737NG Complete loss of electrical power.
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737NG Complete loss of electrical power.
If you were unlucky enough to lose all generators (say a freak lightning strike) and you’re over the sea with the nearest airport 1 hour away (single battery installed).........what are your options?.......what happens when the battery dies?
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You should still be able to fly by looking out the window, and using standby altimeter and airspeed indicator. If you're lucky and happen to be in an aircraft fitted with ISFD, that has its own battery that should last 150 minutes, so you get the artificial horizon as well in that case. Magnetic compass obviously works, but it may be a bit off, since it's normally calibrated with all the electrical equipment switched on.
Flight controls should work normally as you have both EDPs operating (otherwise it's back to manual reversion), but you lose the ability to extend flaps. Emergency landing gear extension should work as well. No reversers on landing, but normal brakes and nosewheel steering should still work.
Not sure if you'd be able to shut down the engines as all valves are electrically actuated, but if you've made it that far, that's the least of your problems
Flight controls should work normally as you have both EDPs operating (otherwise it's back to manual reversion), but you lose the ability to extend flaps. Emergency landing gear extension should work as well. No reversers on landing, but normal brakes and nosewheel steering should still work.
Not sure if you'd be able to shut down the engines as all valves are electrically actuated, but if you've made it that far, that's the least of your problems
Unintended slight thread drift. Having done several simulated approaches to a power on ditching at night in a real four engined maritime aircraft of another era, survival at impact depends heavily on pilot raw data instrument flying skills. Rate of descent no more than 200 feet per minute and optimum nose attitude, IAS as slow as is considered safe. Then because the QNH may be unknown you need to be stablised under those conditions for the last 500 feet at least. In those days we laid our own flare path time permitting using flame floats.
With todays sophisticated simulators a simulated approach to ditching is feasible. Yet in my experience in the airline industry I have yet to see pilots demonstrate their skills at this sequence. Having said that, and probably because I have taken part in several "simulated" ditchings at night in a real maritime reconnaissance military aircraft over real water (requirement to go-around 200 ft above the sea), I can attest it takes very careful instrument flying when 200 miles out to sea at night where it is real black.
To those who say ditching an airliner is so remote so no need to demonstrate skill, consider the possibility of an uncontrollable engine or airframe fire and the need to get down quickly before control is lost and you are over water. A ditch or die situation so to speak.
For thirty minutes twice a year in a simulator, would that not be good confidence builder and value for money? After all, it is the last 1000 ft of descent which need to be practiced in tems of aircraft handling on instruments. Forget checklists and long briefings. That can be discussed in the briefing room. It is all about skilful attitude flying and careful throttle handling over a period of three or four minutes prior to impact. if you have never had the opportunity to practice a ditching approach on instruments, survival chances are slim if it happens for real. From experience I can tell you it takes several practices in the simulator before competency is assured. There are no second chances if it happens for real
Now back to the original post with apologies for hijacking the author's subject of total electrical failure over water.
With todays sophisticated simulators a simulated approach to ditching is feasible. Yet in my experience in the airline industry I have yet to see pilots demonstrate their skills at this sequence. Having said that, and probably because I have taken part in several "simulated" ditchings at night in a real maritime reconnaissance military aircraft over real water (requirement to go-around 200 ft above the sea), I can attest it takes very careful instrument flying when 200 miles out to sea at night where it is real black.
To those who say ditching an airliner is so remote so no need to demonstrate skill, consider the possibility of an uncontrollable engine or airframe fire and the need to get down quickly before control is lost and you are over water. A ditch or die situation so to speak.
For thirty minutes twice a year in a simulator, would that not be good confidence builder and value for money? After all, it is the last 1000 ft of descent which need to be practiced in tems of aircraft handling on instruments. Forget checklists and long briefings. That can be discussed in the briefing room. It is all about skilful attitude flying and careful throttle handling over a period of three or four minutes prior to impact. if you have never had the opportunity to practice a ditching approach on instruments, survival chances are slim if it happens for real. From experience I can tell you it takes several practices in the simulator before competency is assured. There are no second chances if it happens for real
Now back to the original post with apologies for hijacking the author's subject of total electrical failure over water.
Centaurus, A very good point. Not unlike a glassy water landing in a float plane, but infinitely more difficult at night in total darkness.
you lose the ability to extend flaps. Emergency landing gear extension should work as well. No reversers on landing, but normal brakes and nosewheel steering should still work.
Not sure if you'd be able to shut down the engines as all valves are electrically actuated, but if you've made it that far, that's the least of your problems
Not sure if you'd be able to shut down the engines as all valves are electrically actuated, but if you've made it that far, that's the least of your problems
Engine fuel spar valve has its own battery so can always shut engine down.
The battery will die, probably before you know it (don't count on 30 minutes)... Still confused by people saying you can "fly" when the battery dies. Just pray you have a moon to help you out with your manual trim.
If it happens, you are not flying, you are trying to survive in the best possible way and you either die, or you become a living hero.
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You should still be able to fly by looking out the window, and using standby altimeter and airspeed indicator. If you're lucky and happen to be in an aircraft fitted with ISFD, that has its own battery that should last 150 minutes, so you get the artificial horizon as well in that case. Magnetic compass obviously works, but it may be a bit off, since it's normally calibrated with all the electrical equipment switched on.
