787 System Review (recurrent) Interval 4 2021

Recurrent Training Interval System Study Review Interval 4 March 1, 2021 through December 31, 2021 Auxiliary Power Unit Fire Protection Fuel Power Plant APU Basics No bleed Only electricity Probably already know this, but the 787 APU generates only electricity and noise. It's electric capacity though, is quite something. APU altitude limitation It can be started and runs fine all the way up to the maximum certified altitude, flight level 431. However, with no pumps available at all, it won't start above 14,000 feet. Starter generators Just like the engine, the APU is fitted with two guarantee frequency starter generators. As the name suggests, these have only two rules. Start the APU, then function as generators. With ground or engine power, either starter will be used for start. The dedicated APU battery can only power the right starter. For the detail, starter generators. The total load capacity of both APU generators at sea level is 450 KVA. This tapers off somewhat linearly to 127 KVA at 40,000 feet. Clever load shedding, circuitry, make sure these amps are well used. The voltage output is 235 volts AC, with a frequency in the 380 to 440 Hertz range. Unlike APU's on other aircraft, the 787 APU is not running at a constant 100% speed. Instead, it is commanded to run at a speed corrected per ambient temperature, which results in a rotor speed in the 91.4 to 105.8% range. This enhances the ability to deliver load at higher ambient temperatures with good fuel consumption efficiency at lower temperatures. Low range APU speed occur during cold day operation, with the speed increasing linearly as the ambient temperature increases. All this is automatic, and rarely, rarely observed by the flight crew. Fuel feed. The APU is fed fuel from the left manifold by an operating AC fuel pump, or by a dedicated DC fuel pump in the left main tank. When there is AC power available, the left-aft fuel pump is commanded on, regardless of pump switch position. The flight crew operating manual says the APU is designed to be started with no pumps operating when on the ground or in flight up to 14,000 feet. This is sometimes misunderstood as referring to no AC pumps, that the DC pump would only work up to that altitude. But remember, APU started as possible all the way up to the maximum certified altitude. So what the flight crew operating manual is trying to say here is that the APU started as possible up to 14,000 feet, with no AC pumps and no DC pumps either. In other words, complete suction feed. Air inlet door. Located on the upper right side of the tailbone, after the APU firewall, the air inlet door supplies air to the APU gas turbine, and also air for compartment cooling and oil cooling. The APU controller opens this door as one of its first steps in the starting sequence, and it must be fully open before start is initiated. The door is commanded open when the APU selector is in the start or on, and it takes approximately 25 or 30 seconds for it to open or close. Start sequence. Moving the APU switch to start, and then let it spring back to on. We'll begin the automatic startup sequence. Many of us have that old habit of holding the start position for a moment. This probably made sense on aircraft with a mechanical relays involved in the APU star sequence. So maybe back on the 707-7576, but the 7-8 startup command is completely digital. It shouldn't matter how long that switch is in start position before moved back to on, but I guess there is no harm in maintaining that old school ritual either. The APU startup is completely automatic, like some like to observe it on the systems page, but it's not needed. You can only sit back and drink your coffee. If the battery switch is just selected on, the APU controller will wait until all CCS applications are available before proceeding with the start. This takes about one to three minutes and make sure fuel management and fire protection is available. The automatic start sequence then begins. Fuel spar valve is open and fuel pump operation is initiated. The starter generators energize and commanded to provide starting torque, start, starter and ignition cut out happens at about 50% speed. The APU is considered to be running at 95% of target speed plus two seconds. At this point, the APU running, white memo message is shown on the ICAS. Electrical power switching is also automatic. You don't need to do anything except drink coffee. If the startup fails, the amber APU fault light next to the switch comes on and the advisory message APU shut down amber is shown on the ICAS. Moving the switch from on to off resets these fault indications. The APU battery can handle two consecutive start attempts. After that, a five minute cooling period is required before a third attempt. In flight, automatic start, cool fact, if three or more engine generators go offline and flight, the APU automatically starts. In other words, if you lose or lost both engines, calling for the APU start wouldn't really be necessary in a seven eight. It happens anyway. Since the APU switch position is ignored when the APU runs after an automatic start, the only way to shut it down in this situation would be to pull the APU fire switch. Pro tip, don't lose both engines. Shut down sequence. When moving the APU switch to off, do make sure engines are external power is on. The main bus is first