hot wheel assembly. Upon ignition, misting fluid will accelerate a fire, resulting in rapid fire growth and excessive damage to the aircraft if it is not extinguished rapidly. WARNING A broken hydraulic line that causes misting of petroleum-based fluids around an overheated brake assembly can cause a potentially dangerous and destructive fire. Intermittent application of water fog should be used to extinguish this type of wheel assembly fire. Rapid cooling of a hot inflated aircraft tire/wheel  assembly  presents  an  explosion hazard. Therefore, fire-fighting personnel must exercise good judgment and care to prevent injuries. The vaporized products of hydraulic fluid decomposition will cause severe irritation to the eyes and respiratory tract. The following safety information pertains to all aspects of wheel assembly fire-fighting operations: ·  Rapid cooling may cause an explosive failure of a wheel assembly. ·  When water fog is used on a wheel assembly fire, an intermittent application of short bursts (5 to 10 seconds) every 30 seconds should be used. ·  The effectiveness of Halon 1211 may be severely  reduced  under  extremely  windy conditions if the Halon cannot be maintained on the fire source. ·  You must take protective measures to prevent hydraulic fluid from coming into contact with the eyes. Seek medical attention immediately should the fluid come in contact with the eyes. ·  Positive-pressure, self-contained breathing apparatus must be worn in fighting fires associated with hydraulic systems. ·  Although Halon 1211 may extinguish hydraulic fluid fires, reignition may occur because this agent lacks an adequate cooling effect. ·  In a fire, F-14, S-3, and C-5 aircraft with beryllium brakes may produce irritating or poisonous gases. These gases are toxic, and they are respiratory and eye irritants. ·  Because heat is transferred from the brake to the wheel, agent application should be concentrated on the brake area. The primary objective is to prevent the fire from spreading upward into wheel wells, wing, and fuselage areas. Q12-16. Where should you direct the fire-fighting agent for an internal engine fire? Q12-17. What is the primary agent used to combat class C electrical fires? Q12-18. What is the greatest hazard associated with overheated aircraft wheels and tires? Q12-19. In what direction should you approach an aircraft with overheated brakes or a wheel fire? Q12-20. What are the four materials that usually contribute to wheel assembly fires? SUMMARY In this chapter, you have learned about aircraft crash, rescue, and fire-fighting techniques and procedures.  Fire chemistry, fire-fighting agents, and equipment used in dealing with naval aircraft were also covered. 12-21