15AC ACS - Spar Intergranular Corrision

Aeronca Sedan Airplanes
deCreeft
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Re: 15AC ACS - Spar Intergranular Corrision

Post by deCreeft » Wed Apr 20, 2011 10:47

Thanks, Matt
As I remarked in off-forum email, I like the idea of inspection covers with reinforcing rings because if anything it would strengthen and stiffen the wing panels, I would think, and reduce oil-canning...besides providing access for painting or oiling periodically, and access to wiring,,fuel lines,etc....
I suggest that if bore scope access holes are mandated, that we are authorized to install inspection covers as an alternate, approved method of compliance.

Bill

'Facts are facts, and we supply the emotions"
Bill de Creeft

poulter1

Re: 15AC ACS - Spar Intergranular Corrision

Post by poulter1 » Wed Apr 20, 2011 11:07

To all,

Several of us are working on an alternate compliance procedure. The current plan is to make it as flexible as possible to meet the needs of the owners and their mechanics while addressing the safety concern that is driving this whole issue. Burl's procedure will stand for anyone who wants to use it. The alternate procedure that is being worked on now aims at flexibility in what size and how many holes are needed. While someone may not want 4" hole at this time they would be able to put one, or more, in at a later time, as needed or desired. There is much behind the scenes work going on. Much of it involves gathering information which can take some time.

John Poulter

deCreeft
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Re: 15AC ACS - Spar Intergranular Corrision

Post by deCreeft » Wed Apr 20, 2011 11:19

Thanks, John
Just talked to Burl, before i saw this, and he said the inspection holes with support structures is already approved and can be done at any time...so that takes care of my concerns.
I can certainly appreciate anyone's desire for alternate methods...or even a mix of methods.

'40 Plus' degrees today, blue sky, and no wind !!

Bill
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joea
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Re: 15AC ACS - Spar Intergranular Corrision

Post by joea » Sat Apr 23, 2011 04:17

deCreeft wrote:Thanks, John
Just talked to Burl, before i saw this, and he said the inspection holes with support structures is already approved and can be done at any time...so that takes care of my concerns.
I can certainly appreciate anyone's desire for alternate methods...or even a mix of methods.

'40 Plus' degrees today, blue sky, and no wind !!

Bill
Bill,

That's our heartburn with the current FAA proposal. They do not want to let us do it "at any time," they want it all done right away. Add that to the issue that in the proposal Burl's Aircraft is the ONLY source for inspection panel covers and he does not have ANY for sale right now and it means that the entire fleet is grounded after the prelim inspections. Having every Sedan in the world grounded in June, July or August would really perturb a lot of Sedan owners, and so far for pretty much nothing too boot! The "34 cases of spar corrosion" has not been proven, and until it is frankly most of us are very curious how this number was acheived.

Also its simply not necessary to put 8-10 covers on each wing to properly inspect the spar. It can be done by putting 2-3 covers on and inspecting the rest of the area with a borescope. Burl has already signed off on this "mix and match" combination of covers and borescope. If Boeing, Lockheed and so on do it on their commercial aircraft then why can we use a borescope on our Sedans?

Right now John, several of us at the NAA and several others are working together on this to expand the time needed for an inspection, means of inspection and where you can purchase the inspection covers.

Thx,

Joe

poulter1

Re: 15AC ACS - Spar Intergranular Corrision

Post by poulter1 » Fri Apr 29, 2011 14:04

An extension of the NPRM comment period was issued today. The comment period now ends on 3 July.

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Matt
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Re: 15AC ACS - Spar Intergranular Corrision

Post by Matt » Fri Apr 29, 2011 14:11

Not as much of an extension as aimed for, but good news still!
Thanks to everyone involved for their effort!

