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LOT 767 Belly Landing First Investigation Report  
User currently offline3MilesToWRO From Poland, joined Mar 2006, 280 posts, RR: 0
Posted (2 years 9 months 3 weeks 1 day 11 hours ago) and read 11230 times:

First report was issued about last month Warsaw belly landing of LOT 767. The document is in Polish so far but I guess some automatic translator will be sufficient if anyone is interested.
http://bi.gazeta.pl/im/3/10739/m10739573,RAPORT.pdf

In short: just after take off hydraulic system C lost pressure. After consultation with ground the crew decided to keep flying. Upon approach in Warsaw the gear did not come out. Approach was aborted, again of course ground consultation and fighters checking from outside. Finally there was the landing everyone saw, I guess.
Inspection after landing revealed that on panel P6 circuit breaker C829 BAT BUS DISTR was in "off" position and breaker C4248 LANDING GEAR – ALTN EXT MOTOR was in "on" position. State of C829 is not reported to the crew nor written to FDR.
After lifting the aircraft ground power was connected, (A1) BAT BUS DISTR breaker switched on and the gear was extended successfully.

Faulty hydraulic hose was identified and sent to NTSB.

40 replies: All unread, showing first 25:
 
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17039 posts, RR: 66
Reply 1, posted (2 years 9 months 3 weeks 1 day 10 hours ago) and read 11183 times:

Quoting 3MilesToWRO (Thread starter):
After lifting the aircraft ground power was connected, (A1) BAT BUS DISTR breaker switched on and the gear was extended successfully.

So if I'm reading that right, if the crew had set the breaker to "on" they would have landed normally? Is the breaker easily accessible and is it on the gear fault checklist?



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinelonghauler From Canada, joined Mar 2004, 4985 posts, RR: 42
Reply 2, posted (2 years 9 months 3 weeks 1 day 9 hours ago) and read 11158 times:

The breaker is just to the right of the F/O at floor level, easily accessible and visible.

But would you reset it?

First, one would have to determine when it popped. Did it pop before the first attempted Alternate Gear Extension, or did it pop as a result of it? Big difference!

Secondly, if you could determine it was popped all along, (you couldn't, but playing "what if"), then yes a reset is a possibility. But if it did pop when first attempting an Alternate Gear Extension, would you risk resetting it? Why re-energize an electrical system (with a known electrical problem) possibly sitting in a pool of flammable hydraulic fluid?



Never gonna grow up, never gonna slow down .... Barefoot Blue Jean Night
User currently onlineokie From United States of America, joined Jul 2003, 3041 posts, RR: 3
Reply 3, posted (2 years 9 months 3 weeks 1 day 9 hours ago) and read 11151 times:

Quoting Starlionblue (Reply 1):
So if I'm reading that right, if the crew had set the breaker to "on" they would have landed normally? Is the breaker easily accessible and is it on the gear fault checklist?


That is kind of unusually worded.
If the breaker had been "on" then they would have been able to successfully lower the gear by alternate means would be the correct statement.

I can not answer that if after several changes, cycles, of the gear lever and tries of the manual extension if that would allow the manual extension of the gear if controls were out of sequence even if the breaker was returned to the on position.
However the brief explanation above indicated that it could have been accomplished.

The real question here is that even with Mx involved, QRH and the pilots and a with time to spare that the circuit breaker was overlooked for the alternate extension.


Okie


User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9639 posts, RR: 52
Reply 4, posted (2 years 9 months 3 weeks 1 day 8 hours ago) and read 11091 times:

Thanks for the article and translation. The center hydraulic system is what normally operates the gear on a 767. They lost that system shortly after takeoff, so primary extension is effectively dead. It appears that for some reason the alternate system was not working. It's hard to know why since the circuit breaker could have been popped when it was attempted to be used, it could have been inadvertently left open, something else could have happened. It sounds like one of those once in a billion scenarios where two faults happened that are unrelated to each other which happened to disable the landing gear.

