Document 9913
Rev. V
Instruction Manual
Style 3
Runway Centerline Light L-850A & Touchdown Zone Light L-850B
6
9.2
Relamping
WARNING:
WARNING
Light assembly parts are hot when lamp is energized and remain hot for a short time
after lamp/fixture is turned off.
Remove and secure power to the fixture.
Separate the Optical Assembly from the outer ring by removing
the two bolts. There are two pry slots in the optical housing to help separate the Optical Assembly from the
support ring. Turn the Optical Assembly upside down and remove the four screws holding the inner cover to the
light housing. Disconnect the lamp leads from the feed-thru terminals. Remove the Lamp Assembly by gently
pulling up on the lamp reflector base. Inspect the feed-thru terminal for signs of corrosion. Replace feed-thru
assemblies per paragraph 9.7. Clean the inside surfaces of the lens(es) with denatured alcohol. Inspect the lamp
holder bracket(s) for loose hardware; tighten the mounting screws to 30 in-lbs.
CAUTION:
CAUTION
Touching the quartz bulb with bare fingers may seriously shorten lamp life. If the
bulb has been touched, wipe it clean with a piece of lens cleaning tissue or similar
material moistened with denatured alcohol.
Install the new lamp by reversing the procedure above. Make certain the rim of the reflector is flush against the
bracket and seated against the two pins at the bottom of the bracket. Connect the lamp leads to the feed-thru
terminals. Inspect/ replace the inner cover o-ring per paragraph 9.5 (see section 9.3). 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. Tighten the mounting screws to 30 in-lbs. Clean the mounting flange area of the support ring. Place
the Optical Assembly into the support ring. Secure per section 8.2.
9.3
Seal Revision
Fixtures manufactured prior to May 2003 use a high temperature silicone gasket (P/N 21124), bonded to the
inner cover (P/N 21118-X), to provide a watertight seal between the inner cover and the optical housing (P/N
21105-X). Paragraph 9.4, Gasket Replacement, details the instructions on how to replace the 21124 gasket.
Starting in May 2003, a polyurethane o-ring (P/N 10035-62) was used to provide the watertight seal between
the optical housing and inner cover. The o-ring is not bonded to either the optical housing or inner cover. This
revision requires an o-ring groove to be machined into the 21105-X optical housing, and all replacement optical
housings will be supplied with the o-ring groove. Paragraph 9.5, O-Ring Replacement, details the instructions
on how to replace the 10035-62 o-ring. To retrofit an older style inner cover to the o-ring groove style optical
housing, cut the 21124 gasket flush with the mounting surface on the inner cover with a razor blade.
