Final answer:
In aircraft maintenance, the maintenance recommendations of the aircraft manufacturer should be followed when there is a conflict between the advice from both the aircraft and engine manufacturers.
Step-by-step explanation:
The correct answer is D) When there is a conflict between the maintenance advice from both the aircraft and engine manufacturers. In aircraft maintenance, it is essential to follow the recommendations of the aircraft manufacturer if there is a conflict between the maintenance advice from both the aircraft and engine manufacturers. The aircraft manufacturer's recommendations take precedence in such situations to ensure proper maintenance and safety.
For example, if the engine manufacturer suggests a specific maintenance procedure that contradicts the maintenance guidance from the aircraft manufacturer, the maintenance recommendations of the aircraft manufacturer should be followed.