What does it indicate when the MASTER CAUTION, LOOP cue, and No. 2 ENG LOOP A lights are illuminated?

When the MASTER CAUTION, LOOP cue, and No. 2 ENG LOOP A lights are illuminated, it indicates that Loop A is experiencing a fault, which makes it unreliable for providing accurate data regarding engine parameters. This situation arises because the illumination specifically refers to a malfunction in Loop A without indicating the presence of a fire.

The condition suggests that while Loop A is not functioning as intended, it does not necessarily mean that there's an immediate emergency, such as an engine fire. Consequently, the pilot can take appropriate actions based on the nature of the malfunction, primarily by relying on Loop B for accurate readings. Ensuring the functionality of the backup loop is crucial, thus allowing the pilot to continue operations safely until the situation can be diagnosed and resolved.

In this case, the illumination of the lights does not point to a need for drastic measures like shutting down the engine, as there is no indication of fire, supporting the conclusion that Loop A is simply faulty.