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American Airlines Flight 268 9/22/08

Poahi

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My apologies if this has been discussed already. Glad everyone was safe.


NTSB Identification: CHI08IA292
Scheduled 14 CFR Part 121: Air Carrier operation of American Airlines, Inc. (D.B.A. American Airlines)
Incident occurred Monday, September 22, 2008 in Chicago, IL
Aircraft: BOEING 757, registration: N197AN
Injuries: 192 Uninjured.
This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

On September 22, 2008, at 1342 central daylight time, a Boeing 757-223, N197AN, operated by American Airlines as flight 268, diverted to Chicago O’Hare International Airport (ORD) due to electrical system anomalies. During the landing on runway 22R (7,500 feet by 150 feet), the airplane veered off the left side of the runway resulting in minor damage to the landing gear. There were no injuries to the 2 flight crew, 5 flight attendants, or 185 passengers. The domestic passenger flight was being operated under the provisions of Title 14 Code of Federal Regulations Part 121. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed. The flight originated from the Seattle-Tacoma International Airport (SEA), Seattle, Washington, at 0802 pacific daylight time, with an intended destination of the John F. Kennedy International Airport (JFK), New York, New York.

While en route the flightcrew received an AIR/GRD SYS message, an illumination of the standby power bus OFF light, and several advisory and status messages on the engine indicating and crew alert system (EICAS). The flight crew then referenced the quick reference handbook (QRH) regarding the AIR/GND SYS message. The flight crew then followed the procedure referenced in the QRH for STANDBY BUS OFF by turning the standby power selector to the BAT position. The QRH procedure also referenced that, "The battery will provide bus power for approximately 30 minutes." The airplane systems stabilized with several items inoperative and the captain contacted maintenance technical support and subsequently elected to continue the flight on battery power. The flightcrew then reviewed the MAIN BATTERY CHARGER procedure referenced in the QRH.

Approximately 1 hour and 40 minutes later, while in cruise flight, the battery power was depleted at which time several cockpit electrical systems began to fail. The airplane was over western Michigan and the captain elected to turn around and divert to ORD. Also, the flight attendants discovered that public address (PA) and the cabin/cockpit interphone systems were inoperative. A flight attendant wrote a note and slipped it under the cockpit door to inform the flight crew of their communication problems. A short time later, the cabin crew was informed that they were diverting to ORD. One of the flight attendants then walked through the aisle informing the passengers of the unscheduled landing at Chicago.

While aligned with the runway to land, the flightcrew declared an emergency with the control tower as a precaution. As the airplane neared the runway on final approach, the flightcrew discovered that the elevator and standby elevator trim systems were inoperative. The captain then assisted the first officer on the flight controls and the approach to land was continued. The systems required to slow the airplane on the runway appeared to indicate normal, and with the elevator control issues the flightcrew did not want to perform a go-around to land on a longer runway. Pitch control of the airplane was difficult so the flightcrew elected to stop the flap extension at 20 degrees. The touchdown was smooth despite the control issues, however, the thrust reversers and spoilers did not deploy. The captain attempted to manually deploy the thrust reversers, but still was not sure if they deployed. The captain was concerned about the brake functionality and accumulator pressure so he made one smooth application of the brakes, which did not “perform well.” Due to obstructions off the end of the runway, the captain elected to veer the airplane off the left side of the runway into the grass.

As the airplane touched down approximately 2,500 feet down the runway witnesses heard loud pops. Skid marks from the left main gear were evident near the point of touchdown and 165 feet further down the runway skid marks from the right main gear were present. These skid marks were visible for the entire length of the runway up until the airplane departed the pavement. The airplane came to rest with all three main landing gear off the left side of the pavement and the nose of the airplane came to rest approximately 100 feet prior to the end of the blast pad pavement which extended 397 feet past the departure end of the runway.

After coming to a stop, the flightcrew was not able to shut the engines down with either the fuel cutoff valves or by extending the fire handles. The engines were subsequently shutdown by depressing the fire handles. The passengers were then deplaned through the L1 and R4 doors using portable stairs.

Post incident investigation revealed a failure of the B1/B2 contacts in the K106 electrical relay. With the standby power selector in the AUTO position, this failure would have resulted in a loss of power to the battery bus and the DC standby bus, which would have resulted in the AIR/GND SYS message and illumination of the standby power bus OFF light which the flight crew received.

With the standby power selector in the BAT position, as selected by the flight crew, the main battery provided power to the hot battery bus, the battery bus, the AC standby bus, and the DC standby bus. In addition, the main battery charger was not receiving power, and thus the battery was not being recharged. When main battery power was depleted, all 4 of the aforementioned buses became unpowered.
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Source:http://www.ntsb.gov/ntsb/brief.asp?ev_id=20081007X03940&key=1
 

whatitdoing?

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Why would they continue for another 1hr and 40 minutes.....my arse is diverting.
 

Poahi

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Why would they continue for another 1hr and 40 minutes.....my arse is diverting.

