3–3 APU – OPERATING INSTRUCTIONS (cont)

TM 1–1520–238–T–1 Change 8 3–13 3–3 APU – OPERATING INSTRUCTIONS (cont) 3–3 WARNING · To prevent accidental APU start, ensure that the APU circuit breaker in the AFT avionics bay or the APU HOLD and the APU FUEL circuit breakers on the pilot center circuit breaker panel are open when battery or external electrical power is attached to the helicopter and unqualified personnel are in and around the pilot crew station. · APU fires may go unnoticed by crew/operators in crew stations. Post a fire guard in continuous communication via the intercommunication system (ICS) with the crew/operators during APU run–up. NOTE If any aircraft subsystem requires servicing after it has been briefly checked, perform the required servicing prior to proceeding to the next step. 1. The following procedures specify APU operator walk–around and external checks. a. Verify the following fluid servicing points for proper levels prior to APU operation and add as required (TM 1-1520-238-23). (1) Main transmission oil level (left and right side) (2) APU oil level (3) Utility hydraulic fluid level (4) Primary hydraulic fluid level (5) Aft fuel tank level CAUTION Use of excessive force to actuate hydraulic hand pump could cause damage to aircraft components. b. Verify external utility hydraulic pressure gage is indicating within the range of 2600 to 3000 psig. If hydraulic pressure is below 2600 psig, use the hand pump to increase pressure to 3000 psig.