Flight controls should work normally as you have both EDPs operating (otherwise it's back to manual reversion), but you lose the ability to extend flaps. Emergency landing gear extension should work as well. No reversers on landing, but normal brakes and nosewheel steering should still work.
Not sure if you'd be able to shut down the engines as all valves are electrically actuated, but if you've made it that far, that's the least of your problems
Flight controls should work normally as you have both EDPs operating (otherwise it's back to manual reversion), but you lose the ability to extend flaps. Emergency landing gear extension should work as well. No reversers on landing, but normal brakes and nosewheel steering should still work.
Not sure if you'd be able to shut down the engines as all valves are electrically actuated, but if you've made it that far, that's the least of your problems
What about spoiers?
Reversers?
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Flaps will still work, it’s purely a hydro mechanical link from flap lever to flap actuation (thank you 1960s design) but no indication, asymmetry / over speed protection (FSEU obviously has no power). Try it in your next sim if you don’t believe me.
Engine fuel spar valve has its own battery so can always shut engine down.
Engine fuel spar valve has its own battery so can always shut engine down.
A lot of relays and electrically operated valves need to be powered in order to deploy thrust reversers. Think about air/ground logic, radio altimeter, etc.
To those who say ditching an airliner is so remote so no need to demonstrate skill, consider the possibility of an uncontrollable engine or airframe fire and the need to get down quickly before control is lost and you are over water. A ditch or die situation so to speak.
For thirty minutes twice a year in a simulator, would that not be good confidence builder and value for money? After all, it is the last 1000 ft of descent which need to be practiced in tems of aircraft handling on instruments. Forget checklists and long briefings. That can be discussed in the briefing room. It is all about skilful attitude flying and careful throttle handling over a period of three or four minutes prior to impact. if you have never had the opportunity to practice a ditching approach on instruments, survival chances are slim if it happens for real. From experience I can tell you it takes several practices in the simulator before competency is assured. There are no second chances if it happens for real
For thirty minutes twice a year in a simulator, would that not be good confidence builder and value for money? After all, it is the last 1000 ft of descent which need to be practiced in tems of aircraft handling on instruments. Forget checklists and long briefings. That can be discussed in the briefing room. It is all about skilful attitude flying and careful throttle handling over a period of three or four minutes prior to impact. if you have never had the opportunity to practice a ditching approach on instruments, survival chances are slim if it happens for real. From experience I can tell you it takes several practices in the simulator before competency is assured. There are no second chances if it happens for real
Bottom line, simulator time is valuable. You need to prioritize what you're going to train for. And water ditchings of commercial airliners is extremely rare - two in the last 50 years, and those had extenuating circumstance. Sully didn't need to land on the water - he chose that as the best option rather than coming down in the middle of the city. Ethiopian was a hijacking.
Bottom line, there are more likely emergency scenarios that need to be trained for with the limited amount of sim time.
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737 has been flying for more than 50 years and I haven't heard of any incidents where all three AC sources have failed. If you know of any, please share, it would be an interesting read.
FS,
Curious as well regarding the number of jet transport aircraft that have ended up on battery power. I am also unsure of the MEL practices around the world. Agreed that a triple generator failure would be extremely rare in the 737 case, but dispatch with 1 engine generator inop might have an effect on the probabilities given the sometimes temperamental aspects of APU's. The number of possible diversion runways available to become even more limited in the case of the MAX after losing all generators.
The 737 is ranging far more than it has in the last 50 years.
Curious as well regarding the number of jet transport aircraft that have ended up on battery power. I am also unsure of the MEL practices around the world. Agreed that a triple generator failure would be extremely rare in the 737 case, but dispatch with 1 engine generator inop might have an effect on the probabilities given the sometimes temperamental aspects of APU's. The number of possible diversion runways available to become even more limited in the case of the MAX after losing all generators.
The 737 is ranging far more than it has in the last 50 years.
g
If you would end up with two generators at departure you would never end up beyond non-etops, and mentally you are ready for diversion as soon as one other gen would fail in a non-etops environment. Again, 2 not connected systems. And Boeing procedures in case of single generator are simple: land. So this cannot really happen "all of a sudden".
If we consider "user" failures, bus breakers would pop and the fault would be isolated without reaching a power source.
There's a lot that can happen, but there's no need to stretch your lottery chances of I don't know how many unrelated failures happening at the same time... History has shown humanity is more prone to "forgotten" kg to lbs conversions than electrical bugs taking down full electrical systems.
Last edited by BraceBrace; 19th Mar 2021 at 20:27.
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FS,
Curious as well regarding the number of jet transport aircraft that have ended up on battery power. I am also unsure of the MEL practices around the world. Agreed that a triple generator failure would be extremely rare in the 737 case, but dispatch with 1 engine generator inop might have an effect on the probabilities given the sometimes temperamental aspects of APU's. The number of possible diversion runways available to become even more limited in the case of the MAX after losing all generators.
The 737 is ranging far more than it has in the last 50 years.
Curious as well regarding the number of jet transport aircraft that have ended up on battery power. I am also unsure of the MEL practices around the world. Agreed that a triple generator failure would be extremely rare in the 737 case, but dispatch with 1 engine generator inop might have an effect on the probabilities given the sometimes temperamental aspects of APU's. The number of possible diversion runways available to become even more limited in the case of the MAX after losing all generators.
The 737 is ranging far more than it has in the last 50 years.