On November 1, 2019, the FAA issued AC 43.9-1G, “Instructions for Completion of FAA Form 337.” This advisory cancels the existing AC 43.9-1F originally issued on January 25, 2007. In addition to new formatting, the most significant change is to the paragraph titled “Purpose of FAA Form 337.”

Historically, the purpose of Form 337 has been:

  1. To provide aircraft owners and operators with a record of major repairs and major alterations indicating the details and approvals; and
  2. To provide the FAA with a copy of the form for inclusion in the aircraft records at the FAA Aircraft Registration Branch.

The revised AC adds a third purpose:

3. To document and record the compatibility assessment conducted by the installer in accordance with the Form 337 NOTICE in the header block located above Item 8 – Description of Work Accomplished.

The installer must determine whether this design change is compatible with previously approved modifications.

The referenced compatibility assessment is addressed in AC 20-188, “Compatibility of Changes to Type Design Installed on Aircraft.” FAA Order 8110.4C requires the Limitations and Conditions section of a multiple supplemental type certificates (STCs) to include the statement: “The installer must determine whether this design change is compatible with previously approved modifications.”

AC 20-188 states that regardless of the approval basis, new plans for alterations or repairs should be analyzed for compatibility with all prior repairs and alterations. The AC also includes potential compatibility situations, guidance for owners, installer responsibilities, and ways to resolve non-compatible modifications.

Gleim encourages all persons required to complete FAA Form 337 to review the reference ACs and resolve any potential compatibility issues prior to starting a new alteration or repair.

Gleim Inspection Authorization Renewal Course

By March 31 every year, most IAs are required to complete 8 hours of FAA-approved continuing education to maintain their inspection authorization privileges. Though this year is not a reporting year, IAs must still complete the requirements of 14 CFR 65.93(a).

The Gleim Inspection Authorization Renewal Course makes it easy to complete your training with flexible options. Gleim provides 40 FAA-approved study units, each worth 1 hour of training credit. Choose any eight study units to complete your training requirements.

For a list of all 40 study units, visit the Gleim IA Renewal webpage.

Written by Clay Gamber, Aviation Editor, A&P, IA, ATP