Once extended, the speed brake remains extended until which conditions occur?

• A. The flaps are extended
• B. The PCL is advanced to MAX
• C. No action; it remains extended
• D. Both the flaps are extended and the PCL is advanced to MAX

Answer: (D)

The speed brake is designed with an interlock that prevents it from retracting simply on a single change. It stays extended to preserve the added drag until the aircraft reaches a specific configuration that signals it can safely reduce drag. The required condition set—flaps extended and the Power Control Lever advanced to MAX—ensures retraction only when the airplane is in a high-thrust, configured-for-flight state rather than during a partial setup like just having flaps down or just applying more power. In other words, both signals must be present for the speed brake to retract, which is why the correct choice is that it retraction occurs only when both flaps are extended and the PCL is at MAX.