Field Approvals: Part 1: They're still part of the process

Sept. 1, 2003
On May 21, 2003, seven months after the Federal Aviation Administration (FAA) made the first substantive revision to field approval policy in 20 years

On May 21, 2003, seven months after the Federal Aviation Administration (FAA) made the first substantive revision to field approval policy in 20 years, the FAA issued a second revision. This latest revision is Change 16 to Volume 2, Chapter 1, of FAA Order 8300.10, Airworthiness Inspector's Handbook. You can get a copy of the Order and revisions by getting online and pulling up:

It would be an understatement to say that everyone, including the inspectors in FAA local Flight Standards District Offices (FSDO), was happy with the first revision. So, armed with an exemption from the Environmental Protection Agency (EPA), I will attempt to put oil on troubled waters with a two-part article on field approvals. Part 1 will provide a short history of field approvals; in Part 2, I will cover the latest policy that came out in late May of this year. However, before we get too far into the field approval process, I would like to go over a few important facts.


  1. FAA FSDOs nationwide process approximately 23,000 field approvals a year.
  2. Of those 23,000 field approvals, approximately 65 percent deal with avionics installations (major alterations).
  3. FAA airworthiness and avionics inspectors must be trained and authorized by their individual region and office before they can perform field approvals.
  4. However, once approved, the authority and responsibility to perform a field approval is the FSDO inspector's alone.
  5. The FSDO inspector must have experience in the areas that the applicant wants to alter or repair before he or she can sign off block 3 of Form 337.
  6. FAA field approvals are "policy driven," not "regulatory driven." In other words, field approvals are not specifically addressed in FARs.
  7. Because there is no rule that speaks to field approvals, maintenance personnel do not have a regulatory right to get a field approval.
  8. Field approvals are listed in the FSDO inspector's work program as Demand Work, not Required Work, so they do not get extra marks on the bark for each field approval they sign off.

Now, despite what you've been hearing over the mechanic's rumor mill, FSDOs are still in the field approval business. Quite frankly, if FSDOs no longer processed field approvals, in 18 months a major portion of general aviation (GA) as we know it would cease to be. Avionics shops, repair stations, and fixed-base operators (FBO) would die from lack of business because they would be out of the major repair and major alteration business.

The next candidates for the marble orchard would be the equipment suppliers and the vendors. Shortly after we bury the repair stations, suppliers, and FBOs in a mass grave, the next casualty would be the FSDO that caters almost exclusively to the GA world. The FAA would be forced to close some of the FSDOs down or dramatically reduce their inspector work force, which would be based on the logic: "If the town is empty, who needs the cops?" So, despite all of the pessimistic talk in hangar lunchrooms, I am here to tell you that the FAA needs the field approvals business, just as much as industry.

There is an old saying that I just made up: "If you don't know where you've been, how did you get here?" The same is true with field approvals. I have done a bit of research on this subject and I am disappointed to report that as of this date, my research into the actual beginnings of field approvals is less than what I hoped for. This discrepancy in my research is due in part that even 60 plus years ago, field approvals as we now know them, were an instrument of policy, not a rule. As we know, policy is not bound by the strict legal record-keeping requirements that are required by the rulemaking process. However, I will share with you bits and pieces of intel of what I have found so far.

The earliest reference I have found - referencing major repairs - is a directive dated Feb. 20, 1929, from Clarence M. Young, then director of aeronautics in the Commerce Department. The directive required a rebuilder, prior to making the repairs, to furnish the department duplicate drawings and stress analysis of the parts to be rebuilt or repaired if, in the opinion of the Inspector of the department, the aircraft was damaged in excess of 50 percent. The department then approved the repair data. In addition, as part of the final inspection, the repairer must make a statement to the department inspector making the final inspection, under oath, that the repairs were made in accordance with that "approved" data.

The next reference I found was Aeronautics Bulletin NO 7-H Air Commerce Regulations, Alteration and Repair of Aircraft. This bulletin provides the definition of major repair and identifies Form 466, which is used to record the major repairs and major alterations. The form then is sent to the Department of Commerce Inspector involved in the repair or alteration.

In 1938, the Civil Aeronautics Act created the Civil Aeronautics Agency, which was changed to Civil Aeronautics Administration (CAA) in 1941. By word of mouth only, I have found that "field approvals" were first performed by Civil Aeronautics Inspectors, starting back as early as 1939. This policy of "field approvals" was allowed because a sizable number of CAA inspectors were engineers and the field approvals even back then were not complex in nature. During the same period, CAA Form ACA-337, Major Repair and Alteration Form, replaced the now defunct Bureau of Aeronautics Form 466. The need for field approvals dropped to zero during the WWII years because all civilian flying was grounded with the exception of the Civil Air Patrol aircraft.

When the war ended, the CAA was downsized because of budget cuts. The cuts included the CAA's engineering personnel headquarters in Washington, so with the workload piling up, the once frowned-upon field approvals became part of CAA policy. In 1951, President Truman signed an amendment to the CAA Act, which allowed individual mechanics appointed by the CAA and called Designated Aviation Maintenance Inspectors (DAMI) to sign off field approvals. This privilege for DAMI lasted until October of 1956, when this privilege was canceled. I have not found out why, but I suspect it was canceled due to legal problems over the implementing of the policy.

On April 1, 1958, the Federal Aviation Act was signed by President Eisenhower and a massive re-codification of the Civil Aviation Regulations (CAR) into the Federal Aviation Regulations (FAR) began. At the same time, FAA policy was also re-codified along with the rules. One of the first FAA references to field approvals was FAA Order 8310.6, Airworthiness Compliance Check Sheet Handbook. This handbook was a compilation of check sheets that included regulations, structural requirements, hazards, and operating aspects to be considered before making a major alteration and whose beginnings are lost in the mists of time. In the middle '70s, the FAA published FAA Order 8600.1, Airworthiness Inspector's Handbook, which included the first real FAA policy on field approvals. This Order was later superceded by the current Order 8300.10. I had to smile to myself when I discovered that, while the amount of words describing field approval policy has increased tenfold over the past 60 years, the substance of the early policy has remained pretty much the same. In Part 2 of this article I will go over the field approval process under the new policy.

O'Brien's Laws for Field Approvals: 1. Don't cut metal, string wire, or drive a rivet without first having an FAA inspector sign block 3 of your Form 337. 2. Make sure that your major repair or alteration is not going to interfere with other systems or STCs installed on the aircraft. 3. Check all sources first - there might be an STC on the books for the major alteration or major repair you are planning. 4. Use the checklist for instructions for continued airworthiness when making a major alteration. 5. If you have determined that the repair or alteration is minor, state so in the logbook after you did the work and reference data that supports your decision. 6. If you have DER data, check and see if the data covers the installation of the product as well as any major repair or alteration. If the installation is not covered, then you need a field approval. 7. Check and see if the piece of equipment you install is going to stay where it's supposed to stay by figuring out the design loads in chapter 1 of AC 43.13.2A. 8. No matter what, make sure that the repair or alteration meets the type design standard or approved alteration the aircraft was built to. 9. Give the FAA inspector a reasonable amount of time to review Form 337 for a field approval.
About the Author

Bill O'Brien