aoa_777_groundwork_fire-protection_transcript.pdf

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Fire Protection Script Writer: Andrew-John Biggs

Andrew-John Biggs 2013

Hello and welcome to the Fire Protection lesson in the PMDG 777 GroundWork from Angle of Attack. An inflight fire is one of aviations most deadly threats. As pilot in command, your job is to quickly execute the correct procedures for fighting fires and get the aircraft down safely. Assisting you is the 777s advanced fire protection system. Easy to understand and operate, effective use of this system will help maximise your chances in a potentially fatal situation. This lesson will cover the following topics:

Fire Protection System Overview o Fire, Overheat, Detection and Extinguishing for the following systems and locations: o Engines o APU o Cargo holds o Wheel Well

Fire Protection System Testing Lesson Summary

Fire Protection System Overview:

In order to understand the effectiveness of the 777 fire protection system it helps to have a basic understanding of the properties of fire. Even a simple overview can help if you ever find yourself having to tackle one. Three elements must be present in order for fire to exist. These elements form what is commonly called the Fire triangle.

Fuel Oxygen Ignition or heat source

If you remove just one of these elements, the fire will go out. All fire protection systems on the 777 involve removing one or more of these elements. Fuel is something that can burn; pretty much any part of the aircraft can be a source of fuel if the temperature is high enough. Oxygen too is essential in the combustion reaction with about 16% oxygen needed in the atmosphere for fire to exist. Oxygen is obviously in abundance in the passenger cabin, less so in the atmosphere at cruising levels. As we know, fuels dont spontaneously catch fire just because they're surrounded by oxygen. For the combustion reaction to occur, the fuel has to be heated to its ignition temperature. The third element in the fuel triangle therefore is the heat or ignition source that does this. This could be damaged wiring, a naked flame or heat from friction. Fire is the chemical combustion reaction between oxygen and the source of fuel. Heat created by the fire can act as a further ignition source, allowing the fire to be self-sustaining and continue to spread, as long as the fuel and oxygen are not depleted.

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Ignition sources on board the 777 are very rare and components purposely designed as heat sources are controlled very carefully. For example electrical items in the Galley that are designed to reach high temperatures are isolated and monitored closely, with extinguishers always stored within arms-reach. Ignition sources from malfunctioning components that are not continuously monitored are the problem. Damaged or degraded electrical wiring that is sparking and open flames from cigarettes or lighters pose a serious risk. Likewise engines, APUs, electric motors or even in-flight entertainment systems can overheat and cause fire. Dangerous cargo, such as lithium ion batteries have been known to catch fire too. Because of these potential fire risks from rogue ignition sources, airline manufacturers spend thousands of man hours designing and building components that have extremely low risk of catching fire. Rigorous certification and maintenance schedules must be adhered to by airlines and because of these worldwide standards; fire on board airliners is now extremely rare. However, just like the fire extinguisher in your house that may collect dust for years and years, common sense dictates that preparation is vital, and if the time comes, you know where it is and how to use it. Remember no matter what the cause of the fire, separating the three elements; fuel, oxygen and source of ignition not only helps prevent fires from starting, it will helps to control a fire should one occur. Keeping in mind these three essential elements necessary for fire, lets take a look at the main design principles behind fire protection on the 777. These principles are; separation, isolation and control. All components and systems you see on the aircraft are designed using this principle. Separation involves designing components so that the three sides of the fire triangle are separated from one another. A simple example of separation would be routing electrical wiring away from fuel tanks, thus separating the ignition source from the fuel. Isolation involves designing some kind of firewall or bulkhead to isolate components that could potentially catch fire. For example, the 777s APU is built into a compartment at the rear of the fuselage designed to isolate a burning APU for a set period of time. This protects the cabin and airframe structure from fire damage whilst an emergency landing is carried out. The principle of Control involves designing fire fighting capabilities into the component or compartments. Engines, APUs and cargo holds are equipped with advanced fire extinguishing and suppression systems, whilst seat covers and wire insulation are made from non-combustible materials. This way if a fire does occur, it can be controlled and is less likely to spread. Passive systems and active systems are involved to implement these three principles: Passive systems are the first line of defence against fire. Passive systems include the design and use of non-combustible or self-extinguishing materials. Passive systems also include separation by routing, isolation, ventilation,

