How do you start a Boeing 747 engine?

If you later want to use the autostart functionality, make sure that the Autostart switch is on and set the Fuel Control Switches for all engines to RUN first, then simply pull the Start Selector for the engines you want to start. The plane will start the engines automatically.

How is the APU started?

The APU can be started utilizing only the aircraft battery(s) and, once running, will provide electrical power to aircraft systems as well as bleed air for air conditioning and for engine start.

When should I start my APU?

Before Takeoff, If the APU is not used during climb, the APU is normally shut down during taxi checks. If the pilots decide to use the APU during climb, it is started during normal engine start. In this case the APU bleed air is used to feed the cabin pressurization.

How does an APU start a jet engine?

Only after passengers are buckled in and their tray tables are upright and secured does the APU begin sending compressed air to the jet’s main gas turbine engines. The compressed air passes through a small turbine on the outside of the engine, causing it to spin.

Can a 747 start the APU in the air?

$\\begingroup$ 747-100/200 aircraft could start the APU in the air but not use it in the air. If started in the air (usually on final approach), electrical power from an engine bus was used. If started when the engines weren’t running, battery or ground power was used. $\\endgroup$ – Terry Jun 20 ’16 at 0:56.

What kind of Apu does a Boeing 787 have?

The Pratt & Whitney APS5000 APU is the industry’s first all-electric APU for large commercial aircraft. This single-shaft, variable-speed gas turbine APU develops 450kVA of electrical power at sea level that starts and operates up to 43,100 feet. The APS5000 APU was designed exclusively for the Boeing 787 Dreamliner.

What kind of air is used to start an APU?

Pnuematic air (fancy name for compressed air) from the APU’s Load Compressor is used to start the engines via the engines’ pnuematic starters (air driven motors).

How long does it take for an APU to start?

In that case, the APU will be started by the air-driven motor rather than the electric motor, with pressurized air supplied by the still-running main engines. EDIT to answer question in comment: Depending on size, the APU will take something between 30seconds and 2 minutes to start.