b) Bimonthly checks
(1) Check cleanliness of sign faces, and clean with a non-abrasive glass cleaner if
(2) Check for any mechanical damage or misaligned parts, such as cracked faces or
bent frangible couplings.
(3) Check operation of interlocks when the signs are connected to other lighting
(4) Check for vegetation around signs which would obstruct the view of the sign,
check condition of footings and foundations, and repair if necessary.
c) Semiannual checks
(1) Remove power from the sign and check internally for cleanliness and moisture.
(2) Check electrical connections.
(3) Check drain holes and clean as necessary.
(4) Restore power to sign and check for proper lamp current.
(5) Check for loose sign mounts at the frangible supports, and check that the can
mounting flange is secure.
d) Annual checks
(1) Check insulation resistance of power cables.
(2) Check resistance of the grounding system.
(3) Check for the need of paint.
Energizing and Brightness Control. The control systems for airfields and heliports will
consist of properly rated regulators having a constant current output to the lights, and a control
system to energize, de-energize and control the brightness (intensity) of the lighting systems.
Operational safety requires that the air traffic controllers be able to energize, de-energize, change
brightness, and switch the various aviation lighting circuits instantly as required by the dictates
of the operation of the moment. It is essential that the controls in the tower be maintained at all