 Ground crew disconnecting an air start hose from a Boeing B-52 Stratofortress |
Many variations of aircraft engine starting have been used since the Wright brothers made their first powered flight in 1903. The methods used have been designed for weight saving, simplicity of operation and reliability. Early piston engines were started by hand. Geared hand starting, electrical and cartridge-operated systems for larger engines were developed between the First and Second World Wars.
Gas turbine aircraft engines such as turbojets, turboshafts and turbofans often use air/pneumatic starting, with the use of bleed air from built-in auxiliary power units (APUs) or external air compressors now seen as a common starting method. Often only one engine needs be started using the APU (or remote compressor). After the first engine is started using APU bleed air, cross-bleed air from the running engine can be used to start the remaining engine(s).