When inspecting a major alteration for conformity and return to service, the IA must determine that the data used is

When inspecting a major alteration for conformity and return to service, the IA must determine that the data used is

• A. Approved by the manufacturer.
• B. In accordance with the operator's policy.
• C. Compatible with other installations.
• D. Verified by the administrator.

Answer: (C)

When checking a major alteration for conformity and return to service, the data used to judge the modification must be compatible with the rest of the aircraft’s installations. This means the installation data, drawings, and instructions should reflect how the new item will integrate with the existing systems and structure, ensuring there are no conflicts, interference, or mismatches with wiring, mounting points, controls, or neighboring components. Why this is the best focus: even if the alteration is approved or comes from the manufacturer, if the data don’t show how it sits alongside other installations, you could miss clashes or interaction problems that affect safety, performance, or maintenance. Compatibility ensures the modification truly fits the aircraft’s current configuration and operates safely with all other equipment. The other ideas don’t fit as the primary requirement here. Data approved by the manufacturer matters, but it isn’t sufficient on its own to guarantee safe integration with all existing installations. Relying on the operator’s policy isn’t a substitute for approved data, and data verification by an administrator without demonstrating actual compatibility isn’t how the return-to-service determination is made.

When checking a major alteration for conformity and return to service, the data used to judge the modification must be compatible with the rest of the aircraft’s installations. This means the installation data, drawings, and instructions should reflect how the new item will integrate with the existing systems and structure, ensuring there are no conflicts, interference, or mismatches with wiring, mounting points, controls, or neighboring components.

Why this is the best focus: even if the alteration is approved or comes from the manufacturer, if the data don’t show how it sits alongside other installations, you could miss clashes or interaction problems that affect safety, performance, or maintenance. Compatibility ensures the modification truly fits the aircraft’s current configuration and operates safely with all other equipment.

The other ideas don’t fit as the primary requirement here. Data approved by the manufacturer matters, but it isn’t sufficient on its own to guarantee safe integration with all existing installations. Relying on the operator’s policy isn’t a substitute for approved data, and data verification by an administrator without demonstrating actual compatibility isn’t how the return-to-service determination is made.