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drainage, bonding and grounding. Bonding and Grounding prevent static discharges or sparks that could ignite fuel vapours or other materials. An example of a passive fire protection system would be seat covers. Designed to prevent fire from starting or spreading, seat covers on most modern airliners are made from materials that stop burning as soon as the flame source is removed. Passive systems do not require physical action from the crew or an automated detection system to fight the fire. Active systems are the second line of defence against fire on board. Active systems include fire and overheat detection systems, fire-extinguishing systems, temperature sensing, air and fuel shut-off means and automatic shutdown of non-essential systems. Basically something that requires physical action in order to fight the fire is an example of an active system. Looking briefly at the engine fire protection system, we can see both passive and active systems working together: Certain engine sections are susceptible to the accumulation of flammable fluids and vapours. Incorporating drainage and ventilation systems removes these potential fuel sources, offering passive fire protection through the principle of separation. Engine pylons and fire bulkheads are constructed out of heat resistant materials. Fire that does break out can be contained by these firewalls offering passive fire protection through the principle of isolation. Using non-flammable construction materials throughout the engine is an example of passive protection through the principle of control. In terms of Active fire protection in the engine: An example of active separation would involve shutting off the fuel and oil feed to an engine in an effort to separate fuel from the oxygen and ignition source. Active isolation is hard to come by on a 777, but could involve closing fire bulkheads or jettisoning armaments on military aircraft. Active fire control would be the use of suppression and extinguishing agents, manually or automatically directed into the engine APU or cargo compartments in an attempt to control the fire. It is these active fire protection systems on the 777 that we are most concerned with as pilots. Active fire protection systems will be our primary concern therefore throughout this lesson. Now that we have a better grasp of the phenomenon of fire, and are aware of the systems in place on modern aircraft to help prevent fires from starting and spreading, we will move onto of fire detection.

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Airline manufactures use an interesting method for primary smoke and fire detection in the cabin and cockpit: People! Human beings are excellent smoke and fire detectors. We detect fire very quickly, either visually, by smelling smoke, or by feeling unusually high temperatures. A cabin full of passengers will likely detect smoke or a fire quickly simply because the cabin and cockpit are always occupied. Automatic smoke detector units are therefore not fitted in the cabin and cockpit. Parts of the aircraft without automatic smoke detectors are called class A compartments. Unmanned compartments that the crew can access during flight such as an avionics bays and crew rest areas are called class B compartments. These must have smoke detectors fitted. Cargo bays and cargo holds that are not accessible to the crew or passengers are called class C compartments. These have smoke detection and remotely operated fire extinguishers and we will cover these in greater detail later in the lesson as we explore cargo fire protection. Class D compartments are usually cargo bays with increased fire proofing. The difference between a class D and class C is that if a fire does occur here, it will not affect the structure of the aircraft and so is left to burn, usually using up the oxygen in the compartment as it does so with the idea that it will eventually burn itself out. Worth noting, although the galleys on the 777 make up part of the cabin, and are often occupied, smoke detectors are still fitted given the increased fire risk in these areas. Food preparation areas contain many sources of fuel and ignition so they must be monitored closely. Toilets are also fitted with smoke detectors and in the 777 automatic extinguishers are fitted in the waste paper bins to immediately extinguish any fires they detect. To summarize: Smoke detectors are required in galleys, toilets, class B, C and D compartments. Passengers and crew detect smoke in the rest of the cabin. Before we begin to look closely at the specific fire protection systems on the 777, let us examine some principles of fire extinguishing.

