Bon
BA plane 'lost power' before crash landing at Heathrow
This is all very interesting discussion on what could of caused this dual engine failure. All have valid possiblilities. From my experience though, I have taken a bird into a JT8D engine immediately after takeoff and there was no fire. Not even a burp in the engine. Just a very fowl smell of burnt "something". We did see the flock of birds as they splattered along our windscreen so we were pretty sure we took in a bird in the engine. So we turned back and landed the airplane safely. Engine operated normally. Bird injestion. Confirmed! To have birds injested into both engines and fail both at the same time, highly unlikely although possible. Have you guys ever seen the engine tests on the 777 engine with the frozen turkey thrown into the intake? Engine kept running but you should have seen the engine damage. Interesting test but the engine kept ticking.
As far as airports keeping the "pattern" clean of birds, good luck! Birds seem to like the "final approach course".
Engine controls. I have flown cable control fuel control units, FADEC's and EEC's equipped aircraft. I have had a fuel control governer failure, FADEC failures and EEC failures. None resulted in a dual engine failure or even a single engine failure. the closest to a engine failure due to an engine control was in a govener failure on the DC-9 which resulted in reduction of power on that one engine to about 1/3 on the normal operating power and I lost total control of the throttle but still had some power engine and of course had full command of the remaining engine. Those systems are designed to operate independently on each engine. So to have one fail and effect the other engine is pretty much impossible. Electronic engine control or FADEC's are a mystical thing but on each engine they have backups or "dual channels"/"Alternate modes" to prevent the very thing from happening as in the BA 777.
Electrics. All governing authorities (FAA, JAA) require that aircraft can operate on a prescribe emergency power for a prescribed amount of time. Emergency power is, for simple words, batteries that run dc and ac standby electrics supporting limited systems to get you to the ground safely in any weather conditions. This includes the operation the engines of course.
Autoflight systems will disconnect upon engine failure. One or two or more. Typically a loss of an engine will cause a transfer of electric power to the remaining operating generating system causing a shed of power on certain electrical buses to reduce electrical loads and disconnect the autoflight system until you can reengage the autoflight system or recover lost electric systems as necessary. So the theory that the 777 autoflight system was trying to maintain GS and autothrottle settings causing a nose high attitude, I think is false. I fly the 737-700 (it's not the 777) but I would have to imagine that the design is similar in fashion. 737 autoflight system will disconnect upon engine failure and so will the autothrottles.
Fuel contamination. Most aircraft have main wing and center tank fuel cells. Most aircraft fuel tanks feed center tank first then main wing tanks. Starting with the center tank, this tank usually feeds both engines simultainiously then the the wing tanks feed their respective engines when the center tank is empty. If this flight was early on in it's trip and was feeding off the center tank, both engines could have been contaminated at the same time resulting in the loss of power on both engines.
Bottom line, BA aircrew did a fine job saving a bad situation. I would have not wanted to be there!
Again, lots of speculation and arm chair quarterbacking. Just throwing my 2 cents worth out there.
Metro
As far as airports keeping the "pattern" clean of birds, good luck! Birds seem to like the "final approach course".
Engine controls. I have flown cable control fuel control units, FADEC's and EEC's equipped aircraft. I have had a fuel control governer failure, FADEC failures and EEC failures. None resulted in a dual engine failure or even a single engine failure. the closest to a engine failure due to an engine control was in a govener failure on the DC-9 which resulted in reduction of power on that one engine to about 1/3 on the normal operating power and I lost total control of the throttle but still had some power engine and of course had full command of the remaining engine. Those systems are designed to operate independently on each engine. So to have one fail and effect the other engine is pretty much impossible. Electronic engine control or FADEC's are a mystical thing but on each engine they have backups or "dual channels"/"Alternate modes" to prevent the very thing from happening as in the BA 777.
Electrics. All governing authorities (FAA, JAA) require that aircraft can operate on a prescribe emergency power for a prescribed amount of time. Emergency power is, for simple words, batteries that run dc and ac standby electrics supporting limited systems to get you to the ground safely in any weather conditions. This includes the operation the engines of course.
