precept

Given the continuing interest in this accident, the following URLs are links to the US FAA reporting site. Interested parties can access the site and drill down on the current status. The names and positions of US investigators are identified on the first site.

We continue to await governmental, industry and knowledgable individual insight into this potentially catastrophic incident. When you get to the page, click on "factual" PDF page for most complete information.


DCA08RA028

http://www.ntsb.gov/ntsb/GenPDF.asp?...08RA028&rpt=fa

lomapaseo

precept

Where

soem dood

The NTSB site layout is not too intuitive and it's search function is spotty.

Here (link) is a place that you can find all NTSB work-product on foreign investigations, just look for G-YMMM. However, there is really nothing new in there.

NTSB - Aviation - Foreign Investigations

If you suspect there is something in the official docket, but not shown on the website, then you can make a request for that record here:

http://www.ntsb.gov/pubmail/pubmail.asp

paulrcgb

Sorry to ask the question...did anybody (bar the BBC) ever see or find a url to the BA internal report? thx

777fly

Hot rumour at LHR this morning that there has been another 777 engine roll-back.

Swedish Steve

More than a rumour. One engine failed to respond to throttle demands in cloud. Other engine OK. Both OK when leaving cloud.
Sorry don't ask, thats all I know.

DILLIGAFF

Happened last Sunday a/c MMC. Whilst at F/L 370 engine did not respond for 90 seconds. Aircraft is still at LHR, AAIB have inspected it.
D

Mat Sabo

Can bigots pin this on contaminated Chinese fuel again? If so many will be clamouring for the boycot of the PEK Olympics........danger!!!!

Green-dot

DILLIGAFF,

Thanks for the details.

Here is an interesting article which may be related to this latest incident:

High Altitude Engine Flame-Outs | AVIATION WEEK

PS. Apparently asking a few simple questions about altitude and flight phase, just prior to your post, was reason enough for the mods to remove my post?

Regards,
Green-dot

DILLIGAFF

MMC incident was caused by ice crystals forming on TAT probe as A/C flew through cloud leading to a false reading. When A/C came out of cloud ice melted and fueling returned to normal engine throttled up as requested.
By the way the F/O was John Coward.
D

wilyflier

Lucky Coward,
Arent those pitots heated ?

......Was that stuff about high engine ice in strange forms by Prof/Doctor Viellette, (Aviation Week last year) promulgated to all working Aircrew?
.......It seems essential information to me, and should have been shown up in this BA 777 thread at the very beginning by one of you current Captains.

.......I had a reliable report last month of CB up to 80,000 ft in USA . ......... I have seen thin anvil stuff 100 miles ahead of an actual CB-and got iced up pitots at 40,000
(pitot heat working, 3 aircraft lost ASI)

Oluf Husted

Dear Green-dot,

Thanks for the article: "High Altitude Engine Flame-outs" that tells us, we have been flying around not knowing the hard facts about engine icing. And that we still do, since advanced testing is still taking place, also in 2009.

Green-dot please reread our exchanges from may 1. and 2. 2008 in this tread, "your" article just sharpened my theory:

"That engine core icing was the reason for the BA38s engines hesitation"

Oluf

lomapaseo

While I appreciate the latest news about possible engine icing at altitude, I do not believe that it has been linked in any fashion to the BA038 event durring an approach phase at non-icing conditions.

If the speculators and theorists among us want to discuss this aspect then I think that it needs its own thread or else a positive link via the AAIB

Oluf Husted

Dear lomapaeso,

It was indeed: "Icing condition" during the last 10 minutes of BA38s career.

Ground temperature was +11 degrees C. and its RR engines flew in and out of broken clouds.

Boeings definition of "Icing condition":

Anytime the OAT (temperature) is below +10 degrees C. in moist air (dew point within 3 degrees C.)

And the higher the temperature, the more severe is the icing condition, due to the higher cloud water contend.

