View Full Version : 744s range restricted - SYD-LAX no longer nonstop

26th Nov 2002, 20:04
Source: Ozflight.com.au and the Syd airport message board:

Fuel capacity on Qantas 747-400 aircraft cut

Boeing and the FAA released an Airworthiness Directive on Monday relating to the use of fuel tanks on Boeing 747-400 aircraft. This was further supplemented by a second release only late this evening which more strictly restricts the use of fuel tanks on the large jets.

A brief summary of the documentation released indicates that an optional fuel tank fitting to some 747-400 aircraft, situated in the horizontal stabilizer, is now prohibited from being used. Furthermore the center wing tank on these aircraft can no longer be run dry and the aircraft must always operate with a specified amount of fuel in this tank.

The reason for the release of the AD was prompted by “reports indicating that two fuel pumps from different Model 747 series airplanes shows evidence of extreme overheating of parts in the priming and vapor pump section of the fuel pump. Such overheating provides an ignition source in the tank during dry running of the pump, which could result in fire/explosion of the fuel tank”.

The AD aims directly remove the possibility of the “dry running of the pump” by ensuring that fuel remains inside the center wing tank at all times and by prohibiting the use of the horizontal stabilizer fuel tank. The operational requirements addressed by this release are specific to all Boeing Model 747-400, -400D and -400F aircraft.

Australia’s largest and only international airline Qantas operates 28 Boeing 747 aircraft including their newest edition of 747-400ER aircraft. It is believed that these new aircraft will not be affected by the release.

The primary issue facing Qantas and other operators of the 747-400 series is the loss of fuel load on long haul flights. The horizontal stabiliser fuel tank has a capacity of 12.5 tones of Jet A1 fuel and with a requirement for the center fuel tank to possibly hold 3.2 tones of fuel, direct flights between Australia and the United States may be in jeopardy.

The loss of 15.7 tones in fuel capacity will result in two operational options available to the airlines. They can either continue to operate the aircraft with existing payloads but with a greatly reduced range, or fly the same range but with greatly reduced payloads. Either option provides an economic loss for the airlines and may put in jeopardy direct flights between Los Angeles and Sydney and Melbourne, as well as the direct flights between Sydney and Johannesburg.

News Fuel capacity on Qantas 747-400 aircraft cut
Date November 27th, 2002
Source OzFlight.com.au
More specific overview...

HSFT capacity is 3300 gallons - 12.54 tones

CWT capacity unknown, however if the CWT has less than 22.7 tones of fuel in it at aircraft at start up then fuel in the tank must not go below 3.2 tones. However if the fuel in the CWT is greater than 22.7 tones at start up then the fuel in the tank must not go below 1.4 tonnes.

Hence depending on the fuel loading the capacity lost could be either 13.94 tones or 15.74 tones.
Skip Fulton
OzFlight.com.au - The Australian Aviation Directory

Impact so far on Air NZ SYD/LAX flights.

Cannot accept more than 370 pax for SYD/LAX sector when aircraft can hold around 400 pax.... Applicable to all registrations except SUI and SUH which are better performers.... hehe...

LAX/SYD sector will operate via AKL effective Thurs with STA SYD now 0850am. Regards to SYD/LAX sector will see how things go as shorter sector than LAX/SYD but if pax loads go through the roof will have to operate via AKL also...

Major implications for trans pacific carriers and any sector over 10 hours which will impact SYD/JNB services definately as well as most Asia-Europe long hauls... including Korea, Japan services to Europe....

Well this is big news. All SIN - LHR services(QF 31/9) will now require a tech stop in Dubai. Useable fuel in the Horizontal Stabiliser Tank (HST) is 10 000kg and the Centre Wing Tank (CWT) is 53 000kg. All longhaul flights would require more than 22 700kg in the CWT, thus the minimum fuel allowed in this tank would be 1 400kg and so, the total useable fuel load lost is 11 400kg. Typically, cruise fuel burn is around 11 000kg/hr so the lost endurance equalls just over an hour or about 1000km. Hopefully this issue will be rectified ASAP, but in the mean time I'm looking forward to checking out Dubai!

