When does the APU shut down in a plane?
When does the APU shut down in a plane?
The APU may run without cockpit crew supervision when the aircraft is on the ground. In case of fire ‐ APU fire warnings operate in the cockpit. ‐ A horn in the nose gear bay sounds. ‐ The AVAIL light goes out. ‐ The FAULT light in the MASTER SW lights up. ‐ The APU shuts down. ‐ The APU fire extinguisher discharges.
What does the Blue on switch on an APU do?
‐ The APU fire extinguisher discharges. This switch controls the electrical power supply for the operation of the APU and its protective features. It also controls the starting and shutdown sequences. ON : The blue ON light comes on. Electric power goes to the APU system; the ECB performs a power-up test.
When to turn off the APU on an ACFT?
Adv: Displayed if the ECB detects a low APU oil lvl when the acft is on the gnd and the APU is not running. APU AVAIL appears in green when APU N is above N > 99.5 % or 2 s after N is above 95 %. APU starts or shutdowns are permitted during refuel/defuel procedures. If it is necessary to operate a.
How does an APU work in a car?
If pressure is not available (batteries only or pumps off) the APU FUEL PUMP starts automatically. The ECB controls the fuel flow. The APU has an integral independent lubrication system (for lubrication and cooling). The IGVs control bleed air flow, and a fuel-pressure-powered actuator positions the IGVs.
What causes the APU on a 737 to shut down?
The APU will auto-shutdown for the following reasons: Fire; Low oil pressure; High oil temperature / Fault; Overspeed; The OVERSPEED light may illuminate for any of the following reasons: An aborted start (overspeed signal given to shutdown). – Further restart may be attempted. A real overspeed while running. – Do not restart.
Where is line of sight oil filler on Apu?
The APU cowling showing the lines to the discharge discs and the cooling air overboard exhaust. The small access panel above the cowling is the line of sight oil filler, this is sometime located ventrally in front of the cowling for easy access from the ground.
What is the fuel pressure of a Garrett Apu?
The Garrett and Sundstrand APUs are only rated to 55KVA. The fuel source is normally from the No 1 main tank and it is recommended that at least one pump in the supplying tank be on during the start sequence (and whenever operating) to provide positive fuel pressure and preserve the service life of the APU fuel control unit.
How does an APU fire extinguisher bottle work?
The APU fire extinguisher bottle indicators comprise of one yellow disc to show if the squib has been fired and one red disc to show if the bottle has over temperatured (130C) or over pressured (1800psi).
