000 or 85,000 hours before an aircraft inspection is required. This would be a personal use airplane.

An airplane that always must get 100 hour inspections will need this wing inspection at 5000 hours. Typically a training airplane.

The formula calculates mixed use airplanes. To calculate the factored service hours for each main wing spar using the following formula: (N x 100) + [T-(N x 100)]/17 = Factored Service Hours, where N is the number of 100-hour inspections and T is the total hours TIS of the airplane. Examples are in the draft AD.

It is interesting that they came up with 17 as the factor for airplanes that required 100 hour inspections. We all know that airplanes used for training get more abuse, but 17 times more?

This shows that value of continuous logbooks with use history.
 
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bnt83 said:
They say in there is should be round $6k to do so. Of course there are a few dedicated sheet metal shops around that should be able to do it and already have a good handle on typical pricing.

Like these guys http://www.airframecomponents.com/

I'm sure a few will end up as salvage rather than fixing it, if so I think it would be likely that only one wing was bad and the other still usable.

I can't imagine there will be that many rejected.
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True, but opening up a wing has to potential to also open a can of worms. Plus, a shop can charge what they want, both in rate and in hours.
 
bnt83 said:
...I'm not sure how many small airplane shops have eddy current capabilities.
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Or A&P’s with NAS 410 Level 2 certification. Not something they normally do.
 
Mine has 4400 hrs on it with 20 100hrs, I've still got about 3000 hrs before it's due. I really don't see this affecting many airplane except for real high time trainers. Which is exactly what they are aiming at. I thing it's a good compromise.
 
Well so much for preventative MX. Using the FAA's common core math, my plane has a calculated total of less than 800 hours but the previous owner replaced the left wing 5 years ago when they found corrosion during a SB inspection.

It doesn't look like the proposed AD gives any relief for a wing that was replaced so I get to spend the $$ for the Eddy test.
 
k9medic said:
It doesn't look like the proposed AD gives any relief for a wing that was replaced
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There's relief if the replacement wing was TSN:-0-. If the wing was used, then no, as there would be no way calculate the factor hours on that one wing spar. Since this AD would be recurring, I could see tracking different factor hours for each wing in the cases where a wing was changed with a serviceable (not new) wing.
 
What I'm thinking of is something like a formula for a replacement wing with a known total time.

Kind of like several years ago when you had to start counting torque events to determine life limits on some rotor blades.
 
k9medic said:
What I'm thinking of is something like a formula for a replacement wing with a known total time.
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The original formula would like work by replacing the acft TT with the wing TT. Unfortunately, the AD would have to specifically state: used serviceable wings with known TSN to provide relief from the eddy current inspection. Since the wings are not tracked nor have a life-limit that might be why this option was not in the proposed AD. Would make for a good comment to post in the docket.

Considering the number of affected aircraft and the issue that counting 100hrs may not be all inclusive to the aircraft use, I think there will be additional tweaks to this AD.
 
Bell206 said:
The original formula would like work by replacing the acft TT with the wing TT. Unfortunately, the AD would have to specifically state: used serviceable wings with known TSN to provide relief from the eddy current inspection. Since the wings are not tracked nor have a life-limit that might be why this option was not in the proposed AD. Would make for a good comment to post in the docket.

Considering the number of affected aircraft and the issue that counting 100hrs may not be all inclusive to the aircraft use, I think there will be additional tweaks to this AD.
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As written, without a logbook for a used wing, there is no way to know how many 100 inspection were completed and possibly TT. I wonder how many core and refurb wings are in stock without this history.
 
That’s why I think there needs to be some more input. There is a lot of room for argument here.

For additional arguement, my logbook has several “inspected in accordance with 100 hour inspection” but it’s signed off as an annual.

My plane was never a trainer and was never used commercially but that’s how they signed off the annual.
 
bnt83 said:
As written, without a logbook for a used wing, there is no way to know how many 100 inspection were completed and possibly TT.
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Quite true. But as discussed in other threads, even with complete logbooks what if the aircraft only had annuals signed off or used a progressive inspection? No 100hr history either. While I think the factor hour approach is a great step in the right direction, with no established tracking of the wing spars it may fall flat. Perhaps a tiered inspection method would work like a fluorescent dye check then if necessary an eddy current. At least something more accessible/applicable to the average A&P.
bnt83 said:
I wonder how many core and refurb wings are in stock without this history.
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I'd guess every one of them. I know when I helped a friend rebuild wings we only started with a wing root.
 
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Just bought a 1962 PA-28-160. First had the IA go through the logbooks to determine usage history, and AD applicability. Upon finding that the wings were replaced in 1994, we knew we needed the Eddy Current inspection, despite only 2500TT on the airplane and 500 hr’s worth of 100hr inspections. Called around and found Power Aviation in Orlando. They are the shop that inspected ERAU’s planes in Daytona Beach after the accident. Anyways, we had the prebuy shop take out the back seats and prep the spar holes for inspection, then Power Aviation drove from Orlando to Punta Gorda, inspect the holes, and drive back. Then the prebuy shop close her back up. It passed and we bought the airplane. The inspection was $1,130 said and done. $750 for Power Aviation to make the trip, and $380 to have the prebuy shop prep and close the plane before and after the inspection. A hefty price for piece of mind, but if we bought the plane with even one bad wing, we were quoted $9k for a rebuild, and that’s while spars and wings are still available. In my particular situation, it was best to spend the cash up front to benefit in the long run. Cheers,
James
 
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