26th Nov 2002, 20:17
Sorry to ask, but is this related to the similar AD affecting 737ngs, or is this something new?

26th Nov 2002, 21:44
The answer to your question appears to be yes, this article
from the U.S. Newsday Inc.:

FAA Issues Emergency Order on Jets
Reports of overheated pumps spur fuel-tank safety measure
By Sylvia Adcock
November 26, 2002

The Federal Aviation Administration has issued an emergency order requiring certain Boeing jets to fly with extra fuel indefinitely after receiving reports that fuel pumps on two Boeing 747s overheated to a level that could have sparked a fuel tank explosion.

The order, issued Saturday, affects 1,441 U.S. aircraft - all models of Boeing 747s, 757s, and newer models of Boeing 737s. Airlines flying another 1,700 planes registered outside the United States also are expected to comply with the order, which will cost them extra money at a time they can ill afford it, and could mean extra fuel stops on some flights.

"It will definitely be costly," because the added weight will cause the planes to burn more fuel, said Richard Golaszewski, an industry consultant.

The FAA said the order, which takes effect tomorrow, would reduce the range of the aircraft affected by an average of 6 percent, which could mean fuel stops for some Boeing 747s on nonstop trans-Pacific flights.

The fuel pumps, manufactured by Burbank, Calif., -based Hydro-Aire, had been removed for a special inspection after wiring problems were discovered in August. In September, the FAA ordered airlines to fly jets with extra fuel until the individual pumps could be X-rayed, and most have completed that inspection.

But the new problem is more difficult because the FAA and the industry don't know why the pumps on the 747s overheated, reaching more than 1,100 degrees Fahrenheit. A surface temperature as hot as 900 degrees can spontaneously ignite fuel vapors and cause an explosion in the fuel tank like the one that destroyed TWA Flight 800 in 1996.

The FAA's order said one of the pumps showed evidence of "severe overheating," with a metal alloy on part of the pump "blued and cracked from thermal stress," and an aluminum portion of the pump melted. The FAA can't yet order an inspection for the pumps because it doesn't know what to look for; it just knows that thousands of these pumps were made the same way and could have the same problem. So the solution is to keep the pumps covered with fuel, even when the plane is climbing or descending, which means carrying extra fuel that can't be burned.

"We don't know what the problem is," said Boeing spokeswoman Liz Verdier. "We don't have a lot of information. We've got to put them back on this operational restriction until we can figure out what we're dealing with ... We've been working quickly to keep the fleet operating safely."

Boeing received two reports of overheated pumps on Friday, one from a DHL Worldwide Express cargo plane and one from a Singapore Airlines aircraft. On Saturday, the FAA issued the emergency order, and yesterday, the company received a third report of an overheated pump from a 747.

"This is something we have never seen," said Greg Ward, president of Hydro-Aire. "The engineering resources of Boeing and Hydro-Aire are analyzing the parts we have gotten so far and all of us are trying to understand this failure mode."

After the Flight 800 explosion, the National Transportation Safety Board issued a slew of recommendations to the FAA urging that it require some method of preventing the buildup of flammable fuel vapors. The FAA is continuing to test methods to pump nitrogen gas into fuel tanks. The NTSB takes the position that it is impossible to pinpoint all the possible ignition sources in a fuel tank, so the only solution is to keep the flammable vapors out.

The Flight 800 explosion was traced to frayed wiring in the aircraft's fuel measuring system.

FAA spokesman Allen Kenitzer said it was not clear how much the directive would cost airlines, but analysts said it was likely to be thousands of dollars per day for each aircraft affected until the problem is solved.
Copyright © 2002, Newsday, Inc.

26th Nov 2002, 22:17
Well, for most of the year on this route if you operate a double crew then a tech stop is possible without a crew change!:)

Just depends how restrictive your FTLs are.

