Wing Spar AD
 

Can anyone clue me in on the mandatory wing spar AD at 5000 hrs? Cost? How labor intensive? If the spar fails the inspection what happens next?
Thanks in advance,

Dave

Two costs. One for IA doing prep and part of the inspection ( I think it's a dye penetrant inspection). Second costs for a service company to do the eddy current inspection. It is very labor intensive.

The IA part should be about a day. The service company, I think, is about $400.

If it fails, you simply get a new wing. There is no repair except for a new wing. You call Don Neiser, and tell him to ship you one.

wing spar AD
 

Got it. Once again, thanks for the speedy reply Larry.

Dave

I'm not sure a "new wing" is required. There are ways to repair the spare that are "acceptable" to the administrator. However, to my knowledge no one has done it yet...nor ever had to.

You could be correct. I am not certain of the exact remediation steps that would be required.

There are no published corrective actions that I'm aware of. However, it would be up to the IA and his interpetation of the all powerful "acceptable methods to the administrator." Which just might require a new wing...if there is such a thing as a new wing.

The spar inspection and repair procedure does not have to be performed by a mechanic holding an inspection authorization, as any appropriately certificated mechanic may perform this function.

Since the airworthiness directive doesn't call out a specific repair, the mechanic is forced to either:

1. Replace the wing with a servicable unit (likely)
2. Replace the wing with a new unit (unlikely)
3. Hire the services of a designated engineering representative to evaluate the inspection results and develop a repair procedure, this can be very expensive, and will most likely require the existing wing to be removed to enact the repairs anyway. The IA will have to approve these repairs as they will be classified as major repairs.

I guess this is related but... have there been any reports of inflight structural failures in a 337, not related to flying into a storm? I know these did some high stress manuevers in Vietnam and wondered if they had any reported failures? Has anyone used a 337 for airshow aerobatic performances (I don't want to, just curious as to the strength).
Dan

Steve Weaver used to fly a Skymaster called "Bodacious" on the airshow circuit. Smoke on the rear engine only.

The FAC 337's all have to have the spar inspection before being registered as normal category.

The military O-2's have the same requirements that the pure civil aircraft have, that is 3,000 hours for the initial inspections in table 1, note 1, of AD78-08-05. It is not a requirement for civil airworthiness until the times are accumulated.

In my case, my airplane had 2880 hours on it when I had it certified, and it was not due at that time. (Reference Cessna Drawing 10337-065)

Just to clarify, AD 78-08-05 is for DC-10's. The AD we're talking about is 78-09-05. The way I read the AD is the 3,000 hour inspection is not mandatory...but suggested. But I thought the O-2's required an STC to convert them to an N number. And that STC required the spare inspection every 500 hours regardless of how many hours are on the airframe. Do I understand this right?

Otherwise, a "normal" Skymaster requires the inspection starting at 5,000 hours. And Pressurized Skymasters start that inspection at 10,000 hours.

I transposed the D number wrong. There is no STC required to get a civil certification for an O-2. The type certificate data sheet spells out what is required. There are no additional requirements for the spar inspection than what is specified for any other 337 airplane. Please see the AD and Cessna Service Bulletin for details.

anyone aware of civilian skymasters failing the wing spar inspection? Im not aware of any.

I was reading the spar AD again. I noticed it references the Cessna Multi-Engine Service Letter ME78-2 for some details. Does anyone have a copy of this service letter that they could post?

I have a copy I will post as long as it's ok with the admin.

It's ok with me, Tony.
Post away.
It probably will be best if you can post it as a .pdf file.
Thank you

Here is a copy of the SB in PDF.

Thanks for the post. I noticed it mentions the ED-520 Eddy Current machine...the same type I just happen to have.

Anyone know how much?
 

I am within 300 hours of needing to do this inspection for the first time. Does anyone have a ballpark figure for what the cost is?

Jim
I would check with Don Nieser at Commodore Aerospace for estimates. He has performed this on other aircraft.

Commodore Aerospace Corp.

6221 Commodore Lane OKC, OK 73162-6814

Phone: 405.722.4079 Cell: 405.503.4686

nieser.02.337parts@juno.com

How much do you have.
Bring it all.
:):D

I just had this done and the cost for doing this was $550 for the Eddy Current inspection and about 18 hours of labor to disassemble the aux tanks from the wings, do the dye penetration test and reassemble the whole thing. My airplane has 5500 hours on it and passed the check with no issues. It is the second time the test has been done, with the first at 5000 as required although I was not the owner at the time so can't say how this compared with the previous pass. I have a few questions for others who have done this.

