American investigates as 777 engine fails to respond to throttle
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Yes please Halfnut, your source ?
"This crew did a fabulous job handling this situation"
... probably not the most appropriate adjective for a simultaneous use of thrust and speed brakes ?
"This crew did a fabulous job handling this situation"
... probably not the most appropriate adjective for a simultaneous use of thrust and speed brakes ?
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So this was the hotest topic as long as everyone thought it was equipment failure, but as soon as it was seen to be pilot error, it drops dead....not a single post...other than to challenge the source of the information suggesting pilot error.
Early theories of pilot error were quickly scorned, if not outright ridiculed.
That's interesting, as pilot error is the ONE thing flight crews have direct and immediate control over; but nobody seems interested in talking about that. It's highly frustrating from a safety standpoint.
That's all. I am speaking outside my range of experience but I was hoping to learn a few things by observing the discussion here. Instead, the lack of discussion is deafening.
Early theories of pilot error were quickly scorned, if not outright ridiculed.
That's interesting, as pilot error is the ONE thing flight crews have direct and immediate control over; but nobody seems interested in talking about that. It's highly frustrating from a safety standpoint.
That's all. I am speaking outside my range of experience but I was hoping to learn a few things by observing the discussion here. Instead, the lack of discussion is deafening.
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Surely the use of power against speedbrake would have brought up an EICAS caution "speedbrake"?
I would have thought that it would be instinctive to advance the lagging thrust lever in line with the other lever?? I think that there is more to this incident than has been reported by the publisher of the above theory (as reported in Flightglobal.com today).
I would have thought that it would be instinctive to advance the lagging thrust lever in line with the other lever?? I think that there is more to this incident than has been reported by the publisher of the above theory (as reported in Flightglobal.com today).
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Lack of response to throttle movement
Never did have any faith in FBW systems. Lets get back to manual control of FCU's and know that when the throttle is moved the message gets to the FCU via mechanical linkages/cables.
FBW vs. Mechanical Linkage
Seems kind of silly doesn't it? Take a very simple and reliable system like wires, push-rods, and bell-cranks to get a control input out to whatever needs to be moved and we replace it with a computer, wires, and actuators which are dependent, among other things, on the availability of electric power. Oh well, that's the price we pay for progress.
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its not just the fly by wire stuff.
pilots simply are so overwelmed with gadgets , that they are not flying the plane.
a gadget to keep the plane going straight if an engine quits is great! but if the plane in question had started going sideways, the copilot would have hit the rudder pedals and noticed something wasn't right...some pilots are always using rudder and never get the throttles/engines equal.
after getting tired of subconsciously holding rudder, he or she would have looked down to see that the throttles/engines weren't right and fixed it.
demanding approach to LAX? puhleese. then all approaches are demanding.
makes one wonder about pilot induced errors on many mysterious engine problems.
simpler is better!
pilots simply are so overwelmed with gadgets , that they are not flying the plane.
a gadget to keep the plane going straight if an engine quits is great! but if the plane in question had started going sideways, the copilot would have hit the rudder pedals and noticed something wasn't right...some pilots are always using rudder and never get the throttles/engines equal.
after getting tired of subconsciously holding rudder, he or she would have looked down to see that the throttles/engines weren't right and fixed it.
demanding approach to LAX? puhleese. then all approaches are demanding.
makes one wonder about pilot induced errors on many mysterious engine problems.
simpler is better!
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Simplicity vs complexity
The simplicity vs complexity argument was already an old discussion before Pprune but for younger readers someone has to answer the claim that simpler is always more reliable.
This comes from the mathematical "law" that if something breaks every ten years and you have ten of them then you will get *on average* one failure per year. But this is only applicable to stuff that is independent. When the complexity is part of a system then adding more functions can add reliability.
A simple example is multi engine A/C. If I add a second engine to my airplane maybe I double the chances of one engine failing but I improve dramatically the chances of being able to finish the flight with at least one engine. Having two engines doesn't mean I end up in the sea twice as often.
You can also see it from common experience. Old, simple cars used to be supplied with tool kits and breakdowns were common. Modern cars packed with electronics and extra systems yet they fail much less often.
Adding complexity often adds benefits that outweigh any parts count calculations. And be honest with yourself, does the complicated 777 really have a safety record worse than say the DC3?
