Thursday, December 1, 2011

It's the little things

See this?

circuit_breaker_lot.jpg

It's a circuit breaker that's "popped." They sell for about $30.

It apparently contributed to this, which happened a month ago today (and which I wrote about here):



The Polish airliner left Newark and noticed right away there was a leak in the plane's hydraulic fluid. That's when the pilots made mistake #1, according to a report that was just released (available here). They decided to continue flying to Warsaw, where they found out the plane's landing gear wouldn't extend.

An alternative landing gear extension system didn't work because of that $30 part shown above.

Had the pilots noticed the circuit breaker, they could've pushed it in, lowered the gear, and landed the plane.

But these days, airline crews depend on computers to tell them what's wrong and the Boeing airplane wasn't built to tell pilots when a $30 circuit breaker had popped (pilots of smaller airplanes have an old-fashioned fail-proof system: They touch run their fingers across each circuit breaker to be sure they're all engaged before taking off).

When authorities lifted the plane off the runway, pushed in the circuit breaker, applied power, and flipped the landing gear switch, down came the landing gear.

And that's the simple sort of thing that causes major air disasters.

5 comments:

  1. Okay, let's let the investigators due their job and stop the speculation! WAY too early to say that CB caused the incident. Sure It protects the alternate landing gear extension system , along with a dozen OTHER systems. Saying that popping it back in and the gear worked is NOT confirmation that was the issue. (it includes the APU's, were those fired up when they were on the ground lifting the plane? I DOUBT it! Same with the air conditioning.) They MAY have been a coincidental trip in one of those systems as well, causing that breaker to pop. NO WHERE in the report has anyone said that it was tested yet, nor that the CVR or FDR's were reviewed, showing the pilots ignored or. Maybe they'll show the pilots DID try and reset it during flight and it popped again, so they left it. (Hydraulic fluid, flammable, and an electrical short DON'T mix!) Just my .02c.

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  2. This is one of the things I love about the aviation community, this idea that we always have to "let the investigators do their jobs" before we can even begin discussing things.

    Utter nonsense.

    It's an undisputable fact -- based on many, many other investigations -- that a chain of events contributes to disasters and the more we talk about that and the more examples we use, the safer as pilots we'll all be.

    We know for a fact that in the computer and monitoring systems of this model, there is no monitoring of the circuit breaker which -- from the report -- worked fine once reset. We know that pilots took a plane load of people to Warsaw, even though a hydraulic leak was discovered over Newark.

    How much hydraulic fluid do you think you can lose during a trip to Warsaw? Enough to keep your landing gear from coming down, maybe?

    These are FACTS in the report, not conclusion. There's no reason at all we shouldn't consider and discuss facts.

    Maybe the pilots will be exonerated. Good for them. But if you want a list of links to investigations showing the continuing challenge to human behaviors in accidents and the chain of small events that lead up to situations that get out of hand, just holler.

    Me? I like the Al Haynes school of flying better.

    Continuing to fly after discovering on takeoff you've got a leak in the hydraulics.

    Sorry. Stupid.

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  3. I don't take exception to discussing the issues, but to come out and blame the pilots for missing the C/B based on that report is premature and inappropriate. Bear with me and let me explain.

    Also, I was only referring to the C/B issue and not the Hyd. leak. We, as an aviation community can discuss all the issues, but should leave the blame game to the investigators in these cases where it's still not clear as to the full timeline and decision making. The pilots did refer to their operating guidelines and discussion with the airline ops/maint. before continuing on to Warsaw regarding the hyd. leak Why did they continue? Don't know and I'm sure that will be expanded upon during the investigation. I don't like to jump to conclusions so I'd rather even leave that till we can get input from a B767 pilot or mechanic on the specific actions for a leak in this specific system.

    For me, yeah, I always review incidents/accidents to learn from them, but once we actually have ALL the facts. Learning by conjecture can lead to mistakes of their own. I use the same in my job as a FF. We always do debriefs and such, but when there's a big, tragic, incident, there is some discussion prior to the final reports, but the main learning is done when the full facts and events are known.

    But, back on topic, for the C/B issue, we don't yet know WHEN it popped, WHY it popped or even if the pilots did anything with it or if they missed it completely. Until we do, how can we discuss their failure to reset it if we don't even know that they truly didn't try and reset it? So, how can you (and others) say this whole thing could've been prevented if they simply pushed the C/B back in? Do you know they didn't try? Do you know that the other systems that it protects that were NOT activated on the ground when lifting the plane didn't trip it? That breaker also protects the following, according to "767-200/300 SYSTEM SCHEMATIC MANUAL" C829 is also responsible for:
    -CHILLER SHUTDOWN CONT
    -L GEN CONT UNIT
    -R GEN CONT UNIT
    -APU CONT UNIT
    -L GEN DRIVE DISC
    -R GEN DRIVE DISC
    -BUS PWR CONT UNITT
    -STBY PWR CONT
    -DC BUS TIE CONT
    -HYD GEN CONT PWR
    -RAM AIR TURB - AUTO
    -BAT CUR MON PWR

    I highly doubt ALL those systems were active and functioning when they pushed that breaker in to drop the gear post incident. So we can't even say it 'worked fine' as it was not reset and tested in the same electrical operating state the aircraft was in during flight.

    For the hydraulic leak, I hope the pilots have a good reason for continuing the flight, I think it's a long shot, but there may be an explanation. (Familiarity of the airport, time to burn off/dump fuel to attempt a belly landing in New York, etc.) I'll bet the decision came from the airline to continue the flight based on the 'backup' landing gear system. Was it the right thing (obviously not with hindsight since that 'failed' too.)

    And sorry if I sounded like I was attacking you or trying to stop discussion. I didn't mean it to come across that way. We should discuss these issues, but should leave the 'BLAME' part out of the discussion until after the investigation.

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  4. Hey Bob,

    What if they had remote circuit breakers (maybe even solid-state ones) that displayed on the EFIS when they faulted. Maybe that would have helped them notice it.

    Well, your RV has them, and the new 787 has them, but not much in between (yet).

    Cheers,
    Marc

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  5. You know what's funny, Marc? I was out at the hangar yesterday when an episode of Uncontrolled Air Space came on the iPod and they mentioned this article -- and totally butchered the telling of the story -- and THAT was exactly what I thought.

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