If you as the holder of an inspection authorization were approached by an aircraft owner and asked to replace the engine on the aircraft with one of a different make and horsepower rating, which of the following would you consult first in determining acceptability?

If you as the holder of an inspection authorization were approached by an aircraft owner and asked to replace the engine on the aircraft with one of a different make and horsepower rating, which of the following would you consult first in determining acceptability?

• A. Manufacturer's manual
• B. Summary of supplemental type certificates
• C. Type Certificate data sheet
• D. Advisory Circular

Answer: (C)

The key idea is to verify what is officially approved for the aircraft’s certification before making any engine change. The Type Certificate Data Sheet is the primary source that codifies which engines and horsepower levels are approved for a given airframe, along with any required installations, modifications, or limitations. It tells you whether an engine replacement is already authorized for that aircraft type and under what conditions, and it will indicate if an alternate engine would require an additional Supplemental Type Certificate or other approval. If the engine you’re considering isn’t listed, you would then look to the applicable STC or field approval path to obtain regulatory authorization. The manufacturer’s manual provides procedures and limits for operating and maintaining a given engine, but it does not by itself authorize changes to the airworthiness of the aircraft. The Summary of STCs lists approved modifications, which is useful once you’ve checked the TCDS and found a relevant STC, but it isn’t the first source to determine acceptability. Advisory Circulars offer guidance, not regulatory approval, so they don’t establish whether a specific installation is permitted. So, you consult the Type Certificate Data Sheet first to determine if the engine installation is approved for that aircraft and under what conditions.

The key idea is to verify what is officially approved for the aircraft’s certification before making any engine change. The Type Certificate Data Sheet is the primary source that codifies which engines and horsepower levels are approved for a given airframe, along with any required installations, modifications, or limitations. It tells you whether an engine replacement is already authorized for that aircraft type and under what conditions, and it will indicate if an alternate engine would require an additional Supplemental Type Certificate or other approval.

If the engine you’re considering isn’t listed, you would then look to the applicable STC or field approval path to obtain regulatory authorization. The manufacturer’s manual provides procedures and limits for operating and maintaining a given engine, but it does not by itself authorize changes to the airworthiness of the aircraft. The Summary of STCs lists approved modifications, which is useful once you’ve checked the TCDS and found a relevant STC, but it isn’t the first source to determine acceptability. Advisory Circulars offer guidance, not regulatory approval, so they don’t establish whether a specific installation is permitted.

So, you consult the Type Certificate Data Sheet first to determine if the engine installation is approved for that aircraft and under what conditions.