AIR SUPPLY OF AIRCRAFT

AIR SUPPLY OF  AIRCRAFT

The source of air supply and arrangement of essential components depends on the type of aircraft and air conditioning system employed, but in general one of the methods described below may be adopted.

Engine bleed air

This method is adopted in certain type of turbo jet aircraft in which hot air readily available from main engine compressor is tapped off and supplied to the cabin. Before the air enters the cabin it is passed through appropriate control valves and temperature. Control system to reduce its pressure and temperature.

Auxiliary power units (A.P.U)

Auxiliary power units are employed in many types of transport aircraft. Their purpose being to provide a source of electrical power and pressurized air.

Compressor or Blowers

This method is utilized in some type of turbo jet, turbo propeller and piston engine aircraft, the compressor or blowers being driven by the engines via accessory drive gear boxes or bleed air. Air is drawn in through a ram air intake located in a wing leading edge or an engine nacelle fairing. A filter unit may be provided to protect the blower rotors from foreign matter and to ensure a clean air supply. In order to reduce level of noise, silencers are incorporated in the main supply ducting.

Ground Cart

Mobile air conditioning and heating units are grounded support equipment designed to supply conditioned air to heat or cool aircraft. Such units are capable of delivering a large airflow against static pressure at the end of a flexible duct or into aircraft. Reciprocating engine internal super charge provides the simplest means of cabin pressurization. This is accomplished by ducting air from supercharge to the pistons. Air for cabin pressurization can also be ducted from a turbocharger used with a reciprocating engine.