Paperwork Problems in Vintage Aircraft

STCs, Form 337s, Weight & Balance Reports, Equipment Lists And Required Logbook Entries

In the nearly forty years that I’ve been examining aircraft logbooks, I’ve found relatively few in which the required aircraft records are complete according to Federal Aviation Regulations.

Ed Leineweber is licensed to practice law in Wisconsin.  Now, mostly retired from the legal profession, including twenty years as a circuit court judge, Ed focuses his limited practice in Alternative Dispute Resolution, including Mediation, and Aviation law. As a pilot for nearly 40 years, aircraft owner, Certified Flight Instructor, licensed aviation maintenance technician, former Fixed Base Operator, airport manager, and FAA Safety Team member, Ed is experienced in most aspects of general aviation. When not practicing law, he enjoys working in his shop at the airport on aircraft restorations and developing his aircraft kit company, and spending time with family and friends.

In the case of vintage aircraft, I estimate that most contain glaring omissions that seriously affect market value and expose the owner and operator to FAA enforcement proceedings, especially if they are revealed following an accident or incident.  Insurance coverage might also be compromised.  It is worth the effort to have your aircraft records reviewed for completeness and corrected or supplemented as necessary.

          The records problems I have observed generally pertain to issues involving Supplemental Type Certificates (STCs); Forms 337, required in the case of major alterations; outdated equipment lists and weight & balance data; and absence of required logbook entries. These problems all stem from the tendency of successive aircraft owners to modify their aircraft over the years without regard to the legal requirements.  Decades and many owners later, this practice has created quite a mess. Here is a very short review of a few particulars.

          We all know that the owner or operator of an aircraft is primarily responsible for maintaining the aircraft in airworthy condition, FAR §91.403(a), and that it is a violation to operate an aircraft without a valid and current Airworthiness Certificate (AC). FAR §91.203(a)(1). But many don’t realize that the certificate is valid only when the aircraft conforms to its Type Certificate (TC), compliance with which was the basis for issuing the AC.  Modification of the aircraft to vary from the TC can invalidate the AC unless there is a legal basis for such modification, and an appropriate entry is made in the permanent aircraft records.

          Aircraft modifications can be “major,” as defined in FAR §1.1, or “minor” if not included in that definition.  Further guidance of what is “major” is given in FAR Part 43 Appendix A. Major modifications can be made under the authority of a Supplemental Type Certificate or an FAA-authorized “field approval” evidenced by a Form 337, filed with the FAA and copied in the aircraft records.

          Supplemental Type Certificates are owned by a third party and may be used by an aircraft owner to authorize an original Type Certificate modification only with the written permission of the STC owner, usually upon the payment of a substantial fee. FAR §91.403(d) and §21.20

          A major aircraft modification can also be legally made through a field approval upon the basis of “approved data” and evidenced in the aircraft records by a Form 337 signed by an authorized FAA representative.

          What are not major modifications in the eyes of the FAA are therefore minor modifications, which can be made by an A&P based on “acceptable data” and evidenced in the aircraft records by a simple logbook entry.  But note that such modifications while legal must still be documented by a logbook entry complying with the requirements of FAR §43.9.  Even “preventative maintenance” as described in Appendix A of Part 43, often performed by the pilot owner/operator, must be logged under §43.9.

          Each factory-built aircraft is delivered with an initial weight & balance report and list of installed equipment, the latter showing the weight and arm of each such component.  Any change to the aircraft through repairs, alterations or installation or removal of equipment requires that both the weight & balance calculations and the equipment list be updated, and the updated information be included in the required onboard documents. FAA Aircraft Weight & Balance Handbook, last updated in 2016, pages 1-3, 2-10, 3-2, 3-4, 3-8, 5-2, and 7-2 to 3.

          My review of aircraft records following inspection of the aircraft has revealed conspicuous major modifications not supported by STCs or field approvals, even when they could be easily obtained; obvious minor changes without any logbook entries; and weight & balance reports and equipment lists that hadn’t been updated in decades despite avionics upgrades, engine changes, interior renovations and external repainting or paint removal and polishing.  While records of some of these modifications might once have existed (we would hope) they were no longer part of the aircraft records possessed by the current owner and were not on file with the FAA. 

Most of these problems I’ve described can be remedied, although it is time-consuming and expensive. Still, it is worth the effort and expense to protect airman certificates, aircraft market value, and insurance coverage.

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