or you'll regret it. A two minute cool down timer starts and the memo message shows on the ICAS. The generators are unloaded and the APU is ramped down to cool down speed, which may actually be full speed RPM depending on ambient temperature. At any time during the cool down period, the APU can be returned to running by moving the switch back to off. So quickly to review, APU switch to off. APU cool down ICAS memo message displayed. Following the two minute cool down and over speed condition is simulated. This test, the protection components, which leads to fuel shut off, which is what you want it. It shuts down the APU, the spar valve closes, and at 15% speed the air inlet door closes 25 to 30 seconds. It takes the closer the door. Attended and unattended mode. On the ground, for example, when parked at the gate, the APU is in unattended mode. In this situation, it will shut down automatically for any of the following APU fire, manually pulling the APU fire switch or pushing the button on the nose gear. Inlet over temperature, over speed, RPM more than 111%. Loss of air, over speed protection, APU controller failure. Speedroop, RPM less than 82%. APU start failure, no rotation, no acceleration, and no light off. Air inlet door doesn't open when commanded to do so. High EGT, high oil temperature, high low oil pressure. With someone on the flight deck, attended mode, the APU is allowed to continue running for these three last-fold high EGT, high oil temperature, low oil pressure. These three faults will cause the amber APU limit caution message. In other words, the aircraft will ask the pilots to make the APU shut down. For all other faults, the APU will automatically and immediately shut down, just like an unattended mode. How does the aircraft know that somebody is on the flight deck? It is assumed that if either engine is being started or is running on the ground, then yes, someone should be in the flight deck. Likewise, anytime in flight, there should be someone there. So the APU is in attended mode, when either engine starting or running on the ground, or the craft is in flight. No cooldown period takes place when automatic shutdown happens, and the amber APU shutdown advisory message is shown on the eye here. Fire protection basics. Overheat and fire detection. Two detector cables loop around the engine, checking for both overheat and fire conditions in the counting and the missile. These cables are simply tubes that each contain two wires, with a special installation between them. the wires. If the temperature rises that insulation decreases, someone closing the circuit. This is sensed by the system which can then calculate the temperature. Depending on how hot that temperature is, you'll either see the overheat engine amber left or right causes message or the red engine fire engines left or right warning message. Normally both loops will have to detect the same condition in order to set off the message. But if one has failed, it's enough that the remaining one senses it. If both loops fail, the advisory message amber detect fire engine left or right will shell and no fire/overheat detection will be available. Engine fire extinguishers. A common misconception that there are two extinguisher models per engine. That's not the case. There are two bottles and total. Hence the two engine bottles discharge lights. Both these bottles can be discharged into either engine. Engine fire switches. What happens when you pull an engine fire switch? Every command upgrade technical interview ever has asked this question. What happens then? In summary, six things. They are way easier to remember if you tick them off system by system. So here we go. Last time. Fuel. Both valves. Engine and spark. Close. Any ice. These valves close to electricity. Both generators trip off. Hydraulics. The engine driven pump is depressurized and hydraulic fuel fluid supplies cut off. Reverser. Power to the isolation valve is removed. And finally, the system is being prepared to fight the fire. So obviously both engine fire extinguishers are. That's it. That's easy. Graduate level discussion. Engine or firefighting categories. Aircraft rescue and firefighting. Air ARF is based on aircraft length. The Boeing 78. Boeing 788 is category 8 or D. ICAO 8DFA. The Boeing 78-9 is category 9 ICAO or EFA. Normally, you can use airports in lower categories, especially for alternates. But consult your operations manual for these specifics. No. Typically, diversion guides or e-tops suitable airports take these conditions into consideration. APU fire protection. The APU ground control fire protection panel is pretty self-explanatory. However, by the time you get to these buttons during an APU fire, it's unlikely you will make a difference pushing them. APU fire protection on the 787 is fully automatic. On the ground with both engines off, it's enough that the fire is sent just one detector loop to automatically shut down the APU meeting. The system will then wait 15 seconds to let the fuel valve close before discharging the extinguisher bottle. That's it. It's done. You can go back to whatever it was you were in the air. Both loops should normally detect a fire before the same thing happens. The ICAO's warning message red, fire APU shows and the fire bell rings. There are no memory atoms. Just complete the checklist. No. Most reports on APU fire indication incidents