Landing gear typically only has two methods of extension unlike primary flight controls which have triple redundancy. It looks like the odds were not in the favor of that airplane on that day. I wonder if the airplane had been flying with a problem in the alternate extension system for a while and it was only found out when the primary system was disabled due to a hydraulic failure.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineEGGD From United Kingdom, joined Feb 2001, 12443 posts, RR: 34
Reply 5, posted (2 years 9 months 3 weeks 1 day 6 hours ago) and read 11012 times:

I wonder had it not been a technical fault that caused the breaker to trip, whether it was pulled by accident? The panel where it is situated is not ideally sighted and I've known of people to pull circuit breakers by accident when moving crew bags or when accessing charts that are sometimes placed in front of it. If that was the case then it would have been a real unfortunate chain of events but I suppose that is how incidents and accidents of such a low-probability scenario occur.

User currently offline767eng From United Kingdom, joined Oct 2010, 49 posts, RR: 0
Reply 6, posted (2 years 9 months 3 weeks 1 day 6 hours ago) and read 11002 times:

Quoting EGGD (Reply 5):
I wonder had it not been a technical fault that caused the breaker to trip, whether it was pulled by accident? The panel where it is situated is not ideally sighted and I've known of people to pull circuit breakers by accident when moving crew bags or when accessing charts that are sometimes placed in front of it. If that was the case then it would have been a real unfortunate chain of events but I suppose that is how incidents and accidents of such a low-probability scenario occur.

Too true, some airlines have bars across the front of the P6 circuit breaker panel between rows of breakers to stop them accidentally being knocked by crew bags. Ours don't and it is a place where the chart bags are normally kept on longhaul flights.

There is always a risk in pushing in a popped circuit breaker in flight as already damaged wiring may spark causing a fire to start. Tough call to make but from the report it does sound like the c/b was reset on the ground and stayed reset.


User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 7, posted (2 years 9 months 3 weeks 1 day 5 hours ago) and read 10946 times:

So "normal" gear extension failure can be traced back to a:

Quoting 3MilesToWRO (Thread starter):
Faulty hydraulic hose was identified and sent to NTSB.

and "alternate" gear extension failure was due the a pulled (by something or someone unknown) CB!

Kind of "anti climatic"!


User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2556 posts, RR: 24
Reply 8, posted (2 years 9 months 3 weeks 1 day 5 hours ago) and read 10914 times:

Some other Battery Bus powered equipment must have been unpowered as a result of C829 being pulled. Wasn't that noticed or indicated to the crew in some way? Does anyone here have access to 767 wiring information to check what other systems would be affected?


The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineMD11Engineer From Germany, joined Oct 2003, 14026 posts, RR: 62
Reply 9, posted (2 years 9 months 3 weeks 1 day 5 hours ago) and read 10891 times:

Quoting longhauler (Reply 2):
The breaker is just to the right of the F/O at floor level, easily accessible and visible.

This C/B (and others) on the P6 panel is in a location where it easily gets bumped when the F/O puts his flight bag into it´s stowage place.
Boeing has some stupid locations for C/Bs on the B737, B747, B757 and B767.

Jan


User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2556 posts, RR: 24
Reply 10, posted (2 years 9 months 3 weeks 1 day 5 hours ago) and read 10872 times:

Quoting Jetlagged (Reply 8):
Some other Battery Bus powered equipment must have been unpowered as a result of C829 being pulled. Wasn't that noticed or indicated to the crew in some way? Does anyone here have access to 767 wiring information to check what other systems would be affected?

To answer my own question, here's the report in English. It includes a list of the CBs which would lose power if C829 was pulled, together with photos of the CB location.

http://www.transport.gov.pl/files/0/30680/20111400RWenglish.pdf

Apparently none of these would show up to the crew as a caution on EICAS or be recorded in the FDR.



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineTristarsteve From Sweden, joined Nov 2005, 4008 posts, RR: 33
Reply 11, posted (2 years 9 months 3 weeks 1 day 4 hours ago) and read 10861 times:

Quoting Starlionblue (Reply 1):
So if I'm reading that right, if the crew had set the breaker to "on" they would have landed normally? Is the breaker easily accessible and is it on the gear fault checklist?

Yes, and it would not be on a gear fault checklist.

Quoting okie (Reply 3):
The real question here is that even with Mx involved, QRH and the pilots and a with time to spare that the circuit breaker was overlooked for the alternate extension.

