A power transfer unit (PTU) in a hydraulic system:

Transfers fluid between systems

Transfers hydraulic power between systems without fluid transfer

Correct

Converts hydraulic pressure to electrical power

Replaces the engine-driven pump at altitude

Explanation

A PTU uses pressure from one system to drive a pump in another system, transferring power without mixing fluids.

Test yourself with random questions from Aircraft General Knowledge and all other ATPL subjects.