Matt
Aeronca 15AC Sedan – Restoring and flying the classic 4-seater: http://www.n1331h.com

AV8R2
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Re: 15AC ACS - Spar Intergranular Corrision

Post by AV8R2 » Tue May 03, 2011 11:23

I have ordered the tooling for the covers and doublers. Also enough covers and doublers for 50 airplanes so far. 4-6 weeks for the tooling; 6-8 weeks for the parts to be delivered. (Now all I need is a ton of rivets to go along with the kits.)

I have also ordered 300 lbs each of the spar cap angles; enough for approx. 50 planes. Ship date is 8-12 weeks depending on their workload in house. Numbers of parts are also +/- 10%.
This is going to get really expensive really fast.

As for those that are curious to magic number "34" that is how many sets of spar cap angles that I have sold since 1998. I had the dies made then and had 100 lbs drawn at that time.
The dies were very expensive even back then. Fortunately the extrusion plant had not thrown the dies away. They do throw out dies that are not used frequently. Ours were small enough
that they kept them. Otherwise there would be the cost of the dies to put into the mix this time, too.

As for the number of sets that actually replaced corroded parts I could not tell you. Some owners bought for both sides, L & R, when they just needed parts for one side. Shipping is going to be a serious concern, too. The transportation co. quoted a "discounted" rate of $2,200.00 freight only for the parts (caps) but would not quote fuel surcharge which is at 25.8% now and could go to 50%.

So there you have it, boys and girls; the latest and the greatest. I'm doing what I have to since I am the TC Holder; try to imagine where the Sedan would be if I weren't here to support it.

Also, to answer the jackass comment about me "working with the FAA for 3 years making this an AD": You don't know what you are talking about. I put the FAA off for 3 years because I knew this was going to turn into this can of worms. If I wanted to "sell parts" I could have pushed this back in 2008 and had this an active AD within 6 months of Ms. Swartz's Airworthiness Concern Bulletin.

As for those owners that do support my efforts, Thank you. Your parts will be sent as soon as possible after they arrive.

Sorry, folks, I didn't cause the spar caps to corrode; they just got old..............like me.

Burl
When all else fails, go to the source. Factory Approved parts and data will get you back in the air.

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Re: 15AC ACS - Spar Intergranular Corrision

Post by joea » Wed May 04, 2011 09:56

Burl,

Glad to see that things are in production.

Joe

poulter1

Re: 15AC ACS - Spar Intergranular Corrision

Post by poulter1 » Wed Jun 22, 2011 13:02

All,

An alternate means of compliance (AMOC) is being worked for this issue. In order to develop this AMOC is is critical that any data on corrosion of the spar caps be obtained. The EAA has filed a Freedom of Information Act request to obtain this information. As of yet this information has not been received. As the current comment period for this NPRM closes on 3 July I believe it is imperative that as many people as possible request an extension to the current comment period. I have requested a 90 day extension and the EAA has requested a 60 day extension.

To request an extension, or to make any comments on this NPRM, the link to the page is:

http://www.regulations.gov/#!home

paste FAA-2011-0318-0006 in the keyword or ID box. When the page that shows the "Burl Rogers" item is displayed there will be a "Submit a comment" button on the right side of the screen. Select this and then you can submit a comment. I am told that comments with some justification are better than ones with out justification. Lack of documentation as requested through he FOIA should be a valid reason.

Below is the request I sent. It is rather lengthy and a shorter request with some justification should be sufficient.

Please file a request and ask your friends to do the same. You do not need to be a Sedan owner or a pilot to make this request.

Thanks,

John

I am writing to request a 90 day extension to the current comment period. I am part of a group that is working to produce an AMOC to the current NPRM for the Sedan spar corrosion issue. The current terms of the NPRM are overly restrictive in terms of compliance times and in costs involved with compliance. Furthermore the proposed method for inspection requires 15 inspection holes be added to the wing. While I am in favor of additional inspection points 15 additional points are far more than is necessary to conduct a thorough inspection.

