FAR/AIM: § 135.607 Flight Data Monitoring System.

After April 23, 2018, no person may operate a helicopter in air ambulance operations unless it is equipped with an approved flight data monitoring system capable of recording flight performance data. This system must:

(a) Receive electrical power from the bus that provides the maximum reliability for operation without jeopardizing service to essential or emergency loads, and

(b) Be operated from the application of electrical power before takeoff until the removal of electrical power after termination of flight.