107 - ENVIRONMENTAL FUNDAMENTALS

.1 Discuss the purpose of the aircraft cabin pressurization and air conditioning.

The air-conditioning and pressurization system provides crew environment control and electronic equipment cooling both in flight and on the ground. Oxygen is required above 10,000 feet of altitude in an unpressurized cabin. The P-3 pressurization system allows the crew to move about freely in the airplane at altitudes above 10,000 because the system keeps the cabin pressurized to the equivalent of an altitude less than 10,000 feet. The pressure controller is in "Hg" or inches of mercury. The pressurization system can tolerate a max differential of 13.3 Hg between the outside air pressure and the cabin air pressure.

.2 Discuss the purpose of aircraft oxygen systems.

The oxygen system is designed to supply an active flight crew of three members for approximately 3.5 hours at an altitude of 25,000 feet. Seven portable bottles are stored at tactical stations and the rear of the aircraft. With the user experiencing little or no exertion, approximately 22 minutes of oxygen is available.

While the cockpit oxygen system is primarily for emergency use, non-emergency situations may exist which result in the aircraft having a cabin altitude of 10,000 or higher. In such situations, the flight deck crew (pilot, copilot and flight engineer) are required to be on oxygen. The portable oxygen bottles for the tactical crew are strictly for emergency situations.