g) Cleaning Procedures. Glassware, reflectors, lenses, filters, lamps, and all optical
surfaces should be washed. Washing may increase the light output by as much as 15 percent
more than wiping with a dry cloth.
(1) Do not use strong alkaline or acid agents for cleaning.
(2) Do not use solutions that leave a film on the surface.
(3) Remove the unit when possible and clean in the shop.
(4) For reflectors or other optical surfaces that cannot be removed for cleaning, use
alcohol or other cleaning agents that do not require rinsing or leave a residue.
(5) Where washing is not practical, glassware (but not reflectors) may be cleaned
with fine steel wool and wiped with a dry clean cloth.
(1) Water and Condensation. Water is the most common cause of problems in
airfield lighting fixtures. In bases, water may cause grounding of the lamp or circuit; in the
optical assembly it may submerge optical components, cause corrosion and deterioration, form
condensation on optical surfaces, and accelerate the accumulation of dirt on optical surfaces.
Preventing water from entering bases is very difficult. The alternate heating and cooling of the
lights can create a strong "breathing" effect, especially when the base is located in saturated
ground. The water may also enter through conduits, along the conductor or the cable, through
gaskets and seals, through damaged glassware, or through fine holes in the walls of the bases.
(2) Protection From and Removal of Water. The immediate problem of water in
lights and bases is removal and prevention of reentry. In the light bases, the accumulated water
can usually be drained or bailed out. Drain holes should be drilled, or cleaned out if already
present. Gaskets, seals, and clamps that may admit water should be checked. Chipped, cracked,
or broken glassware should be replaced. If water cannot be eliminated from light bases, ensure
all electrical connections and insulation are watertight and above the waterline.
(a) Operation of lights on brightness step B4 or B5 should dry up any
condensation. Also, maintaining a low brightness setting, rather than turning the lights off,
should prevent more condensation from forming. Cost and energy conservation would be factors
in determining the efficacy of this method.
(b) A hand or power driven pump is very useful for removing water in light
bases. Water can also be removed by dipping and mopping.
(c) Light bases can be modified for easy pumping by installing an air valve in
the cover and soldering a tube to the cover that extends to near the bottom of the base. Applying
compressed air to the air valve will force the water up the tube and out of the base.
(d) Cable may need to be replaced if water travels along and enters around the
(e) Before installing the cover plate, blow out cover bolt holes to make certain
that fastening bolts are not anchored in sand or debris that prevents the cover from being torqued
sufficiently on the gasket. Make sure the bolt holes have serviceable threads and that the gasket
is in good condition and properly placed.