have the words "Energency services found no trace of fire, heat or smoke." In other words, most of them are false indications. That said, if the warning does not clear, follow the checklist and land at the nearest suitable airport. Recurrent training interval system study review. Interval 4 March 1, 2021 through December 31, 2021. Auxiliary power unit, fire protection, fuel power plant. APU basics. No bleed. Only electricity. Probably already know this, but the 787 APU generates only electricity and noise. It's electric capacity, though, is quite something. APU altitude limitation. It can be started and runs fine all the way up to the maximum certified altitude, flight level 431. Standard generators. Just like the agency, APU is fitted with two garrardless frequency starter generators. As the names suggest, these have only two rules. This tapers off, somewhat linearly, to 127 KVA at 40,000 feet. The voltage output is 235 volts AC with a frequency in 380 to 440 hertz range. All this is automatic and rarely, rarely observed by the flight crew. Fuel feed. When there is AC power available, the left-aft fuel pump is commanded on regardless of pump switch position. But remember, APU start is possible all the way up to the maximum certified altitude. So what the flight crew operating manual is trying to say here is that the APU start is possible up to 14,000 feet with no AC pumps and no DC pump either. Air inlet door. The APU controller opens this door as one of its first steps in the starting sequence and it must be fully open before start is initiated. The door is commanded open when the APU selector is in the start or on and it takes approximately 25 or 30 seconds for it to open or close. Start sequence. Moving the APU switch to start and then let it spring back to on will begin the automatic start up sequence. This probably made sense on aircraft with a mechanical relays involved in the APU start sequence. So maybe back on the 707-7576, but the 7-8 start up command is completely digital. The APU start up is completely automatic, like some some like to observe it on the systems page, but it's not needed. It just takes about one to three minutes and make sure fuel management and fire protection is available. The starter generators energize and commanded to provide starting torque. Start, starter and ignition cutout happens at about 50% speed. At this point, the APU running white memo message is shown on the ICAS. If the start up fails, the amber APU fault light next to the switch comes on and the advisory message APU shutdown amber is shown on the iKat. After that a five-minute cooling period is required before a third attempt. Inquite automatic start. Cool fact. If three or more engine generators go offline in flight, the APU automatically starts. It happens anyway. Pro-tip. Don't lose both engines. Shut down sequence. When moving the APU switch to off do make sure engines are external power is on. A two-minute cool down timer starts and the memo message shows on the iKat. At any time during the cool down period the APU can be returned to running by moving the switch back to off. So quickly to review. APU switch to off. APU cool down iKat's memo message display. Following the two-minute cool down and overspeed condition is simulating. This test, the protection components, which leads to fuel shutoff, which is what you want it. It shuts down the APU. As far as valve closes and at 15% speed the air inlet door closes 25 to 30 seconds. It takes the close to the door. On the ground for example when parked at the gate the APU is in unattended mode. In this situation it will shut down automatically for any of the following APU fire, or manually pulling the APU fire switch or pushing the button on the nose gear. Inlet over temperature. Overspeed RPM more than 111%, loss of air overspeed protection, APU controller failure, speed troop RPM less than 82%, APU start failure, no rotation, no acceleration and no light off. With someone on the flight deck attended mode, the APU is allowed to continue running for these three last fault, high EGT, high oil temperature, low oil pressure. It is assumed that if either engine is being started or is running on the ground then yes, someone should be in the flight. Likewise, anytime and flight there should be someone there, so the APU is in attended mode when either engine starting or running on the ground or aircraft is in trouble. No cooldown period takes place when automatic shutdown happens and the amber APU shut down advisory message is shown on the eye here. Fire protection, basic. Two detector cables loop around the engine, checking for both overheat and fire conditions in the counting and then the fault. These cables are simply tubes that each contain two wires with a special insulation between the wires. If the temperature rises, that insulation decreases. Someone closing the circuit. Depending on how hot that temperature is, you'll either see the overheat engine amber left or right classes message or the red engine fire engines left or right warning message. Normally both loops will have to detect the same condition in order to set off the message, but if one has failed, it's enough that the remaining one senses it. If both loops fail, the advisory message amber detect fire engine left or right will shell and no fire flash overheat detection will be available. A common misconception that there