The SA227 family of aircraft are low wing monoplanes, built by Fairchild These aircraft include the Merlin IIC, Merlin IVC, and the Metro III. These three aircraft are powered by two turboprop engines equipped with constant speed, full feathering, four blade, reversible propellers made by Dowty-Rotol, or McCauley propellers.The cabin is pressurized, heated and cooled by bleed air which is ducted through valves, heat exchangers, and refrigeration unit. The air conditioning system supplies cold, hot, and fresh air to both the cockpit and the cabin. These aircraft have two independent systems; both are capable of complete air conditioning. Bleed air is supplied by each engine to drive cooling turbines that provide the cool air. The bleed air is routed to the center section of the aircraft and mixed with cool air to provide hot air. Fresh air is supplied by a blower and motor assembly located in the nose baggage compartment. Either bleed air system may be operated on the ground when the respective engine is operating. Ducts within the fuselage distribute the airflow to the passengers and the crew. An automatic temperature control system senses and regulates the temperature within the aircraft.PRESSURIZATIONThe cabin is pressurized to increase passenger comfort. The pressurization system automatically compensates for increasing aircraft altitude by maintaining cabin altitude as near to field elevation as possible. The cabin altitude will remain at sea level until airplane altitude reaches approximately 17,000 feet. The pressurization system also provides for the emergency dumping of cabin pressurization, automatic over pressurization relief, and negative relief.The pressurization system, within the limits available, maintain the cabin of the aircraft at any selected pressure altitude equal to or lower than the aircraft altitude. In normal operation, the system controls the increase or decrease in cabin pressure and the rate ...
