Poof in Boots

In spite of many months of investigations and now the AAIB preliminary findings, talking to my Flight Crew colleagues on the 777, none of them seem to believe that ice was the problem.

VC10's in the 60's used to fly reglularly over 40,000 feet. There did not seem to be any problems with fuel icing in those days?

grebllaw123d

Poof in Boots,

"In spite of many months of investigations and now the AAIB preliminary findings, talking to my Flight Crew colleagues on the 777, none of them seem to believe that ice was the problem."

OK then: what DO your colleagues believe was the problem?

BAe146s make me cry

BA Engineering maintenance is under scrutiny at present due
to a variety of non-compliances raised in the form of reports
to CHIRP. The Engineering Director at CHIRP is incidentally
ex-BA. UKCAA SRG (Many ex-BA staff) have yet to comment.

On commercial aircraft, routine maintenance is performed daily.
The time intervals of daily routine maintenance cannot be deferred.
These tasks would include the draining of water from fuel tanks
IAW the Aircraft Maintenance Manual.

I would hope that attitudes to task completion have not altered significantly since I worked there. Documentation & certification of all tasks undertaken must be recorded. AAIB must ensure previous draining
of fuel tanks tasks for this A/C were actually completed (Not simply penned off).

BAe146???

Re-Heat

What exactly are you insinuating? There is not only no suggestion that this is the case, but this is extremely off-topic when the recent report has narrowed down the investigation to some very specfic areas. Further, the non-compliance to which you refer did not to my knowledge ever relate to tasks not being completed and later falsified, but instead to people of incorrect qualification working on tasks at Cardiff.

Judicious deletion of irrelevant posts from the moderator please?

lomapaseo

Flight safety is not decided by poll taking.

Questions are natural as this thread has proven. However, when Service Bulletins are issued by the manufacturers and/or authorities they should be complied with.

When the pilot community have questions about the application of a SB that is the responsibilty of the issuer to defend.

Many questions remain and hopefully many will be answered in time. However as some are answered then solid recommendations will be issued.

777fly

Grebllaw123d:

In answer to your question, I suggest you read the whole thread again.There are plenty of alternative suggestions as to the cause....

BAe146s make me cry

RE-HEAT

Please step down from the box. This is a public forum and
as such, informed opinions from people in industry (or otherwise)
can and should be aired and shared.

There appear to be fundamental problems with how BA Engineering operates at present. This has been initiated by concerned BA maintenance
personnel.

Some of the best Licenced Aircraft Engineers remain at BA Engineering, however, not many as so many have chosen to leave. In closing,
the compliance or deviation of/from AMM practices & company SOPs within BA Engineering, early 2008 shall always be relevant to the
loss of this B777...

BAe146???

CargoFlyer11

I don't have any technical knowledge like other who have posted here, however, I've been flying transport jets myself since 1978, current wide body captain, and I've never heard of fuel icing of this nature. Certainly, in most cases, such an occurrence would not be a one time thing, considering how many hours are flown each day by different types of aircraft exposed to different cruise altitudes temps and fuel loading conditions; if anyone has any knowledge of a previous occurrence, that might add some credence to this scenario....

Bobbsy

SLF here. I've avoided any comment until now because I have no knowledge to add to the topic.

However, one thing I can say is that my faith in the 777 is in no way dented and I happily fly that plane. One isolated incident does not a pattern make.

Bob

Poof in Boots

One theory being propogated is that the incident was more to do with the software....ie: the lines of software code.

Perhaps on the BA038, glitches buried somewhere in all those lines of software code came together like holes in a cheese......

Shaka Zulu

dear PinB,

I am one of your 777 Flight Crew and as such used to believe that it might be an EEC software error however the NEW AAIB report clearly narrows the possible cause down to one specific area.
Software errors always happen, on any plane so it would have been plausible.
The AAIB wouldn't have written this report without proving that another error would have been a better fit for what has happened.

Fact of the matter is we don't know how ice behaves at high altitude at extreme low temperatus in a complex mix of JetA1.
Certainly in my mind we can put the software glitch to bed.