are two extinguisher models for engines. That's not the case. There are two bottles in total, hence the two engine bottles discharge lights and both these bottles can be discharged into either engine. So what happens then? So here we go. Lifetime. Fuel. Both valves. Engine and fire. Close. Any ice. Hydraulics. Reverser. That's it. That's it. Aircraft rescuing firefighting. The Boeing 78, Boeing 788 is category 8 or D. ICAO 8DFA. Boeing 78-9 is category 9 ICAO or EFA. Normally, you can use airports in lower categories, especially for alternates, but consult your operations manual for these specifics. No. APU fire protection. That's it. It's done. You can go back to whatever it was. In the air, both loops should normally detect a fire before the same thing happens. The ICAO's warning message red, fire APU shows and the fire bell ring. No. Most reports on APU fire indication incidents have the words emergency services sound no trace of fire, heat, or smoke. In other words, most of them are false indications. The overhead panel shows there are two AC pumps per fuel tank. The center ones have a higher output pressure, so center tank fuel is used before main, left and right, tank fuel when all pumps are running. The pressure lights on the switches don't work the same for all pumps. When the main tanks switches are off or those pumps have low pressure, the pressure lights will illuminate. For the center tanks, the lights will come on for low pressure, but they extinguish when you turn the switches off. The ICAO's message, Amber, fuel and center will show when you have more than 16,000 pounds in the center tank and the center pumps are off. Note, center tank pumps during engine start. Did your 787 get modified? Yes it did. According to the Boeing service bulletin, we have corrected the center pumps that can fill during electrical power transfer after engine start. The procedure used to be to wait until after each engine generator power the buses before turning the center pumps on. That avoided the problem, the software has been updated. As mentioned earlier, center tank fuel is always used first. All pumps are on. As you can see or as depicted on the synoptic display all pump show green outlines but because the center tank pump output pressure is higher the main tanks are sidelined until later represented by main tank lines not being green this is with all the generators online in a non-normal situation with loss of some generator power the aircraft will load shed some fuel pumps if necessary this is automatic but can be observed on the synoptic load shed will be indicated or shown next to the pump symbol one pump is sufficient to provide pressure for one engine under all conditions when there is approximately 4800 pounds left in the center tank the fuel low center amber message shows and the procedure is to manually turn off the center fuel pumps like it's 1957 it could surely be automatic but I assume it's for common procedures with previous Boeing models the remaining center tank fuel is then scavenged to the main tanks the scavenged system is automatic and starts when there is around 35,000 pounds left in the main tanks the output is quite high during cruise it usually keeps up with the engine fuel flow so main tanks stay at 16,000 pounds or even increase a bit while the remaining center tank fuel is used you can learn all the numbers above please don't learn from the service bulletin number but really the eye cast messages will tell you what to do and what APU fuel as you probably guess the answer to the question earlier has to do with APU burn on the ground prior to engine start and the question was when you look at the fuel panel or the fuel indicate indicators fuel quantity indicators why is the left side lower and that has to do with APU fuel burn on the ground prior to engine start the APU is fed from the left fuel manifold by either pump on that side if no AC power is available a dedicated DC powered fuel pump will provide fuel until the AC buses come online typically a system exam question might ask when AC power becomes available the left after AC pump runs automatically regardless of pump switch position to provide APU fuel hence the extinguished pressure light in the is indicated on the panel fuel system not normal so landing is required and your weight is nowhere near close to max landing weight or the performance landing distance requirement for the runway bill you have two options overweight landing or fuel jettison over what overweight landing is another topic but what can be mentioned is the fact that the FAA should abolish and back in 1972 giving some examples when pilots are expected to make an overweight landing it boils down to time critical situations so basically if the checklist says land at the near suitable airport or you have a medical emergency on board go ahead and land overweight for overweight landings follow the unenunciated checklist and check the required performance fuel jettison first request permission from ACC they will probably want to have you jettison in some designated area if possible Boeing says minimum altitude for that procedure is 4,000 feet but ICAO pans ATM requires at least 6,000 feet doing it at 15,000 feet is an uncommon ATC policy might vary from place to place but most of them probably think that higher is better second there's a checklist for fuel jettison also found in the