helicopters. The field includes two M-21 aircraft recovery systems. two FLOLS, and field lighting and communications systems. An EAF may readily be converted to a strategic expeditionary landing field (SELF).

The SELF is a portable airfield that provides a surfaced runway 8,000 feet long and 96 feet wide, as shown in figure 6-30, view E. The SELF is a pre- positioned war reserve (PWR) setup. The airfield provides turnoff, maintenance, and parking areas to accommodate up to six squadrons of light-to-medium fighter/attack aircraft, a detachment of tanker aircraft, and various transient logistic support aircraft. The SELF configuration includes two M-21 aircraft recovery systems as well as two FLOLS and field lighting and communications systems.

AIRFIELD LIGHTING VAULT

The beginning of the airfield lighting system is the airfield lighting vault. The primary power feeder enters the vault and supplies power to all of the major components. These components, in turn, control and operate the airfield lights. The vault houses the high- voltage power cables, the current regulators, the relay cabinets, and the control panels.

The control cables are installed between the vault and the control tower or other control points. The high- voltage cables are connected to the regulators and run out to the lights. The lighting control panels are used to give local/remote control of the system. The same type of remote control panel that is in the vault should also be installed in the control tower.

The airfield lighting vault should be about 3,000 feet from the runway. This distance ensures that no interference will occur with the operation of the airfield, and still. it is not so far away that voltage drops might cause a problem. The lengths of the control circuits between the control tower and the vault are limited by operational characteristics; for example, size of field, obstructions, and so forth. The minimum distance is 350 feet; that is to prevent the equipment in the vault from causing radio interference. If the control cable leads terminate into actuating coils of relays in the pilot relay cabinet, the maximum distance is 7,350 feet.

Safety

The airfield lighting vault should have certain items of safety equipment affixed to a board. This board should be an open display and easily accessible. It should be a minimum of 1/2 inch thick and 4 by 4 feet in width and length. The color should be dark green with white letters and borders.

On this board, some of the safety items you should have are as follows:

1. Operating instructions for the equipment in the vault

2. Resuscitation instructions

3. A phone and a list of emergency phone numbers

4. A first-aid kit

5. A switch stick with a minimum length of 5 feet and a 300-pound pull ability

6. A hemp rope, l/2 inch thick, with a minimum length of 15 feet

7. Insulated fuse pullers (for secondary cartridge fuses)

8. A nonmetallic-encased flashlight marked with luminescent tape to aid in its location in the dark

9. A shorting stick

10. Rubber gloves

For the safety of personnel, the airfield lighting vault must be grounded. That may be accomplished by using two 1/2-inch-diameter, 8-foot-long, copper- plated electrodes, driven into the ground about 8 feet apart and connected in a loop with the vault or ground cable part of the ground grid. This typical connection is shown in figure 6-31.

Power Supply

In many cases, the power supply will not be all high or low voltage. In fact, in many expeditionary airfields, the system may be a combination of high and low voltage. However, if you are assigned to a naval air station, chances are that you may be required to main- tain high-voltage airfield lighting systems. Basically, the systems are identical, but because of safety require- ments, the high-voltage systems will have a few variables. As an example, take the isolation trans- former (IT) in the high-voltage system; it serves to step the voltage down, but its primary purpose is to prevent an opening in the primary series loop when a lamp failure occurs. In a low-voltage system, the transformer is usually a 2: 1 or 1: 1 ratio unit that serves to maintain a closed loop-the same function as the one in the high-voltage system. Even though we will