BA 777 Update

[rjmore]

Originally Posted by seagull

To my knowledge, only NWA actually tests the fuel and uplinks the actual temp to the International flights, after departure.

Now that would be cool. The only airport we get a report on the temp is PANC. Everywhere else we use the most conservative, which is why we get an amber fuel low temp at -37C. We can somewhat ignore it as long as we know for sure what we have on board.

I'm not sure where they were but terrain along the Asia-Europe/UK routes wouldn't probably allow them to descend low enough to make a difference, especially if they were on Y1. Anyone know MMO on the 777?

[seagull]

Originally Posted by rjmore

Now that would be cool. The only airport we get a report on the temp is PANC. Everywhere else we use the most conservative, which is why we get an amber fuel low temp at -37C. We can somewhat ignore it as long as we know for sure what we have on board.

I'm not sure where they were but terrain along the Asia-Europe/UK routes wouldn't probably allow them to descend low enough to make a difference, especially if they were on Y1. Anyone know MMO on the 777?

Most of the World, outside the U.S., use Jet A1. Look on your fuel ticket (or ask, if you don't get a copy of it with your paperwork). On the -11, we just enter the fuel type in the FMS and it adjusts the temp in the system for the fuel system controller.

[rjmore]

I know that the rest of the world uses A1. I should have clarified, the only place we get an adjusted temp for Jet A is PANC. The -400 doesn't have the capability to adjust the bells and whistles in the FMS, at least not ours.

[Joe]

Originally Posted by Nick

In looking up "prist" after reading this, here is a page I found that might be of interest to anyone curious about the basics of this subject:

http://www.csdinc.org/prist/prod_info.htm#Why

I always heard corporate pilots saying "with prist" on some fuel orders. I know little about it -- does it get mixed into the airport fuel supplies at places like Beijing and the rest of the world's airline hubs?

At my FBO we use DICE (yet we still call it PRIST, which is just another trade name... I think the military calls it "FIZZY"... but I digress...). It is stored in bottles on our fuel trucks, and we inject it into the fuel when requested at a ratio of around 1 gallon of Prist/1,000 gallons of Jet-A. I believe fuel can be delivered to the airport premixed as well, but we don't do that here. I'll see if I can take some pictures of it and post them later.

[Nick]

Originally Posted by rjmore

Anyone know MMO on the 777?

.87 and the 777-300 and everything else newer such as the LR is .89

[srleslie]

Originally Posted by Nick

.87 and the 777-300 and everything else newer such as the LR is .89

I'm guessing this has something to do with Mach but what exactly does MMO stand for?

[Nick]

Originally Posted by srleslie

I'm guessing this has something to do with Mach but what exactly does MMO stand for?

Mach - maximum operating.

[taildragger173]

Whats the difference between Jet A and Jet A1?

[Hacker15e]

Originally Posted by JaceTheAce

Throttles?

Are you mocking the use of the term 'throttles' with respect to a jet engine? That it should be 'PCL' or something of the like?

Originally Posted by taildragger173

Whats the difference between Jet A and Jet A1?

From Wiki:

Jet A is similar to Jet-A1, except for its higher freezing point of −40 °C (vs −47 ° Jet A-1). Like Jet A-1, Jet A has a fairly high flash point of 38 °C, with an autoignition temperature of 410 °F (210 °C).

[Fly4Pay]

Originally Posted by seagull

More problematic is fuel cooling to the point it is like jello on long haul ops. It can be thick enough so the fuel pumps won't pull it in. I would not imagine that would be true in this case, as it should have warmed on the way down, and the fuel low temp sensors would have alerted the crew well before their approach.

After a long-haul, high-altitude flight where the fuel has cold soaked, you won't have significant warming in the relatively short time period of the descent. The air is warmer, but it has a much lower thermal coefficient than the fuel (kind of like why you thaw a turkey in water instead of air--heat moves less efficiently in air).

Originally Posted by rjmore

I think if it were a fuel contamination problem there would have been other instances of this occurring out of PEK that day.

But how many other flights flew that high, for that long? We don't know. And other flights may have had problems, but to a lesser degree, and they could have easily gone unnoticed or at least unreported.

Originally Posted by Minuteman

If fuel was a cause, I would have expected the problem to manifest more gradually and asymmetrically: one engine goes to a reduced thrust, recovers, declines, then the other has trouble later.

I'm not sure why you would expect that. Both engines would have been feeding from the same tank. If gelled fuel went into the fuel lines, the reaction from both engines would have been virtually simultaneous.

Actually, to me, the gelled fuel scenario seems the most likely, especially given the unusually low temps that day and the long flight time of the sortie.

[rjmore]

Originally Posted by Fly4Pay

But how many other flights flew that high, for that long? We don't know. And other flights may have had problems, but to a lesser degree, and they could have easily gone unnoticed or at least unreported.

