What is the function of the Ram Air Turbine (RAT) on the 787?

What is the function of the Ram Air Turbine (RAT) on the 787?

• A. To provide emergency power (and optionally emergency hydraulics) when normal power sources are unavailable.
• B. To regulate cabin pressure.
• C. To assist in engine starting on the ground.
• D. To power wing anti-ice systems.

Answer: (A)

The Ram Air Turbine is an emergency power source that activates when normal power sources are unavailable. It taps in ram air to spin a turbine that drives a generator and a hydraulic pump, supplying essential electrical power and, if needed, emergency hydraulic power to keep critical systems and flight controls operating. This lets the aircraft remain controllable and capable of a safe diversion or landing even with engines and APU not providing power. It isn’t used to regulate cabin pressure, isn’t meant for engine starting on the ground, and doesn’t power wing anti-ice systems.

The Ram Air Turbine is an emergency power source that activates when normal power sources are unavailable. It taps in ram air to spin a turbine that drives a generator and a hydraulic pump, supplying essential electrical power and, if needed, emergency hydraulic power to keep critical systems and flight controls operating. This lets the aircraft remain controllable and capable of a safe diversion or landing even with engines and APU not providing power. It isn’t used to regulate cabin pressure, isn’t meant for engine starting on the ground, and doesn’t power wing anti-ice systems.