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737NG Complete loss of electrical power.

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737NG Complete loss of electrical power.

Old 19th Mar 2021, 08:59
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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 youíre 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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Old 19th Mar 2021, 09:32
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Is the RAT on your destroyed by lightning list.
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Old 19th Mar 2021, 09:35
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He said 737 not Airbus!
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Old 19th Mar 2021, 11:03
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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
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Old 19th Mar 2021, 11:52
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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.
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Old 19th Mar 2021, 11:59
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Centaurus, A very good point. Not unlike a glassy water landing in a float plane, but infinitely more difficult at night in total darkness.
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Old 19th Mar 2021, 12:21
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Originally Posted by FlyingStone View Post
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
Flaps will still work, itís 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 donít believe me.
Engine fuel spar valve has its own battery so can always shut engine down.
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Old 19th Mar 2021, 14:51
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Originally Posted by skysod View Post
If you were unlucky enough to lose all generators (say a freak lightning strike) and youíre over the sea with the nearest airport 1 hour away (single battery installed).........what are your options?.......what happens when the battery dies?
I'm not a fan of these purely hypothetical questions. Why make it easy and take the NG? Take a 737 classic, 30 minute battery. Same rules apply.

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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Old 19th Mar 2021, 15:57
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Originally Posted by FlyingStone View Post
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
What's electrical concerning normal gear extension?
What about spoiers?
Reversers?
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Old 19th Mar 2021, 16:39
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Surely you would have a GPS in your bag,or on your wrist...????
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Old 19th Mar 2021, 17:32
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Originally Posted by Gin Jockey View Post
Flaps will still work, itís 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 donít believe me.
Engine fuel spar valve has its own battery so can always shut engine down.
Ah, right. I thought everything goes through FSEU on the NG.

Originally Posted by 411A NG View Post
What's electrical concerning normal gear extension?
What about spoiers?
Reversers?
You're right about the gear and spoilers - they should operate normally, except for ground spoilers of course.

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.
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Old 19th Mar 2021, 18:09
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I glad to finally see a subject that recognizes the problem flying the NG and the even the 737MAX ETOPS or remote areas.
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Old 19th Mar 2021, 19:03
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Originally Posted by Centaurus View Post
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
We'd had this sort of discussion with the FAA more than once - not specifically about water ditching, but about 'why can't we train them for this in the simulator'.
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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Old 19th Mar 2021, 19:16
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You're forgetting about an ATR that had to ditch in the Mediterrenean Sea. Also the Air Transat A330 event caused by a fuel leak was a close call.
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Old 19th Mar 2021, 19:20
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Originally Posted by WhatsaLizad? View Post
I glad to finally see a subject that recognizes the problem flying the NG and the even the 737MAX ETOPS or remote areas.
You're talking about a triple failure to get there, after which the aircraft is still flying normally, albeit for a limited period of time, and is then still controllable with extremely limited instrumentation.

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.
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Old 19th Mar 2021, 19:48
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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.
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Old 19th Mar 2021, 21:10
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g

Originally Posted by WhatsaLizad? View Post
I glad to finally see a subject that recognizes the problem flying the NG and the even the 737MAX ETOPS or remote areas.
You can have a gen failure, but the problem shouldn't go "far" as AC sides are not interconnected (no parallelling of AC sides). And there is a mandatory backup (APU).

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 21:27.
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Old 19th Mar 2021, 21:28
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Originally Posted by WhatsaLizad? View Post
The number of possible diversion runways available to become even more limited in the case of the MAX after losing all generators.
Any particular reason why MAX would be more limited in that regard than NG?
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Old 19th Mar 2021, 21:48
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Originally Posted by WhatsaLizad? View Post
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.
I only have experience of one companyís ETOPS requirements on the NG so itís not definitive, but we couldnít dispatch an ETOPS flight unless both engine generators and the APU generator was serviceable. In flight the APU had to be started prior to the ETOPS entry point and if it didnít start or one of the engine driven generators failed prior to the entry point then we had to re-route to ensure we remained within one hour of a suitable airfield. I would imagine that would apply to most ETOPS aircraft unless they have a RAT that can provide sufficient power if one of the other sources fails.
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Old 19th Mar 2021, 22:02
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Originally Posted by FlyingStone View Post
Any particular reason why MAX would be more limited in that regard than NG?
Required runway length for the MAX with a loss of all generators scenario. I'm not sure of the reason, but the loss of anti-skid along with the loss of the electric flight/ground spoilers might be the culprit. The numbers are surprisingly large, especially for a wet/good runway.

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