What is standard industry practice for repair design approval? 2

[KirbyWan]

Howdy all,

I work for a repair station that deals mostly with nacelle systems. We've been trying to meet our customers requirements while at the same time satisfy FAA code issues, but these have been in conflict. Here are two issues that we've had.

A foreign customer requires an 8110-3 approval on any work outside the engine manual. They have asked that we seperate the inner and outer skin of the CF6-80C2 blowout door and remove all traces of the adhesive, which originally used asbestos, and rebond it with an adhesive that does not use asebestos. No problem we write up the process and substantitate it. This is a minor repair according to FAA policy as elaborated in AC120-77. The DER has told us that he is no longer allowed to provide 8110-3s on minor repairs. So I'm faced with selecting one of the decision criteria to force this into a major repair classification so I can get and 8110-3.

A different customer requires all work to be done to approved FAA data. If a repair is not in the engine manual they consider this to be an MRB action and expect us to get approval from the manufacturer for the design change. For a CF6-50 translating cowl there are cracks on the blocker door lands. This is a common problem I think caused by the doors being rigged improperly and hitting to hard on the lands. The usuall repair is to stop drill and pin rout the crack and install a doubler on the back side with three rivets on either side of the crack. Easy to substantiate with a comparison of P-loss in the crack compaired with P-gain from the doubler and the rivets both having a positive margin of safety. Again this is a minor repair. They feel that we do not have the authority to perform this repair without either a DER approval which we cannot get or the approval of the manufacturer, MRAS.

My questions is what authority as an Engineer for an FAA repair station do I have? For a minor repair on secondary structure is my approval, and that of my boss who reviews our EOs, not enough? How should I try and get a customer to accept that we have the authority to design and install minor repairs without going to the manufacturer or the FAA for every little change? Sorry for the novel but I wanted to have concrete examples to get the best responses. BTW there is a seperate forum for FAA code issues, but It's not used and felt this forum would have the most people that deal with these issues.

Thanks for everyones input.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[dgapilot]

If you have the in house engineering capability, apply for an MRA ODA and issue your own 8100-9 for the repair design. An alternative is to get an FAA approved repair specification in accordance with Order 8300.14.

Unfortunatly when dealing with foreign CAAs, there are problems going back and forth and differences in their requirements. It may be worthwhile for your to look up the Bilaterals and Implementation Procedures and Special Conditions with the foreign entity. You may find that they can't even accept a repaired article unless it is as a special condition. The world of import and export is quite complex when dealing with foreign CAAs.

 

[KirbyWan]

Im not that familiar with ODA or form 8100-9, but from what I can figure out this would be more for major repairs or alterations. I think everything we're doing would be considered a minor repair and should be acceptable as is based on our analysis and substantiation that the repair restores the aircraft to an airworthy condition. I would like to be able to trace for our customer the regulations and advisory circulars that support my view, and yes I expect this to be futile, but it's knowledge I should have just so I'm confident in my own authority and limits thereof. So far I've paged through AC120-77 and AC43-18. There's a lot of gold in these advisory circulars, and they are easier to read then the FARs but still not quite plain english enough to feel I'm interpreting them correctly. I feel like I need a minor in legalese.

Thanks for your help dgapilot.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[dgapilot]

Kirby,
ODA = Organization Designation Authorization, think of it as a group of DERs and DARs all working together. An MRA ODA is a Maintenance facility that has engineering and airworthiness expertise and can issue approvals for thos things within that area of expertise. An 8100.9 is almost the same as an 8110-3 except an ODA signs for it rather than an individual DER.

Since you are using materials that were not part of the original design, I question your decision that it is a minor alteration. You might at least want an approval for an alternat material (or lack of an original material Asbestos). It may be easy to accomplish, but the engineering to substatiate it needs to be documented.

David

 

[YoungTurk]

My questions is what authority as an Engineer for an FAA repair station do I have?

As I understand it, none. The delegated authority of the repair station lies in the inspection/QC department and is largely limited to performing repairs in accordance with previously approved repairs such as the SRM. Your DER is correct that he is not supposed to approve minor repairs and alterations, those are also within the purview of your inspection department (and as such they probably don't need engineering for coverage).

Understand that your company approval, or that of your boss, carries no authority in terms of FAA certification.

By requesting FAA engineering approval of a repair, you, the applicant, are implying that it is major repair. The major minor determination is to be made/proposed by the applicant and the role of the delegated authority (inspector or engineer) is to concur (or not) and provide the relevant type of approval.

You will have a difficulty rectifying this FAA process with the requirement of some customers and foreign agencies (EASA) to have engineering approval of your repairs or changes. You are correct, you are left with chosing a criteria which makes your repair major to obtain the necessary approval for your customer and their authority. (There are other options, but no magic that I am aware of.)

 

[KirbyWan]

YoungTurk,

Your post left me with more questions. As I understand your post if the repair does not fit in the CMM or SRM limitations I do not have the authority to approve a minor repair, but if the repair is minor I can't get approval from the FAA or their designee. So who approves minor repairs that do not fit within the limits of a CMM/SRM? (or AMM i guess, though I don't use these myself) Would the quality/inspection department with whom the delegated authorty lies have that authority? Also I'm confused where you say the applicant makes the major/minor determination, who is the applicant? I know that half my struggle is with the legalese in which regulations are written.

dgapilot,

I understand that a material change could be classified as a major repair/alteration, would this apply to all things? If I was changing grades of aluminum I would think this was a major, but would this include adhesives? paints and coatings? What process do liason engineers use when the manual calls out an adhesive that is no longer avaiable?

Thanks to both of you for responding.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[YoungTurk]

Kirby,

I'm not a repair station expert, I work on the other side of the fence with the ODA at a facility which also happens to have a repair station. Also, not all repair stations have the same procedures and requirements, so take my info with a grain of salt and find your repair station manual which, should answer most of your questions - and probably leave you with many more!

To answer your questions: Yes, QC/Inspection at the repair station should be "approving" minor repairs and alterations. "The applicant" in FAA lingo, is you, your company, and/or your customer. Whoever is requesting data for a major repair or alteration to be approved is "applying" for certification in some way.

 

[dgapilot]

KirbyWan,
There are a couple things at play here. The first thing that needs to be determined is if this change is a Major/Minor change in type design per 14CFR21.93. in short this is the applicable section " A "minor change" is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are "major changes" (except as provided in paragraph (b) of this section)." The proposed change could have an impact on structural strength (change in adhesive), reliability (how it reacts with the environment without the asbestos). If it is determined to be a major change in type design, then you would need to apply for an STC to get approval.

If it is determined that it is a change in type design, you are dealing with an alteration, and you then have to make the determination of major or minor alteration. If you go the STC route for a change in type design, the STC is the approved data for the major alteration. Without an STC, your choices would be a Field Approval or a DER approved alteration. Field approvals are outlined in Order 8900.1 Volume 4 chapter 9. DER work is covered in Order 8110.37.

If it is determined that it is a minor change in Type Design and a Minor Alteration or Repair, you only need accepted data. Typically that would be the maintenance manual. If there is nothing in the standard practices section (Chapter 20) about your proposed change/repair, your next option would be to write up a procedure that is used to do the repair/alteration including inspection criteria, and present it to your PMI for his acceptance. If it is something that you do all the time, I would submit it as a repair procedure to be included in the repair station opspec.

If this sounds confusing, it is. I have a powerpoint that I gave at an IA seminar on the Major/Minor issue that I can email to you. Send me a request at n14ky@aol.com

Hope this helps

David