damage to filter element may result
Clean filter element by passing
air or drycleaning solvent, Federal Specification P-D-
680, through it in reverse direction after removal from
filter bowl. When these methods fall to clean element, it
should be replaced.
Use dry, filtered air to blow out
any dust that may have accumulated in ignition unit.
Wipe out any oil with a dry, clean cloth.
Secure all heater drain plugs
with lockwire to prevent loss of plugs and resultant
flame discharge. Prepare drain plugs for safetying as
1 Drill hex head bolts across a
corner with a No 52 drill.
2 Drill countersunk hex head
plugs completely through and countersink drilled head
90 degrees by 3/32-inch diameter on both sides of plug.
3 Secure drain plugs to any
suitable adjacent point using steel wire, ASTM A580
Combustion heaters require an
installation of the heater or
The test will be performed at a
heat duct opening with the heater
full on. An indication of 50 parts
per million (ppm/0.005 percent)
or greater requires corrective
Detector Kit, Carbon Monoxide,
Colonmetric, NSN 6665-00-618-
Carbon Monoxide, NSN 666500-
(3) Pressurized system. A pressurized
system maintains the cabin pressure altitude at a
constant value. Pressurized air is pumped into the
sealed fuselage from cabin superchargers. The
superchargers deliver a constant volume of air at all
altitudes up to a designed maximum Air is released from
the fuselage by a device called an outflow valve The
outflow valve, by regulating the air exit, controls the
pressure within the aircraft. Maintain in accordance with
the applicable maintenance manual.
Repair of Flexible Air Ducts. Cracked
flexible air ducts, constructed of fiberglass material, will
be inspected and repaired on the aircraft when
economically feasible. Silicone damage shall not
exceed 3.0 inches in length and 1.5 inches wide with
limits of two repairs per foot of duct or three percent of
total surface area. Reworked areas will be sanded or
buffed to fair in with adjoining material. Repair flexible
air ducts using the following procedures.
Clean damaged area with Toluene
TT-T-548. Allow cleaned area to air-dry a minimum of
Apply to a brush coat of Room
Temperature Vulcanizing (RTV), M IL-A-46146, on
damaged area with a 0.5 inch overlap from edge of
Smooth and cure by air drying a
minimum of two hours at room temperature or until it is
dry to the touch.
fiberglass cloth, the limitation is no
more than 10 percent of surface area
after completion of repair.
Clean the complete circumference of
the air duct in the vicinity of damaged area with
Toluene. Allow cleaned area to air-dry a minimum of 30
Use brush to apply a thin coat of
adhesive to the complete circumference of the duct in
the damaged area and smooth out adhesive.
Cut a piece of fiberglass cloth, MIL-C-
9084, of sufficient size to cover the complete
circumference of the duct, with a one-inch overlap of the
Wrap fiberglass cloth around duct and
Allow to air-dry a minimum of two
hours or until dry to touch before handling.