What happens to an aircraft if the APU fails?

Failure of an APU in air or ground results in cancellation or delay in flight departure, which inhibits flight operations. An aircraft APU that requires maintenance after 7000 flight hours, would require a maintenance cost of nearly $0.4 Million [4].

What external warning is there for an APU fire?

APU fire-detection displays and controls are located on the flight deck. When a fire is detected, the APU fire handle illuminates, the MASTER WARNING lights illuminate, warning and status messages are displayed on EICAS, and the aural warning is activated.

Why does the APU have its own fire detection and extinguishing system?

APU Fire Detection and Extinguishing System Description. The fire detection system warns the flight crew if an APU overheat condition is present. The fire extinguishing system allows the flight crew to discharge a fire bottle into the APU enclosure to extinguish a fire.

What is APU compartment?

APU is an additional engine, used in air-vehicles development, which provides power to start the main engines, runs accessories while the engines are shut down and provides electrical and hydraulic power (depending on the design) before engine start (pre-flight tests, cabin ventilation, etc.).

Can plane fly without APU?

Without an APU an aircraft would depend on GSE only for starting one engine with pressurized ground supplied air. Aircraft are allowed in general to fly without an APU. Exceptions are flights with two-engined aircraft and long routes over water or terrain without an alternate airport – so called ETOPS flights.

Does the APU run during flight?

It’s pilot-proof! Crews normally run the APU before flight for electrical power, air conditioning and engine start. After landing, the APU is started so engines can be shut down as soon as the aircraft arrives at the gate. If the APU is needed during flight, it can be started in about a minute.

What are the two basic types of continuous loop fire detection systems?

Most modern aircraft use a fire detection system called a continuous loop; of which the two main types are electrical and pneumatic.

How does a typical fire bottle work engine & APU?

The fire detection installed on engines and APU are sensitive loops like protected wirings. This operates when it detects the temperature increasing and suffers variation in its material composition and sends an electrical signal to the smoke detector computer which informs the pilots.

Why do plane engines catch fire?

A drop in fuel pressure or a fluctuating fuel pressure reading may suggest a broken fuel line — a common precursor to an engine fire. A rough-running engine might be caused by a cracked cylinder, which can leak oil or hot gas and ignite a blaze.

How do you start an airplane without APU?

The requirements for no-APU is simply a ground start “huffer” cart at your departure airport. Ideally you want one at the destination as well but if not available you can possibly coordinate leaving an engine running during the turn.

Is APU always on?

In most cases, the APU is shut down before takeoff and reignited when the aircraft clears the runway after landing. While most of an APU’s active service life occurs as the aircraft sits on the ground, in some instances the APU is used as an emergency electrical power source while the aircraft is airborne.

How can I tell if my Apu is on fire?

If an APU fire is detected in flight, the APU must be manually shut down, and the agent manually discharged. FIRE WARNING INDICATIONS – An APU fire is indicated by an aural continuous repetitive chime (CRC), the illumination of the APU FIRE switch and MASTER WARN lights, and by an ECAM warning on the E/WD.

Where can I find Apu fire switch 6.3.3?

See APU Fire Switch page 6.3.3. If a fire is detected on the ground, a warning horn in the nose wheel well sounds, and the APU FIRE light illuminates on the external service interphone panel, see APU Fire Light page 2.3.4. The light extinguishes and the horn silences when the fire is extinguished.

What happens if an APU fails on an airplane?

“Though failures are rare, sometimes the failure of the APU or the ground power unit will result in a loss of electrical power to the aircraft – and if its at night the aircraft will be plunged into darkness (apart from the emergency exit lights which are supplied by the aircraft batteries)!”

How does a firefighter shut down an APU?

The control panel on P62, has a red and black push activated button. The red button will shut down the APU, and the black button will discharge the onboard halon extinguishing agent directly into the APU. With this remote panel, firefighter action allows a big margin of safety for the firefighters on the ground.

What do you need to know about Apu fires?

This month let’s take a look at auxiliary power unit (APU) fires. The APU itself provides power to start the main engines. Heavy turbine compressors must be turned to a significant speed to start the engine. Before these engines are to be turned though, the APU must be started, generally done by a battery or hydraulic accumulator.

What happens when an APU is detected on the ground?

If an APU fire is detected on the ground, the APU automatically shuts down and the extinguishing agent is automatically discharged (3 seconds after fire warning is activated). If an APU fire is detected in flight, the APU must be manually shut down, and the agent manually discharged.

“Though failures are rare, sometimes the failure of the APU or the ground power unit will result in a loss of electrical power to the aircraft – and if its at night the aircraft will be plunged into darkness (apart from the emergency exit lights which are supplied by the aircraft batteries)!”

See APU Fire Switch page 6.3.3. If a fire is detected on the ground, a warning horn in the nose wheel well sounds, and the APU FIRE light illuminates on the external service interphone panel, see APU Fire Light page 2.3.4. The light extinguishes and the horn silences when the fire is extinguished.