EASA can issue an ETSOA (Euro-Technical Standard Order Authorization/Approval) for certain equipment design, to simplify installation authorization on an aircraft type design.

I found no notice of such an ETSOA expiring at a certain date or for a certain certification basis. Still, at some point regulations evolve and ETSOA'd equipment may stop meeting those regulations. How is this managed?

As an example: suppose a few years ago, an equipment was designed and manufactured as per some ETSO, and approved by EASA for that ETSO under a certification basis including the now obsolete DO-178B.

Now or in the near future, an aircraft manufacturer wants to use that equipment on a new aircraft type that is required to use the updated DO-178C. What would the aircraft and the equipment manufacturers have to deal with as extra certification work for that equipment? And in the case there is no extra work, how will the EASA deal with new regulations in the years to come?

(this question is not specifically targeted at EASA's ETSOAs: consider the same question for FAA's TSOAs and similar mechanisms in other countries)

  • $\begingroup$ Just to note, DO-178B isn't "obsolete" for products that used it during their certification. New products must use DO-178C but there isn't any restriction on previously TSO'd equipment. I'm sure there is still quite a lot of equipment flying that was certified with DO-178A. $\endgroup$ Nov 17, 2017 at 14:21
  • 1
    $\begingroup$ Also the last paragraph is really another question, you might move it to a new question $\endgroup$ Nov 17, 2017 at 14:37

1 Answer 1


From the Code of Federal Regulations CFR 14

§21.613 Duration.

(a) A TSO authorization or letter of TSO design approval is effective until surrendered, withdrawn, or otherwise terminated by the FAA.

(b) If a TSO is revised or canceled, the holder of an affected FAA letter of acceptance of a statement of conformance, TSO authorization, or letter of TSO design approval may continue to manufacture articles that meet the original TSO without obtaining a new acceptance, authorization, or approval but must comply with the requirements of this chapter.

From the FAA's page on TSO Cancellation/Withdrawal:

What is the difference between a "Canceled TSO" and "Withdrawal of a TSO authorization"?

A "Canceled TSO" means that the TSO has been rendered inactive and the FAA will no longer issue new TSO authorizations against that particular TSO. However, any existing TSO Authorizations obtained prior to the cancellation of the TSO are still valid and may continue to be manufactured and marked in accordance with that authorization.

The "Withdrawal of a TSO authorization" means that a specific authorization letter is withdrawn by the FAA and the approval to manufacture that particular article is terminated.

In summary, if the TSO is canceled, you can still make the article but you can't apply for a new authorization to that particular TSO revision level. If the TSO is withdrawn, you can't even manufacture the article under the TSO system (i.e. the FAA won't let you put a TSO label on it).

An example of the FAA suspending a TSO Authorization NavWorx ADS-B


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