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View Full Version : Double ENG failure 733 what would you do?


endofeng
21st Jan 2010, 17:09
Scenario: TOC you get fuel filter cautions - both engines, followed by simultaneous eng shutdown.

Actions: Action the QRH, get the APU started and on bus. You are unable to restart the engines so you head for the nearest longest airfield, join the overhead and continue to descend at best glide speed. You have approx 12k feet to loose in the overhead.

My question is:

Can you use your APU to assist in dropping the gear and flap operation? If so how????

Many thanks in advance:ok:

Gary Lager
21st Jan 2010, 17:19
Yes but since you can only put it on one bus at a time whilst airborne, i suggest you fly a 'high' profile to runway at 210kts, drop the gear when you KNOW you're going to make it (500'?), swap the APU onto the other bus, select Flap 40 and just land with whatever flap you have by the time you touch down. Works quite well in the sim!

endofeng
21st Jan 2010, 17:41
Thanks GL,

I knew you could do this, ie one bus at a time, but just wanted clarification and best technique.....

Forgive my laziness here ( not got my tech manual to hand), but which bus for gear and which bus for flap?

Thanks:ok:

FE Hoppy
21st Jan 2010, 17:51
If you are 12K in the overhead isn't there some merit to dirtying up early to get a feel for your descent rate when configured?

Empty Cruise
21st Jan 2010, 18:16
Depends on altitude... If at 500 ft after T/O, I'd just drop the nose, call for gear and flaps (hope that a bit of windmilling might assist), then call for manual gear extension and hope for a decent site to put her down.

Above FL100, again, memory items for hot relight, trim to green dot speed while calling for the APU and calling for masks on, deciding where we're going in and then attempting relight once APU was up and running.

Higher up, I'd start the stopwatch (12 min O2 in the PSUs) and might consider trying a windmill relight after deciding where we're heading and being happy that we have the altitude to do it. Then cranck the APU when lower etc etc.

If on approach - well, depends on altitude, speed and distance to go :-/

Kirks gusset
21st Jan 2010, 19:15
Endofeng, I am confused , we have reached the TOC and now have a pressurisation issue and a power issue. We assume you have:

Declared a MAY DAY.

Completed the recall items for Loss of Thrust on Both Engines

Established the appropriate speed for a immediate windmill restart attempt,

( higher probability of start due to higher engine RPM), but drift down may be required to below FL30 to improve windmilling capability if unsuccessful.

Started the APU when available ( relight not guaranteed above FL250).

Initiated the Rapid Relight Recall items before attempting APU start.

Do not confuse the establishment of APU power with engine driven gen power at idle rpm.

Turned towards the landing airport and started the drift down.

Of course, at lower levels, you are trading altitude for speed and in reality you will have to decide when to abandon the relight attempt and " Fly the airplane" as 12K feet only gives you about 36 track miles to configure and land.

As one comment states you can only Power one Bus from the APU and thus you would need to prioritise and switching buses at a critical phase of flight may not be a good idea. You would subsequently get more master cautions and distractions as well as load shedding, dont create your own chaos.

Gear is dropped using alternate method, flaps use alternate method if system B pressure is low. I would tend to put the APU on Gen bus 1 and leave it there. You have 30 mins battery power at least and only 10 mins in the air:)

Straight in final, configure early to allow for incresed flap time, drop gear as late as possible.

In FCTM there is a good section on Non Normals outside of the scope of the checklist.. worth a look

endofeng
21st Jan 2010, 19:43
KG,

Thanks for your thoughts. I was thinking more on terms of a short hop so cruise 180 or the likes. Yes I agree - prioritise ie pressurisation, ANC, recalls etc but relight unsuccesful, committed to double eng failure landing scenario sort of thing, highly unlikely, but possible!

I'm more interested in peoples thought processes and as already mentioned the use of the APU gen for gear/flap extension. I think I'd be inclined to head for the nearest suitable available airfields' overhead, better to crash on a runway than 2 miles short, fly the green dot and configure as late as possible. My priority for landing would of course be gear over flaps, especially on a long R/W, but as I've asked would using the APU gen ( which gen?) be beneficial over the alternate gear extension?, as the alternate gear extension is gravity drop and at a moment of high workload would it be worth swapping gens etc over pulling the altn gear?

Thanks guys:ok:

Checkboard
21st Jan 2010, 20:14
TOC you get fuel filter cautions - both engines, followed by simultaneous eng shutdown.

