plug is called a safety plug. The relief valve relieves the excess pressure in the container instead of completely emptying the container. Some larger aircraft use more than one fire extinguishing agent container to direct the agent to several points within an area. With cockpit switches set at various positions, the agent can be released through specific discharge outlets; and if the fire persists, the switch positions can be changed to release agent from a second container to different discharge outlets within the same area. The fire extinguishing system of the P-3 air- craft is an example of this type of system. The containers used in the P-3 system are also equipped with two-valve (bonnet) assemblies for discharging the container; however, only one assembly is fired at any one time to discharge the container. This dual arrangement provides a secondary means of discharging a cylinder in the event a cartridge fails for any reason to fire and discharge the container. MAINTENANCE Maintenance of the CF3Br fire extinguishing system at the organizational level of maintenance consists of replacement of faulty components and discharged or below pressure containers, maintenance of associated plumbing, and per- forming operational checks. Containers should be replaced when the pressure falls below that indicated on the container or in the applicable MIM. Each container has a pressure indicating gage. Suspected leakage in system plumbing requires disconnection of the container(s) and pressure leakage testing of all lines by using nitrogen pressure and a leakage tester. The leakage tester measures pressure drop over a specified period of time, as outlined in the MIM. The operational checkout of the fire ex- tinguishing system, primarily a checkout of electrical circuitry such as wiring continuity checks, proper switch operation, etc., is per- formed by personnel of the AE rating. THERMAL RADIATION PROTECTION UTILITY SYSTEMS Learning Objective: Recognize the purpose of the thermal radiation protection system. Naval aircraft used for special weapons delivery have means of protecting the pilot and crew members from the effects of heat and light that such weapons emit. Several of the Navy attack aircraft are equipped with a thermal radiation protection system and flak protection curtains. The A-6, for example, can be equipped with radiation enclosures for the windshield and canopy. These enclosures shield off the see- through portions of the cockpit, which gives the flight crew protection from the extreme heat and light created by a special weapons delivery. The radiation shields consist of fixed and sliding fiber glass panels mounted on each side of the canopy. The sliding panels are equipped with rollers and suspended on a system of tracks between the fixed side panels and the canopy center overhead spline structure. The sliding panels for each side of the canopy move independently of each other and are manually positioned by the pilot or bombar- dier/navigator. The shield is closed by pulling the forward sliding panel towards the canopy forward arch. The forward panel is equipped with a lip, which engages on the lip of the aft sliding panel, drawing it forward at the same time. The sliding panels will automatically lock in one of three positions; open, closed, or half open, as desired. A latch handle on each forward sliding panel releases the detent pins, unlocking the panels. If the panels are closed and ejection becomes necessary, it may be initiated through the closed shields. The windshield curtain is a fiber glass cloth assembly with an aluminized coating. It is fastened between the instrument panel glare shield and the windshield bow structure to close off the entire windshield area. Springs pull the windshield curtain down flat on the glare shield for stowage when the curtain is unzipped. Flak curtains, similar to the canopy curtain, are mounted beside the pilot and bombardier/ navigator foot area, cockpit side area, and along the lower portion of the canopy. They provide a limited measure of protection from flak and small arms fire when making low-level attacks on enemy positions. The canopy-mounted curtain is a sandwich- type pad constructed on vinyl-coated glass cloth with a nylon center. The cockpit area side panels are basically of the same construction with the outboard vinyl coating deleted. The foot guard panel is constructed of a metal plate with a nylon curtain riveted to the outboard side. Installation 1-34