How much fuel?

[CAEBr]

Interesting report from Flight Global - SIA 777 getting airborne with 41t more fuel than expected.

https://www.flightglobal.com/news/articles/refuelling-crew-foxed-before-sia-777-turnback-449734/

[Cloudtopper]

Personally speaking , if the pilots did not realise something was amiss with longer ground run , rotation speeds , and initial optimum/ Max altitudes then one needs to question there overall experience

Singapore appears here quite often for topics related to safety .....

[Black Pudding]

How the hell can the actual uplift and calculated uplift discrepancy not tell them there was something wrong.

Who filled in the tech log and who who signed the tech log.

[Herod]

It seems to me that the crew were not at fault here. The basic error would appear to be the fact that the ground staff did not dip ALL the tanks. Basic requirement I would have thought.

[Piltdown Man]

Herod - I disagree with your interpretation. The wing tanks were assumed to be full so the sum of their contents was added to an incorrectly dipped centre tank. Measuring the wing tanks would not have changed the numbers. What I find interesting is that the blame fell in the shoulders of the techie and none on the manufacturer. After all, how difficult can it be to dip a tank? Maybe Boeing’s ‘Magastick’ checking procedures need reviewing as does their QA process for installing programable fuel sensors that enable spurious tank values to be displayed. And how many times has this happened before? I also find it interesting that the additonal 41 tonnes went unnoticed in performance terms but as I only fly bug smashers I’ll let someone more qualified comment.

PM

[Landflap]

Beats the hell out of departing with 41 tons less than expected.

[MaximumPete]

Back to basics!!! What fuel load did it arrive with on board and how much did they put on. Now that can't be hard, or can it?

[am111]

I'm not familiar with the Magastick procedure but sounds like confusion coupled with confirmation bias as it sounds like absolutely no discrepancy was found first time round?

[crwkunt roll]

So how much above MTOW was it? No way could it be below it, on a 13 hour sector, with 40t too much gas.

[mustafagander]

FFS, an uplift way exceeding the planned fuel load needs investigating. Simple. The only thing I would accept is a full magnastick check of all tanks as well as a reasonable explanation of how come the uplift was so much higher than calculated. In my mob we went through fuel measuring problems in the B747SP era when the fuel tended to stratify. We did, however, delay for long enough to resolve each discrepancy.

[172_driver]

Back to basics!!! What fuel load did it arrive with on board and how much did they put on. Now that can't be hard, or can it?

Did I miss something? That's what they were concerned with, hence dripping the tanks. It was the dripping that wasn't done correctly. I sympathize with the crew if they were told 86 T onboard after the check.

There was an Air France A319 that ran one tank dry despite it showing over 1000 kg remaining. Google it!
Funny little things those indication systems.

[spannersatcx]

Whenever a fuel measuring stick check is required to verify the fuel uplifted / fuel quantity inside the tank due to MEL applied, Fuel Measuring Stick Manual has to be used. It is quite time consuming to look up for correct fuel quantity value using this manual and human error might occurs.

To reduce the inconvenience caused, Boeing has released an iPad app, Boeing FMSM, to calculate fuel quantity using the fuel measuring sticks. The Boeing FMSM app is an electronic version of the referenced FMSM available in MyBoeingFleet. The Boeing FMSM app performs all the calculations and table lookups. The app can perform two different functions:

 Identify the fuel sticks to be checked for a given fuel load

 Calculate the fuel quantity for a given fuel stick reading

[BAengineer]

The technicians, it says, had "limited" experience in performing the check and that the magnastick readings were "likely not correct".

I can quite believe that. I worked for several airlines in the Middle East before I retired and a decision to fuel stick an aircraft was a big deal (with possible delay indications) simply because the Engineers and Technicians had no experience of the task. Many didnt understand the concept and were totally lost when it came to reading the charts - this was not because they were bad engineers or technicians it was just that those airlines tend to use new modern aircraft where the fuel systems are usually accurate and reliable, they just dont ever need to stick the tanks. I grew up on DC10's and other old birds were we did stick checks before each flight so a task that was easy for me to carry out on a 777 (say 15-20 minutes) could take 2 hours for inexperienced technicians.

