Field Approvals, Part 2, Still part of the process

Oct. 1, 2003
In Part 2 of my tome on field approvals, we will cover current field approval policy found in Change 16 to FAA Order 8300.10.

In Part 2 of my tome on field approvals, we will cover current field approval policy found in Change 16 to FAA Order 8300.10. You can pull up Change 16 on our web site at:

In order for the rest of the article to make sense, we have to first agree that a repair is a procedure or a process whose intent is to restore the aircraft or one of its parts back to the original design or properly altered condition. An alteration is a change to the original design or properly altered condition.

Is or isn't?
Before running to the FSDO for a field approval, your first question should be whether the repair or alteration staring you in the face is either major or minor. Making this is or isn't determination is not as easy as it sounds. If we look in 14 CFR part 1, the definitions of major repair and major alterations are strikingly similar. If we consolidate and paraphrase the two 14 CFR definitions of a major repair and a major alteration into one, it would look like this:

1. If a repair or alteration is improperly done, it might affect weight and balance, structural strength, performance, powerplant operations, flight characteristics, or other qualities affecting airworthiness.

2. That is not done according to accepted practices or cannot be done by elementary operations.

If you take that definition at face value, any repair or alteration that you do on an aircraft would be major because everything you touch on an aircraft affects something else. Even as a mechanic working at North Philadelphia airport 25 pounds ago, I always believed that the lawyers who wrote the part 1 definitions for major repairs and alterations should have worked a little harder to narrow the definitions down to a level of understanding we did not need a second legal opinion for.

So where do you go next to figure out major or minor? Try Part 43, appendix A. It lists major repairs and major alterations by powerplant, airframe, and appliances. But you may have a problem with the appendix A list. The problem is the lists in the appendix are not all that inclusive, so your repair or alteration may not be identified as major on the list. So if you roll craps, then try the manufacturer and see if it can tell you if what you want to do is major or minor. But it has been my experience that most manufacturers are less than helpful in the major repair or major alteration department because lawyers have made cowards of us all. In an act of final desperation, you can call your FAA inspector and ask your major or minor question.

Let's say you tried all of the above and still no luck. As a last gap measure I have a possible solution for you. Ask yourself three questions. If the answers to any of those questions are no, then the repair or alteration you want to perform is major. While not perfect, the three-part question enables you to focus on the decision in front of you. The question begins with: If the repair or alteration you performed totally fails, can the aircraft:

1. Continue to fly?
2. Land?
3. Keep passengers, crew, and people on the ground unharmed?

If the answer to all three questions is yes, then you have a minor; if the answer to any one of the three questions is a no, then you have a major repair or a major alteration.
Let's say you now have determined that you have a major alteration. The next thing you need is data to do the work and all major repairs and major alterations must use data approved by the FAA.

There are two kinds of data: acceptable and approved. Acceptable data can be manufacturer's manuals, bulletins, Advisory Circulars 43.13-1B, Acceptable Techniques and Practices, Aircraft Inspection and Repair, and AC 43.13-2A, Aircraft Alterations. Acceptable data is used for regular old inspections, maintenance, and minor repairs and alterations. Ninety-eight percent of maintenance performed on aircraft is done using acceptable data.

However, to perform a major repair or a major alteration, parts 43, 65, 121, and 145 say you must use FAA-"approved data." This data must be approved because you are either changing the type design of the aircraft with a major alteration or returning the aircraft back to its original or properly altered condition with a major repair. Some examples of FAA approved data are Type Certificate drawings, Airworthiness Directives, approved portions of the manufacturer's manual (like structural repair chapter), CAA Forms 337 dated before 10/1/55, and DAS data. For even more examples of approved data, please see Change 16 revision to the field approval chapter in FAA Order 8300.10.

I wish I could tell you that in every case, the word acceptable means acceptable, and the word approved means approved. But when you read the Order you will find out that there are exceptions. For example, you can use an appliance manufacturer's manual to make FAA-approved major repairs to their product even though the manual does not say FAA-approved. Or you can use AC 43.13-1B for major repairs on nonpressurized areas of aircraft only when the mechanic determines that the major repair is:

1. Appropriate to the product being repaired;
2. Directly applicable to the repair being made; and
3. Not contrary to the manufacturer's data.