Autoflight systems will disconnect upon engine failure. One or two or more. Typically a loss of an engine will cause a transfer of electric power to the remaining operating generating system causing a shed of power on certain electrical buses to reduce electrical loads and disconnect the autoflight system until you can reengage the autoflight system or recover lost electric systems as necessary. So the theory that the 777 autoflight system was trying to maintain GS and autothrottle settings causing a nose high attitude, I think is false. I fly the 737-700 (it's not the 777) but I would have to imagine that the design is similar in fashion. 737 autoflight system will disconnect upon engine failure and so will the autothrottles.
Fuel contamination. Most aircraft have main wing and center tank fuel cells. Most aircraft fuel tanks feed center tank first then main wing tanks. Starting with the center tank, this tank usually feeds both engines simultainiously then the the wing tanks feed their respective engines when the center tank is empty. If this flight was early on in it's trip and was feeding off the center tank, both engines could have been contaminated at the same time resulting in the loss of power on both engines.
Bottom line, BA aircrew did a fine job saving a bad situation. I would have not wanted to be there!
Again, lots of speculation and arm chair quarterbacking. Just throwing my 2 cents worth out there.
Metro
Well, for the follow on post:
Now for the biggest question: Does anyone know what the Boeing-patentd two way digital data bus is. Could this of had anything to do with the loss of power. I guess the 777 data systems are different than the typical data systems.
I did a little reading since my last post and have a few different thoughts on the matter. This "two way digital data bus" is someting I have not heard of before and seems to be particular to the 777. Maybe this had something to do with it??
This is from the Boeing site on the 777.
"A key part of the 777 systems is a Boeing-patented two-way digital data bus, which has been adopted as a new industry standard: ARINC 629. It permits airplane systems and associated computers to communicate with one another through a common wire path (a twisted pair of wires) instead of through separate one-way wire connections. This further simplifies assembly and saves weight, while increasing reliability through a reduction in the amount of wires and connectors. There are 11 of these ARINC 629 pathways in the 777"
As in a report in one of the links posted here, it explains that the 777 crew several times tried to produce power with no throttle response but at no time did it say they had dual engine failure. Just no throttle reponse to pilot input. This could explain the Autoflight system staying connected and the nose high attitude trying to maintain the approach. Humh?
Does anyone have any specific info on this "data bus" system?
Boy, is this confusing. I guess we will just have to wait and see what the report uncovers.
Metro
Now for the biggest question: Does anyone know what the Boeing-patentd two way digital data bus is. Could this of had anything to do with the loss of power. I guess the 777 data systems are different than the typical data systems.
I did a little reading since my last post and have a few different thoughts on the matter. This "two way digital data bus" is someting I have not heard of before and seems to be particular to the 777. Maybe this had something to do with it??
This is from the Boeing site on the 777.
"A key part of the 777 systems is a Boeing-patented two-way digital data bus, which has been adopted as a new industry standard: ARINC 629. It permits airplane systems and associated computers to communicate with one another through a common wire path (a twisted pair of wires) instead of through separate one-way wire connections. This further simplifies assembly and saves weight, while increasing reliability through a reduction in the amount of wires and connectors. There are 11 of these ARINC 629 pathways in the 777"
As in a report in one of the links posted here, it explains that the 777 crew several times tried to produce power with no throttle response but at no time did it say they had dual engine failure. Just no throttle reponse to pilot input. This could explain the Autoflight system staying connected and the nose high attitude trying to maintain the approach. Humh?
Does anyone have any specific info on this "data bus" system?
Boy, is this confusing. I guess we will just have to wait and see what the report uncovers.
Metro
Ain't that the truth!!! A few years ago we took a flock of 'unidentified birds' that dented the skin on the nose, leading edge on one wing and made a bowl shaped dent on one of the engine inlets, the size of a basketball... and where did it happen? - Stabilized on the final approach course, of course!Metro wrote:As far as airports keeping the "pattern" clean of birds, good luck! Birds seem to like the "final approach course".
Interesting reading your posts Metro. Good points! I read somewhere from the associated press that the investigation had found a likely cause the other day, but it had yet to be made public pending further investigation. I think we're all waiting to read the report on this one, given its baffling nature.Metro wrote:I guess we will just have to wait and see what the report uncovers.