When I say they didnt get the concept it appears that the SQ guys didnt either - you do a stick check when you dont trust the onboad fuel system and want to know exactly what fuel is onboard so checking all the tanks is obviously needed.

[CargoOne]

I am finding it quite peculiar that official report says nothing about aircraft all up weight, performance and envelope basically omitting the basic items for ICAO report standards.

[Sailvi767]

I thought every airline crew had to perform a fuel verification checking the uplift against the arrival fuel. It’s a basic safety precaution.

[am111]

They did spot a discrepancy...

Although the aircraft's cockpit and refuelling-panel indicators showed total fuel of 86t, the refuelling had taken longer than expected, and the ground personnel found that the dispenser had apparently delivered 121.5t to the aircraft.

The ground team was uncertain about the discrepancy, initially believing that the fuel-flow counter might not have been reset before the fuel was dispensed.

This prompted them to dip the centre fuel tanks and somehow managed to come to the same 86t figure the aircraft came to. Their logical but false conclusion must have been that the discrepancy lay with the fuel bowser and not the aircraft.

[dweeks]

I thought every airline crew had to perform a fuel verification checking the uplift against the arrival fuel. It’s a basic safety precaution.

Well, at my carrier ( one of the US Big 3) we don't even get a fuel slip any more, unless there is some MEL or non-standard procedural requirement for one. If the totalizer number agrees with the ECAM fuel page numbers, you're good to go with no fuel slip.

[BluSdUp]

So, Here we have armchair experts PAYED to investigate and they dont even come up with a proper ICAO standard report .
Namely the fact all the V1 V2 and Vr and Vref was WRONG with a factor close to 1.3 or 1.2.
On the 737 one ton equals ca 1 knot, so if I take off with speeds for a a 10 to lighter aircraft I would use Vspeeds that are ca 10kts to slow.
I would ask you 777 drivers to do a quick calculation for the two scenario we have here : 1 the calculated one and 2 the actual one.
Also C\G is wrong as the 777- 200ER Center Tank is more forward.
Boeing and the Airline got of hook this time as I can not think of how this could have gone the other way, Gimli Glider style.
Standing by to be corrected.
Cpt B

[Sailvi767]

Well, at my carrier ( one of the US Big 3) we don't even get a fuel slip any more, unless there is some MEL or non-standard procedural requirement for one. If the totalizer number agrees with the ECAM fuel page numbers, you're good to go with no fuel slip.

Wow, lots of trust in your fuelers, they must be highly trained.

[BluSdUp]

And this fueler was 62 years old and had 40 year experience!

[PAXboy]

The start of the problem is listed in the second paragraph the Flight Global report:
For reasons that could not be determined, the aircraft's internal fuel-quantity indicator had registered the aircraft as a 777-200, which features a smaller centre fuel tank than the -200ER. This caused the aircraft's instruments to under-measure the amount of fuel on board.
So, it was wrong from the start and NO MATTER who did what it was always going to be wrong. No one would imagine that a/c 'thought' it was a different model to what it actually was!
Possibly time for some slack to be given.

[Pugilistic Animus]

Or even worse than the gimli glider...an Air Florida at DCA

[Capt Fathom]

The aircraft involved (9V-SVC) was undamaged during the 16 April 2014 flight.

Is that date a misprint or has Flight Global dug up an old report?

[BAengineer]

The start of the problem is listed in the second paragraph the Flight Global report:

So, it was wrong from the start and NO MATTER who did what it was always going to be wrong. No one would imagine that a/c 'thought' it was a different model to what it actually was!
Possibly time for some slack to be given.

I don't blame the flt crew, the fault is entirely with the engineering staff. They knew there was a discrepancy, they took appropriate rectification action but failed to do that correctly.

There is no excuse really.

[Black Pudding]

It's very simple........expected calculated uplift in litres and actual calculated uplifted in litres don't even come close.