Read more about it here: www.whistleblowers.dk

Oluf Husted

punkalouver

Service experience generally indicates that turbine engines are not susceptible to mixed phase or glaciated icing conditions, with the possible exception of two known potentially vulnerable engine design features. These two design features are (1) pronounced inlet bends (such as particle-separator inlets), or inlet flow reversals, where inlet flow can stagnate and accumulate ice, and (2) high solidity dual row front stage compressor stators that can be susceptible to non-aerodynamic ice buildup on the stator airfoils resulting in core airflow blockage. These two design features should either be avoided or carefully scrutinized by analysis and testing to assure their non-susceptibility to mixed phase or glaciated icing conditions.

I know it is a bit off topic but which jet engines fall into thise two categories?

ChristiaanJ

In category 1) I would think you'll find engines such as helicopter turbines, some turbo-props, and some ancient engines with centrifugal compressors.
Not sure about category 2)

arcniz

The poster's highly emotional comment, and the underlying concept, are misplaced here.

A number of reasonable persons consider fuel a likely or at least possible cause for the power failure because it is one of the few critical elements in common for both turbines on BA038.

Quite early in the post-incident investigation, the investigating authorities clarified that the fuel was not obviously 'contaminated' . Some people see as possible, however, the concept that the fuel might have met all prevailing specifications and still might have had some property differing from other "normal" supplies in common use, thereby defining an uncommon circumstance that might help explain why 038 uniquely had a problem.

The aviation community is international and very cosmopolitan. In regard to matters of safety, the focus is on finding answers and preventing future failures. While individuals may have their own biases, the consensus interest is directed toward empowering safe and reliable global aviation for all parties and all nations - not looking for persons or places to blame.

This is clearly not fertile ground for bigots, so please try to get a grip on yourself.

ChristiaanJ

arcniz already has mostly answered this...

bigots? Haven't really seen any here. Some far-fetched suggestions, yes, but that's what R&N is all about.

contaminated ... fuel? It already seems to have been established the stuff wasn't contaminated.

... Chinese fuel? Maybe the particular 'cut' of fuel may end up having some relevance, although it sounds less and less likely. Tons more of the stuff were uplifted on the same day from the same place, and nobody else ended up just short of the runway.

... again.? The venom is in the tail. When did this happen before?
In short, I think we can class this one as a wooden-spoon-stirring post.

Far more interested in the ice accretion discussion.
As a non-engine engineer, I thought compression heated the air.
So with an OAT of about +10°C, wouldn't any earlier ice have melted rather promptly, once OAT was over 0°C?

Green-dot

Dear Oluf,

Having re-read our May 1st and 2nd exchanges i can see (as i did then) your point regarding core icing. Although i keep several options open to the cause of the BA038 accident, the AAIB reports so far reveal no indications that engine icing is suspected. The AAIB specifically stated in the S3/2008 bulletin, released in May (after our exchange), that there was no evidence of core engine icing and that the reduction in thrust on both engines was the result of reduced fuel flow and all engine parameters after the thrust reduction were consistent with this.

To my knowledge, if an engine rollback was caused by core icing, EGT would have increased (with fuel flow required available). Quoting the article on "High Altitude Engine Flame-Outs":

"Incident investigators using data from DFDRs found that the uncommanded thrust reductions were manifested initially by a gradual decay in fan rotation speed and a final stabilization of the engine at a sub-idle operating condition. The engine speed decay was also associated with an increase of turbine gas temperature and a failure of the engine to respond to movement of the throttles/thrust levers. The term "rollback" has commonly been used to describe this condition."

The recorded engine parameters, according to the AAIB, do not show high EGT readings consistent with possible core icing. However, not ruling anything out before the cause has been substantiated by facts, could BA038 have flown anywhere near thunderstorm anvils along its route that day, possibly accumulating ice consistent with what has been described in the mentioned article? I assume the AAIB will have looked into that possibility?

I do not rule out your theory. Although the rollbacks occurred at low altitude, ice accretion could have commenced at high altitude near TOD, keeping compressor temperatures low enough during the CDA for more ice to accumulate at lower altitudes. If so, the recorded engine parameters revealing the contrary, will have to be explained.


Green-dot

boguing

Technically speaking, ice (water) doesn't thaw until +4 Deg Celsius. But I know that you knew that! Pedant mode off.