unenunciated menu that will take you through the steps when you push the arm button fuel to remain will be set so that you're at maximum landing weight once the jettison is complete perhaps you still have a long distance to fly to your diversion airport and if so it might be prudent to change that to change the fuel to remain amount the checklist will ask if you want to do this no matter what it's probably a good idea to have a brief discussion about it before the decision is taken next to fuel to remain for easier landing weight planning the expected after jettison gross weight of the aircraft is also shown but the overhead panel switch still sets target fuel to remain and that's why the fuel number is in magenta and the white weight is in white once armed and in flight pushing the nozzle switches will open all the required valves defuel isolation plus jettison isolation bells and the nozzles begin the process the center tank jettison isolation valve opens allowing center tank fuel to flow into the jettison refuel manifold fuel in the main tanks is jettison by opening the defuel isolation valve on each engine feed manifold the fuel is then pumped into the jettison refuel manifold from the jettison fuel refuel manifold fuel flows out of the jettison nozzles the nozzles are very visible and can be found between the aileron and outboard flap on each wing for lightning resistance their ball valve design is plastic that's pretty cool but the downside is slower operation compared to other valves it's not that bad though normal case is four seconds and the worst case is 12 seconds in very cold temperatures no you don't have to remember any of that just push the buttons jettison complete you probably be carrying out other tasks while the jettison is in process jettison goes on until the selected quantity is reached though nevertheless then eighty seven hundred pounds per main tank and then stops automatically the system does this by closing the defuel isolation and jettison isolation valves but you still have to close the nozzles valves manually by pushing the switches again I guess this design was put in place to be certain that sky net wouldn't secretly dump your fuel the valves are hardwired to the flight deck switches so they can't be controlled by the software you'll close the nozzles when you complete the fuel jettison checklist the second part of that checklist begins with a box item that says when fuel jettison is complete since shutoff is automatic there is no major alert to the crew that jettison is complete however commonly seen in the simulator it often leads to an I cast caution message namely fuel auto jettison this message comes with a beeper amber why does this message show because one of the criteria for activation is that the total fuel is less than the fuel to remain and the nozzle is still open so if you think about it that makes sense jettison is complete but you haven't completed the last part of the jettison checklist which includes closing the nozzles so the engines will burn off fuel and moments later the fuel on board will be less than the fuel to remain if you complete the jettison checklist the message should go further jettison considerations since fuel jettison takes some time a third option could be to jettison fuel part of the way through towards max landing weight and then still do an overweight landing but this this one being somewhat lighter expect higher workload as you have to work with two checklist but it might be something to consider fuel imbalances the fuel imbalance limitation is stricter at higher fuel loads because the longitudinal axis load increases the amber fuel imbalance message is displayed well prior to the F AFM limitation it's recommended to only balance fuel when that message is shown no that the primary purpose of this AFM limitation is the structural life of the airframe and landing gear and not for control ability like crew training mat this means that in the long term it would be bad for the aircraft but in a very short term it won't affect your single engine landing this message has a tendency to show up when workload is already at the maximum do do an engine failure if time allows do the checklist and balance fuel but it would also be acceptable to continue in land without doing so that said the fuel imbalance will increase trim drag and result in higher fuel consumption there are two options cross-feed or use the fuel balancing system describe non-normal procedures assume that the fuel balance balance system is used as the primary method. Crossfeed, as done on all Boeing models, is available as a backup method. The fuel balance system is capable of a rate up to 135 liters per minute, and is generally faster than crossfeeding. A thousand kilogram of end balance would be corrected in about seven minutes with the fuel balance system. Crossfeeding in the same situation would take up to 12 minutes since it is limited by fuel flow. Fuel balance system. It's kind of foolproof. Push the button and hold for one second, and fuel from the tank with the higher quantity is transferred for the defueled jettison valve over to the other side. It might take up to 30 seconds for the system to activate when both tanks have the same quantity the system stops automatically. That said, what isn't foolproof might be why your fuel is unbalanced in the first place. Make sure it's not a fuel