intervals to assure
Removal of ice accumulations using undi-
luted defrosting fluid is expensive and slow.
If tires are frozen to ground, use undiluted
defrosting fluid to melt ice around tire.
Move aircraft as soon as tires are free.
APPLICATION OF EXTERNAL POWER.
Before connecting the 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 sys-
tems will be of different potentials.
Should they come in contact while the
GPU is operating, arcing could occur.
Turn off all external power while connect-
ing the power cable to, or removing it
from the external power supply recepta-
cle. Be certain that the polarity of the
external power source is the same as that
of the aircraft before it is connected. 3ini-
mum GPU requirement is 400 amperes
continuous and 1800 amperes for one
tenth of a second.
An external power source is often needed to sup-
ply the electric current required to properly ground
service the aircraft electrical equipment and to facil-
itate starting the aircrafts engines. An external DC
power receptacle is installed on the underside of the
right wing leading edge just outboard of the engine
nacelle. An external AC Power receptacle is installed
on the underside of the left wing leading edge just
outboard of the engine nacelle.
2-102. SERVICING OXYGEN SYSTEM.
The oxygen system furnishes breathing oxygen
to the pilot, copilot and first aid position Oxygen
cylinder location is shown in figure 2-19.
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 oxy-
(1.) Keep oxygen regulators, cylinders,
gages, valves, fittings, masks, and all other compo-
nents of the oxygen system free of oil, grease, gaso-
line, and all other readily combustible substances.
The utmost care shall be exercised in servicing, han-
dling, and inspecting the oxygen system.
Do not allow foreign matter to enter
(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 regula-
b. Replenishing Oxygen System.
Remove oxygen access door on outside
of aircraft (fig. 2- 19).
Remove protective cap on oxygen sys-
tem filler valve.
3. Attach oxygen hose from oxygen ser-
vicing unit to filler valve.
If the oxygen system pressure is below
200 PSI, do not attempt to service sys-
tem. Make an entry on DA Form
Insure that supply cylinder shutoff
valves on the aircraft are open.
Slowly adjust the valve position so that
pressure increases at a rate not to
exceed 200 PSIG per minute.
Close pressure regulating valve on oxy-
gen servicing unit when pressure gage
on oxygen system indicates the pres-
sure obtained using the Oxygen System
Servicing Pressure Chart (fig. 2-31).