Explain the difference between engineering changes and maintenance instructions and how each is approved.

• A. Engineering changes modify the design or configuration and require engineering approval and regulatory authorization; maintenance instructions describe tasks to restore or modify without changing design and follow maintenance approvals.
• B. Both require engineering approval and regulatory authorization.
• C. Maintenance instructions modify design; engineering changes are routine tasks.
• D. Engineering changes do not require approval.

Answer: (A)

The main idea is to distinguish actions that change the aircraft’s design or configuration from those that simply follow approved maintenance procedures. An engineering change is a true design or configuration modification to the aircraft or its systems. Because it affects the certification basis, it must go through engineering approval and regulatory authorization before it can be installed. This involves developing the engineering data, having the change reviewed and approved by the proper design authority, obtaining the regulator’s sign-off if required, and updating the aircraft’s airworthiness records with the approved data.

Maintenance instructions, on the other hand, cover the tasks needed to restore or preserve airworthiness without changing the design. They are executed using approved maintenance data (maintenance manuals, service bulletins that specify procedures, ADs, MELs, etc.) and must be performed under the appropriate maintenance approvals, with a release after the work is completed. They do not require the design-level approval that an engineering change does.

So the correct statement captures that engineering changes modify design or configuration and require engineering approval and regulatory authorization, while maintenance instructions describe tasks to restore or modify without changing design and follow maintenance approvals.