What FAA approvals are necessary when installing an engine not on the aircraft type certificate?

When an engine that is not included on the aircraft type certificate is installed, it is essential to obtain a Supplemental Type Certificate (STC) or a field approval from the FAA. An STC provides a formal alteration approval for the aircraft, ensuring that the proposed engine installation complies with safety and regulatory standards. This certification demonstrates that the new installation has been evaluated and meets the necessary performance and safety requirements.

Field approval is another option that may be pursued for certain modifications. This is a less formal process than obtaining an STC and allows for the installation of non-type certified equipment under specific circumstances. However, it is generally preferable to obtain an STC for significant changes to ensure a more thorough review.

While type certification is critical for the aircraft itself, it does not encompass the installation of additional engines that are not originally included. Likewise, Part 145 repair station approval pertains to maintenance and repair of aircraft components but does not apply specifically to the alteration of the aircraft by installing a non-type certificated engine.

Therefore, the requirement for either an STC or field approval is the correct route to take when addressing this modification.