As we now know, removing one of the three elements in the fire triangle should put out the fire. Fire extinguishers remove one of these elements by applying an agent that either cools the burning fuel, or removes or displaces the surrounding oxygen or interrupts the chemical process of combustion.

Popular extinguishing agents used throughout the aviation industry are Halon 1211 and Halon 1301. Both of these agents are used on board the 777.

Halon is a liquefied, compressed gas that stops the spread of fire by chemically disrupting combustion. Halon 1211 is a liquid streaming agent and Halon 1301 is a gaseous flooding agent. Halon leaves no residue and is remarkably safe for human exposure.

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Halon is suitable for use on class B flammable liquid fires and has proven to be an effective extinguisher against class A common combustibles fires. Because it does not conduct electricity back to the extinguisher operator, is also suitable for fighting class C electrical fires too.

Halon has the advantages of nearly all other types of fire extinguishing agent. It offers some of water's cooling effect and some of carbon dioxide's smothering action, but the main advantage lies in its ability to interrupt the chain reaction of the combustion process. Unlike CO2, with Halon there is no danger of cold shocking avionics or other sensitive electrical equipment behind panels or in avionics bays. Furthermore, whilst dry chemical fire extinguishers are effective on A, B and C class fires they are highly corrosive, and create billowing clouds of choking dust which are not ideal for the confined occupied compartments of a 777 cabin.

Foam extinguishers are effective on class A and B fires, and are particularly useful for preventing ignition of flammable liquid spills. Airport fire vehicles often use foam for this reason, however foams are inferior to Halon in that they are not for use on electrical fires. Finally, because Halon 1211 is a liquefied gas which, when discharged, leaves the nozzle in a stream that is about 85% liquid and 15% gas giving the agent a range of 9 to 15 feet, ideal for fighting fires in large aircraft cabins.

Hand held Halon 1211 fire extinguishers are therefore available in the cockpit and throughout the cabin of our 777. Both Halon and water extinguishers are available.

Now lets take a closer look at the Engine fire detection and protection system.

Engine Fire, Overheat, Detection and Extinguishing: Needless to say it is critical that engines incorporate extensive and reliable fire protection systems. The primary purpose of the engine fire detection system is to give warnings on the flight deck if there is a fire in an engine nacelle. The system also gives caution indications when engine overheat temperatures are reached or exceeded. Engine fire detection equipment must be sensitive enough to detect the fire immediately, but still be robust enough to withstand the high temperature environment in and around the engine core and not give off erroneous alerts. Pilots reacting to a spurious fire warning could put the aircraft at unnecessary risk. To prevent unwanted fire warnings, engineers use an ingenious dual loop fire detection system. Each engine has two of these dual detection loops and under normal operating conditions both loops have to be activated for a fire to be reported.

