When considering another alteration to be made in accordance with a supplemental type certificate (STC), the approving mechanic with inspection authorization must ensure?

When considering another alteration to be made in accordance with a supplemental type certificate (STC), the approving mechanic with inspection authorization must ensure?

• A. The STC is compatible with other previous alterations.
• B. The STC is applicable with the make and model.
• C. Both A and B.
• D. None

Answer: (C)

When approving an alteration under an STC, you must verify two things: that the STC data apply to this exact aircraft make and model, and that the new modification will not conflict with any other alterations already installed. STCs are issued for a specific aircraft configuration, so applying them to a different model or alongside other incompatible modifications can create safety issues. If the STC isn’t valid for the aircraft, or if it interferes with existing alterations, the alteration cannot be approved under that STC. Ensure the installation follows the STC data and approved supplemental information, and that there’s no interference with systems, structure, or performance.

When approving an alteration under an STC, you must verify two things: that the STC data apply to this exact aircraft make and model, and that the new modification will not conflict with any other alterations already installed. STCs are issued for a specific aircraft configuration, so applying them to a different model or alongside other incompatible modifications can create safety issues. If the STC isn’t valid for the aircraft, or if it interferes with existing alterations, the alteration cannot be approved under that STC. Ensure the installation follows the STC data and approved supplemental information, and that there’s no interference with systems, structure, or performance.