All flight control surfaces and which component must be clear of personnel and equipment prior to applying or removing hydraulic power?

• A. Thrust reversers
• B. Ailerons
• C. Flaps
• D. Rudder

Answer: (A)

Before applying or removing hydraulic power, you must keep the area around movable components clear of any personnel and equipment. Thrust reversers are at particular risk because they are hydraulically actuated and can move into their stowed or deployed position suddenly when power is introduced or removed. That rapid movement could strike people or equipment nearby if the area isn’t fully clear. While other flight control surfaces like the ailerons, flaps, and rudder are also movable and require caution, the reversers pose the most immediate hazard in this scenario, which is why they must be clear.