The pilots and the QRH had no chance at all.
Maint had a very small chance. The CB concerned is not in Chap 32 Gear, it is in Chap 24 Electrics.
If you go to the FIM for the alt gear, the elect diagram says power from Batt. To find out more would take time (and more fuel onboard!)
If you don't know which CB you are looking for, I would not expect a pilot to find any tripped CB on P6.


User currently onlineokie From United States of America, joined Jul 2003, 3041 posts, RR: 3
Reply 12, posted (2 years 9 months 3 weeks 1 day ago) and read 10607 times:

http://www.transport.gov.pl/files/0/...0RWenglish.pdf

See if this works.

Quoting Tristarsteve (Reply 11):
If you go to the FIM for the alt gear, the elect diagram says power from Batt. To find out more would take time (and more fuel onboard!)
If you don't know which CB you are looking for, I would not expect a pilot to find any tripped CB on P6.


Thanks Tristar,
The more I think about it even if the F/O had noticed the breaker was tripped the F/O would not necessarily know that it was involved with the alternate extension.
Ok, here it comes............. but a F/E probably would.

Okie


User currently offlineKELPkid From United States of America, joined Nov 2005, 6385 posts, RR: 3
Reply 13, posted (2 years 9 months 3 weeks 19 hours ago) and read 10241 times:

Quoting okie (Reply 12):
The more I think about it even if the F/O had noticed the breaker was tripped the F/O would not necessarily know that it was involved with the alternate extension.
Ok, here it comes............. but a F/E probably would.

Okie

What do you want to bet we will see an accident board recommendation that a tripped breaker will trigger an EICAS alert when the primary extension hydraulic system is INOP   



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 14, posted (2 years 9 months 3 weeks 18 hours ago) and read 10237 times:

Quoting KELPkid (Reply 13):
What do you want to bet we will see an accident board recommendation that a tripped breaker will trigger an EICAS alert when the primary extension hydraulic system is INOP

I'll take that bet...you won't see that recommendation. You'll probably see a guard on the breaker.

Tom.


User currently offlineT prop From United States of America, joined Apr 2001, 1029 posts, RR: 1
Reply 15, posted (2 years 9 months 3 weeks 18 hours ago) and read 10222 times:

So if a C/B is out, and the crew knows about it, they have the choice of trying to reset it and see if the gear comes down, or belly it in. Why wouldn't they reset it? Try it once, if it pops again, well there's a short somewhere, now you have to deal with it. If it stays in and the gear comes down, this thread doesn't exist.

Quoting longhauler (Reply 2):
Why re-energize an electrical system (with a known electrical problem) possibly sitting in a pool of flammable hydraulic fluid?

To set Skydrol on fire, you have to try real hard, you'd have to do something like land with the wheels up, slide along on the belly with sparks and flames emitting from where the airframe is dragging on the ground, grind holes through the skin and... hey wait!


User currently offline3MilesToWRO From Poland, joined Mar 2006, 280 posts, RR: 0
Reply 16, posted (2 years 9 months 3 weeks 15 hours ago) and read 10152 times:

Considering that THE circuit breaker was not included in checklist for landing gear I guess that most useful recommendation would be to to expand this checklist (and all others, actually) with information about all breakers potentially involved. This way they would not be omitted like this one.
There is, indeed, some danger of fire since the breaker goes off for some reason. But I guess that balancing the risks is the job of people who write the flight manuals anyway.


User currently offlineTristarsteve From Sweden, joined Nov 2005, 4008 posts, RR: 33
Reply 17, posted (2 years 9 months 3 weeks 15 hours ago) and read 10140 times:

Quoting KELPkid (Reply 13):
What do you want to bet we will see an accident board recommendation that a tripped breaker will trigger an EICAS alert

What like an Airbus?
The A320 says CB tripped on rear or overhead panel.
A330 says which CB and which system.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 18, posted (2 years 9 months 3 weeks 10 hours ago) and read 10017 times:

Quoting T prop (Reply 15):
So if a C/B is out, and the crew knows about it, they have the choice of trying to reset it and see if the gear comes down, or belly it in. Why wouldn't they reset it?

They certainly might...but do we have any indication that the crew actually knew the CB was open in this case?