leak. You've got before you push the button, the checklist will guide you through this process. Since we all know that you love long lists of conditions, here's one. The fuel balance system won't work if a center tank pump is on. On the ground, if an engine or two is running, during fueling operation, during fuel jettison, or if you have either amber fuel disagree, amber fuel quantity low, amber fuel balance system messages are active. The last one being a bit obvious. So, the fuel balance system is inhibited during fuel jettison, and if you're started fuel balancing and then decide to start jettison, the jettison will take priority. Fuel balancing will stop, and fuel balance system will show. The only time we've used the fuel balance system outside of the simulator is on the ground when the APU has been running for a long period of time. We recommend getting the flight crew operating manual supplementary procedure chapter out in any case and work from that. It will tell you exactly how to do it. The general electric GENX is a dual rotor actual flow high bypass turbofan engine. What does that all mean? Well, we learn back in ATPL ground school, and then promptly forgot about it. So, let's break it down for an easy refresher. Dual rotor. The GENX has two rotors, also called spools or shafts. The low pressure shaft N1 connects the low pressure turbine to that 60, sexy 111 inch 18 blade fan, and also the four stage low pressure compressor. Meanwhile, the high pressure shaft N2 lets the high pressure turbine turn the 10 stage high pressure compressor, also the accessory gearbox. Pro note, the Rolls Royce Tramp 1000, the other 787 engine option, has a third rotor and three. Actual flow. This means airflow is parallel to the engine axis of rotation. High bypass. Bipass and GENX is simply about training exhaust velocity for extra mass flow. Famously described as gearing down the flow. You get the required thrust for subsonic flight using less fuel. Pretty much all airliners today have high bypass engines for fuel economy and reduce noise to very popular things these days. In the later years of the jet age, the GENX bypass ratio is about 9 to 1. Turbofan. This is a given in order to be high bypass. A turbofan engine can be thought of as a turbojet ducted or a turbojet driving a ducted fan. While both of these parts contribute to thrust, the fan of the GENX stands for about 80% of the total thrust during takeoff. Engine start. For engine start, the overhead panel start selectors are set to start to engage the starter motors. Remember, it's all electrical, no bleed air. And the fuel control switches are set to run to arm fuel flow and ignition. The start sequence is then fully automatic and controlled by the EEC. The APU generators are powering the buses which in turn power the large motor power system. They in turn provide the electricity for the engine driven starters or the engine starters. Chevrons. Those sawtooth patterns on the back of the engine the cells are called Chevrons. It's a relatively new invention developed by Boeing and NASA and they have only one purpose. Noise reduction. The Chevrons help smooth the mixing of the air that's gone through the engine. With the air that flows outside and around it as this mixing of air becomes less turbulence, noise is reduced. NASA uses the expression smooth the mixing. The relatively small projection of the Chevron Apexes into the jet produces aerodynamically smooth flow guidance to force an accelerated mixing process of jet to jet or jet to ambient air and generates significant stream-wise vorticity which further accelerate the mixing process. The resultant shorter mixed jet plume length and reduced plume perimeter results in lower levels of audible jet noise and significantly reduce infrared signature. So in a way small turbulence is created to mix the air and that way avoid bigger noisy turbulence. Beyond the definition it works really well so so well that the 7-8 requires several hundred pounds less fuselage noise insulation. Ice, crystal, icing, protection, icing conditions are usually encountered at lower levels, close to where the temperature is at or just below zero Celsius. Until recently it was assumed that any ice particles at higher levels would just bounce off the aircraft pass harmlessly through the bypass ducts or melt inside the engine. Perhaps because of the new engine designs this isn't always the case. In certain conditions small ice particles melt in the engine core and then accumulate on internal surfaces. This has caused engine issues such as thrust loss and even damage in a number of cases. The GE-NX engine has a software-based ICA ice crystal and a icing function which when in icing conditions are detected or when icing conditions are detected it automatically cycles the VBV variable bypass valves situated between the booster and the high pressure compressor ejecting any ice into the bypass duct. The ICA won't only activate above 30,000 feet when it activates it runs for at least 30 minutes plus an additional 15-minute increment while still in icing conditions. ICA shows on the ICAS but it is important to understand that this doesn't necessarily mean that ice is encountered just that the conditions for it are present. It is normal to see engine parameters fluctuate. Impact on fuel consumption is insignificant. The system terminates when descending below 28,500 feet.