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The loops themselves are made up of two long pieces of fire wire that attach to a support tube. The support tube is fixed to various locations within the engine nacelle, strategically placed to detect fires in places where they are most likely to start. The fire wire elements connect to make loop one and loop two. A cross section of each fire wire shows two fine central electrodes surrounded by a thermistor type filler material. The outside of each fire wire is made of an Inconel type alloy; a conductor that is oxidation and corrosion resistant, excellent for use in extreme environments like this. This Inconel tube containing the filler and central electrodes is earthed. One of the central electrodes is attached to the Inconel tube meaning it is earthed as well, whilst the other is suspended in the filler material and attached to the fire detection card. The fire Detection card closely monitors and tests all engine overheat parameters, communicating its collected data with the Aircraft Information Management System, AIMS and to the Warning Electronics Unit WEU which displays the warnings to the crew in the cockpit. An electrical potential is put across the suspended electrode, via the fire detection card, but because the loop is continuous, i.e. it has no earth connection to complete the circuit, no current will flow. When the area of the engine being monitored is within its normal operating temperature range, this is how the system will remain. No current flows between the central electrode and the earthed electrode. In a fire situation however, the temperature of the thermistor filler material increases, and as a result its electrical resistance decreases. This decreasing resistance allows current to flow from the suspended electrode to the earthed electrode. The fire detection card monitors this decreasing resistance closely. If the resistance decreases past the overheat threshold, then an overheat signal appears on the flight deck. If the resistance continues to decrease to the fire threshold, a fire warning is sent to the flight deck. If the fire goes out and the temperature of the filler material decreases its resistance increases back to the reset point and the warnings are cancelled. Interestingly it is the rate of change of resistance that distinguishes between an electrical short in the loop or a real fire. If there is a short circuit, the resistance will also give a low signal to the fire detection card. However the resistance decreases at a faster rate with an electrical short compared to the rate during a fire. The detection card identifies this kind of signal as a fault. Under fault conditions, dual loop redundancy is sacrificed and single loop operation comes into play. In this condition only one loop detecting a fire is enough to set off the fire alarms. If both loops fail the EICAS advisory message DET FIRE ENG for the associated engine is displayed. This means fire detection is no longer available for the effected engine.

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The fire detection card for each engine continuously monitors the two loops for fires, overheat conditions and faults. The engine fire detection system incorporates self-test equipment. Each dual loop system is automatically tested at system power up and continuously monitored thereafter for faults. The fire and overheat detection systems can also be manually tested and we will look at this at the end of the lesson. Failures in the detection system cause EICAS messages.

There are four fire detection locations in each engine.

Engine fire detector - aft right aft left aft lower forward lower

Each detector is placed near engine components that are most likely to cause fire if they fail. Components such as the accessory gearbox, hydraulic pumps, engine oil reservoir and fuel control units often fall under this category. In some abnormal circumstances even compressor blades could touch the engine case and create a metal fire. The tables below show the temperature threshold that cause fire and overheat warnings in the various detector locations. Temperatures are in degrees Fahrenheit and degrees Celsius. Reset temperatures are also shown.

Now we know how the engine fire detection system works, lets look at how pilots interact with it. An engine fire needs immediate attention, and although extremely rare, pilots are routinely tested on their abilities to deal with them.

The crew extinguishes engine fires from the engine fire panel located just aft of the throttle pedestal. Two engine fire switches shut down the engines and discharge the fire extinguisher bottles. Two fire bottles protect both engines. The switches are locked into position when no fire is detected. The locks are electrically operated. In addition to the master warning light and fire bell, when an engine fire is detected by the fire detection loops, an EICAS warning message FIRE ENG L,R appears. Also notice the fire indications on the associated engine fuel control switch and engine fire switch. The associated engine fire switch will also unlock.

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When a fire warning is given, if the auto throttle is on, it should be disengaged. This allows the effected engines thrust lever to remain where it is manually positioned. Next close the thrust lever of the engine that is on fire. This assists in recognition of the effected engine as we continue to put out the fire. Now move the associated fuel control switch from RUN to CUTOFF. Once this has been accomplished we can pull the engines fire switch. Pulling the engine fire switch accomplishes many things at once: The engine and spar fuel valves close, if not already closed by the fuel control switch. The engine bleed air valves also close. The engine driven hydraulic pump is depressurized and hydraulic fluid is shut off. The engine generator field and breaker are tripped. Finally the appropriate discharge squib is armed on each engine fire bottle. By accomplishing these actions, the fire protection system should remove the fuel element of the fire triangle in the engine, extinguishing the fire. However if the FIRE ENG L, R message is still displayed after the switch is pulled, indicating the engine fire still exists, then we need to activate the engine fire extinguishers. Flooding the engine with Halon 1301 gas should put out fire. If the threat of an engine fire exists at cruise altitude, fire extinguishers must provide the fire suppressant agent in a gaseous form at very low temperatures. Many extinguishing agents revert to liquid form when the outside temperatures are so low, and would not be as effective at combating engine fires in this state. Halon 1301 however boils at a very cool minus 68 degrees Celsius, meaning it will usually always be a gas at cruise altitudes making it an ideal candidate for engine fire extinguishing. There are two engine fire extinguishing bottles. Each contains fire extinguishing agent Halon 1301, pressurized with nitrogen. One or both bottles can be discharged into either engine. To release the Halon into the engine rotate the fire switch for the appropriate engine to the left or right and hold against the stop for one second. The switches are normally locked closed using a solenoid. When a fire is detected the solenoid energizes to release the switch. If this mechanism fails, the fire override switch underneath the handle can be pushed to release the lock. Moving an engine fire switch to the DISCH 1 position discharges fire bottle number one into that engine; moving it to DISCH 2 discharges bottle number two into the same engine.

