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Air Transat's unscheduled stopover in Azores

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Air Transat's unscheduled stopover in Azores

Old 30th Aug 2001, 14:04
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Fozmouth and Squawk 8888

Many thanks for the knowledge.

It just seems incredible that they covered 100nm in 20 minutes. This a an average speed over the ground (water) of 300 knots and a 1:16.5 glide slope.

I wonder if the Gimli guys could have done that in a 767??
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Old 30th Aug 2001, 14:56
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I hate speculation, but just a thought on why you might want to crossfeed from the left wing. What's the maximum fuel imbalance acceptable in a 330?

Maybe better a glider than a certain spin-in.
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Old 30th Aug 2001, 15:12
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FROM TODAYS GLOBE AND MAIL

_____________________________________________
POSTED AT 2:16 AM EDT Thursday, August 30

Jet crew's handling of fuel leak questioned

By PAUL KORING
From Thursday's Globe and Mail

Even with a serious leak in its right-side engine, Air Transat Flight 236 should not have lost all its fuel last week — unless massive amounts of fuel were pumped from the undamaged left side to the engine with the leak, sources close to the investigation say.

The Air Transat A330 Airbus was forced to make an emergency landing without power in the Azores last Friday. The emerging scenario that investigators are considering, as yet unconfirmed by detailed information from the flight data recorder, is that the pilots pumped fuel to the leaking side, turning a serious but not life-threatening situation into a near-disaster that was averted by their skilled emergency landing at a military air base with both engines out.

In spite of a serious fuel leak on one side of the twin-engined jet, the flight crew should have been able to fly the plane safely on one engine with plenty of fuel reserves unless the cross-feed pumps were engaged, sending fuel from the undamaged left side to the right-hand engine, according to senior
pilots familiar with the design and operation of the Airbus A330.

The Air Transat pilots were exhaustively interviewed by investigators after the incident. Air Transat declined to comment Wednesday on whether its pilots cross-fed fuel from the left-wing tanks to the leaking right engine.

"The pilots probably know, but I can't answer that right now," said Seychelle Harding, spokeswoman for the Montreal-based charter airline. She said the pilots "didn't know where the leak was until the plane was on the ground."

Ms. Harding also said the crew "followed the proper checklist."

Officials investigating the mishap will want to determine whether Airbus instrumentation could lead pilots to misdiagnose a serious fuel leak to one of the plane's Rolls Royce engines and whether the appropriate procedures were followed by the pilots.

Meanwhile, Airbus Industrie issued an alert Wednesday ordering all airlines flying A330s with Rolls-Royce engines to conduct an urgent inspection within 72 hours to ensure that all fuel lines are properly installed.

Without actually fingering Air Transat, which installed a new right-hand engine on the A330 only four days before the near-disaster, Airbus said the airline had only "partially applied" previously issued instructions. The result was the fuel pipe reconnected to the new engine chafed against a hydraulic pipe, leading to a crack and severe leak, Airbus said.

Air Transat declined comment on the Airbus assessment or its directive that all airlines check A330s with Rolls Royce engines to insure adequate separation between the fuel and hydraulic lines.

"That's what Airbus says. ... I can't comment until the investigation is complete," Ms. Harding said Wednesday.

The pilots, hailed as heroes for managing to land their powerless airliner with 291 passengers and a crew of 13, held a news conference in Mirabel, Que., earlier this week.

Veteran pilot Robert Pich้ said: "I don't consider myself a hero." At the news conference, neither he nor co-pilot Dirk
DeJager, 28, said what they did to cope with the leak. Even with a severe and uncontained leak on one side of the aircraft, in this case a cracked, high-volume, low-pressure
fuel-feed pipe to the right-hand engine, sufficient fuel would have remained in the left-wing tanks to fly the aircraft to its
destination, the sources said.

"There's no way to get fuel from one side to the other without opening the cross-feed," said one source, who has intimate knowledge of A330 design and flight procedures.

The source said the only way the Air Transat plane could have lost all its fuel — including the still substantial amounts in
the left-wing tanks unaffected by the leak — was that it was pumped to the right-side engine.

The cross-feed allows pilots to correct imbalances in fuel loads. It is initiated by the cockpit crew, which starts the pumps to transfer fuel.

The Airbus checklist for correcting a fuel imbalance — as opposed to its procedures for isolating a fuel leak — calls for a pilot to cross-feed fuel to the lighter wing and expressly warns against cross-feeding in the event of a leak. There are dozens of checklists for coping with different problems.

Like all modern jetliners, the A330 has established procedures to follow in the event of fuel leaks. The tanks have valves to isolate sections of them and reduce loss. If the leak is in or near the engine, as was the case with Flight 236, the fuel pumps feeding the engine should be shut down.

As well, a shut-off valve in the engine can be closed, although the fuel leakage would not stop if the crack were upstream of the valve. Shutting off that valve also shuts down the engine.

Pilots are often reluctant to shut down a malfunctioning engine, preferring to let it idle so it can be used without the restart procedure.