Quoting 3MilesToWRO (Reply 16):
Considering that THE circuit breaker was not included in checklist for landing gear I guess that most useful recommendation would be to to expand this checklist (and all others, actually) with information about all breakers potentially involved.

Flight crew checklists don't generally include circuit breakers, especially not as troubleshooting steps; the crew isn't supposed to have to screw with them in flight. They're supposed to be notified of any that are open during the dispatch process and anything that trips in flight 1) has a reason for tripping that the crew probably can't diagnose and 2) will generate an EICAS indication if it impacts a system that the crew needs for continued safe flight and landing. In this case, the gear (correctly) indicated on EICAS that it was still up.

This was one of those corner cases of the intersection of two totally unrelated failures impacting two redundant systems at the same time.

Quoting Tristarsteve (Reply 17):
What like an Airbus?
The A320 says CB tripped on rear or overhead panel.
A330 says which CB and which system.

What level ECAM message are individual circuit breakers on an A330?

Tom.


User currently offlinelonghauler From Canada, joined Mar 2004, 4985 posts, RR: 42
Reply 19, posted (2 years 9 months 3 weeks 10 hours ago) and read 10009 times:

Quoting T prop (Reply 15):
So if a C/B is out, and the crew knows about it, they have the choice of trying to reset it and see if the gear comes down, or belly it in. Why wouldn't they reset it? Try it once, if it pops again, well there's a short somewhere, now you have to deal with it. If it stays in and the gear comes down, this thread doesn't exist.

Because they have no way of knowing that the circuit breaker didn't already pop, and that there isn't already a short somewhere, and that the circuit breaker isn't already doing what it is supposed to do ... and that is protect the rest of the aircraft.

If there is a short somewhere, and now "You have to deal with it", it may not be something you can handle. One of the odd quirks about these breakers is that normally they don't just power one system, and this one is a prime example. Have a look at the list at what this breaker powers. It is a lot more than just the Alternate Gear extension. In fact, the "short" might have been somewhere other than the Alternate Gear Extension itself, and powering up an unknown already shorted system is never a good idea.



Never gonna grow up, never gonna slow down .... Barefoot Blue Jean Night
User currently offlineyeelep From United States of America, joined Apr 2011, 659 posts, RR: 0
Reply 20, posted (2 years 9 months 3 weeks 9 hours ago) and read 9949 times:

Here's the FAA's take on circuit breakers. I'm not sure if its the latest version. Each operator will have there own policy on resetting circuit breakers.

FAA Aviation Safety
SPECIAL AIRWORTHINESS INFORMATION BULLETIN
SAIB: CE-10-11
SUBJ: Electrical: Fire Hazard in Resetting Circuit Breakers (C/Bs) Date: December 23, 2009
This is information only. Recommendations aren%u2019t mandatory.

2. Essential C/Bs should be reset in flight only once:
a. after at least one minute;
b. if there is no remaining smoke or burning smell and
c. the affected system and equipment is needed for the operational environment.
3. Do not reset any non-essential C/Bs in flight.

From my airlines QRH manual 737-400/NG:

Circuit Breakers
WARNING! Opening, resetting or cycling of CBs is prohibited
except when following an approved QRH, Flight
Handbook, MEL procedure or in the Captain%u2019s
judgment an extreme condition exists which
makes it necessary for the safety of flight.
WARNING! Do not reset a tripped Fuel Pump, Fuel Quantity
Indication System, or (400) Lavatory Flush Motor
circuit breaker under any circumstance.
If a tripped circuit breaker needs to be reset, a two-minute cooling
period should be observed before resetting. If the circuit breaker
trips again, do not attempt another reset.
A Maintenance Logbook write-up, including a description of the
exact conditions when the trip occurred, when the CB was reset
and the results of resetting the CB, is required and may provide the
key to effective troubleshooting and corrective action by
Maintenance.
2/15/

[Edited 2011-12-02 07:06:21]

User currently offline767eng From United Kingdom, joined Oct 2010, 49 posts, RR: 0
Reply 21, posted (2 years 9 months 3 weeks 9 hours ago) and read 9905 times:

Quoting Tristarsteve (Reply 17):
What like an Airbus?
The A320 says CB tripped on rear or overhead panel.
A330 says which CB and which system.

