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Legal Interpretations

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Puckett 2017

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Summary

The Question

When a supplemental type certificate is held jointly by two entities, must both provide the written permission required by 14 CFR 21.120 for someone to use it?

Background

An aviation consultant, for an aircraft owner whose engine modification used STCs issued jointly to two separate entities, said one holder insisted it must issue the modified data plates while the other said no permission was required.

The FAA’s Interpretation

No, not on the face of the regulation. 14 CFR 21.120 requires an STC holder who allows a person to use the STC to give that person written permission acceptable to the FAA, but does not require both holders to provide it. Under 14 CFR 91.403(d), the owner may not alter the aircraft using the STC without written permission from the holder.

Requester
Puckett
Issued
October 24, 2017
Subjects
General Operating & Flight Rules · Rulemaking & Enforcement · Aircraft & Parts Certification

Regulations Cited

  • 14 CFR Part 13
  • 14 CFR 21.120
  • 14 CFR 91.403

Page 1

U.S. Department
of Transportation
Federal Aviation
Administration
ocr· 2 ~ 1011
Mr. Jim Puckett
Agent for Service
for John Cottle
Office of the Chief Counsel
800 Independence Avenue, S.W.
Washington, D.C. 20591
Re: Request for Legal Interpretation Concerning Legal Responsibilities
of Dual Holders of a Supplemental Type Certificate (STC)
Dear Mr. Puckett:

This letter is in response to your August 8, 20 17 letter on behalf of your client, Mr. John Cottle, requesting interpretation of the Federal Aviation Administration's (FAA) regulation concerning the responsibilities of a holder of a supplemental type certificate (STC) to provide written permission to a person whom the holder allows to use the STC to alter an aircraft, aircraft engine, or propeller-in particular when there are two holders of the STC. On August 11, Mr. Cottle sent an E-mail to us asking the same question. Mr. Cottle inquired whether, if an STC is issued in the names of two separate entities, would the FAA require that both paities provide written permission to the person who is altering an aircraft using that STC? To the extent that two parties hold the same STC, the regulation requiring the written permission, does not, on its face, require that both holders must provide it.

The regulation at issue, 14 C.F.R. § 21.120, states:

A supplemental type certificate holder who allows a person to use the supplemental type certificate to alter an aircraft, aircraft engine, or propeller must provide that person with written permission acceptable to the FAA.

We have been advised that the two STC holders may be engaged in litigation over this STC. Therefore, regardless of FAA regulations, Mr. Cottle' s rights with regard to this STC may be affected by the outcome of any such litigation. We assume from the facts available to us that

Page 2

Mr. Cottle purchased the STC(s) at issue from one of the holders and received only oral permission (either implied or explicit). Also, we learned from you that, for a number ofreasons (including his inability to obtain required documents from the STC holder), Mr. Cottle has removed the STC from his aircraft at considerable expense and restored it to its previous airworthy condition. You also stated that Mr. Cottle initiated a complaint with his local Flight Standards District Office (FSDO) to enforce delivery of the required documents, but that the FSDO " found nothing wrong."

If the litigation results in a finding of a "rightful" owner of the STC, the FAA should revise its records to reflect the single holder. We offer no opinion as to what avenues Mr. Cottle might pursue going forward. It is clear that, if the STC holder allows Mr. Cottle to alter his aircraft using the STC, that holder must provide him with the requisite written permission. If the holder, in turn, refuses to provide all of the required documentation, Mr. Cottle could seek a civil remedy in an appropriate court of law. And, if the holder " allows" Mr. Cottle to alter his aircraft by providing the STC without providing the written permission as required by § 21.120, Mr. Cottle could file a formal complaint with the FAA under the procedures provided in 14 C.F.R. part 13. Also, note, as you are no doubt aware, that under 14 C.F .R. § 91.403(d), Mr. Cottle may not alter his aircraft using the STC unless he has written permission from the STC's holder.

We appreciate your patience and trust that the above responds to your concerns. This response was prepared by Edmund Averman, an attorney in the Regulations Division of the Office of the Chief Counsel.

Sincerely,

Lorelei Peter

Assistant Chief Counsel for Regulations, AGC-200

Page 3

...-·

Jim Puckett,..,,, Aviation Consultant

Technical, Legal & Certification Expert

Office of the Chief Counsel
800 Independence Ave., SW.
Washington, DC 20591

Dear Sir,

August 8 2017

. ;.

This letter is intended to request a legal interpretation related to granting permission by a second party to use a Supplemental Type Certificate (STC).

My client contracted with a company that perlorms aircraft engine, aircraft alterations and modifications. A question was raised that that we have not encountered before but requires your interpretation. My client contracted with an FAA certified Repair Station to alter his aircraft with an improved engine, This modification required two Supplement Type Certificates STCs, one for the modified engine and of course one for the installation of the engine in the aircraft. After all the work was perlormed several issues were encountered.

Of the most disturbing is the fact that the two STCs were issued to two separate entities i.e. Entity One "AND" Entity Two. One of the main issues is the legitimacy of co owned STCs. ln this case the two entities are not located in the same area. After some discussion with entity two we were advised that the required, modified data plates for the engine and the aircraft must be issued by entity two. We are told by entity One that no permission is required.

We are contacting you to help us define reality here. We are under the impression that the "AND" includes both for proper documentation and historical records.

We thank you in advance for your assistance.

Regards

Jim Puckett

Jim Puckett Aviation

Regulations Referenced

14 CFR 21.12014 CFR 91.403

Snapshot retrieved August 6, 2026.

Summary

The Question

When a supplemental type certificate is held jointly by two entities, must both provide the written permission required by 14 CFR 21.120 for someone to use it?

Background

An aviation consultant, for an aircraft owner whose engine modification used STCs issued jointly to two separate entities, said one holder insisted it must issue the modified data plates while the other said no permission was required.

The FAA’s Interpretation

No, not on the face of the regulation. 14 CFR 21.120 requires an STC holder who allows a person to use the STC to give that person written permission acceptable to the FAA, but does not require both holders to provide it. Under 14 CFR 91.403(d), the owner may not alter the aircraft using the STC without written permission from the holder.

Requester
Puckett
Issued
October 24, 2017
Subjects
General Operating & Flight Rules · Rulemaking & Enforcement · Aircraft & Parts Certification

Regulations Cited

  • 14 CFR Part 13
  • 14 CFR 21.120
  • 14 CFR 91.403