DOCUMENT 2421
REV. L
Instruction Manual
ICAO Approach Fixture
11
Remove the old o-ring from the groove in the optical housing. Carefully clean the o-ring
groove and flange mating surface on the inner cover. Take care not to damage the mating
surface. Clean the new o-ring (P/N 21385) with denatured alcohol. Position the new o-ring in
the center of the groove and press it into place. Torque the inner cover screws to 30 in-lbs.
Perform a pressure test as described in paragraph 8.6. Secure the light fixture to the base per
section 7.
8.4
Lens Replacement
If an outer lens is broken, leaks, or is badly pitted or scarred, it must be replaced. It is highly
recommended that this task be performed in a clean shop environment. Lens Replacement Kit
P/N 21480-X contains all necessary parts to change a lens.
Remove and secure power to the
fixture.
Turn the fixture upside down and remove the six screws holding the inner cover to the
light housing. Remove the lens retaining bracket screws from the light housing. Remove the lens-
retaining bracket and discard the lens-retaining gasket. Firmly push the lens/boot assembly from
the outside of the light housing; discard the old lens and boot. Thoroughly clean the lens opening
with isopropyl alcohol and let dry. Inspect the lens opening for scratches or pits; a damaged lens-
opening surface will not seal properly. Place a new lens boot (P/N 21277) over the replacement
lens (P/N 21276-X). Apply a thin coat of Dow Corning FS 1292 grease over the entire outside
surface of the lens boot. Align the lens/boot assembly in the lens opening and press it into
place. Verify that the lens boot is not pinched in the lens opening. Using a new lens-retaining
gasket (P/N 21479), fasten the lens-retaining bracket (P/N 21477) to the light housing. Torque
the mounting screws to 55-60 in-lbs. Inspect/replace the optical housing’s o-ring per
paragraph 8.3. Assemble the inner cover onto the light housing. The screw-hole patterns in
the inner cover and light housing are offset to insure proper alignment. Torque the mounting
screws to 30 in-lbs. Perform a pressure test per paragraph 8.6. Clean the mounting flange
area of the base. Secure the light fixture to the base per section 7.
NOTE
: Lighting Fixtures built/installed before June 2009 will require the 21276-X Lens
Replacement Kit. The 21276-X Kit contains the P/N: 21101 lens-retaining gasket and the P/N:
21100 lens-retaining bracket. Lighting Fixtures built/installed after June 2009 require the
21480-X as listed above.
NOTICE
NOTICE:
A bad o-ring seal is the most common cause of inset fixture leaks.
A new o-ring must be installed every time the
Optical Assembly is opened
NOTICE
NOTICE:
The groove is designed to be wider than the o-ring. This provides room for the
displacement of the o-ring when compressed between the housing and mating surface.
Properly tightened screws are important in obtaining a complete seal.