That's why I posted the link. It seems strange to me. It might have been that they did have electrical power but that the battery wasn't being charged and then the problem resurfaced later? These guys are sharp pilots from what I understand and they wouldn't have continued without a reason. I don't think they continued solely on battery power, but by reading the report, that's what you'd be led to believe.
 

aa73

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Why would ANY pilot continue cross country if they knew they only had 30min of battery power? No, my guess is they did not realize the electrical predicament they were in. What's really baffling is they followed the QRH to the letter and ended up with a dead battery. Really strange.

Glad it all turned out okay in the end.

73
 

jmreii

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That's why I posted the link. It seems strange to me. It might have been that they did have electrical power but that the battery wasn't being charged and then the problem resurfaced later? These guys are sharp pilots from what I understand and they wouldn't have continued without a reason. I don't think they continued solely on battery power, but by reading the report, that's what you'd be led to believe.


I have yet to see a vehicle of any kind, be it plane, train, boat, or car recharge it's own battery from a battery source. You know your in trouble when you cannot get a source of positive generation from a generator powered by an engine.
There is a way to verify what your source is powering; if you are unable to verify the power source, you don't go. Period. DOES NOT MATTER WHAT THE MACHINE IS.
 

Poahi

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I have yet to see a vehicle of any kind, be it plane, train, boat, or car recharge it's own battery from a battery source. .

As I understand it, it was a contactor failure. I think the generators were fine. It sounded like they lost critical busses. That's why I say it was unlikely they would have continued the flight under a total AC power loss. The preliminary report was cryptic on what power they really had after they decided to continue.
 

Cobra17

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commuters?
 

AA717driver

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Nowhere (until AFTER this incident) in the QRH does it say to 'Land at the nearest suitable airport' with STBY power ON.

I know both pilots in question, one of which knows the 767 systems as well as anyone outside of Boeing. The other is as sharp as they come.

It will be interesting to see the final outcome of the investigation.

As with many incidents like this, pilots often get led down the path by procedures. TC
 

Truckdriver

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It sounds like they were lead to believe that they were operating on the batteries, but the batteries were being charged. I'm not sure how the systems on the 757 work, but it could be possible to have engine generators that won't power the main buses, but will power a battery bus that in turn may run the battery charger. If that is what the QRH and the MX folks on the radio led them to believe, then I can almost see the rationalization for them to continue. In any case, it's kinda nice to know that you can actually run the airplane for 100 minutes on the batteries and not just 30.
 

Junkflyer

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From looking at the report the problem seems to be with standby buses not the main AC. Normally the main AC (left and right) supplies the standby AC and DC buses. Moving the standby power selector to battery position allows the battery to supply these buses and batt/hot batt of course, but it also takes the battery chargers out of the loop. This how the 767 works and I would think the 757 is similar. The apu wouldn't help in this case.
 

mamba20

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why they no start apu?


If there was a fault of some kind the prevented the buses in question from getting power then adding another generator to the equation would'nt matter. Sounds to me like they had a problem that was one of those "we don't have a procedure for that" kind of things.

I will agree that flying past airports that you can easily land at while having an emergency is stupid, but what if you don't know if your having an emergency?

I have a hard time believing that they KNOWINGLY flew past ORD, etc etc thinking that things were going south on them. I think by the time they realized that the problem that had was not one that they were able to solve it was too late and they did what they could.

The best part: EVERYONE WAS FINE!
 

bubbers44

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Boeing should have had a way of monitoring battery voltage on the 757. They would have diverted earlier if they knew for sure they were losing essential busses.
 

AA717driver

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You can pull up battery voltage via a button on the accessory panel. It displays on the lower EICAS.

I'm not sure you can do it in flight but they are coming out with a procedure to check battery volts after the failure of the APU to start (different issue) so that's the only way to check volts.

Up till now, AA forbade you to use those buttons on the acc. panel. Guess you have to call a mech. anytime the APU won't start on the first go... TC
 

Poahi

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I find it hard to believe that a major airline would continue a long distance flight relying on a battery charger - especially one that flies ETOPS. We are missing some key facts here.
 

bubbers44

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I find it hard to believe that a major airline would continue a long distance flight relying on a battery charger - especially one that flies ETOPS. We are missing some key facts here.

The only time during ETOPS there is any drain on the battery is if standby power is placed in bat position. You would have to lose both generators plus the hydraulic driven generator to degrade to that point or have the K106 relay fail as happened to AA last month.
 

goodgig

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So cliff notes for someone who has 0.0 time in a Boeing.

Do you think the crew KNEW that they were using only batteries to power these buses? As in we are on battery power up here?
 

AA717driver

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So cliff notes for someone who has 0.0 time in a Boeing.

Do you think the crew KNEW that they were using only batteries to power these buses? As in we are on battery power up here?

Knowing the crew, I'm guessing they knew the battery was discharging but at a very slow (but unknown) rate. The busses that didn't fail were still being powered off the engine generators.

All conjecture on my part, though. TC
 
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