DozyWannabe

PinB:

Head back to post #1661 and you'll find a series of posts from one of the guys who worked on the RR FADEC system. The whole discussion was pretty much encapsulated there.

scrivenger

'Fact of the matter is we don't know how ice behaves at high altitude at extreme low temperatus in a complex mix of JetA1.'


I find this statement, if true, to be extremely worrying. I mean haven't we been flying for many, many years with JetA1 at high altitude and extremely low temperatures or am I missing something?

Oilandgasman

Some of the physics of water in Jet A1 at www.facetinternational.net/pdfs/aviation/aircraft_refueling.pdf It would appear that the behaviour of water as the fuel temperature falls is understood.
Back at the AAIB report graph on page 5. (bottom rt hand corner, enlarge to 800% for a clear view) Does anyone understand why the fuel consumption from the left hand main tank increased immediately after the scavenge from the centre tank. This following 7 hours when the fuel consumption from both tanks was identical?

tanimbar

It is true that the AAIB report that 'little is known' about ice crystals in fuel at temperatures below 18C (0F) - see my post 1725,page 87.

Its worse because the AAIB don't mention the overall operating environment, just temperature and not pressure, vibration, fluid circulation etc..

This is not meant to imply any wrongdoing on the part of the AAIB. Actually, I suspect that if you were to have a private conversation with the AAIB report writers the air would turn blue if you asked them to describe the industry's fuel standards. I wonder when the AAIB realised that 'the standard' has a huge whole in it.

But, has the industry simply lost or forgotten the knowledge that may have been gained from tests/experiments etc. conducted decades ago?

Some older crew have already posted here .... can anyone shed light on fuel tests back in the '50s and '60s that lead to the development of the fuel standards?

Regards, Tanimbar

tanimbar

Thanks for the link to the PDF from Clarcor. Just read it and it doesn't help us understand the behaviour of water in fuel as the temperature drops, other than in a general way.

Clarcor, as you know, make fuel filters and systems for ground based operations - storage of, transport of and re-fueling of aircraft. Fascinating to read that Fuller's Earth is still used as surfactant. Now that is an example of modern technology using knowledge gained centuries ago.

The discussion on microbes in tanks was interesting too.

Regards, Tanimbar

Oilandgasman

Tanimbar
The section I thought may be relevant concerns precipition of absorbed water from Jet A1 as the temp falls. This precipited water will form droplets then sink to the bottom of the tank. SG of Jet A1 0.78-0.80. Ice 0.9-0.95? In the case in point this precipited water will be in the form of ice crystals. Note your comments on microbes. If tanks are not treated with biocide during cleaning then they are another matter, will be present if water present, but are easily identified under the microscope. This must have been checked post incident as they are a well documented contaminant as are fungal spores.
The bottom line is that in the first sentence of ASTM spec for Jet A1, includes the phrase " bright, clear, and FREE from water". Not drops, not ppm, not entrained...none. If this is not what is being delivered on every occasion then there is a quality control issue.

CONF iture

dxzh
Do you give any credit to what you call that apparently FAA leaked memo

Therefore what do you think of the AAIB reports which do not mention:
- A maintenance message indicating excessive water in the center tank set during taxi on the two previous flight legs
- An auxiliary power unit (APU) auto start sequence
- A crossfeed valve opening

M.Mouse
As you correctly mentionned the fuel on board and the flap retraction before the AAIB did confirm your words, would you like to comment on that apprently FAA leaked memo ?

dxzh

CONF iture,

I am certainly now prepared to give more credence to the "apparently leaked" FAA memo dated 24 January 2008 (which popped up on the internet by 1 February 2008). This is because the purported inside knowledge in the memo of what seemed to be non-public, pertinent information at that stage of the investigation has been subsequently corroborated in many varied respects by information in the AAIB's later bulletins and reports. Was the memo as leaked only a draft (or even a forgery) I do not know - however, I try to note well the cautionary words drummed into us by PPRuNe about not taking everything at face value and hence I wrote "apparently". The memo itself ends with the words "Information only. This information is preliminary and is subject to change". If very curious about the memo's provenance, maybe the answer is for some brave soul to pick up the phone to its supposed author, Doug Pegors, and ask him - his direct line at the FAA is publicly available.

