Which of the following is NOT listed as a method emergency gear extension systems may use?

• A. Mechanical
• B. Alternate hydraulic
• C. Compressed air
• D. Electric motor

Answer: (D)

Emergency gear extension systems are designed to move the gear out and lock it even when the primary hydraulic system isn’t available. The typical back-up methods are mechanical/manual extension, alternate hydraulic extension using a separate hydraulic supply, and a pneumatic (compressed air) extension that uses stored air to drive the gear actuators. An electric motor, while it can power actuators in some designs, isn’t usually listed as a separate emergency extension method in standard references. Electrical power may not be available during a failure, and design conventions treat electric-drive as part of a broader system rather than a standalone emergency extension method.