In the case of Flight 236, both engines were kept running until they failed within 13 minutes of each other. Investigators have determined that both failed because of "fuel starvation."

Experienced pilots say that a serious fuel leak in or near an engine should be dealt with by shutting down the engine and the pumps that feed fuel to it. That standard operating procedure applies not just to A330s but to all modern, multiengine jetliners.

Flight 236's pilots said the aircraft had used a normal amount of fuel until about two-thirds of the way through its overnight Toronto-Lisbon flight. Then, at about 5 a.m. local time, with Lisbon still more than 1,600 kilometres away, they noticed serious fuel loss.

Twenty-five minutes later they requested a diversion to the Azores. An hour later, the aircraft had no fuel left, the second engine quit and the crew, still about 180 kilometres from Lajes air base, had to glide to a heavy but successful landing.

An Airbus 330 burns about five tonnes of fuel an hour in high-altitude cruise. According to one source, Flight 236 lost nearly 12 tonnes of fuel, much of it from the undamaged left side, in 30 minutes; total fuel loss was greater than 20 tonnes.

Although the fuel system on modern jetliners is complex, with two main tanks in each wing and often a centre fuselage tank and a tank in the tail for trimming the aircraft, the principle underlying the design is simple: to separate the left and right sides of the system so a single leak anywhere cannot result in the loss of more than half the remaining fuel. Only by transferring fuel can the reserves in the undamaged side leak out.
_____________________________________________
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Old 30th Aug 2001, 15:36
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For anyone that's interested in the effects of 60mins vs 180mins ETOPS, here you go. The 60 minute limitations are outlined in light blue; the 180 in mid blue with the direct great circle track between YYZ and LIS shown.

 
Old 30th Aug 2001, 15:51
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Those familar with A330 systems could answer directly, but is it possible that the 330 handles fuel imbalance automatically? If so, could it also be possible that the crew was unable to close the ship crossfeed valve(s) due to system malfunction? Another Airbus "software" problem perhaps?
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Old 30th Aug 2001, 16:15
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Foxmoth I've not flown a 330, however I would guess that not only would there be extra drag from the wind milling fans, but there would also be an effect due to the loss of residual thrust.
That being the case you could easily add 500 fpm to the normal "thrust lever closed" descent rate, this would probably reduce the normal distance calculations by 10-15nms.
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Old 30th Aug 2001, 16:24
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The A330 does not handle fuel imbalance automatically, that has to be done by the pilots.

The FUEL IMBALANCE checklist says "Do not apply this procedure if a fuel leak is suspected. Refer to FUEL LEAK procedure".

In the FUEL LEAK procedure the following (and more) can be read: "Even with a fuel imbalance of one inner tank full/one inner tank empty there is no special procedure required for approach and landning".
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Old 30th Aug 2001, 17:34
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One thing you can be sure of. The airframe and engine manufacturers will be doing their damnedest to ream this guy a new a**hole.
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Old 30th Aug 2001, 18:17
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As a bystander in these matters (or should that be a bysitter?) Visiting the flight deck on an A340-200 last year, when discussing fuel burn and the maximum sector distances, the F/O said that the wing of the A340 was extremely efficient in the cruise.

"So much so, that getting it to slow down can sometimes be a bit of problem."

Therefore, Traffic's comment that Airbus make good gliders, it seems that they just might!
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Old 30th Aug 2001, 19:50
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"I also heard that the FDR and CVR have gone to France for Investigation. Is this normal? Should they not have gone to TSB or do they normally go to manufacturer?"

On the Tech Log forum I asked a question about whether the FDR and CVR would be powered by the Ram Air Turbine after the loss of both engines on the 330.
http://www.pprune.org/cgibin/ultimat...c&f=3&t=002419

The answer that came back was "the digital flight data recorder (DFDR) is powered by AC BUS 1 in the A330-200. Hence without engine driven generators or the APU it is inoperative!"

It thus would appear (as with the SwissAir 111 crash) that there will be no data available about the extraordinary last phases of flight for the Air Transat airbus.

There will unfortunately be no record of this pilot's wonderful deadstick landing.
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Old 30th Aug 2001, 21:19
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This situation is similar to other mishaps where the crew were initially hailed as heroes then later criticized for not taking appropriate action. Remember the Air Canada DC-9 fire in 1983? The crew was at first commended for their airmanship. Subsequent investigation revealed that a popped high amperage lav cb was reset repeatedly and closer airports were overflown to get to CVG where 23 pax died in the flames.

Another famous case was TWA 727 upset at FL 390 in 1979 where captain Harvey "Hoot" Gibson was publicly lauded for his aerobatic abilities in the recovery. The NTSB later determined that "flight crew manipulation" of the circuit breaker panel had induced the initial departure from controlled flight.
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Old 30th Aug 2001, 23:00
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In spite of a serious fuel leak on one side of the twin-engined jet, the flight crew should have been able to fly the plane safely on one engine with plenty of fuel reserves unless the cross-feed pumps were engaged, sending fuel from the undamaged left side to the right-hand engine (...)
Holy sh...! I guess you may end up being right, Airbubba.

