2. Pull the filter down and out of the
retaining springs on the evaporator
coil.
3.
Fold the new filter to insert it through
the access doors. The filter; must be
carefully inserted between the coil
assembly and the refrigerant plumbing
under the retaining springs.
4. Install the access doors.
b. Aft Evaporator Filter Replacement.
1.
Remove the carpet and floor panel
behind the rear spar, and remove the
cover of the evaporator plenum.
2.
Remove the old filter from behind the
retaining springs on the evaporator
coil.
3. Insert the new filter between the
retainer springs and the evaporator
coil.
4. Install the plenum cover, floor panel,
and carpet.
c. Anti-icing, Deicing and Defrosting Protec-
tion. The aircraft is protected in subfreezing weather
by spraying the surfaces (to be covered with protec-
tive covers) with defrosting fluid. Spraying defrost-
ing fluid on aircraft surfaces before installing protec-
tive covers will permit protective covers to be
removed with a minimum of sticking. To prevent
freezing rain and snow from blowing under protec-
tive covers and diluting the fluid, insure that protec-
tive covers are fitted tightly. As a deicing measure,
keep exposed aircraft surface wet with fluid for pro-
tection against frost.
TM 55-1510-221-10
NOTE
Do not apply anti-icing, deicing and
defrosting fluid to exposed aircraft sur-
faces if snow is expected. Melting snow
will dilute the defrosting fluid and form a
slush mixture which will freeze in place
and become difficult to remove.
2-100. ANTI-ICING, DEICING AND DEFROSTING
TREATMENT.
Use undiluted anti-icing, deicing, and defrosting
fluid (MIL-A-8243) to treat aircraft surfaces for pro-
tection against freezing rain and frost. Spray aircraft
surface sufficiently to wet area, but without exces-
sive drainage. A fine spray is recommended to pre-
vent waste. Use diluted, hot fluid to remove ice
accumulations.
1.
Remove frost or ice accumulations from air-
craft surfaces by spraying with diluted anti-
icing, deicing, and defrosting fluid mixed in
accordance with table 2-12.
2. Spray diluted, hot fluid in a solid stream
(not over 15 gallons per minute). Thor-
oughly saturate aircraft surface and remove
loose ice. Keep a sufficient quantity of
diluted, hot fluid on aircraft surface coated
with ice to prevent liquid layer from freez-
ing. Diluted, hot fluid should be sprayed at
a high pressure, but not exceeding 300 PSI.
3.
When facilities for heating are not available
and it is deemed necessary to remove ice
accumulations from aircraft surfaces, undi-
luted defrosting fluid may be used. Spray
undiluted defrosting fluid at 15 minute
Table 2- 12. Recommended Fluid Dilution Chart
AMBIENT
PERCENT
PERCENT WATER
FREEZING POINT
TEMPERATURE
DEFROSTING
BY
OF MIXTURE (F)
(ºF)
FLUID BY VOLUME
VOLUME
(APPROXIMATE)
30º and above
20
80
10º
20º
30
70
0º
10º
40
60
-15º
0º
45
55
-25º
-10º
50
50
-35º
-20º
55
45
-45º
-30º
60
40
-55º
NOTES:
1. Use anti-icing and deicing fluid (MIL-A-8243) or commercial fluids.
2. Heat Mixture to a temperature of 82º to 93°C (180º to 200°F).
2-83