This comes from the mathematical "law" that if something breaks every ten years and you have ten of them then you will get *on average* one failure per year. But this is only applicable to stuff that is independent. When the complexity is part of a system then adding more functions can add reliability.
A simple example is multi engine A/C. If I add a second engine to my airplane maybe I double the chances of one engine failing but I improve dramatically the chances of being able to finish the flight with at least one engine. Having two engines doesn't mean I end up in the sea twice as often.
You can also see it from common experience. Old, simple cars used to be supplied with tool kits and breakdowns were common. Modern cars packed with electronics and extra systems yet they fail much less often.
Adding complexity often adds benefits that outweigh any parts count calculations. And be honest with yourself, does the complicated 777 really have a safety record worse than say the DC3?
Last edited by deltayankee; 9th Mar 2008 at 17:54. Reason: typo!
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Simply adding a second engine DOES NOT assure redundancy!
Look at FAR 23.49 - if a multi-engine ship cannot meet a specified OEI climb profile, then it is constrained to a Vso no greater than 61 kt., same as a single, because is it assumed a forced landing is likely.
Wartime C-47s were often flown at TOGW 20% above the civil limit, and their OEI performance at that weight was nil - the plane was going DOWN. Thus the second engine doubled their risk; they would have been better served by a single R-2800!
Granted, no modern transport is so constrained, but this example serves as a reminder: multiple systems DO NOT automatically provide redundancy.
Look at FAR 23.49 - if a multi-engine ship cannot meet a specified OEI climb profile, then it is constrained to a Vso no greater than 61 kt., same as a single, because is it assumed a forced landing is likely.
Wartime C-47s were often flown at TOGW 20% above the civil limit, and their OEI performance at that weight was nil - the plane was going DOWN. Thus the second engine doubled their risk; they would have been better served by a single R-2800!
Granted, no modern transport is so constrained, but this example serves as a reminder: multiple systems DO NOT automatically provide redundancy.
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deltayankee
your comparisoin of the dc3 and the 777 is unfair. they have different kinds of engines...so at least compare jets with jets.
compare the 727 and the 777.
your comparisoin of the dc3 and the 777 is unfair. they have different kinds of engines...so at least compare jets with jets.
compare the 727 and the 777.
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It seems after reading the report, maintenance did an extensive check of all pertinent systems and found no faults, then did an extensive flight check trying to duplicate the problem and found everything normal. Trying to duplicate the lax landing profile they found that by keeping your hand on the speedbrake handle while deployed it was possible to restrict the left throttle from advancing with just 1.5 lbs resistance to that thrust lever. This procedure was standard after the Cali crash. If the auto throttle was on and the speed knob was set above or at the speed the ac slowed to the throttles would advance even though the pilot didn't intend for them to since the speed brake was out. They decided the FO's left arm might have restricted the left thrust lever inadvertently causing the delay in spool up. Sometimes with all that automation you have conflicting results you don't expect but sort it out when it happens. I have seen similar things happen dozens of times but it is easy to fix once you see the conflict. The 777 automatically adds rudder with assymetical thrust so it would be difficult to notice with no yaw.
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Wartime C-47s were often flown at TOGW 20% above the civil limit, and their OEI performance at that weight was nil - the plane was going DOWN. Thus the second engine doubled their risk; they would have been better served by a single R-2800!
Might have a slightly better chance of survival... especially at night.
An update indicates that the investigation found no aircraft defects. It goes on to say that there is potential for the F/Os arm to restrict thrust lever movement when using the speed brake lever.
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Modern cars packed with electronics and extra systems yet they fail much less often.
...and many taking say a modern diesel Tdi overland in hostile environments where failure cannot be tolerated, replace the Tdi injection system with a mechanical diesel injection pump with just a couple of 12V feeds, rather than using a black box that when it fails, can leave you stranded without a chance in the world of a fix.
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Overall a very informative thread, I'm not wishing to upset any of the "pro's", but would this happen on, say, a FBT system?
Two sides to every argument I say...........
Two sides to every argument I say...........
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Back in Zorst's post #8:
To me - this is strangely analagous to the GPS navigation situation that led to the GOL 1507 midair. The more identical the two paired systems become, the better the chance of the holes in the cheese lining up...
... Many systems are identical but paired, a few are much closer to each other than even the manufacturer believed...