1. There was a recent response in the Cessna Pilots Association Magazine suggesting that removing the aux tanks wasn't really necessary to do the dye penetration test. Has anyone had this done without removing the aux tanks?

2. Does anyone know how many airplanes have actually failed this test?

3. If you had a failed airplane, the AD recommends replacing the spar cap doublers or other cracked components. Has anyone done this or did you just get a new wing as was suggested in the string?

The inquiry in the CPA magazine was from my mech who just did my airplane a few months ago. We did not remove the aux tanks for the inspection. As I recall (sitting here in front of the TV), Tom Carr, a Skymaster guru, responded that it's a little lost to Cessna history how the necessity for removal of the aux tanks got started but the SB spells out a method to comply with the AD without removal of the tanks. I think the total bill was around $4K and change with all labor and bringing in the NDI guys with the machine. I should add that a small crack in one filler fitting was found when the main tanks were pulled - that repair is included in the $4K.

My bird was done at about 4700 hours (since I was about to start our heavy survey season). No spar issues and no corrosion inside the wing. Good news since most of our work is low altitude over salt water with a fair amount of yanking and banking.

Joe
N337NE

Wing Spar AD
 

If you read the AD it says that if the aircraft is being flown low altitude high G flying such as pipeline surveying or military flying, the wing spar AD must be done at air frame total time of 3,000 hrs and repeated every 500 hrs thereafter. If the aircraft is not flown in high G flying then the AD must be done at 5,000 hrs total air frame time and repeated every 500 hrs thereafter. There are 2 parts to the AD inspection; Eddy Current inspection of 3 holes in the bottom of the front spar just outboard of the the strut, and a dye penetrant inspection of the rear spar web inside the inboard main fuel tank bay. The Cessna drawing that spells out everything we must do to covert an 0-2A or 0-2B from military to FAA Standard Registration, states that we must do the Wing Spar AD no mater what the total air frame time is. After this inspection then it must be repeated every 500 hrs. We have done more than 30 aircraft since specializing in Skymaster aircraft and have never seen a crack. It is true that the dye penetrant inspection part can be done by an A&P, however the Eddy Current parts has to be done by an FAA Repair Station Eddy Current qualified person. The costs for this Eddy Current qualified person varies around the country. I did an accident investigation of the 0-2A that broke apart in flight over central Florida a few years ago and there was no evidence of any cracks where the AD specifies the inspections.

Every thing I have said above about the Eddy Current part of the inspection applies only to the early model 337's and all 0-2's. Late model 337's wings were beefed up and the AD lists the applicable aircraft serial numbers. These late model 337's have rivets where the screws/bolts are in the early model 337's. Cessna's great wisdom in developing the SID inspections forgot to read the applicable aircraft serial numbers in the Wing Spar AD and made a SID inspections almost exactly the same wording as the Wing Spar AD but made it applicable to all Skymasters. The real problem is now in countries outside the US, the SID's are treated as mandatory. (This is another horror story).

The labor intensive part of doing the AD is taking the fuel tank covers off the top of the wings. If all the screw have not been off for a long time, many may have to be drilled out and some nut plates replaced. The problem is that one of the screws in the bottom of the front spar that must be removed to do the Eddy Current inspection, has a nut on the back side and the only access is in thru the fuel tank bay. I know the AD says there is an alternate method to do the dye penetrant inspection, but I cannot see how one could then see the rear spar web.

I bought one of the California Department of Forestry's 0-2A that had 11,000 to 12,000 total air frame time and they said it had a crack at the locations spelled out in the wing spar AD. It turned out that it did not have a crack at the AD locations but it had a crack where the wing tie ring is located.
If you want more information about our experiences give me a call;
Don Nieser, (02&337 parts guy) Commodore Aerospace Corp, 405-503-4686
nieser.02.337parts@juno.com

Re: "...the wing spar AD must be done at air frame total time of 3,000 hrs..."

Actually, the AD verbiage for terrain following ops is, "Cessna recommends and FAA strongly urges inspections at intervals shown to the right of this note." [i.e. the 3000/500 hour provision]

Certainly, prudence would dictate factoring in how the airplane was handled during these kinds of operations (as well as your tolerance for being second-guessed by the FAA if something happened). In my case, I know that over the past 1000 or so hours, ops have been mostly overwater, the airplane hasn't been bounced around excessively or manhandled, and our maneuvering has been smooth. Hence, I was comfortable waiting until nearing 5000 hours before having the AD complied with.

Joe

Also might be worth noting that the table in that AD specifically references the time in service for the wing components, not the aircraft time. So if those components have been replaced for any reason...