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 MIL-HDBK-1023/4
d) Bimonthly checks
(1) Bolt Torque. The torque of the bolts attaching the light to its base should be
checked. The impact of aircraft wheels can loosen mounting bolts and cause misalignment or
fixture damage; this is particularly troublesome in the touchdown zone.
e) Semiannual checks
(1) Remove the light, and clean and service as described in par. 5.5.2. If an
intensity check reveals that the light has sufficient brightness, then it need not be disassembled;
however, the light should be removed from its base so that the base and cable connections may
be examined.
(2) Check the base for the presence of water. Any water found should be removed
and the base should be sealed to prevent its reentry. This check should be conducted more
frequently in winter months since freezing may cause damage to the fixture by shearing the
fixture hold-down bolts or rupturing the base. Having a dry light base is the exception rather
than the rule. Water in light bases is very common, resulting from the miles of conduit that leak
and slowly fill the system with water. To avoid water freezing in bases, place 2 inches thick by 8
inches diameter ETHA-foam (also known as closed cell foam) disks in the bases to displace the
water. This prevents ice damage to the base, fixture and transformer by allowing any remaining
water to crush the ETHA-foam disks.
(3) To maintain maximum system performance and minimize unscheduled outages,
group replacement of lamps for in pavement fixtures should be considered. The fixtures should
be relamped when the time on the high-intensity step equals 80-100 percent of the nominal lamp
life.
f) Unscheduled maintenance
(1) Snow should be removed from around the lighting fixtures as soon as possible
after a snowfall to prevent obscuring the light fixtures. Extra care should be exercised to prevent
striking the lighting fixtures with snowplow blades. After snow removal operations, inspect all
lighting fixtures and replace any damaged light assemblies. Whenever snowplows must traverse
over in-pavement light fixtures, they should be traveling at less than 5 miles per hour or have the
blades lifted clear of the fixture. Rubber and plastic snowplow blades that are especially suited
to plowing wet or slushy snow are available; rotary brooms are also recommended. If snow
removal is a frequent winter job, high-strength steel light fixtures may be specified to better
withstand the impact of snow plowing.
(2) Check wireways in saw kerfs. If wires are floating out, reinstall using wedges
for anchoring wires. Space wedges 2 feet (60 cm) on center. Seal wireways using P-606 sealer.
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