4 ms·

> We are issuing this AD to prevent loss of all AC electrical power, which could result in loss of control of the airplane So the 787 doesn't have a mechanical

> We are issuing this AD to prevent loss of all AC electrical power, which could result in loss of control of the airplane So the 787 doesn't have a mechanical backup for the flight controls? So much for the Boeing fanboys talking about their mechanical yokes. Through realistically that says very little about actual reliability and safety, just look at the 737 rudder issues.

gsnedders 8y ago
Even the 777 has very little in way of mechanical backup (it has a couple of spoilers and the horizontal stabilizer with mechanical linkage). The main difference is the duplicated controls in the cockpit are mechanically interlinked, so moving one will always move both. I believe the 787 is Boeing's first (commercial) aircraft with no mechanical backup, but there's not been much for decades.
supernova87a 8y ago
When you say "mechanical", in a 787 or any large airliner it doesn't mean straightforwardly what it might mean in a small plane. In any large airliner the pilot's controls are indirectly linked to the flight surfaces by either hydraulic or electrical systems. There's no way a person could produce the forces needed to handle a plane that large adequately. So I suppose it depends on the specific system, but if electrical power were to be totally lost, perhaps they would be dead in the water. (air) As is my rudimentary understanding.
- foldr 8y ago
  https://en.wikipedia.org/wiki/Ram_air_turbine https://en.wikipedia.org/wiki/Ram_air_turbine
- M_Bakhtiari 8y ago
  > In any large airliner the pilot's controls are indirectly linked to the flight surfaces by either hydraulic or electrical systems. I understand the 777 and 787 are special cases, but my impression of the rest of their line was that the flight controls are directly linked by control cables and are assisted by mechanical-hydraulic servos, a bit like hydraulic power steering on cars. So with a total loss of electrical systems they would still have normal primary flight controls. Of hydraulic servos can fail (for example the aforementioned 737) and even triple hydraulic systems can be taken out by something like the uncontained engine failure of United Airlines Flight 232. I tend to think that electrical and electronic systems can ultimately be more reliable and maintainable, but I worry that the safety culture is much worse among the designers of such systems than their mechanical equivalents (no wonder, we've been tinkering with the latter for thousands of years and the former only a few decades).

gsnedders 8y ago

Even the 777 has very little in way of mechanical backup (it has a couple of spoilers and the horizontal stabilizer with mechanical linkage). The main difference is the duplicated controls in the cockpit are mechanically interlinked, so moving one will always move both. I believe the 787 is Boeing's first (commercial) aircraft with no mechanical backup, but there's not been much for decades.

supernova87a 8y ago

When you say "mechanical", in a 787 or any large airliner it doesn't mean straightforwardly what it might mean in a small plane. In any large airliner the pilot's controls are indirectly linked to the flight surfaces by either hydraulic or electrical systems. There's no way a person could produce the forces needed to handle a plane that large adequately. So I suppose it depends on the specific system, but if electrical power were to be totally lost, perhaps they would be dead in the water. (air) As is my rudimentary understanding.

foldr 8y ago
https://en.wikipedia.org/wiki/Ram_air_turbine https://en.wikipedia.org/wiki/Ram_air_turbine
M_Bakhtiari 8y ago
> In any large airliner the pilot's controls are indirectly linked to the flight surfaces by either hydraulic or electrical systems. I understand the 777 and 787 are special cases, but my impression of the rest of their line was that the flight controls are directly linked by control cables and are assisted by mechanical-hydraulic servos, a bit like hydraulic power steering on cars. So with a total loss of electrical systems they would still have normal primary flight controls. Of hydraulic servos can fail (for example the aforementioned 737) and even triple hydraulic systems can be taken out by something like the uncontained engine failure of United Airlines Flight 232. I tend to think that electrical and electronic systems can ultimately be more reliable and maintainable, but I worry that the safety culture is much worse among the designers of such systems than their mechanical equivalents (no wonder, we've been tinkering with the latter for thousands of years and the former only a few decades).