As regards the AAIB reports to date, I believe they are concise and well-written, concentrating correctly on the contributory factors to the underlying accident, rather than the consequent events as the aircraft impacted the ground. Actions at the time of impact may not be wholly irrelevant in so far as they may reflect on the status and set-up of the aircraft on or prior to the underlying accident. However, the key concern here is to understand the unheard of rollback of each of two seemingly fully-functioning engines at a critical stage of flight. I am not surprised that the AAIB's clear focus is on understanding the duplicated rollback and how to avoid a double failure condition in the future.

There are clearly gigabytes (let alone pages) of raw data and analysis which could be made public but that would be a disclosure exercise of an altogether different quality and for a very different purpose - this investigation is not the subject of some hugely expensive public enquiry or court case (thank goodness) and, as ever, safety in aviation has generally benefitted from measured disclosure of facts concentrating on solutions and not scapegoats and thereby encouraged full and frank offline discussions with accident investigators (rather than a**e covering for fear of litigation and a blame culture). The AAIB has already disclosed much more than it might have, but given the degree of rumours and speculation perhaps a balance has had to be struck.

Am I surprised or concerned that I have not received a download of all the data in the QAR, FDR and NVM or test rig papers etc? No. Am I surprised or concerned that the AAIB may omit from the 21 page interim report certain information about events which I assume the AAIB is confident happened on or about impact (perhaps technically part of flight until aircraft stationary, perhaps interesting to a pilot, but not relevant to the focus of the investigation)? No. Am I concerned that information in earlier AAIB bulletins such as about FOD (eg plastic scraper) has not made it into the interim report? No. In fact I really believe the AAIB is doing a great job synthesising the information and keeping the correct focus on the critical failure condition.

Nevertheless, I do speculate about the uncorroborated centre tank messages even though I can understand why if they did exist the AAIB might have discounted their evidential importance given the sumping and, perhaps, a suspicion that the message is not as reliable as it might be and it would consequently be misleading to draw from it a conclusion that there really was 600+ litres of free water in the centre tank! On the point of water in the centre tank (as opposed to the omission of messages (if there were any, I stress) from the interim report), I feel a little rebellious as water in any tank bears on the underlying accident, even without any suggestion of such a message, and to my mind there is circumstantial evidence in the design and track record of 777 centre tanks suggesting a tendency to accrue ice and free water there. There is even in the (apparently leaked) FAA memo a second statement of information learnt on 22 January 2008 that "There was a message of water in the center fuel tank shortly after departure from Beijing." - ie implying that not just on the two previous legs, as learnt on 24 January 2008, but on the actual accident flight there might have been some ice which melted into free water in the centre tank. I could envisage a scenario along the lines of: existing ice already in the centre tank is gradually melted following the uplift of warm RP-3 fuel; the resulting free water triggers a message; and sufficient free water is then dissolved back into the bulk of the fuel by the water scavenge pumps' operation to clear the message.

As to the APU start sequence (around termination of QAR recording) and cross feed valve, I am very curious and have lots of questions and ideas, but I personally see little relevance to the real focus of the investigation even assuming as I do what is stated in that apparent FAA memo is not complete fiction - to the extent either were involved in events after the dual rollback process had started, I strongly suspect that the AAIB would see them as playing a secondary role and the data bears out that there was a much bigger issue already playing out - namely a critical restriction in both fuel lines.

Fargoo

BAe146s make me cry

I respectfully request you wind your neck in and start a fresh thread in the Engineering section of these forums if you have an axe to grind.

I'm not sure what your agenda is here but it's clear that the AAIB do not feel BAs Engineering or Flight Crew were the cause of this accident. I'm further confused by you're insinuation that BA Engineers deviatied from the AMM with regards to this aircraft. Also for you to even suggest that this task was "penned off" is a terrible accusation from a fellow member of the engineering community founded on not a shred of evidence.

These may be talking points and forums for discussion but you really need to be careful when slinging mud in a direction it is not deserved.