Document 9913
Rev. V
Instruction Manual
Style 3
Runway Centerline Light L-850A & Touchdown Zone Light L-850B
9
9.9
External Support Ring Gasket Replacement
Everytime a light fixture with the optional external support ring gasket is removed from the support ring, the
gasket on the inner cover should be examined and replaced if necessary. Any gasket that is stretched, torn, has
a permanent set or some other defect, will allow water to enter the light base. Remove the old gasket from the
inner cover by carefully scraping. Take care not to damage the inner cover. Form a thin bead of high
temperature silicone adhesive, such as GE RTV 106, on the inner cover sealing surface. Position the new
gasket (P/N 21180) on the inner cover in the same location as the old gasket. Allow the silicone to cure for 4 to
12 hours. Cure times depend on the amount of silicone use, ambient temperature, and relative humidity. Apply
a thin coat of Dow Corning FS 1292 grease over the entire outside surface of the gasket before placing in the
support ring. Secure per section 8.2
WARNING:
WARNING
Do not exceed 20 psi when pressure testing the fixture. Serious injury and/or
permanent damage to the fixture may result if a higher air pressure is used. Once
the pressure test is complete be sure to relieve the air pressure.
9.10 Cleanliness and Workmanship
Service life depends upon the entire assembly being waterproof. All surfaces must be clean, dry and free of all
foreign matter if the light fixture is to operate for extended periods without requiring maintenance.
9.11 Maintenance Program
In order to insure maximum light fixture life, the installed units should be subject to a maintenance program in
accordance with the following:
A daily operation check should be made of the lighting fixture. The lights should be energized and visually
inspected. If any lamps are out, the location of the fixture should be recorded and the lamps replaced at a time
when the circuit is de-energized. (See Section 9.2 )