I don't know that you are going to trust the APU in this case! :hmm:

12,000 feet in the overhead, 4,000' per orbit, two orbits, then position so that you are over the outermarker at twice the chart height AGL. (typically this will be about 3,000' AGL), gear up, flap 5 and inbound. If you make that point, gear down flap 15 and landing isn't a problem. :ok:

Manual gear extension, and windmilling engines for enough hydraulic power to get the flaps out.

frontlefthamster
21st Jan 2010, 21:25
Gping
Fatboy

endofeng
21st Jan 2010, 21:30
Cheers guys....confirmed my suspicions and some:ok:

Although I'm not sure what Gping means:confused:

CHfour
21st Jan 2010, 23:09
Loss of thrust on both engines (http://www.b737.org.uk/lossofthrust.htm)

Right Way Up
22nd Jan 2010, 00:00
Avenger,
Like BOAC I cannot see how configuring early will lessen altitude loss for same track miles. Perhaps I have misunderstood. :confused:

mvsb1863
22nd Jan 2010, 02:18
Hi Friends
Fortunately loss of thrust on both engines or double engine failure is an exceptionally rare occurrence. So rare that I have never, let me say again, I have never heard about a real case of Loss of thrust on both engines that has happened in the Boeing 737 history with a happy end. Not at all. So, why worry ???
I do believe that everybody here understand what does "exceptionally rare" mean!!!

NEVERRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR !!!!!!!

Thanks: :D

737 Checker
22nd Jan 2010, 03:39
"mvsb1863 Hi Friends
Fortunately loss of thrust on both engines or double engine failure is an exceptionally rare occurrence. So rare that I have never, let me say again, I have never heard about a real case of Loss of thrust on both engines that has happened in the Boeing 737 history with a happy end. Not at all. So, why worry ???
I do believe that everybody here understand what does "exceptionally rare" mean!!!

NEVERRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR !!!!!!!"

Seem to remember a classic that had a double failure as a result of rain ingestion and landed on a levee. Ryanair had one too last year, too many birds. A/C written off but no px dead. Rare yes, never happened no.

kijangnim
22nd Jan 2010, 04:41
Greetings
Engine Failure or Engine Flame out? because Both Engine Flame out exists, and happened on the A330 GE engines and not only once , forcing GE to provide a software "Patch" to work around the problem, which means that the problem is not solved yet:E

jeff64
22nd Jan 2010, 09:35
And I'm sure 320 drivers didn't heard any double engine Shutdown before Cactus 1504.

endofeng
22nd Jan 2010, 10:17
CHfour,

Thanks for the link - Perfect, just what I was looking for. Rare, maybe, but in the sim not so.....

Forewarned is forearmed etc....:ok:

Avenger
22nd Jan 2010, 10:30
BOAC I've edited the text, the intention was to state that at a lower speed the required ROD would be less and the time to landing more, allowing for alternate systems to extend flaps etc. You are quite right.. it didn't make sense in the previous format.. thanks

Big Pistons Forever
23rd Jan 2010, 01:28
And I'm sure 320 drivers didn't heard any double engine Shutdown before Cactus 1504.

Not sure you can even count this as a double failure as I thought both engiens were producing a little thrust, not enough to fly but enough to power systems. I believe the aircraft was in normal law when it hit the river. The only total power loss landing in any modern jet airliner that I can think of was the Air Transat A330 deadstick in the Azores and the AirCanada B767 incident at Gimli. So far we are batting 1000 on deadstick landings :ok:

lunav
23rd Jan 2010, 02:38
dear endofeng to answer to your question:
Gen Bus 1 to extend the FLAPS
gen Bus 2 to extend the GEAR.

framer
23rd Jan 2010, 04:10
Man there are a million ways to skin a cat aye?
In the sim I mucked around with it a bit and found that 4000ft aal, green dot, clean at 10nm, no wind , worked well. How you get there is going to depend on the day, it may well be more appropriate to go overhead. I configured late but can't remember if I did it with alternate or by swapping APU gens.
The idea of configuring early is, in my opinion, a bad one.

john_tullamarine
25th Jan 2010, 12:02
For what it's worth, some years ago I ran this exercise with some ex-Chinese AF fighter jocks who were then flying with a Chinese 733 operator.

Just about every pilot did it differently, from dirty on high to fast initial .. and every pilot got in just fine.

Not sure what to make of that but it was interesting to watch from the organ grinder's seat in the back.

RAT 5
26th Jan 2010, 12:40
Lunav: Well done; short sharp correct answer due to the cross over of buses to relevant ELEC HYD pumps. Remember that to swap over the busses you have to first de-select the APU off the bus then reselect it on the other bus. I gave an electrical/hydraulic scenario in the sim where this switching over was chosen by one command candidate. However, he was confused why it didn't work. Other candidates chose manual gear extension over manual flaps, but it was a combination of hydraulic & electrical problems that left you with only electrical choices. It also gave the choice of what system to have powered in the case of G/A.
To complete your double engine failure scenario UP speed should give enough windmill power to use the engine driven pump, but I suspect more slowly than normal rate, however, the gear once unlocked should fall anyway. Once in your descent window F5 idle power gives almost a 3 degreee glide angle, so MK. 1 eyeball will be in tune with the normal picture. Aim at the far end of the Rwy, depending on length. When certain drop F15 & gear, then any more flap as required. If I had to choose for the APU I'd put it on Bus 1 to use the flaps more quickly, and be ready to pull the gear handles if the normal system sticks.