[haughtney1]

These things do happen from time to time, however, based on the story as published there is no way I would be moving the aircraft until I was satisfied. Engineers do have a habit of wanting you out of their hair.

[WingNut60]

Putting the Gimli Glider aside for a moment, was there not a similar case with an ATR in Italy where the wrong card had been installed and it thought it had a lot more fuel onboard than it actually had.
ATR72 vs ATR42?
Ended up in the Mediterranian with some loss of life, if I recall.

[Bksmithca]

For reasons that could not be determined, the aircraft's internal fuel-quantity indicator had registered the aircraft as a 777-200, which features a smaller centre fuel tank than the -200ER. This caused the aircraft's instruments to under-measure the amount of fuel on board.

So I'm thinking that this fuel issue has existed from day one of this aircrafts life so that means it's been under reporting the fuel load by 41Tons. So how many times have they landed above the allowable maximum landing weight and were these Heavy landing recorded and inspected?

Bk

[tdracer]

So I'm thinking that this fuel issue has existed from day one of this aircrafts life so that means it's been under reporting the fuel load by 41Tons.
Bk
Not likely. It's common for LRU's to be 'pin selected' for different configurations of the aircraft. On some aircraft, it's literally done with programing pins, but on the newer stuff it's typically done with a software key. All it took was for some engineering work to have been done on the FQIS that was not done correctly.
Hard to believe that this aircraft had been flying around for years with a 41 ton weight discrepancy that was never noticed...

[rationalfunctions]

Official report here: https://www.mot.gov.sg/docs/default-source/default-document-library/b777-(9v-svc)-fuel-discrepancy-16-april-14-final-report.pdf

Few interesting actions and recommendations, including that the aircraft manufacturer upgraded subsequent versions of the FQPU to be able to detect and prevent incorrect program pins configuration.

[JammedStab]

Or even worse than the gimli glider...an Air Florida at DCA
Or.....MK Airlines in Halifax.....not enough thrust used for the runway length based on its actual weight.

[LeadSled]

Putting the Gimli Glider aside for a moment, was there not a similar case with an ATR in Italy where the wrong card had been installed and it thought it had a lot more fuel onboard than it actually had.
ATR72 vs ATR42?
Ended up in the Mediterranian with some loss of life, if I recall.
In short, yes.
Tootle pip!!

[Super VC-10]

Putting the Gimli Glider aside for a moment, was there not a similar case with an ATR in Italy where the wrong card had been installed and it thought it had a lot more fuel onboard than it actually had.
ATR72 vs ATR42?
Ended up in the Mediterranian with some loss of life, if I recall.

Tuninter Flight 1153, 6 August 2005, 16 of 39 on board killed.

[nonsense]

The aircraft involved (9V-SVC) was undamaged during the 16 April 2014 flight.

Is that date a misprint or has Flight Global dug up an old report?

The report has only just been published, 12/6/2018.

[MaximumPete]

I like to keep things simple. Just one question:- What happened on previous flight?

MP

[CargoOne]

Am I the only one who suspects the weight/performance/envelope information was omitted for a reason in this report?

[747-8driver]

I like to keep things simple. Just one question:- What happened on previous flight?
MP
What would you expect to happen when they departed with hardly any or no fuel in the CWT?

[Check Airman]

I thought every airline crew had to perform a fuel verification checking the uplift against the arrival fuel. It’s a basic safety precaution.

None of the airlines I've worked for have any provision for this. You'd have to dig into the ACARS to find the arrival fuel (which could well be meaningless if the plane's been on the ground for a while), and go out to the wing to speak to the fueller. We don't get fuel slips.

[FullWings]

As a 777 pilot, that’s really interesting. My experience of the fuel quantity system is that it is very accurate 99.9% of the time but every now-and-then gets confused. I remember once the indicated fuel quantity dropping quite rapidly in one wing, to the point that we thought an engine shutdown might be on the cards but as there was no roll tendency with the AP out and no visible leaking, we had a further think about it and while we were doing that, the fuel came back again!

