The intermediate and tail gear box may run at cruise flight for how many minutes, with loss of all oil?

• A. 10
• B. 30
• C. 20
• D. 40

Answer: (B)

The situation tests a time-based abnormal operation limit for critical gearboxes. If oil is completely lost from the intermediate gear box and tail gear box, these transmissions are designed to keep running for a limited period, specifically 30 minutes, during cruise flight. This window exists to give the crew a safe margin to control the helicopter and reach a suitable landing area before overheating or bearing damage could occur.

So the best choice is the 30-minute duration because it matches the published tolerance for continuing flight without oil, balancing the need to maintain control with the reality that continued operation without lubrication can quickly lead to damage. Times shorter than that (like 10 or 20 minutes) would not align with the official limit, and a longer time (such as 40 minutes) would exceed the safe tolerance established for these gearboxes.