(f) Use corrosion-resistant cover bolts, and keep the bolts well greased to
facilitate their removal and lessen the possibility of moisture entry around their threads.
(g) The base flange bolts should be drawn down in opposite pairs until all are
tightened to the recommended torque. Avoid excessive torque.
i) Strikes and Blast Damage. Light units damaged by strikes from aircraft or vehicles,
or by propeller or jet blasts, should be repaired or replaced immediately. The fact that these
lights have been hit indicates a critical need for them. Areas where this damage recurs should be
checked frequently. A careful check should be made following damage of this type because the
attaching cable may also be damaged.
(1) Repair and Replacement. When possible, the entire damaged unit should be
replaced. Simple repairs usually consist of the following:
(a) Remove the broken frangible coupling from the base cover.
(b) Connect the new light to the secondary connector.
(c) Install a new light on a new frangible coupling.
(d) Check for correct alignment; align as required.
j) Frangible Coupling Replacement. Frangible couplings are used primarily to reduce
damage to aircraft in case of a strike. They provide an intentional weak point and aid in
preventing damage to other components. An open-end wrench, pipe wrench, cold chisel, and
punch and hammer are usually sufficient to remove and install frangible couplings. Some styles
require replacement of the entire column when the frangible point breaks.
(1) Remove damaged coupling.
(2) Use Locktite Antisieze Thread Compound #767 on new coupling threads.
(3) Tighten by hand and use wrench to snug down.
k) Scheduled Painting. Scheduled painting is usually accomplished annually, but
touch-up is a constant requirement.
(1) Clean and remove rust, corrosion, dirt, and loose paint.
(2) Apply suitable primer coat.
(3) Apply finish.
(4) After repainting light fixtures, restore assigned identification by stenciling or
painting number in a conspicuous location in large numerals.
Constant Current Regulators. Constant current regulators come in two basic types, air
cooled and liquid filled. The two basic types of regulators can be further classified as either
magnetic or electronic. Magnetic types typically utilize either a resonant circuit or a saturated
reactor principal. In a resonant network circuit the current output is proportional to the input
voltage and is independent of the impedance of the load. It is recommended that manufacturer
literature on the operations, theory of operation, and recommended maintenance procedures for
the particular regulator being used be obtained.