The times for compliance contained in the NPRM are also extremely restrictive. The initial inspection period is only ten hours after the publication of the final rule. There is no valid reason for this highly restrictive period. It is not uncommon to fly a Sedan for ten or more hours in a single day. Thus the rule could be finalized and 5 minutes after a pilot takes off on a cross country and by the end of the day he could be in violation of not complying with the AD that came out that morning. In addition the initial inspection should have already been accomplished during an annual or 100 hour inspection according to appendix d of FAR Part 43 section F. I am not aware of a Sedan ever experiencing a failure of the wing, in-flight or otherwise, due to spar cap corrosion. There is only on SDR on file for the Sedan that mentions corrosion in relation to the spars. The NPRM states that "Since first discovered in 1998, we have received 34 reports of intergranular corrosion and exfoliation found on the upper and lower wing main spar cap angles on Burl A. Rogers Models 15AC and S15AC airplanes."

In order to develop an AMOC it is important to have any information that is available regarding corrosion of the spar caps. Currently the only official data is contained in the one SDR. There validity of the 34 cases of corrosion specified in the NPRM appears to question as the certificate holder has stated that he does not know how many cases of corrosion have been discovered in the 15AC. A request for any information the FAA had on this issue was requested. After some time the FAA informed those who were requesting the information that they would have to file a Freedom of Information Act request in order to get any of the information. The FOIA request was filed by the Experimental Air Craft Association on 25 May 2011. As of yet no information has been received from the FAA. As the current comment period comes to end in less than a month and given the fact the information critical to producing a valid AMOC has not yet been released I believe that at a minimum, that a 90 day extension to the current comment period is warranted.

Once the requested information from the FAA is received it will take some time to examine it and to craft a suitable AMOC. Until the requested information is received it is impossible to proceed with producing a valid AMOC.

A significant portion of the operational 15AC fleet has been inspected since this NPRM was issued. To the best of my knowledge no corrosion has been detected. This, coupled with the facts that only one official public record of spar corrosion exist combined with the fact that there has apparently never been a case of structural failure of the 15AC spar indicate that safety is not compromised by granting an extension.

Many owners and operators of 15AC's have been patiently waiting for the information requested from the FAA to be provided. They have not commented as they know that there is considerable work being done behind the scenes. Please do not take their silence as a lack of interest or as their approval of the NPRM as it currently stands. The general consensus regarding the NPRM from many people that I have spoken to about it is that it is excessively restrictive, costly, and unduly complicated. There is also considerable thought that it is not necessary at all based on there being only one SDR on the subject.

Please consider granting this request for an extension.

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Re: 15AC ACS - Spar Intergranular Corrision

Post by AV8R2 » Wed Jun 22, 2011 15:18

To clarify the Service Bulletin: Within the next 10 hrs the first part of the inspection (peeky through the aileron bay spar lightening holes) needs to be complied with. AFTER THAT; Within the next 25 hours the Service Bulletin must be complied with (install covers/doubler and inspect spar caps). All totaled, this is a 35 hour window, not 10.

I didn't come up with the quantity of covers and doublers or the pattern; FAA did.

Burl

PS
Covers and doublers have arrived; spring blanks yet to arrive. Expect kits to be available in 2-3 weeks. Spar caps expected to ship week of 27th; no confirmation on date yet.
When all else fails, go to the source. Factory Approved parts and data will get you back in the air.

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Re: 15AC ACS - Spar Intergranular Corrision

Post by joea » Thu Jun 23, 2011 12:49

When I flew the Sedan from Arizona to Middletown it took 43 hours there and back, including an hour or so doing sight seeing flights for the Aeronca folks there.

With the 10 hour window you would be sunk and stuck on the road somewhere. With the additional 25 hour window you would still be stuck somewhere out in the middle of no-where with an airplane you could not fly nor even ferry home.

This so called "spar cap corrosion issue" is not the problem that we were all led to believe years ago. We have exactly ONE case of its happening on ONE set of wings out in the field, and that was not even an airplane that was airworthy. Believe that this aircraft has been on floats in the past and exposed to salt water. We also have one airplane whose wings also showed some corrosion but the wings had been in storage in the Mid-West for many years that we suspect had been on floats in the past. Thats it, four wings out of the over 1100 wings that Aeronca built for the Sedan.

