AMOC for Spar Inspection

Aeronca Sedan Airplanes
poulter1

AMOC for Spar Inspection

Post by poulter1 » Wed Apr 18, 2012 16:35

An AMOC for complying with the Sedan Spar AD has been approved. I believe that it will be made available shortly. The initial inspection is the same as Burl's, so no immediate change. The AMOC makes provisions for using a borescope to conduct the detailed inspection of the spar. It also makes provisions for making small access holes, as needed.

I think most will be happy with this AMOC.

V/R,

John Poulter

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rkittine
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Re: AMOC for Spar Inspection

Post by rkittine » Thu Apr 19, 2012 08:53

The mechanic that does most of the work on my planes had a friend at a local hospital. When the hospital upgraded there equipment, he was able to get a Colonoscopy Machine (cleaned) :lol: that included the probe, monitor, printer and video recorder. He now uses it to Scope the inside of wings to check spars and other parts. (amazing how long the fiber optics probe is to get though the small and large intestines) :roll: When St. Vincent's Hospital closed in New York City, I was able to pick one up for free also.

So check with you local hospital or watch for hospital closings and you might be able to get one for free.
Robert P. Kittine, Jr.WA2YDV
West Nyack Aviation, L.L.C.
New York, New York 631-374-9652
rkittine@aol.com

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Re: AMOC for Spar Inspection

Post by MikeB » Fri Apr 20, 2012 07:35

Image

I bought this from Harbor Frieght to inspect the wings on my Champ for around $80 if I remember correctly. I think the 'probe' is around 36" and lighted. It gives a pretty good picture. I tend to not want to buy stuff from there as most of it is made in China but couldn't pass it up at the price.

MikeB

poulter1

Re: AMOC for Spar Inspection

Post by poulter1 » Wed Apr 25, 2012 17:12

The corrected paperwork from the FAA has been received. The AMOC is now legal to use. I will try to get the AMOC posted soon. Thanks to the FAA in Alaska and Carl Bahn for getting this done.

John

poulter1

Re: AMOC for Spar Inspection

Post by poulter1 » Wed Apr 25, 2012 17:36

OK,

Here is an unoffical copy of the AMOC. At this time I do not have the software necessary to cut and paste the approval letter that goes along with this AMOC.

John


Carl Bahn Service Bulletin Number 1, Rev. 1, April 16, 2012

Title: Spar Cap Borescope Inspection

Subject: Visual inspection of wing upper and lower spar caps for corrosion using a borescope

Models Covered: All Rogers (Aeronca) 15AC and S15AC series aircraft

Scope:
This procedure is intended to be used as an alternate method of compliance to Airworthiness directive 2012-04-10. The borescope procedure contained in this service bulletin replaces the inspection procedure outlined in sections F (2) through F(7) of that AD. It provides an option to use a borescope instead of the installation of access covers that are required in the AD. Additionally, it provides for alternate access points for corrosion treatment application.

Personnel: IMPORTANT: All work and inspections required by this Service Bulletin are to be performed by a properly rated and equipped certified mechanic or repair station with appropriate authorization, experience in the work, use of equipment, inspections, and repairs listed.
Statement of difficulty: The Aeronca model 15AC/S15AC features a main spar composed of extruded aluminum spar caps 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. 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.

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.

The lack of access points have also made it difficult, if not impossible, to treat the wing with corrosion prevention chemicals. This service bulletin provides for careful inspection of the wing spar caps for corrosion and for introducing access points that allow for the application of approved corrosion prevention treatments.
Compliance, Part 2 (Perform Part 1 in accordance with AD 2012-04-10):

Within the next 12 months, after the effective date of the AD, comply with Steps A and B instead of F(2) through F(7)of AD 2012-04-10.

Thereafter at each annual or 100 hour inspection, if required by operating rule, repeat Step A instead of F(2) through F(6)of AD 2012-04-10. Repeat Step B, instead of F(7) (applying corrosion prevention compound)of AD 2012-04-10, as determined necessary by the inspector conducting the inspection required in Step A. Step B, when required, must be completed within 10 flight hours or 30 days, whichever comes first, after the inspection required in Step A is completed.