"It was fortuitous that the aircraft had been fuelled with much more fuel than it needed," says the inquiry.
I’m afraid I disagree with that one. Being >40t overweight for your calculated performance is a big deal in these days of multiple derates, improved climb and CofG adjustments. You could hit something AEO, let alone OEI, not to mention being on the wrong side of the drag curve the whole flight.

From my reading of it, the problem was with the centre tank programmed capacity, so once the CT fuel was down to what the aeroplane thought was its nominal capacity (it’s used first) it’s likely that the total fuel indication would have been correct. There would still have been a large discrepancy between that and the totaliser, so definitely still an issue that might have caused a precautionary landing but not a fuel exhaustion scenario.

[Check Airman]

Does the 777 have a CHECK GW message on the FMS to warn of potentially incorrect weight entries? I'm not 100% sure how this failure mode would play out on an Airbus, but I'd imagine that the flight control computers would have sensed something before the fuel tank sensors snapped back to their senses.

[am111]

Is the model not displayed on the FMC ident page?

[PJ2]

None of the airlines I've worked for have any provision for this. You'd have to dig into the ACARS to find the arrival fuel (which could well be meaningless if the plane's been on the ground for a while), and go out to the wing to speak to the fueller. We don't get fuel slips.

The airline I worked for required a manual (paper) log-book entry recording the fuel-on-board at shut-down. Also, we were delivered the fuel upload slip, in litres.

During FMC programming, a quick, approximate mental check of the fuel required in kilograms multiplied by 1.25* gave a good approximate amount required, in litres. If the fuel slip showed around that expected amount, we were good to go. The assumption of course is, that the on-board fuel at shut-down was accurate, and it appears as though it would have been in this incident.**


* 1.2658 @ SG 0.78 is the actual conversion factor
** Re 'arrival fuel could well be meaningless', (either from ACARS or the paper log), no, I don't think so. If I understand correctly, the B777 APU uses ~250kg/hr. While an APU usage of say, 10hrs is possible, (though, one hopes, rare!), that's only 2.5T of fuel, well within the rough figures and error-detecting range when using the above method. So, FOB at shutdown, 5.5T, fuel required 86T; 80.5 x 1.25 = 100k litres expected on the fuel slip. Actual fuel delivered in litres would have been approx 151k litres.

[swh]

For reasons that could not be determined, the aircraft's internal fuel-quantity indicator had registered the aircraft as a 777-200, which features a smaller centre fuel tank than the -200ER. This caused the aircraft's instruments to under-measure the amount of fuel on board.

So I'm thinking that this fuel issue has existed from day one of this aircrafts life so that means it's been under reporting the fuel load by 41Tons. So how many times have they landed above the allowable maximum landing weight and were these Heavy landing recorded and inspected?

Bk

SQ operated a number of their 777-200ERs in a regional configuration with a deactivated centre fuel tank effectively making them 200As, to do this the pin programming of the FGPU was changed by SQ. My guess is the FGPU from one of these aircraft was swapped onto this 200ER that was being used as an ER. Due to the SQ internal pin programming changes to the FGPU it performanced correctly as a 200A. The part was the correct part for the 200ER, just their poor Mx procedures could not catch the FGPU pin setup was wrong, it is Ann a SQ maintenance cockup, putting the wrong part on, unable to resolve a fuel discrepancy per the AMM.

Thus is what happens when good la engineers make procedures up on the fly not following the AMM and expect the aircraft to fix their mistakes.

The report is a joke, this is a systemic issue with SQs maintenance procedures.

[BAengineer]

I agree it is a maintenance error but to clarify some points. It is a FQPU (Fuel Quantity Processing Unit) and the configuration is changed by software, not pin programming.

[PJ2]

The report is a joke,
It certainly doesn't answer all questions that would be helpful in further understanding how this occurred.

Canada's "Board of Inquiry Report" on the Gimli accident is far more thorough. Unfortunately, it is not available online.

