The RAM Air Turbine

The ram air turbine is often referred to as the RAT, a moniker offered up with much affection by the pilots who understand its purpose.

- Rob Mark

Deployment of the RAT in actual flight operations signifies a cockpit crew has nearly run out of power-source options, usually because all engine-driven generators as well as the APU have become inoperative. With no electric power except for ship’s batteries, there is little energy left to operate the hydraulic or electrical systems necessary to move the flight controls and power critical systems.

The RAT is a small turbine connected to a support bracket that allows it to hang beneath the aircraft once it is deployed. RATs come in a variety of power options, including hydraulic, electric and hybrid, and include a variable-pitch propeller that normally faces into the slipstream to spin an internal electric generator or hydraulic pump. The propeller’s pitch varies in order to maintain a constant output from whichever device is connected.