Which document authorizes deactivation of installed equipment when not using MEL?

Which document authorizes deactivation of installed equipment when not using MEL?

• A. Engineering Order
• B. Service Bulletin
• C. Engineering Order or Service Bulletin
• D. MEL

Answer: (C)

Authorization to deactivate installed equipment when you’re not operating under the MEL comes from formal directives, not from the MEL itself. An Engineering Order provides the operator’s engineering department the authority to modify or deactivate equipment on a specific aircraft, with approved procedures. A Service Bulletin from the manufacturer often includes accepted deactivation procedures and the related maintenance actions, and once incorporated and approved, those instructions authorize the deactivation. Together, either document gives the sanctioned means to deactivate equipment safely and in accordance with airworthiness requirements. The MEL describes what may be left inoperative and how to operate under those limits; it does not by itself authorize deactivation when you’re not using MEL. That’s why the correct source is either an Engineering Order or a Service Bulletin.

Authorization to deactivate installed equipment when you’re not operating under the MEL comes from formal directives, not from the MEL itself. An Engineering Order provides the operator’s engineering department the authority to modify or deactivate equipment on a specific aircraft, with approved procedures. A Service Bulletin from the manufacturer often includes accepted deactivation procedures and the related maintenance actions, and once incorporated and approved, those instructions authorize the deactivation. Together, either document gives the sanctioned means to deactivate equipment safely and in accordance with airworthiness requirements. The MEL describes what may be left inoperative and how to operate under those limits; it does not by itself authorize deactivation when you’re not using MEL. That’s why the correct source is either an Engineering Order or a Service Bulletin.