Currently the FAA is with-holding information from us that will allow us to make a "alternative means of compliance" for this so called issue. If its effecting ONLY four wings out of over 1100 made, then why in the world do we have a "10 hour, then 25 hour" limitation being placed upon the ENTIRE fleet?

IMHO this is something that needs to be inspected at each annual inspection and if any corrosion is found, then and only then go to possibly installing additional inspection covers "AS NEEDED" (not 8-10 per wing!) to completely inspect and work with any corrosion found.

poulter1

Re: 15AC ACS - Spar Intergranular Corrision

Post by poulter1 » Wed Jun 29, 2011 17:24

All,

As the comment period ends on 3 July and no word of an extension has been heard I submitted the following AMOC. I would much prefer to do this after seeing the information that the EAA has requested but given that if an extension is not granted an no AMOC has been submitted we will be stuck with the FAA's proposal. 0Of course there is no guarantee that they will entertain my submission.) If you have not posted a request for an extrension of the comment period please do it now!

John


Here is a copy of what I submitted:

Aeronca 15AC Wing Spar Proposed AD
Suggested Means of Compliance
Background

The Aeronca model 15AC/S15AC features a main spar composed of extruded aluminum spar cap riveted to an aluminum web. There have been instances where intergranular corrosion has been found in the spar cap extrusion. The exact number is not known but is believed to be very low. Intergranular corrosion is not uncommon in extruded aluminum pieces. It is a result of the grain of the metal and the boundary between the grains interacting with an electrolyte. A corrosive environment, i.e. a salt water/salt air environment, can contribute to the formation of intergranular corrosion. There have been no reported instances of failure of a wing due to spar or spar cap corrosion on the 15ACor S15AC model planes. Only one SDR has been completed for spar cap corrosion. However, there have been some verbal, but undocumented, reports of spar cap corrosion that were found by inspection or when the wing was opened to repair physical damage to the wing.

Experience with the 15AC indicates that this corrosion can be detected by visual inspection which is greatly aided by the use of a borescope. The difficulty lies in the fact that the 15AC has limited access to the wing for an inspection to be conducted. Current openings in the wing such as the inspection ports above and below the aileron bellcrank, the landing light port in the left wing, openings in front of the ailerons, and openings in the wing root allow for the majority of the spar in each wing to be to be inspected with a borescope with a length of 34" or more. This is somewhat variable depending on the equipment in use, technique, etc. Tests have shown that with a six-foot borescope the entire right wing would be able to be inspected with the addition of only one additional inspection hole. Borescope inspections are a normal practice in the industry and have become much more practical for the general aviation fleet as availability of the equipment has gone up and prices have come down.

Based on field experience, corrosion of the spar cap tends to manifest over multiple areas on the spar. The portion of the spar cap aft of the spar is believed to be the area most likely to exhibit corrosion. It is believed that an inspection of 50% or more of the spar would reveal the presence of corrosion in a particular wing.

The intergranular corrosion can be stopped or prevented by the application of a corrosion control substance such as CorrosionX.[1] A substance such as CorrosionX will wick its way between the cap strips and the skins and spar web. It will then work its way into any corroded area where it will stop any existing corrosion by forming a dielectric barrier. It will also prevent any new corrosion from forming. This product will not negatively react with wiring in the wing or with fuel bladders and lines. The wing can probably be treated through the existing openings in the wings with the wings on the airplane. However, it would be far easier, and would only require common corrosion treatment application hardware, if it were permissible to drill two holes in each wingtip so that a standard treatment wand could be inserted along the length of each spar for the purpose of applying the specified corrosion control product to the entire spar and interior of the wing.

