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 MIL-HDBK-1023/4
(3) Check filters, when used, for cracking or misalignment and replace or adjust as
required.
(4) Clean all reflectors, globes, filters, and covers as required. When hood or
shield is used, check adjustment.
(5) When closing the light, confirm that the gaskets are positioned for proper
sealing. Tighten all screws, clamps, and fasteners.
(6) Check frangible couplings for cracks.
(7) Check the horizontal and vertical alignment of the lights for proper adjustment.
(8) When all outages have been corrected, energize the circuit and make a visual
check of the repaired units for proper operation. Record the repairs.
b) Spare Unit Replacement. In some instances, it may be more convenient to fix
defective edge lights by replacing the entire light with a spare unit. This will minimize the
runway downtime and allow troubleshooting and refurbishment of the defective light at a more
convenient location. Spare unit replacement is very convenient for repairing lights struck by
lightning or vehicles.
c) Film Disc Cutouts. Some of the older installations use fused film disc cutouts to
bypass failed lamps. Some circuits that have more than one light on the secondary side of each
isolating transformer use them to bypass a burned-out lamp and keep the other lamps on the
transformer operating. When replacing lamps in these lights, the film disc cutout must also be
replaced. Use the disc cutout of proper type and size. The film disc is located within the light
enclosure and is installed between spring-loaded terminals.
d). Inspection. When replacing the lamp, inspect the light thoroughly for other
damage. Check for water in bases or lights, cracked and chipped glassware, defective or
incorrectly positioned gaskets, loose connections, cracked or deteriorated insulation, and
misalignment of lights or shields.
e) Cleaning. When changing lamps, clean the light fixture inside and outside, as
required. Light surfaces must be kept clean to transmit light satisfactorily. In establishing a
cleaning program, first consider the sources of the dirt problem. Many airfield lights are located
at or near ground level and are subject to blowing dirt or dust, rain spattering, jet exhaust residue,
bird droppings, corrosion, and heat and static attraction of dirt. In some cases, submersion or
exposure to water may be a problem. Cleaning procedures will vary depending on the cause of
the problem and its effect on the system. Cleaning problems may often be reduced by preventive
measures.
(1) When bird droppings are a problem, installation of a thin, stiff vertical wire on
top of the light may be helpful in preventing birds from perching.
(2) When spattering is a problem, paving or sodding of the area may help.
(3) When lights tend to fill with water, improved gaskets and better sealing
procedures may be required.
f) Cleaning Schedule. The cleaning schedule will vary at each location depending on
such factors as environment, geographical location, and the types of lighting units. Each light
hould be cleaned thoroughly at least once a year.
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