Table of Contents
- 1 What external warning is there for an APU fire?
- 2 What is an APU fire?
- 3 What does the red indicator on the APU fire bottle indicates?
- 4 Where is the APU fire extinguisher bottle located?
- 5 What are continuous type fire detectors?
- 6 Where is the APU ground control panel?
- 7 Where are the engine and APU fire switches installed?
- 8 What does NAC mean on a fire panel?
- 9 How does the fire extinguisher work on the APU?
- 10 What are the fire hazard mitigation principles of the APU?
What external warning is there for an APU fire?
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 is an APU fire?
If there is an APU fire, the APU fire detection system gives fire warnings and automatically stops the APU. If the APU is running, it stops when the fire switch is pulled. The fire switch isolates the APU from the airplane systems.
How does a fire loop work?
How Does The Fire Loop Detect A Fire? So if you retract your gear and one of your wheels or brakes catches fire, how does the loop detect it? The two wires inside of the loop are separated with an insulating material called a thermistor. The thermistor, which is a resistor, is temperature dependent.
What does the red indicator on the APU fire bottle indicates?
The red disc is the thermal discharge indicator and is ejected by extinguishant escaping to atmosphere due to thermal expansion in the lines. Each responder unit detects engine fire conditions by sensing the gas pressure in its loop.
Where is the APU fire extinguisher bottle located?
The fire-extinguishing-agent bottle is located on the forward side of the APU firewall. The single discharge line directs agent to a nozzle located in the APU compartment. The APU-extinguishing-agent bottle design is similar to that of the engine.
What devices are on a NAC circuit?
In the Notification Appliance Circuit (NAC), conventional fire horns, bells, strobes, chimes, and speakers, all have the Notification Appliance Riser Circuit Wiring in common. This circuit, under normal circumstances, is in either one of two different conditions: Supervision or Alarm.
What are continuous type fire detectors?
A continuous-loop detector, or sensing system, permits more complete coverage of a fire hazard area than any of the spot-type temperature detectors. They are overheat systems, heat-sensitive units that complete electrical circuits at a certain temperature.
Where is the APU ground control panel?
The APU can supply both electrical and air conditioning for ground operation. All controls for APU operation are located on the third crewman’s panel and auxiliary panel.
How many fire extinguishing bottles are available for fighting an APU fire?
On this airplane model, two fire-extinguishing-agent bottles and associated tubing are installed in the leading edge of each side of the wing. APU fire extinguishing. The APU fire-extinguishing system located in the aft fuselage is a single-shot system provided to extinguish a fire in the APU compartment.
Where are the engine and APU fire switches installed?
Most APU installations are located in the airplane tailcone outside of the pressure vessel or passenger compartment.
What does NAC mean on a fire panel?
Notification Appliance Circuit
A: Each NAC (Notification Appliance Circuit) in a fire alarm panel or booster power supply has a maximum current rating. This information can be found in the manuals provided with the panels. The total current draw for all the devices connected to the circuit cannot exceed the NAC rating.
How do I know if there is a fire in my Apu?
On the top of the panel, there is a red lens that, if illuminated, shows if there is a fire in the 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.
How does the fire extinguisher work on the APU?
FIRE PROTECTION – A single fire extinguisher bottle is provided for the APU. 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).
What are the fire hazard mitigation principles of the APU?
The APU installation uses the same fire hazard mitigation principles as the engines listed above, plus: Automatic shutdown of the APU. Automatic shutoff of air source. The APU compartment firewall isolates the APU from the rest of the airplane.
What is an APU on an airplane?
Some APUs are also connected to a hydraulic pump, allowing crews to operate hydraulic equipment (such as flight controls or flaps) prior to engine start. This function can also be used, on some aircraft, as a backup in flight in case of engine or hydraulic failure. On most larger aircraft, the APU is installed in the rear of the airplane.