Boeing 777 Cbt #25 Engine And Apu Fire Protection

Summary

This video script covers the comprehensive fire protection systems in aircraft engines and the APU, explaining their detection and extinguishing procedures for fires and overheat conditions. The system uses dual-loop fire detection for both engines and the APU, with manual and automatic discharge mechanisms for fire bottles. Alerts and indicators, including ICAST messages, fire bells, and master warning lights, notify the crew of fire events. The script also discusses non-normal situations, such as detection loop failures and fire switch malfunctions, detailing the procedures to handle these issues effectively, ensuring safety and operational readiness.

Takeaways

• 😀 The 777 engine and APU fire protection systems are similar to other jet transports, designed to detect and extinguish fires in both engines and the APU.
• 😀 Both the engine and APU fire protection systems use dual-loop fire detection systems that automatically test and continuously monitor for faults.
• 😀 If a fire is detected, the engine fire switch shuts down the engine and discharges the engine fire bottle, with the system alerting the crew if both loops detect a fire.
• 😀 The engine fire switch also closes the engine fuel valves, bleed air valves, and arms the discharge squib on each engine fire bottle when pulled.
• 😀 If pulling the engine fire switch does not extinguish the fire, the crew can rotate the switch to discharge the second fire bottle, with a system alert indicating the discharge status.
• 😀 The APU fire protection system operates similarly, with a fire switch that shuts down the APU and discharges the APU fire bottle when pulled.
• 😀 If an APU fire is detected, the APU shuts down automatically and the fire bottle is manually discharged when necessary, either from the flight deck or the nose gear panel.
• 😀 When both engines are shut down and the APU is operating, only one detection loop is needed to detect an APU fire, which causes an automatic shutdown and fire bottle discharge.
• 😀 The APU fire switch and bottle discharge systems are designed to automatically handle fire situations, but they can be manually controlled if needed.
• 😀 Non-normal situations, such as failure of a fire switch or a detection loop, are handled by the fire override switch, which allows the crew to manually override the system and operate the fire switch.

Q & A

What systems are involved in the fire protection for the 777 engine and APU?

The fire protection systems for the 777 engine and APU include dual-loop fire detection systems that detect both fires and overheat conditions. The systems automatically test at power-up and are continuously monitored for faults.

How do the fire detection systems work for the engine and APU?

Both the engine and APU have dual-loop fire detection systems that detect fire and overheat conditions. If both loops detect a fire, the system alerts the crew. The detection is automatically tested at power-up and can be manually tested as well.

What happens when a fire is detected in the engine?

When an engine fire is detected, the engine fire switches are activated. These switches shut down the engine, discharge the engine fire bottles, and perform several other functions like closing fuel, air, and hydraulic valves, as well as tripping the engine generator breaker.

What does the crew do to extinguish an engine fire if the first fire bottle is insufficient?

If the fire is not extinguished after the first fire bottle is discharged, the crew rotates the engine fire switch to the left or right to discharge the second fire bottle.

How does the APU fire protection system work?

The APU fire protection system works similarly to the engine system. When a fire is detected, the APU shuts down automatically, and the APU fire bottle must be manually discharged by rotating the APU fire switch. This also triggers the APU generator breaker to trip.

What happens when both engine fire detection loops fail?

If both detection loops fail, the system switches to single-loop detection. The crew is then alerted if the remaining operating loop detects a fire. If both loops fail, an advisory message is displayed, and fire indications are no longer available.

What is the purpose of the fire override switch?

The fire override switch is used to manually unlock the fire switches if they fail to unlock automatically when a fire is detected. Holding the override switch unlocks the fire switch to allow the crew to perform fire-fighting procedures.

What happens when the APU fire bottle is discharged?

When the APU fire bottle is discharged, the associated icast advisory message is displayed, and the APU fire bottle discharged light illuminates. This indicates that the fire bottle has been discharged to extinguish the fire.

How is an APU fire extinguished when the airplane is on the ground?

When the airplane is on the ground, the APU fire can be extinguished manually from the flight deck or by using fire controls on the nose gear panel. The APU fire bottle automatically discharges if both engines are shut down and the APU is operating.

What happens when the APU fails to shut down automatically after detecting a fire?

If the APU fails to shut down automatically after detecting a fire, the crew must manually pull the APU fire switch. This will close the fuel valve, close the bleed air valve, and trip the APU generator breaker, among other actions.