Step A:
Inspect the leading and trailing edges of both the upper and lower main spar cap angles and web on both the left and right wing for signs of cracks, intergranular exfoliation, and corrosion with a borescope as described below in the borescope requirements section of this service bulletin. Except for the area covered by the fuel tanks, 100% of both the upper and lower spar caps and web must be inspected.

If only light corrosion is found, skip to stem B: If moderate or worse corrosion is discovered the wing must be removed from service or repaired in accordance with an Alternate Means of Compliance approved by the regulatory authority. Replacement of the spar cap per the service bulletin is acceptable. To facilitate this inspection, additional inspection locations may be installed per Burl's Aircraft, LLC Mandatory Service Bulletin No. 15AC06-08-10, Amendment B. Alternatively, additional inspection openings may be made in the underside of the wing 4 to 6 inches forward/aft of the main spar rivet line and centered between the ribs, plus or minus 1 inch. It is recommended that these holes be placed where they would be removed if the Burl’s Aircraft, LLC Mandatory Service Bulleting, No. 15AC06-08-10, Amendment B, method were followed.

The diameter of the hole shall be 1/4, 3/8, 1/2, 3/4, or 1 inch, as required by the equipment being used. One hole per bay is allowed. No holes shall be made in the bays under the fuel tanks/bladders. 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/equipment used. The holes will be plugged with a nylon/plastic hole plug, or covered with aluminum tape, see materials list. Any combination of inspection holes from this or the Burl’s Aircraft service bulletin are acceptable.

Step B:
Corrosion prevention treatment must be applied to the spar caps after completing step A on the initial inspection. Refer to the schedule in "Compliance, Part 2" section for treatment requirements after subsequent inspections.

To facilitate this treatment, a hole of 1/4, 3/8, 1/2, or 3/4 inch diameter may be placed in the outboard end of each wing tip and in rib part numbers 5-469 R and 5-469 L, forward of the main spar, as required, for corrosion treatment of the spar and wing. These holes may be made 5 inches, +/- 1/2 inch, if front of the main spar cap strip vertical rivet line so that the holes will be in line with the nose rib lightning holes. The holes shall be plugged with a standard nylon/plastic hole plug, or covered with aluminum tape, see materials list. Holes in the rib do not need to be plugged. Treatment with an approved solution shall cover, at a minimum, the entire front and aft portion of the spar with the exception of the area covered by the fuel tanks on the front of the spar so that the material can "creep" between the skin of the aircraft, the spar web, and the spar caps. It is recommended to treat as much of the fuel tank area as practical. Follow the manufactures instructions for product application. It is recommended that any painting be completed before treatment with the corrosion inhibitor.

Repairs
If repair of the spar cap is necessary it shall be done per Burl's Aircraft, LLC, Mandatory Service Bulletin No. 15AC06-08-10, Amendment B, along with any other requirements specified by the certificate holder. Alternately, repairs may be made following approved data from a DER if presented and approved as an alternate method of compliance to AD 2012-04-10 by the applicable regulatory authority.

Materials list

Plastic hole plugs appropriate to the size hole drilled:
Crown bolt: 1/4" part number 14628, 3/8" part no 14728, ½” Part number 14748, ¾” 14978, 1” part number 15188, or equivalent
Grainger: 1/4" P/N 1ELU2, 3/8" P/N 1ELU6, ½” P/N 1ELV2, ¾” P/N 1ELV9, 1” P/N 1ELV7, or equivalent
Aluminum tape:
3M 051138-95166 425 Aluminum Foil Tape, or equivalent
Approved corrosion treatments:
ACF-50 brand corrosion inhibitor
CorrosionX Aviation corrosion inhibitor or equivalent products meeting, or exceeding, Mil-C-1309E type II, or Mil-C-81309E Amd 3, Type ll and specified for aircraft use.
Any product that would obstruct the view for later inspections shall not be used. Products such as LPS 3 or Boeshield T-9 fall into this category. Besides not having the necessary properties to "wick" into the joints of the spar assembly, they can also hide corrosion from view and are thus unacceptable.
Flashlights: Maglight LWSA301, or equivalent
Borescope minimum specifications:

Given the literally dozens of video borescopes that are on the market today, along with the rapid advances and introduction of new models, it is impossible to list every model that is sufficient for the purposes of this inspection. However, at least two models have shown that they are sufficient for the task. These are the Milwaukee 2300-20 M-Spector Digital Inspection Camera with a 320x240 resolution color screen, and the AGPtek GB8803 camera with the 3.5" monitor 480x240 resolution color.
Other systems may be acceptable if they meet the following minimum specifications:
Minimum focal length of 1" or less to infinity
Minimum resolution 320x240 color
Magnification is not required; however, most video borescopes provide magnification, which may be helpful. The image viewed must be actual size, or larger when the camera or lens, is 4 inches from the area being inspected.
Must include a self-contained high intensity light source, which is adequate for illuminating the areas to be inspected.
The length of the scope probe must be at least 34 inches in length. Longer probes may require fewer access points.
The probe shall be of the "obedient" or controllable articulation type.

A simple test to help determine if a system is sufficient is to view a recent U.S. $20 dollar bill. The small amber "20" symbols which are printed on the back of the bill should be readily visible and in focus when viewed from a maximum distance of one inch when viewed in a dark location. Additionally, the hash marks inside the letters of the word twenty, which is printed over the Department of the Treasury seal on the right side of the front of the bill should be visible when viewed in a dark area, using only the illumination provided by the borescopes light source.

The final decision of suitability shall rest with the properly licensed inspector making the inspection consistent with the guidelines above.

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Re: AMOC for Spar Inspection

Post by joea » Thu Apr 26, 2012 10:19

I cannot attach or copy the official letter from the FAA to Carl and John, but here is a "cut and paste" version of it.

The AMOC is now legal and accepted practice to comply with the AD. We no longer are forced to cut 18 holes in our wings as per the SP. That said, I will be putting some of the inspection covers in my wings to make things easier and with that and the AMOC below and a borescope can comply with the AD and have a nice looking Sedan!

We all need to thank John Poulter and Carl Bahn for their help on this. We have been working on the ANC FSDO for years on this and finally its been approved, and now we have options.