Not all circuit breakers are monitored on the A320 though , only the green ones.


User currently offlineTristarsteve From Sweden, joined Nov 2005, 4008 posts, RR: 33
Reply 22, posted (2 years 9 months 3 weeks 8 hours ago) and read 9858 times:

Quoting tdscanuck (Reply 18):
What level ECAM message are individual circuit breakers on an A330?

Master warning with Amber caution and single chime
for all cbs except commercial ones.
Pushing CB button on ECAM control panel (in front of throttles)
will list all tripped cbs by name, position and FIN number.

But remember on A330 and also B777 and later aircraft, all the CBs are downstairs and
are not really accessible in flt.


User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9639 posts, RR: 52
Reply 23, posted (2 years 9 months 3 weeks 8 hours ago) and read 9838 times:

Quoting T prop (Reply 15):
Quoting longhauler (Reply 2):
Why re-energize an electrical system (with a known electrical problem) possibly sitting in a pool of flammable hydraulic fluid?

To set Skydrol on fire, you have to try real hard, you'd have to do something like land with the wheels up, slide along on the belly with sparks and flames emitting from where the airframe is dragging on the ground, grind holes through the skin and... hey wait!

Skydrol will only burn when in mist form and exposed to continuous source of ignition and it will not burn continuously. Flammability is a major reason why the nasty stuff is used over the much more mundane Mil Oil of the past. I don't think that's a concern.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineSaafnav From South Africa, joined Mar 2010, 276 posts, RR: 1
Reply 24, posted (2 years 9 months 3 weeks 7 hours ago) and read 9802 times:

Quoting yeelep (Reply 20):

WARNING! Do not reset a tripped Fuel Pump, Fuel Quantity
Indication System, or (400) Lavatory Flush Motor

I understand the Fuel Indicators and Pumps CB's. We have the same SOP's, but why the Lav Flush Motor?

Regards,
Erich



On-board Direction Consultant
25 litz : That probably comes from the DC9 that burned out due to a fire caused by an overheated lav flush motor ...
26 MD11Engineer : I once had a 737NG with a popping lav flush motor C/B, which was resetted repeatetely by the pilots. The reason of the C/B popping was a badly routed
27 longhauler : If you are referring to AC797, DFW-YYZ that ended up in CVG ... it was the other way around. The fire caused the flush pump to pop the circuit breake
28 Jetlagged : True, but what was needed in this case was an attention getter to alert the crew that an important CB is tripped (whether that's because of an electr
29 tdscanuck : I would say the lack of landing gear coming down was a pretty serious attention getter. Even if they'd known exactly why (CB open) they wouldn't know
30 ZANL188 : Could they have setup a CB reset while on, say a 5 mile final, try the gear and then land whatever the result? If the fault that tripped the CB start
31 vc10 : I feel very sorry for the crew, who no doubt will be blamed. Before my retirement if the drill was completed with no success, assuming time is availab
32 Tristarsteve : I work on ramp maintenance. I trip and reset CBs every day. Quite often I will trip a CB, do something, then go and reset it, but can't see where it
33 747classic : I couldn't agree more. Not at our proficiency checks but during the type recurrent simulator checks we always got the more complicated, time consumin
34 tdscanuck : Yes, that would technically work, but it would be against procedure at some airlines. True. The thing you really worry about, and what's behind the o
35 MD11Engineer : This is why I love the MD-11. Except for a handfull of APU related C/Bs (located in the center equipment compartment), all C/Bs are located in the co
36 Jetlagged : It wouldn't be at all obvious that as well as the ALTN EXT MOTOR CB a battery bus CB had also to be checked. Alternate gear extension is something yo
37 Goldenshield : And to take it one step further, the FAA has been rather paranoid about in-flight circuit breaker resets after the AS261 accident.
38 Post contains links ADent : There was that NASCAR Cessna 310 that went down to resetting a circuit breaker. Good article here: http://www.airforce.forces.gc.ca/dfs...sv/pub/nr-sp
39 HAWK21M : Understandably for Chapter 28 related pop outs,but why the rest.
40 Goldenshield : This is th FAA we're talking about. When AREN'T they paranoid? However, ADent provides a great example why. I don't know too much about it myself, si
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