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When you move the switch to the discharge position an electrical current is sent from the fire extinguishing circuit to the fire bottle squib. The squib is a miniature explosive cartridge that detonates when a current passes through it, penetrating the diaphragm used to seal the fire bottle. When this diaphragm is broken, the high pressure nitrogen forces the Halon extinguishing agent out at very high speed through the discharge port. The gas is directed along the discharge manifold to the discharge nozzle in the effected engine. Because Halon can be stored at extreme pressures, it only takes about a second for the agent to reach the engine from the bottle when released. The two engine fire bottles are stored in the right sidewall lining of the forward cargo compartment, aft of the cargo door. When fire bottle number 1 is discharged by moving the switch to the left, an EICAS advisory message BOTTLE 1, DISCH ENG is displayed and the engine bottle 1 discharge light illuminates. The engine bottle discharge lights indicate the condition of the engine fire bottles, the lights are extinguished when the fire bottles are full. If the FIRE ENG message does not go out after 30 seconds, discharge the other fire bottle by rotating the switch to the opposite side. The corresponding EICAS discharge message will display. The fire warning indications are removed when the fire condition no longer exists.

The engine fire protection system also detects engine overheat conditions. The system alerts the crew of an overheat condition only if both detection loops detect an overheat. In addition to the master caution light, when an engine overheat is detected an EICAS caution message OVERHEAT ENG L, R appears. When the overheat condition no longer exists, the overheat indication is removed. Now lets look at the fire detection and extinguishing system for the APU.

APU Fire, Overheat, Detection and Extinguishing:

The APU has three dual loop fire detectors that operate in the same way as the engine detection loops. The APU has one fire bottle also containing Halon and is pressurized with nitrogen. The bottle is located forward of the APU fire wall, isolating it from the APU compartment, protecting it if a fire does occur. In addition to the master warning light and fire bell, when an APU fire is detected, an EICAS warning message FIRE APU appears. The APU fire switch and warning light on the APU fire panel also illuminate. When an APU fire signal is detected on the 777, the Electronic Load Management System and the APU Controller automatically shut down the APU. The EICAS message; APU SHUTDOWN will appear. The APU fire protection has two modes of operation; attended and unattended.

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With either engine running, or the aircraft in the air, the system operates in attended mode. In this mode, the APU fire protection system alerts the crew of an APU fire only if both detection loops detect a fire. The APU shuts down automatically but the APU fire bottle must be manually discharged by the attending crew. When the airplane is on the ground with both engines shutdown, the APU will run in unattended mode. In this mode, the fire signal will be sent to the cockpit if only one detection loop has detected a fire. If a fire is detected in unattended mode the APU will automatically shutdown and the fire bottle will automatically discharge. This logic gives maximum safety in case the cockpit is left unattended during the turnaround with the APU running.

