Boeings Don’t Like Water Much Either

By Robert Mark on January 9th, 2008

I remember early on in the computer revolution when laptops first moved to the forefront of mobile computing.

They were much heavier than today’s models, Dell but they certainly made connecting on the road a valuable option for many of us road warriors.

But those machines did have their limitations.

They didn’t take shock very well – dropping turned them to instant trash. They also didn’t like mixing with liquids as many a traveler found out when they spilled a cup of java on a keyboard. But seldom was anyone’s life threatened by a damp Dell.

Airplanes are – thankfully – designed much differently with multiple redundancies … or at least I thought they were until I saw the report about a major electrical failure aboard a Qantas 747 on arrival at Bangkok.

If you’re an instrument-rated pilot you’ll probably cringe when you read this. If you’re simply a frequent flyer though … well, you’ll probably cringe too.

The Australian said a generator control unit aboard the Qantas Boeing 747 failed about 15 minutes outside Bangkok killing all the cabin lights and depriving the aircraft of electrical power from all the working generators. Luckily the aircraft was on approach and landed with no incident. But that’s not the scary part.747

What really made this episode hair raising, even though no one was hurt, was the cause.

It turns out that water leaked through a cracked galley drain tray and found its way down through the floor and onto some of the aircraft’s electronics killing most electrical power. Essentially, that means that the 747 with 344 passengers on board was running on batteries. Depending upon the condition of those batteries, they might have provided as much as 45 minutes worth of electricity and then … well then everything goes completely dark … no lights, no flight instruments in the cockpit for the pilots, no radios … nothing.

While 45 minutes might seem like a long time, that’s only because the aircraft was preparing to land. If this had occurred over open water – say 1,000 miles from the nearest land when the aircraft went dark – this story might have evolved much differently.

Airline officials are going over the information stored on the 747s flight data recorder to look for additional clues. The Boeing was repaired and returned to the Qantas base in Sydney before being sent back into service.

In case you’re wondering, no … this isn’t supposed to be able to happen. But it did.

Boeing is expected to issue an alert to all of its customers to prevent a similar occurrence on other aircraft.

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5 Responses to “Boeings Don’t Like Water Much Either”

  1. Bill P. Says:

    Rob,

    I think you were being a little too sensational in your what-if scenario. Those comments are usually reserved for “journalists” who know little to nothing about aviation, yet seem to spew about it with authority anyway. (we all have read their misinformed articles).

    The article did say that they since they were at a low altitude already they didn’t get to try “other things” (like starting the APU, isolating and resetting sections of the electrical system, among others). So that’s not the disaster scenario either.
    While I can’t speak for the 747 fleet, all the long range, over water, two engine aircraft (and at least the 3 engine DC-10, and MD-11 to boot) are not simply out of luck when battery power runs out. They each have yet an additional generator – when even all the engine and APU generators go ka-put.
    What they each have is a ram-air-turbine, that drops down into the wind and turns a small propeller hooked up to either a generator, hydraulic pump or various combinations of both. Now that won’t run large load items, but it is certainly enough to keep the instruments and a radio running. The Airbus A-330, which I fly, has a more sophisiticated scheme that switches between enroute critical items like weather radar, fuel pumps, and HF radios to approach oriented items like a landing light, landing gear control, ILS receiver, when the pilot selects.
    Now, you should also know that the operation of the flight controls and engines on that 747 do not require any electrical power to operate that doesn’t come from an independent source on the engine itself. So, probably even the worst case scenario for that airplane is they have 30 min to an hour to get into VMC, and then fly on good old fashioned pneumatically operated standby airspeed, altimeter to a VFR landing, so your mention of “no flight instruments in the cockpit …nothing” was taking it a bit too far.
    Now sure, it was an irresistable incident to comment on. But I would have hoped for a more accurate comment from an aviation professional.

    Sincerely,

    Bill

  2. Robert Mark Says:

    I agree with you to a degree Bill.

    I probably should have been more clear that the airplane was going to fall out of the sky after this failure because like you, I know the engines would keep running.

    But I do believe the end to the story might have been a little different if this happened at night in IFR three or four hours from a suitable landing spot.

    I didn’t grab on to this to be sensational, but really because I made a connection to how absolutely vulnerable to a water spill this particular airplane had become just like the laptops.

    As I said in the story, this should not have been able to happen, cracked drain tray or not. But then remember the 74 the blew up off Long Island?

    No one ever thought flying those things with an empty center fuel tank could ever have been a problem either.

    All this being said, you’re point about watching for sensationalism is well taken.

    Consider me suitably warned about watching for that sort of dribble. My readers do expect that much.

    Thanks for your comment.

  3. Bill Says:

    >>But I do believe the end to the story might have been a little different if this happened at night in IFR three or four hours from a suitable landing spot.<<

    Maybe. My point is, neither you or I know enough about that particular model of 747 to say. Were all the GCUs located in the same place – even the one for the APU? Could they have been isolated and reset? Were there backups available that were not yet activated?

    Additionally, we are relying on a news article by someone who probably knows NOTHING about airliners, to extrapolate what-ifs. We both know there are probably significant errors or omissions from the story – in order to keep it digestable to the public and under a certain word count. We, however, don’t have the luxury of knowing what those errors are. So, we need to be really careful about speculation.

    Now, I DO agree that it sure would have made for an interesting night! But, what would and would not have happened is more the relm of John Nance’s aviation fairy tales.

    As a side note, I know Boeing isn’t totally out to lunch on the effects of water. I recall the 727 and models since then, having collectors and drain lines that captured and disposed of condensation from the cockpit overhead panel area before it dripped on something important. We could see the clear tubes running down between the windows, with water drops flowing.

    Thanks again for considering my feedback.
    Keep up the good work,

    Bill

  4. Rob Mark Says:

    That’s the nice thing about this sort of media Bill. The fact that readers can easy tell authors what they think does affect what we write. Sometimes we bend, sometimes we dig in more.

    I do very much appreciate the time you spend generating your posts.

    In this case, I have to agree that Boeing is not out to lunch and I thought I mentioned that in my post, but I might have left it out.

    This probably is one of those one in a million issues and sure, we didn’t talk about the other backups the airplane should have on board like the wind turbine.

    I only have some time in 737 and don’t claim to be the expert on those turbines. Can they be brought out at any airspeed? Are they heated if the airplane is in icing conditions?

    I’m curious.

    PS – I’m glad to know I’m not the only person who thought some of Mr. Nance’s tales were a bit much.

  5. Bill Says:

    The Ram Air Turbins (commonly referred to as a RAT) can be manually or automatically deployed. Manually, obviously anytime and automatically depending on the aircraft. Since they usually serve as a back up for both hydraulic and electrical power (some turn a hydraulic pump that turns a generator (if needed), the B-787 will turn both in parallel. So the automatic deployment can be based on hydraulic or electrical parameters.

    I have not encountered one with a maximum speed, but the minimum effective speed is somewhere either side of approach speed. At least some Airbus aircraft pre-emptively go off the RAT (and on to battery) prior to apporach to prevent it loosing power at a critical time on approach.
    None that I know of have anti-icing capability.

    Had a good chuckle on the Nance comment :-)

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