[stallfail]

SQ operated a number of their 777-200ERs in a regional configuration with a deactivated centre fuel tank effectively making them 200As, to do this the pin programming of the FGPU was changed by SQ. My guess is the FGPU from one of these aircraft was swapped onto this 200ER that was being used as an ER. Due to the SQ internal pin programming changes to the FGPU it performanced correctly as a 200A. The part was the correct part for the 200ER, just their poor Mx procedures could not catch the FGPU pin setup was wrong, it is Ann a SQ maintenance cockup, putting the wrong part on, unable to resolve a fuel discrepancy per the AMM.

Thus is what happens when good la engineers make procedures up on the fly not following the AMM and expect the aircraft to fix their mistakes.

The report is a joke, this is a systemic issue with SQs maintenance procedures.

I do agree agree with your statement and even there were a lot of discussion about all those cheese holes,which finally aligned, the primary problem is not related to SQ maintenance, nor to the flight crew , it is much more related to the way the industry is moving to.
Based on my practical knowledge, it seems ridiculous to me, not to be seriously alerted by a difference of about 40 tons fuel uplift difference.
Further not stopping the departure and figuring out what is going wrong and try to work it out in accordance with the Fuel Measuring Stick Manual (FMSM) is kind of awkward. Maybe this task was not manageable for this particular ground crew within the given timeframe, still they should have had the opportunity to call for help.
​​​​​​​In these days,flight crews neither maintenance staff, do not have the opportunity to gain their experience and proper judgment over years, instead regulators like FAA and EASA are following the commercial pressure and will simply agree to the demands given by the industry, which means you will find 3000 FH blokes on the LH seat in an airliner and you will find a CAT A signing off a 777.
This simply leads into decision making which is task orientated instead of being "common sense" based, meaning by that, we rely more and more on automated aircraft systems while loosing our senses whats wright and wrong (don't get me wrong, I really appreciate all these aids in modern aircrafts,cause it makes my life much more easier).

[Anilv]

I had previously attended a flight where the lower forward hold was supposed to be empty on arrival but when we opened it up we found that there was around 12,000kgs which were not offloaded at the previous station.

Pilots had already left the aircraft but I met them when they took the next airplane out and told them what happenned... I also asked if they noticed anything on the flight in but they said everything was normal. Looks like the holes in the cheese didn''t line up but I can imagine a different scenario with a heavier load, shorter runway etc.

Plane was an MD-11 from SHJ.

Anilv

[underfire]

Canada's "Board of Inquiry Report" on the Gimli accident is far more thorough. Unfortunately, it is not available online.

https://reports.aviation-safety.net/1983/19830723-0_B762_C-GAUN.pdf

[flash8]

Namely the fact all the V1 V2 and Vr and Vref was WRONG with a factor close to 1.3 or 1.2.
Says it all really.

[A Squared]

however, based on the story as published there is no way I would be moving the aircraft until I was satisfied.


Well, the crew had a "correct" (but erroneous) fuel quantity indication on their cockpit gauges, which agreed with the engineer's tank sticking results, and a plausible explanation for the uplift quantity discrepancy (Counter was not reset) which was incorrect, but not obviously so. I think a whole bunch of pretty diligent aircrew would be "satisfied" by this trap.

[A Squared]

The only thing I would accept is a full magnastick check of all tanks

OK, I'll bite, if the problem is that you suspect too much fuel uplifted. And your cockpit fuel gauge fuel gauge indications show the wing tanks to be full ... and the engineers stick quantity calculations assume the wing tanks are full, and the wing tanks are in fact full, what useful information would have been added by sticking the wing tanks and confirming that they are indeed full, just like the engineers correctly assumed, and just like the cockpit gauges correctly indicated? ?


as well as a reasonable explanation of how come the uplift was so much higher than calculated.

Well, they believed that the delivery meter had not been reset to zero. If you have two completely independent measurements of the fuel on board (quantity gauges and engineers stick measurements) which agree, and show the correct load on board I think a lot of crew would tend to accept explanations that involve the uplift quantity being in error. Not having the results of the investigation in front of you before the incident, it's hard to know which pieces of information in front of you are in error.