If it is necessary for the crew to manually use the APU fire extinguishing system, they use the APU fire switch on the APU panel. In the normal position the APU fire switch is mechanically locked, it unlocks automatically during an APU fire warning However if a fire warning fails to unlock the switch, the fire override switch can be used in the same manner as on the engine fire panel. Hold the switch in whilst you pull the fire handle. Should an APU fire occur in attended mode, for example during normal flight, the APU fire switch should be pulled. This accomplishes the following:

The APU fire extinguisher bottle is armed The APU fuel valve closes The APU bleed air valves closes The APU air inlet door closes The APU generator field and generator breaker are tripped The APU shuts down if automatic shutdown has not already occurred.

Now the switch should be rotated immediately in either direction and held against the stop for one second to discharge the APU fire extinguisher bottle into the APU compartment. The APU bottle discharge light indicates the condition of the APU fire bottle. The light is extinguished when the fire bottle is fully charged. When the fire bottle is discharged, the EICAS advisory BOTTLE DISCH APU displays and the APU BTL DISCH light above the switch illuminates. When the fire is out, the fire warning indications are removed. On the ground, an APU fire can be extinguished manually from the flight deck or by using the fire controls on the nose gear panel. Remember an APU fire will cause an automatic shutdown of the APU.

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Cargo Fire, Overheat, Detection and Extinguishing: Cargo bays that do not need to support life can employ extinguishers that use chemicals that deplete the oxygen in the compartment. By removing the oxygen element from the fire triangle the fire should go out. There are two cargo compartments on the 777; forward and aft. Each compartment is equipped with a single smoke detection unit. The smoke detection units monitor the cargo compartment air for smoke. They do this by drawing in air and analysing it using photoelectric smoke detectors. If a fire is detected in a cargo compartment, the master warning light and fire bell alert the crew to the fire situation. In addition an EICAS warning message FIRE CARGO AFT, FWD appears. The crew extinguishes cargo fires from the Cargo Fire Panel, located on the overhead panel. If a fire is detected, the ARM light illuminates for the respective cargo hold, forward or aft. The crew must then press the appropriate ARM switch to arm the system. ARMED will now display in white. As an example, during an aft cargo compartment fire alert, pushing the AFT cargo fire arm switch accomplishes the following:

Firstly it arms all fire bottle squibs plus the flow valve squib for the aft compartment.

The cargo heat systems are shut down

Various ventilation and recirculation fans are shut down and the air conditioning packs are commanded to provide the minimum air flow required for pressurization. This reduces airflow in and around the compartment, prevents additional air from feeding the fire and reduces extinguishing agent leakage from the compartment.

Both cargo compartments are protected from fires by five cargo fire bottles containing Halon 1301, again pressurized with nitrogen. The next thing to do during a cargo fire alert is to discharge this Halon in the cargo hold. First ensure the respective compartment switch is armed, then press and hold the discharge switch for one second. When pressed, two of the five bottles empty immediately into that compartment, the other three meter the extinguishing agent over time. Pressing the discharge switch also activates the flow valve squib for the aft compartment allowing the agent to pass through it. After the rapid dump bottles have discharged the EICAS message BOTTLE DISCH CARGO displays.

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Note: Do not push both forward and aft cargo compartment arm switches prior to discharge. If both compartments are armed before discharge is initiated, the extinguishing agent is divided between the two compartments. This results in an insufficient concentration in both compartments and the fire may continue to burn. You can disarm either compartment by pushing the associated arm switch again. This closes the corresponding flow valve for that cargo compartment. If a fire exists in the forward compartment, pushing the FWD cargo fire arm switch accomplishes the same items as before, however the equipment cooling in the avionics bay automatically reconfigures to the override mode. This attempts to the clear the avionics bay of smoke. As a result, if operating at low altitudes and low cabin differential pressure, i.e. low airflow through the avionics compartment, overheating of avionic systems may occur, and after 30 minutes electronic systems and displays may fail. After these initial fire fighting steps have been taken, the crew should plan to the land the aircraft at the nearest suitable airport. Furthermore, it is recommended that during a cargo fire situation, the landing altitude selector be pulled out and set at 8000ft in order to increase the cabin altitude. Normal cruise cabin altitude would be around 6000ft, this extra altitude helps to reduce the overall cabin differential. As a result, slightly less air flows through the cargo compartment on its way overboard, keeping more Halon in the cargo hold where it is needed. When at the top of descent the landing altitude selector can be pushed back in restoring automatic selection of the FMC landing altitude. Next, lets look briefly at what we need to do if there is a wheel well fire warning.