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Old 31st Aug 2001, 00:03
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Just to clarify my earlier point. The A330 Fuel leak checklist allows you to open the crossfeed valve (there are no crossfeed pumps) once it has been established that the leak is at the engine and the engine has been shut down. So I think some of the so called experts in User123's post are not reading the correct checklist.
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Old 31st Aug 2001, 01:32
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There is one other possibilty which could explain fuel transferring from a "good" tank to the "bad" side with the crossfeed closed. It is extreme but I know it to have happened for sure on a B757. I may get some of the finer detail wrong and I haven't dug out the schematics but it basically boiled down to a ruptured refuelling gallery or pipe WITHIN the tank and the tank booster pumps pressurised the fuel into the ruptured gallery which as I remember delivered fuel to the centre tank. Could the same thing have happened between wing tanks here?

This would of course still require an external leak such as an engine fuel line to cause the problems of the A330 and that is looking at double failure scenarios but is it possible? Any engineers out there with access to Service Bulletins? It would have been late 80's to early 90's and involved fuel lines which were constructed with a sort of spiral or twist effect and although I used the word rupture it was more a case of the spiral or twist unwrapping itself! I know it sounds weird but could anyone else amplify on this?
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Old 31st Aug 2001, 01:35
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Kimoki, Even with the xfeed open (for a possible relight?) it would be pretty obvious that fuel was disappearing quicker than the good engine was burning it. The sensible thing would then be to close the xfeed.
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Old 31st Aug 2001, 10:46
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Crusty, I agree with you and I would be very wary about opening the crossfeed at all if I had enough fuel in the good side to reach an airport. However I was just pointing out that it is in the checklist as a standard procedure.
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Old 31st Aug 2001, 18:17
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My earlier question on qty of Fuel flow tranducers , is there one at the tank outlet and one near the engine fuel control. If so a major discrepancy of fuel flow should ring some warning bells ( either physically or metaphorically). If it is only measuring fuel flow at the fuel control nothing would appear strange as the fuel is leaking aft of it.
 
Old 31st Aug 2001, 18:58
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As far as I can see from FCOM the fuel flow is only measured just prior to the injectors so would be no warning. The FMC constantly displays the fuel on board at landing on the flight plan page so this would be where you would first spot an anomaly. An ECAM advisory would come up once the inbalance reached 3000kgs in the inner (main) tanks.
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Old 31st Aug 2001, 19:24
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Having studied all this thread with interest(and I do hate second guessing things like this)I`m going to stick my neck out and think it went like this:

@ 0525 they noticed fuel leak - probably by an unbalanced tank. If they did the standard calculation they would have realised they were indeed loosing fuel. Which checklist? They kept the no.2 engine running throughout so if they did a checklist it had to be the "leak not from engine or leak not located" drill. In this case the X-feed stays in AUTO i.e.closed and you descend to gravity feed ceiling FL200 and then switch pumps off. If they had identified the leak from the no.2 engine then they would have done the "leak from engine" drill which means you shut down the engine and can then use X-feed if you want to. They kept the no2 engine running.
Somewhere else on the thread it says they lost about 20 tons and I reckon that about right. They were approx 1hr30mins to 2hrs away from Lisbon so 20 tons at that point is not unreasonable. Remember that 6 of this will be in the two outer tanks and a further 2 or so in the trim tank. That would normally leave about 6 tons in each inner tank. Obviously they had quite a bit less than this in the right inner due to the leak and once it got below 4000kgs the trim tank would transfer forwards its contents. As the right inner had so much less than the left one the trim tank probably all went to the right inner - however if the X-Feed was open (to achieve some sort of balance) then not necessarily so. Once inner contents get down to 3500kgs the outer tank transfers to the inner about a further 3 tons.
So if the x-Feed had stayed closed throughout they would have had 6 tons in the inner and 3 tons in the outer = about 9 tons (plus a ton say from the trim tank) to feed the no 1 engine and plenty to cruise for 250 miles and start a descent from FL200 (gravity fuel feeding ceiling) on one engine. If the no2 had been shut down they would have had loads more. They kept the no2 engine running.
The fact that both engines failed from fuel starvation within 10 mins of each other -whilst there was a massive loss on one side -means the X-Feed must have been used and would explain the rapid loss of fuel from the LHS of the system.
I truly hope I am wrong about this. We may yet hear there were further system failures but I doubt it. I think it was their reluctance to shut down the no2 engine coupled with opening the X-Feed that will be their downfall. That`s v.easy to say sat here - quite another to be there at night over the Atlantic with a leaking fuel system. They DID do a good job with the deadstick but I figure if they had just kept the X-Feed closed they would have at worst done a single-engine approach and landing.
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Old 31st Aug 2001, 21:43
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Interesting story out today in the Canadian press.....apparently Capt Piche was arrested in the early 80's in the Usa for smuggling drugs aboard his little Cessna. Let the dirt come out now !!

[ 01 September 2001: Message edited by: PPRuNe Towers ]
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