When considering a major alteration to be made in accordance with a Supplemental Type Certificate (STC), what must the approving mechanic with inspection authorization ensure?

When considering a major alteration to be made in accordance with a Supplemental Type Certificate (STC), what must the approving mechanic with inspection authorization ensure?

• A. The STC was legally obtained.
• B. The STC is compatible with other systems.
• C. The STC is in compliance with the certification rule.
• D. The STC is applicable with the make and model.

Answer: (B)

When you install a major alteration under an STC, the approved data guide exactly how that modification must be integrated into the aircraft. The approving mechanic with inspection authorization must verify that the new installation will work safely with the airplane’s existing systems, not causing interference or unsafe interactions. This means confirming that electrical loads, wiring interfaces, avionics, power sources, controls, and other related systems can operate together as the STC specifies. If the STC data shows specific interfaces or limitations, those must be followed so the modification remains airworthy. While it’s also important that the STC is valid for the make and model and that the data is properly approved, the key focus in this context is ensuring compatibility with the aircraft’s other systems to prevent negative interactions.

When you install a major alteration under an STC, the approved data guide exactly how that modification must be integrated into the aircraft. The approving mechanic with inspection authorization must verify that the new installation will work safely with the airplane’s existing systems, not causing interference or unsafe interactions. This means confirming that electrical loads, wiring interfaces, avionics, power sources, controls, and other related systems can operate together as the STC specifies. If the STC data shows specific interfaces or limitations, those must be followed so the modification remains airworthy.

While it’s also important that the STC is valid for the make and model and that the data is properly approved, the key focus in this context is ensuring compatibility with the aircraft’s other systems to prevent negative interactions.