Wheel Well Fire, Overheat, Detection and Extinguishing: The main gear wheel well contains a dual loop fire detection system for each main gear. There is no extinguishing system for the wheel well. Each dual loop system is automatically tested at power up and continuously monitored thereafter for faults. The system can also be manually tested. High brake temperatures alone will not activate the fire warnings. The system is designed to sense only the excessive temperatures associated with a fire. If temperatures in the wheel well are high enough to activate the fire detection system the master warning light and fire bell will alert the flight crew to the problem. The EICAS warning FIRE WHEEL WELL will also display.

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As there is no fire extinguishing system for the gear well, Boeing recommends that the gear be lowered in an attempt to put out the fire. The speed of the outside airflow should be enough to reduce temperatures in the wheel well and blow the fire out. To do this, we first observe the gear extend speed limit which is two hundred seventy knots indicated, or Mach point eight two, then we can extend the landing gear. Extending the landing gear will also keep the gear away from any fire present in the wheel well, and vice versa. When temperatures in the wheel well drop below the fire threshold, the EICAS warning is removed. Once the gear is down it should remain down and a landing made at the nearest suitable airport. Remember flight with the gear extended increases fuel consumption significantly. If the gear needs to come back up to increase performance, twenty minutes should elapse between the EICAS fire message going out and the gear being retracted.

Fire Protection System Testing:

The fire detection system on the 777 has automatic fault testing. Fire detection loops and circuits are continuously tested for faults. As we read earlier, if a fault is found, single loop operation in fire detection loops occurs, however complete faults result in EICAS advisories. Manually testing the Fire Protection System on the 777 is straightforward. Use the FIRE/OVHEAT TEST switch on the overhead panel to test the system. By pushing and holding the switch, fire overheat test signals are sent to the engine, APU, wheel well and cargo compartments fire detection systems. It is our job up the front to make sure that the systems report no faults, with all cockpit fire alarms, overheat alarms and displays working correctly. When the switch is pushed, indications to look out for are:

The fire bell sounds The EICAS warning message FIRE TEST IN PROG is displayed The nose wheel well APU fire warning horn sounds, when on the ground.

Check to see the following lights illuminate during the test:

The master warning light The left and right engine fire warning lights The APU fire warning light The FWD and AFT cargo fire warning lights The left and right fuel control switch fire warning lights

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When the test is complete the EICAS warning message FIRE TEST PASS or FIRE TEST FAIL replaces FIRE TEST IN PROG. It is very important that you do not release the test button until the EICAS message FIRE TEST PASS OR FIRE TEST FAIL is displayed. Releasing the switch whilst FIRE TEST IN PROG is still displayed will result in the test ending without completing properly. To end we will now review the EICAS messages associated with fire and overheat conditions you may encounter during your 777 command.

Lesson Summary: This lesson covered the following topics:

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Fire Protection System Overview Fire, Overheat, Detection and Extinguishing for the following systems and locations: Engines APU Cargo holds Wheel Well Fire Protection System Testing Lesson Summary

This lesson aimed to give you a practical overview of fire protection systems on the 777. Armed with this new knowledge and provided your quick reference handbook is within reach, you should be able to deal with most fire and overheat conditions experienced in flight. Remember fly the plane first, follow the checklist, and get the aircraft on the deck as quickly as possible to maximise your chances in a fire emergency. We hope you have enjoyed this lesson.

Until next time; THROTTLE ON!

aoa_777_groundwork_fire-protection_transcript.pdf

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