Commercial Fixed Wing
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Human Factors
The crew reported the Air Driven Generator (ADG) auto-deployed at altitude in mild turbulence. When I arrived at the aircraft the ADG was already re-stowed by other maintenance personnel. Upon inspection of the manually deployed ADG; I noticed the manual retraction pump reservoir contained no hydraulic fluid through the sight glass. The reservoir was serviced to the full level with hydraulic fluid. I cycled the ADG to the stowed position several times to bleed the system per the AMM [Aircraft Maintenance Manual]. With the reservoir and the system full; the ADG was completely in the stowed position.
A maintenance technician identified that other maintenance personnel had re-stowed an Air Driven Generator (ADG) without verifying that the hydraulic reservoir had been serviced to full. He serviced the unit and bleed the system prior to completing the task.