This would not only be beneficial for controlling corrosion of the spar but also for preventing and controlling corrosion in the wing itself. A product such as CorrosionX would not hide corrosion or other defects from view as would paint or zinc chromate. Additionally it will creep into current corrosion and stop its progress, something paint cannot do. The holes would only need to be approximately 1/8" to 1/2" in diameter and could be plugged with a standard nylon hole plug, a metal hole plug, or covered with tape or fabric. These holes could also be used for borescope inspection. The CorrosionX treatment would be good for at least two years.
This approach is likely to be more quickly and properly complied with due to its low cost and relative ease of compliance. It will not place undue burden on the aircraft owner and will provide for the continued airworthiness and increased safety of the aircraft while providing for a means to prevent and detect future corrosion of the spar and the wing in general.


Recommended process:
To be accomplished within 360 days of this AD being published or at the next annual or 100 hour inspection, whichever comes first. This procedure is in regards to this AD only and does not change any of the requirements from an annual or other required inspection. Definitions of corrosion limits may be found in AC-43-4A, page 151.

A. If no, or only light, corrosion is found by an inspection that looks at 50% or more of the spar, through the existing access points, the wing shall be inspected thereafter at each annual in accordance with this AD. No further action is required although treatment with an approved corrosion preventative treatment is recommended. If no, or only light corrosion, is found and the spar is treated with CorrosionX it will not need to be inspected for two years from the date of the last inspection or retreated for two years from the date of the last treatment.

B. If evidence of more than light corrosion is found during the inspection additional access points may need to be provided so that the remainder of the spar can be inspected (see Para C.). If the corrosion found is more than moderate the wing will have to be removed from service for repair or replacement. If light to moderate corrosion is found document its location in the aircraft logbook. The wing will have to be treated with an approved corrosion treatment product every two years, or as recommended by the products manufacturer. Further reoccurring inspections will be conducted at each subsequent annual to confirm that the corrosion is not increasing. This will be allowed until the corrosion exceeds a moderate amount at which time the wing will have to be removed from service. Any pitting corrosion will have to be cleaned and the depth of the pitting must be less than the definition of moderate corrosion as specified by AC-43-4A.

C. If additional inspection holes are required, or desired, they shall be made in the underside of the wing 3 to 6 inches aft of the main spar and more than three inches from any rib. It is recommended that these holes be placed where they would be removed if the service bulletin method was followed. The diameter of the hole shall be from 1/4" to 1" as required. One hole per bay is allowed. All holes shall be properly deburred on both edges. A Unibit or similar tool is recommended. The diameter, number and location of the holes shall be as required, subject to previous limitations in this paragraph, to inspect and the remainder of the spar. This will vary depending on the borescope in use.

The holes may be plugged with a standard nylon/plastic hole plug, a metal hole plug, or covered with tape or fabric.
Optionally the inspection doublers and covers from Burl's Aircraft P/N 2-1271 and 2-1285 may be installed in one or more of the locations specified by Burl's Aircraft, LLC Mandatory Service Bulletin No. 15AC06-08-10, dated June 8, 2010. A doubler and cover plate may also be fabricated and installed in the locations specified in the previously referenced mandatory service bulletin. See later page for materials and dimensions.

D. If a corrosion treatment is required, or desired, two holes with an approximate diameter of 1/8 to 3/4 inch may be placed in the outboard end of each wing tip, as required, to facilitate corrosion treatment of the spar and wing. Consideration should be taken of the relative location to the spar lightning holes and items such as the aileron bellcrank. The holes may be plugged with a standard nylon/plastic hole plug, a metal hole plug, or covered with tape or fabric. Treatment with any approved solution should cover, at a minimum, the entire aft portion of the spar so that the material can "creep" between the skin of the aircraft, the spar web, and the spar caps. Treatment of both sides of the spar is preferred but not required.

E. Approved corrosion treatments: CorrosionX Aviation, ACF-50 or other products meeting Mil-C-1309E type II, or Mil-C-81309E Amd 3, Type ll and specified for aircraft use.