Joe A

~~~~~

U.S. Department of Transportation
Federal Aviation
Administration


Aircraft Certification Service
Small Airplane Directorate
Anchorage Aircraft Certification Office
222 W. 7th Ave, #14
Anchorage, AK 99513-7587


April 18,2012

Mr. Carl Bahn
P.O. Box 956
Willow, AK 99688

Dear Mr. Bahn:

The Federal Aviation Administration (FAA) received your letter on April 18, 2012, proposing a global alternate method of compliance (AMOC) to Airworthiness Directive (AD) 2012-10-04.

The Anchorage Aircraft Certification Office (ACO) approves your global AMOC proposal to paragraphs f (2) through f (7) of AD 2012-10-04 to utilize a borescope to inspect the wing spar for corrosion in accordance with Carl Bahn Service Bulletin number 1, revision 1, dated
April 16,2012.

This AMOC applies to all 15AC and S 15AC model numbers including all airplane serial numbers, certificated in any category, that are subject to AD 2012-10-04.

This AMOC is transferable with the aircraft to an operator who operates the aircraft under U.S. registry.

Before using this AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.

All provisions of FAA AD 2012-10-04 that are not specifically referenced above remain fully applicable and must be complied with accordingly.

The Anchorage ACO will revoke this AMOC if the Anchorage ACO later determines that this AMOC does not provide an acceptable level of safety.

If you have any questions or need additional information, please contact Mr. August Asay at (907) 271-2668, fax (907)271-6365 or e-mail at august.asay@faa.gov.

Sincerely,

August A. Asay
Manager, Anchorage Aircraft Certification Office

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Matt
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Re: AMOC for Spar Inspection

Post by Matt » Fri Apr 27, 2012 00:35

Thank you!

To Carl, John and anyone else who might have contributed to the development of this AMOC! I slowly begin to understand the US/FAA procedures. Even though I had been told about AMOCs, before, I didn't realize then, you can still submit them, after an AD is already in force. Because I had previously only been flying Swiss registered airplanes, this is the first time I witnessed the "birth" of an AD. Whatever the cause for an AD, the process itself seems reasonable and democratic to me.

At this point, I would therefore also like to express a thank you to August Asay and anyone else at the FAA involved in this for their work and reason.

I cannot judge whether the complaints about filed but unanswered comments submitted to the FAA, during the comment period, are still justified, today, but as far as I understand from reading the comment and reply section of the AD, the FAA did consider and explain their final decisions. And I guess, it is the nature of the beast that often both sides don't come to the same conclusion. The FAA will – hopefully – always tend to safety and, unfortunately, improved safety often comes at a price.

Anyhow, I think it isn't a bad thing to every now and then be able to peek into hidden corners of 60+ year old wings that our lives depend upon. Whether using removable inspection covers or tiny holes for a borescope. If we look at things in the long run, this will hopefully help the Sedans to still be around, when their current owners are long gone...

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

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Re: AMOC for Spar Inspection

Post by joea » Sat Apr 28, 2012 08:47

Matt,

The real results will come in within this next year or so once everyone looks at their airplanes.

If we find a lot of Sedans with spar problems, then the AD was needed. If we find that this was a "knee jerk" reaction to a small problem, then we know otherwise.

If one looks at the reports to the FAA of problems in the Sedan family in the past 40 years, there has been ZERO reports of spar issues or corrosion. For that matter, there have been only 4 maintenance issue reports period (none dealing with the wings), and one of those was in error, being for a Chief. We will see in a years time if this was needed or not and then guessing that a difficult discussion will be forthcoming. I know that it will be a very hot topic in Middletown in two months...

The one thing I do know and can prove today is that there has not been ONE accident in a Sedan that was caused by wing spar issues and the last I heard there was only 3 airplanes (NOT the 34 mentioned in error at first) with issues in this area.

My 2 cents worth...

Joe A

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Re: AMOC for Spar Inspection

Post by Matt » Wed Oct 10, 2012 08:47

Where can the above AMOC be found officially with the FAA? Since it has been approved for all Sedan S/N's, shouldn't this now somehow be "linked" to the AD on the FAA website?

Thank you

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

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Re: AMOC for Spar Inspection

Post by joea » Wed Oct 10, 2012 11:10

Matt,

If you want a copy I can send you one.

If its going to be posted somewhere on the FAA site I do not know as it was not generated by the FAA.

Joe

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Re: AMOC for Spar Inspection

Post by Matt » Wed Oct 10, 2012 13:59

Not necessary, Joe, thanks.

I am in the process of cutting and assembling a video of the AD installation (the large inspection holes) in our Sedan's wings and thought, I would also mention that there is an AMOC, but realized that I didn't even know myself where to look for the exact AMOC procedure. So, anybody interested in the AMOC could ask the NAA, I suppose.

Thank you,

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

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Re: AMOC for Spar Inspection

Post by joea » Wed Oct 10, 2012 15:58

Matt,

The "Guts" of the AMOC are "cut and pasted" in the post above by John Poulter, so anything I could send out would be a copy of the above post. If you still want a .pdf copy pls let me know.

Thx,

Joe

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Re: AMOC for Spar Inspection

Post by Matt » Wed Oct 10, 2012 16:33

Thank you, Joe

The above will do for my purpose.

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

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Re: AMOC for Spar Inspection

Post by poulter1 » Wed Feb 06, 2013 12:30

All,

The PDF versions of the AMOC for the Spar AD and the FAA approval letter can now be found on the Hangar 9 Aeroworks website.

http://www.hangar9aeroworks.com/Aeronca ... hInfo.html

Thanks to Mr. Baker for publishing these documents there.

V/R,

John
Last edited by poulter1 on Wed Feb 06, 2013 12:57, edited 2 times in total.

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Re: AMOC for Spar Inspection

Post by Matt » Wed Feb 06, 2013 12:54

Perfect, thanks a lot to both John's!

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

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