ATR 42-300
AIRCRAFT HANDLING MANUAL
AIRCRAFT SERVICING
3.3 EXTERNAL POWER
The DC and ACW electrical distribution system can be supplied from ground power sources,
connected via the separate “External Power” receptacles which are located on the lower right side of the
fuselage, just aft of the nose gear.
The specification of the DC GPU for ATR 42 requires the ground unit to be able to provide a steady
current of 300 to 400 Amp under 28 volts to insure correct functioning of all electrical services prior to
startup.
For engine start, the GPU must be able to provide ADDITIONNAL STARTER CURRENT of
1000Amp while keeping more than 12 volts (ie 16 KW instantaneous power).
CAUTION :
If DC EXT PWR voltage on maintenance panel still shows less than 26 v despite the full
load load shedding, the GPU MUST BE CONSIDERED AS COMPLETELY
UNUSABLE.
If DC EXT PWR voltage on maintenance panel is above 26 v, the DC GPU may be
used to maintain aircraft batteries charge whilst using all other ground services
normally (cargo door, refueling, cabin lighting, etc…)
WARNINGS :
Do not disconnect external power while the GPU is supplying power to the aircraft.
Failure to obey this may cause serious burn injuries and blindness to personnel, and
severe damage to the external power receptacle and GPU power cable connector.
If the external power earth grounded neutral is open, the aircraft will have an
electrical potential above earth ground, which may cause an electric shock with
possible serious injuries to personnel touching the aircraft. If an electric arc is
observed when touching the aircraft, make sure that all personnel are kept clear of
the aircraft and contact maintenance, or the commander immediately.