Very true, but I was thinking more along the lines of fuel mixing and maybe that aircraft had been to the US in the past couple days. But what you are saying is also plausible since any airplane going to Europe out of there would go the same way.

[PGT]

Update:
http://www.flightglobal.com/blogs/fl...acciden-1.html

fuel contamination and/or ice is what they are looking at now

[seagull]

Originally Posted by JaceTheAce

Throttles?

Most people I know call them that, including our flight manuals.

[seagull]

Originally Posted by Fly4Pay

I'm not sure why you would expect that. Both engines would have been feeding from the same tank. If gelled fuel went into the fuel lines, the reaction from both engines would have been virtually simultaneous.

Actually, to me, the gelled fuel scenario seems the most likely, especially given the unusually low temps that day and the long flight time of the sortie.

Good post, just wondering about the fuel feed. I'm not familiar with the 777 fuel system. Are there two wing tanks a center tank, so they were feeding off the center tank? Why wouldn't it be "tank to engine"?

[E6BAV8R]

Originally Posted by seagull

Good post, just wondering about the fuel feed. I'm not familiar with the 777 fuel system. Are there two wing tanks a center tank, so they were feeding off the center tank? Why wouldn't it be "tank to engine"?

One would think it would be 'tank-to-engine' at that late of a flight. Most airliners with 3 tanks will burn the center tank first so I'd imagine they were on 'tank-to-engine' by that point.

[Doug Taylor]

That is kind of weird. We turn down the center tank to about 1000 lbs immediately and then go tank wing to engine... on the 757/767.

[seagull]

Originally Posted by Doug Taylor

That is kind of weird. We turn down the center tank to about 1000 lbs immediately and then go tank wing to engine... on the 757/767.

Burning the fuel out of the center tank first, and leaving fuel in the wings for last, makes sense from a variety of perspectives. It is probably required, due to wing bending limitations. Of course, that leaves the coldest fuel for last, but I would assume the 777 has an auto fuel circ system, (or, considering Boeing, a procedure the crew has to follow...), to keep the wings mixed with the (probably) larger center tank.

[Copperhed51]

Alright, so hopefully nobody flames me for even posting this, but this is a conversation I overheard my airline's manager of safety and manager of training having the other day while I was waiting nearby for my oral.

Safety guy comes in and says there is a new theory about what happened to the BA 777 at heathrow...i didn't catch where he said he heard it from. Anyway, he said something to the effect of there being a royal family motorcade that was passing the airport on a road that would come near final approach course of the 777 and that the motorcade has equipment that gives of some kind of electric scrambling signals of some sort. Theory is that the signals somehow interfered with the FADEC's and caused the engines not to respond to the pilot inputs.

It sounds pretty crazy but I just thought I'd share in case anybody was interested.

Oh yeah, as for the oral, I passed! On to the sim!

[Minuteman]

Originally Posted by Copperhed51

Alright, so hopefully nobody flames me for even posting this, but this is a conversation I overheard my airline's manager of safety and manager of training having the other day while I was waiting nearby for my oral.

Safety guy comes in and says there is a new theory about what happened to the BA 777 at heathrow...i didn't catch where he said he heard it from. Anyway, he said something to the effect of there being a royal family motorcade that was passing the airport on a road that would come near final approach course of the 777 and that the motorcade has equipment that gives of some kind of electric scrambling signals of some sort. Theory is that the signals somehow interfered with the FADEC's and caused the engines not to respond to the pilot inputs.

Don't know about any royals, but Gordon Brown's 777 was on the taxiway fixin' to leave for China at the time of the accident.

My favorite theory so far is:

1. A significant amount of water froze in the center tank, which hindered the function of the scavenge pumps (a low output pump pressure should have triggered an EICAS message. I'm not aware of any water/contamination detection, other than filter bypasses).
2. During descent and approach, ice melted enough to let the scavenge pumps move more fluid again, which belched water/fuel into both mains (both, being the key there)
3. Enough ice made its way into the preheater and on to the engines to hinder the ability to respond to an increase in thrust.

The only problem with that theory is that the temperature of the fuel in the tanks doesn't get back above 0°C until a long time after the aircraft has landed and parked. There are heat exchangers for the hydraulic system in the center tank, but they'd have to be abnormally warm to keep the temperature above freezing. I guess, if the liquid water were agitated by a pump it might freeze into smallish crystals in the mains.

The EEC does relay the thrust command it thinks it received, so I'm confused as to why there is speculation about the improper function of the EEC (due to EMI or whatever). The EEC's echo of the received command should be in the recorded flight data. I would expect something much more complex like an engine computer to be affected by noise much more easily than a wire and servo for a fuel metering unit ... at least, affected more consistently.

[DZERO]

Originally Posted by Screaming_Emu

And forgot to do a mag check before takeoff

Nah...definitly carb icing. Any fool know that.