2-97. APPLICATION OF EXTERNAL POWER.
cables from the external power
source to the aircraft, insure that
the GPU is not touching the
aircraft at any point. Due to the
voltage drop in the cables, the
two ground systems will be of
different potentials. Should they
come in contact while the GPU is
operating, arcing could occur.
Turn off all external power while
connecting the power cable to, or
removing it from the external
power supply receptacle. Be
certain that the polarity of the
external power source is the same
as that of the aircraft before it is
An external power source is often needed to supply
the electric current required to properly ground service
the aircraft electrical equipment and to facilitate starting
the aircraft's engines. An external DC power receptacle
is installed on the outboard side of the right engine
nacelle. An external AC power receptacle is installed on
the outboard side of the left engine nacelle.
2-98. SERVICING OXYGEN SYSTEM.
The oxygen system furnishes breathing oxygen to
the pilot, copilot and first aid position. Figure 2-19
shows the location of oxygen cylinder.
a. Oxygen System Safety Precautions.
Keep fire and heat away from
oxygen equipment. Do not smoke
while working with or near oxygen
equipment, and take care not to
generate sparks with carelessly
handled tools when working on
the oxygen system.
(1) Keep oxygen regulators, cylinders, gages,
valves, fittings, masks, and all other components of the
oxygen system free of oil, grease, gasoline, and all
other readily combustible substances. The utmost care
shall be exercised in servicing, handling, and inspecting
the oxygen system.
(2) Do not allow foreign matter to enter oxygen
(3) Never allow electrical equipment to come in
contact with the oxygen cylinder.
(4) Never use oxygen from a cylinder without
first reducing its pressure through a regulator.
b. Replenishing Oxygen System.
1. Remove oxygen access door on outside of
aircraft (fig. 2-29).
2. Remove protective cap on oxygen system
3. Attach oxygen hose from oxygen servicing
unit to filler valve.
Table 2-10. Recommended Fluid Dilution Chart