Orphan Supplemental type Certificates: a hidden challenge to the continuing airworthiness

Aircraft operators are responsible for the safe operation and continuing airworthiness of their aircraft – airframe and engines. Over their long lives, aircraft typically accumulate several Supplemental Type Certificates (STCs) that demonstrate compliance of the respective modifications to airworthiness standards. The operators’ responsibility for airworthiness includes the rigorous knowledge of the status of their aircrafts’ relevant STCs. Therefore, continued technical support of the STCs is required. However, when an STC is no longer supported by the design approval holder (DAH), operators can face severe challenges as a result of the “orphan” STC.

Potential Imperils on Continuing Airworthiness

When a design approval holder removes its support of an STC, this can create major risks for the operation and challenges to restoring continuing airworthiness. There are a variety of reasons why a DAH might stop supporting an STC. Some circumstances that can result in orphan STCs include the business closing, the loss of its approval as a design organization or in rather seldom cases the invalidation of an STC by aviation authorities that had granted its approval. Any one of these situations creates a problem.

Orphan STCs

The risk associated with different types of orphan STCs varies. Invalidated STCs, those that aviation authorities rescind, would render the aircraft non-compliant. In these situations, the aircraft may no longer be operated until the modifications are removed or are re-certified with an appropriate STC. While the likelihood of this situation is low, the severity of the risk is high.

Surrendered STCs

In the case of a surrendered STC, where the DAH has declared it will no longer support the STC, the initial risk is low, however risk increases with lack of support. Airworthiness Directives might be issued or design deficiencies might arise, compelling the operator to find a new means to support the affected STC.

Abandoned STCs

An abandoned STC, where the DAH has simply stopped supporting it, without informing the authority and the operator(s) of the affected aircraft, leaves operators unaware and again, at increased risk. In these instances, risk is further increased because the operator is unaware of a situation that could both require immediate attention and potentially lead to an aircraft on ground (AOG) scenario.

How Do the Aviation Authorities Deal with Orphan STCs?

While the FAA and EASA have procedures in place for dealing with orphan STCs, they are quite different. On the one hand, while the FAA encourages the certificate holder to transfer the STC to a responsible party, they will take possession of an orphan STC, after a rather lengthy notification process. On the other hand, EASA’s policy is strictly limited to continued airworthiness oversight. In either case, the trouble is that these activities only come into to play after the fact, leaving the operator with additional risk.

IAMA recognises that managing the risk around orphan STCs and its effects on continuing airworthiness is extremely complicated. This is why we have developed our position on the issue and are working towards solutions that will help operators avoid the considerable obstacles.