27th Nov 2002, 00:38
Blue Eagle QF heavy crews can do 16.5hrs duty (extendable) but only on single sector ops. (CAO limit).
Looks like they will slip in DXB when operating SIN-LHR. Something new for the crew!:D

27th Nov 2002, 01:49
Well nz14 got wheels up at 0100z from SYD for LAX and will be non-stop. With the stab tank not in use it normaly be on a DDP operation (Refile) to maximise payload

It is the LAX-SYD which is the marginal one unless the earth changes its direction of rotation

27th Nov 2002, 03:20
'twill be interesting to see how our northern neighbours handle this one. I think they must use refrigerated fuel to allay any reserve problems.:D

27th Nov 2002, 03:39
Or is SYD-LAX still nonstop - but with lower payload???

Empty field myopia
27th Nov 2002, 06:45
If this is the case (and it seems likely), Auckland Airport will be receiving a few extra flights in and out as people fill up for the tasman hop!

Wouldn't want to be a crew sheduler :eek:

Buster Hyman
27th Nov 2002, 09:14
I won't even bother asking about LAX-MEL!!!

How different is the fuel tank wiring in the Airbus jets?

27th Nov 2002, 11:08
And aaaaah who do I make the cheque out to Mr CASA?
Yep that's right geoff and aaaah your dispo is in the mail!!!!:rolleyes:

28th Nov 2002, 12:15

Depending on the model, not all have centre tanks, there are eight configurations on the 330/340. Some have jet pumps, others immersed. Centre fuel pumps automatically shut off when they go dry (within 300 seconds).

The 321 is different again, unlike the A319/A320, it has two Additional Centre Tanks, and no outer wing tanks. All the wing fuel is in one wing tank.

The A321 Centre Tank does not have the same pumps as the A319/320 but uses jet pumps instead. These jet pumps are “powered” by the fuel pumps in the main wing tanks and the jet pumps transfer fuel from the Centre tank to the respective wing tank.

The two Additional Centre Tanks automatically feed to the Centre tank when the Centre tank burns down to a certain level. The Additional Centre Tanks do not have pumps but use cabin air pressure to feed the center tank through transfer valves.


29th Nov 2002, 07:19
I don't know about the last 4 days as I was off, but MEL-LAX is still non-stop and the stab tank is used.

The stab tank is fuelled to whatever is required and during the flight the crew switch from the stab tank when there is 700kg of fuel remaining in it.

The rest of the flight then continues as normal, but the usual payload restrictions that are normally applied still apply. This is the only change as far as I am aware. I would assume that the flights to Europe operate the same.

Cheers Rammel :)

29th Nov 2002, 11:38
Looks like Mr Boeing will have to take the queue from Airbus and install an automatic cut off to the pumps. Maybe there should have been one all along.......TWA800??????

Have a nice day

30th Nov 2002, 04:23
Geez guys, just did LAX-SYD non stop last night and the LAX-MEL flight operated direct.

There are however a few limitations operationally with respect to the Horizontal Stabiliser Tank and Centre Wing Tank fuel quantities and a few fuel weight limits which are "no go" quantities so to speak.

Apart from that we did the job with a good load of pax and freight and still got in on time and without having to stop.

Hopefully this problem should be resolved by Boeing in the very near future judging by the resources they've devoted and investigative work.
Better to be safe than sorry.

Buster Hyman
30th Nov 2002, 09:38
Thanks Zeke. Very informative. How about the quantity measuring devices in the tanks? What sort of system do they use?

30th Nov 2002, 15:50

The automatics side of things is all done by computers. The fuel quantity indication system is the system that provdes the aircraft with information on the volume, mass, and temperature of the fuel (aircraft meaning the refuelling panels and the cockpit). On the 320 its a Fuel Quantity Indicator Computer, A330/340 Fuel Control & Management Computer which in Boeing speak is like the Fuel Quantity Processor Unit on the 777.

The fuel level, temperatre, and density is measured by capacitance probes, and a cadensicon (densitometer + permittivity compensator) sensor. The probes give the computer level and temperature, and the sensor lets the computer determine the fuel mass. If the sensor fails a capacitance index compensator kicks in which gives the dielectric constant of the fuel, which is the backup to compute the fuel mass (not as accurate).

Manual mode - just like a Metro, the fuel quantity can be manually checked by using the magnetic level indicators.


Buster Hyman
1st Dec 2002, 00:20
Thanks Zeke.

Some big words in there, I better start looking them up!! ;) ;)