Qantas Airways A-380 passenger plane QF32 with its partially damaged engine sits on the tarmac after making an emergency landing at Changi airport in Singapore November 4, 2010. The Qantas Airways passenger plane carrying 459 people was forced to shut down an engine and return to to Singapore's Changi airport on Thursday, ending speculation that it had crashed, the airline and Singapore state TV said. REUTERS/Vivek Prakash (SINGAPORE - Tags: TRANSPORT DISASTER BUSINESS) (© Vivek Prakash / Reuters)

Qantas' perfect storm of failures

The airline's emergency landing earlier this month was a lot more serious than it first appeared


Patrick Smith
November 19, 2010 1:30AM (UTC)

On Nov. 4, the left inboard engine of a Qantas Airways Airbus A380 suffered an uncontained failure shortly after takeoff from Singapore, peppering the huge jetliner with shrapnel. The plane returned to Singapore for an emergency landing. There were no injuries, and at first the incident seemed minor.

That's how I described it, for one, here on Salon. What follows is not a mea culpa, exactly -- I wrote my article when the story first broke, and relatively little was known -- but it's definitely time for an update. It turns out things were a lot more serious than it first appeared: The failure of the giant Rolls-Royce turbofan triggered a massive fuel leak, as well as 50 or more failures and malfunctions of various systems and subsystems, some more serious than others and not all of which are yet understood.

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Bear in mind there were five Qantas pilots on the flight deck at the time, including a training captain and relief crew. All five were suddenly a lot busier than they ever expected to be, handling a slew of warning and caution messages; running checklists; coordinating communications with company dispatchers, maintenance staff, air traffic control, passengers and flight attendants. They did their best to follow the checklists and standard operating procedures, but this was a scenario of unusual and rapidly compounding problems that required some quick decision-making and, frankly, a bit of improvising.

The following rundown is drawn from second- or third-hand accounts, but I take it to be reliable. This, in a nutshell, is what the crew of Flight QF32 was dealing with. 

  • Complete, uncontained failure of No. 2 engine. As I noted in my original story, a four-engine jet can operate safely with the loss of one, and, in most cases, even two engines. Still, an engine failure is never taken lightly, especially one that has sprayed the airframe with red-hot pieces of metal. 
  • Shrapnel hole on one of the left wing-flap fairings (those long, canoe-shaped structures that jut from the bottom of the wing). This hole was described by once source as "big enough to fit your upper body through." 
  • Large shrapnel puncture clear through the forward section of the left wing. (Debris entered the bottom of the wing and exited, several feet later, out the top.) 
  • Assorted electrical problems. Electrical bus No. 2, normally powered via the No. 2 engine, will automatically switch to bus No. 1 in the event of failure. (Such auto-transfer capabilities are standard in commercial aircraft to keep important systems running if their normal power source is lost.) For reasons still unknown, this transfer didn't happen. Electrical buses 3 and 4, meanwhile, will supposedly power bus 2 in the event of an auto-transfer failure, but this didn't happen either. End result: Various components/systems/instruments were inoperative when they shouldn't have been. 
  • Total loss of all fluid in one of the plane's two main hydraulic systems. This required, among many other complications, a manual extension of landing gear. 
  • Substantial leaks in two of the plane's left wing fuel tanks. Literally thousands of gallons were pouring out. 
  • Electronic and/or mechanical failure of important fuel transfer functions. This prevented the crew from addressing a major fuel imbalance -- and subsequent flight stability issues -- brought on by the leaks.

Additionally, a substantial amount of fuel became trapped in the aft, so-called trim tank, leading to a serious center-of-gravity issue during descent and landing. The crew received repeated caution messages about this impending out-of-balance condition, but was unable to address it. 

  • Malfunction of the fuel jettison system. This hindered the ability to reduce weight for the emergency landing. Overweight landings entail higher landing speeds and a longer rollout distance (and though it's unlikely, there can be structural ramifications). Very overweight landings entail very high landing speeds and very long rollout distances. 
  • Partial failure of leading edge slats. These are the panels that slide forward from the leading edge of the wing. Similar to flaps, they increase lift and allow for slower takeoff and landing speeds. The lack of slats increased the plane's landing speed even further, perhaps beyond the rated groundspeed limits of its tires. 

(Planes slow down in stages, deploying flaps, slats and gear at particular target speeds. These speeds are usually obtained from the flight management system, but reportedly there weren't enough data fields on the input screen to account for all the necessary corrections. The crew did the best it could, entering what it thought were the most critical corrections to come up with reasonable numbers.) 

  • Partial failure of speed brakes and ground spoilers. These are panels that lift from the wings to aid in deceleration, both aloft and on the ground. Not only was the landing roll going to be unusually long due to the aforementioned high approach speeds, but the ability to decelerate would also be hampered. 
  • Loss of brake anti-skid system. Ditto. 
  • Inability to shut down the adjacent, No. 1 engine using normal or emergency ("fire switch") methods. This was not discovered until after landing, but it meant there had been no fire protection available for the No. 1 engine after the uncontained failure of the one directly next to it. Had there been shrapnel damage to this engine as well, causing a fire, there would have been no way to shut it down. 
  • Plus a host of other, smaller problems and failures. 

I have been told that the crew chose to commence its approach not because the problems were sorted out, but because of worries over fuel balance and center-of-gravity.

In the end, the plane used virtually all of the 13,000-foot runway at Changi Airport. Brake temperatures neared 1,000 degrees while fuel poured from the punctured left-side tanks.

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The crew elected not to evacuate as the emergency trucks were on hand instantly, but a fire was a real possibility.

Really the biggest issue was about stopping. Pilots practice overweight or high-speed landings all the time in simulators, but this was a perfect storm of multiple failures.

A near disaster? Not quite, but it could have been much, much worse than it was. Had the plane gone off the runway and caught fire, or burst into flames because fuel was ignited by the overheated brakes, it is still entirely possible that everybody could have survived (see Air France in Toronto, et al.). However, Qantas Airways' proud record of zero fatalities, intact since the 1950s, would have been in very serious jeopardy. 

Was this an Airbus issue, a Rolls-Royce issue, a Qantas issue or some combination? And were the jet's cascading malfunctions and redundancy failures a symptom of internal design flaws? All newer airplane models endure certain teething problems -- one remembers the 747, for example, whose early-on difficulties nearly bankrupted Boeing -- but I reckon this was a closer and more perplexing call than anybody at Airbus, Rolls or Qantas is comfortable with.

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We'll find out eventually. Until then, all we know for sure is that more than 400 people emerged unscathed thanks to a well-trained and fast-acting crew -- and to a little bit of luck as well.

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Do you have questions for Salon's aviation expert? Contact Patrick Smith through his website and look for answers in a future column.

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Patrick Smith

Patrick Smith is an airline pilot.

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