If you forget where the three limitations are for using the AC, they are easy to find: they are on the first page, in the first paragraph of the signature page of the AC. For other examples of approved data, see FAA Order 8300.10 Change 16, Vol. 2, Chapter 1. If you do not have an STC in your pocket, then you are in the market for a field approval.

Definition of a field approval
A field approval is an approval by the Administrator, through an authorized FAA inspector, of technical data and/or installation used to accomplish major repairs and major alterations. Such data or installation becomes technical data approved by the Administrator and it is used for a one-time installation.

So, there are two kinds of field approvals: one for data which is the most common. The data is usually generated by the mechanic doing the repair or alteration. The mechanic must make sure that the data that is supplied to the inspector meets or exceeds the CAR or FAR standard the aircraft was built to, or your application will be rejected.

The second kind of field approval is for installations and repairs that were previously done by parties unknown. This second one comes in pretty handy when, during an annual inspection, you find an installation that obviously has been on the aircraft forever. For example, let's say bigger battery/battery box installation than what the type certification (TC) called for, and you have zero paperwork. To fix the paperwork/approval problem, you fill out Form 337 just as if you were doing the installation and get your local FAA inspector to approve the installation, based on his inspection, and by signing off Block 3 of Form 337. Then, you approve the installation by signing your name and certificate number in Block 7 of the form. You must also create the Instructions for Continued Airworthiness (ICA) for this installation and attach the ICA to the form.

Instructions for continued airworthiness
This policy sets forth a requirement for field approvals for major alterations; the mechanic or repair station doing the work must create instructions on how to maintain the continued airworthiness of that alteration for the mechanics that follows. The policy came out in 1999 and I am the one responsible for it. If you want to find out more about the background and the reason why the policy came to be, you can read my articles titled: "Red Tape" and "Dead Cat's Replacement". The articles can be found on the AMT website.

The requirement to develop Instructions for Continued Airworthiness (ICA) is simple to comply with. You can use the checklist found in Change 16 to the FAA Airworthiness Inspector's Handbook, Vol. 2, Chapter 1. The Handbook can be found on the FAA website: The checklist contains 16 blocks you must check off. Field trials of the form indicate that only five to eight blocks are usually filled out with information, the rest of the blocks can be filled in with N/A. There are a couple of pluses to using the ICA checklist. First, the form is standardized, and it is national policy so it meets 14 CFR. Next, the ICA checklist allows you to identify replacement parts for your alteration, so you won't need another field approval to replace a part, and it allows you to revise the checklist when a need arises.

What are the changes to field approval policy?
For the most part, field approval policy has remained 90 percent the way it was. The three biggest changes to field approvals were: first, the deletion of the third kind of field approval, the multiple field approval that was performed by the original modifier. Second, the addition of a decision flow chart (appendix 1-2) for the field approval process that is applicable both to industry and FAA inspectors to improve standardization. Third, was the incorporation of a 12-page job aid for major alterations. This job aid is what all the fuss was about.

The opening paragraph for the job aid for major alterations contains a statement that says: The following lists indicate which method(s) may be used for approving major alterations to TC'd and STC'd products. These lists are not all-inclusive and each alteration should be evaluated on a case-by-case basis. So, in reality, this job list is not so much different from earlier field approval policy, but it does provide a structure for decision-making.

For example, the job aid contains a list of major alterations broken down into four broad categories such as general aviation aircraft; transport aircraft; rotor craft; and engines, propellers, and APU. Each category is further broken down into areas such as: weight and balance, structural strength, operational characteristics, airworthiness, and crashworthiness.

Within each area there is a list of applicable alterations. At the right-hand side of each individual alteration is a block that is marked with the letters STC, EVL, or ENG. The letters STC stands for Supplemental Type Certificate. This means an STC must be approved for that particular alteration. The letters EVL mean that particular alteration may be eligible for an approval other than an STC, like a field approval. The letters ENG means that the local FAA Airworthiness Inspector needs input of some kind from FAA Engineering.

In summary, the old saw says change can be good, it can be bad, or it can keep the status quo. But it is only our reaction to change that matters. I want you to examine the new policy on field approvals, and discuss it among your peers. Only by educating yourself can you make the decision whether or not the new policy is good, bad, or if it just keeps the status quo. You can start your education on field approvals by pulling up our web site: The latest Change 16 revision to our FAA Order 8300.10 is listed there. If you have any comments, good or bad, get back to me at william.o'[email protected].

About the Author

Bill O'Brien