F. Repairs. If repair of the spar cap is necessarily it shall be done with approved data from a DER or other source acceptable to the administrator. Spar caps shall not be spliced within two feet of the lift strut attach point.


Notes
1. The hole plugs are not required for flight but are recommended.
2. The additional holes, if required or desired, are considered a minor alteration.
3. Allow owners to treat aircraft with approved corrosion treatment in accordance with manufactures application instructions.
4. Need a provision for those who have already replaced their spar caps or who have opened their wings for repairs etc and have not found any corrosion.
5. Corrosion definitions and limits are contained in FAA Advisory Circular (AC) 43-4A, paragraph 640 (a) (b) (c).
6. ACF-50 Information. http://acf-50.com/userfiles/ACF-50%20Tech%20Specs.pdf,
http://acf-50.com/userfiles/Product%20S ... ations.pdf

Cost:
The cost of compliance under this suggested procedure will range from approximately 2 to 4 hours of labor for an inspection where no corrosion is found. If additional, drilled type, inspection or treatment holes are required this will require approximately 1-2 hours of labor to drill and deburr the holes. Installation of original type inspection holes will require approximately 2 hours labor per hole plus parts costs. The cost of the corrosion treatment product will vary with the product used but the amount of CorrosionX required to treat both wings cost approximately 25 dollars. Labor to treat the wings is expected to be 1 to 2 hours.

Endnote
1. Information provided by Corrosion Technologies Corporation, makers of CorrosionX.



Doubler and inspection hole cover fabrication.

Doubler O.D. 5.00" +.2", -.10", I.D. 3.5" +.10", -.15"
14, -3 2017 "AD" universal head rivets centered on a 4" diameter circle
Doubler fabricated from .063 2024 T3 Alclad. .071 or .050" is acceptable as a substitute.
Fabricate cover plate to fit from .020 or .025 tempered aluminum. Attach flat spring retainer with two
-3 or -4 universal head rivets. Spring can be taken from a standard fabric inspection hole cover.

Use original inspection holes and cover as a pattern. Hole in skin to be 4" +.15", -.20". Deburr and rivet in accordance with ac 43-13-1B chapter 4.

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Matt
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Re: 15AC ACS - Spar Intergranular Corrision

Post by Matt » Thu Jun 30, 2011 09:38

Thanks for your effort, John!

Hope, it helps. It would really be disappointing, if the serious, honest comments made to the FAA went unheard, before the deadline. It sure is a fantastic freedom to be able to comment on such issues. But it is a deceiptful freedom and really only maculation, if the comments are not considered and/or at least responded to, after all. :(

Matt
Aeronca 15AC Sedan – Restoring and flying the classic 4-seater: http://www.n1331h.com

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Re: 15AC ACS - Spar Intergranular Corrision

Post by Paul Agaliotis » Thu Jun 30, 2011 13:31

All of this nonsense was caused by someone thinking they were doing the right thing. The Sedan doesn't have a chronic corrosion problem or wing related operational concerns.

Early in my A&P career I thought I should save the world. As a result of my actions and reporting we now have AD 75-18-05 on the T-craft. Later I found out the factory had a defect on the one mount,mine. No deburr of the hole as called out. Once I learned of this issue I informed the FAA about this new information I was unaware of when submitting the MDR. All I knew was we were having a malfunction and needed reporting. The response was to just ignore it. It would be harder to cancel the AD than just let it be. And that's just what the FAA did.

Unless I'm specifically asked to report in FAA approved data, I don't. This shouldn't be the way to handle operational issues, but the FAA is painfully ill-equip to handle vintage or antique aircraft.

Be careful what you ask for, the Feds might give you what you need.

Paul
Mailing Adress : Paul Agaliotis 2060 E. San Martin, San Martin,Calif. 95046

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Re: 15AC ACS - Spar Intergranular Corrision

Post by joea » Fri Jul 01, 2011 05:37

Paul,

Then how do we end this nightmare that has been thrust upon the Sedan community?

Almost everyone agrees that its not needed.

Joe A

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