Aileron failure

[Guest Martin]

A little story for anyone who's interested...http://ftp.avsim.com/dcforum/DCForumID47/4297.htmlAnd a question: Is it possible for the ailerons - and nothing else - to just fail like that? I guess, in theory, but you would have to have a lot of bad luck for that to happen!Martin767 fetishistIt's a lot like life and that's what's appealing

[Guest Ian_Riddell]

>And a question: Is it possible for the ailerons - and >nothing else - to just fail like that? I guess, in theory, >but you would have to have a lot of bad luck for that >to happen! It is possible Martin, but there are a lot of backups in the 767 aileron/roll system. Each pilot has his/her own aileron control cable system. Even if your control wheel jams, your F/O, with a bit of effort, may be able to override (bypass) the jam with his/her control wheel.The control cables which go from the cockpit to the ailerons (or close thereto) are broken up into different sections (with various servos/devices inbetween). Looking at the Boeing Maintenance Manual, it appears that even if all the aileron control cables in the wings and in the wheel wells broke (stopping the ailerons from operating) "transducers" under the cockpit floor will pick up cable movement in the first section of the cable system and generate electrical signals to control the spoilers (to help with roll control).If you find that one autopilot is not controlling the aircraft, try another autopilot. If that doesn't work, try another. If you don't have autopilot or manual control, try aileron trim (there is a remote chance that it still might be working).From your description on the other site, it is quite difficult to make a full diagnosis of the problem. I would need to know a bit more about what was happening with your aircraft (e.g. Were there any messages generated on the EICAS? Did the A/P eventually disengage? Was your control column (aka joystick) jammed? Were the spoilers operating for roll control (in the outside view)? Were there any hydraulic problems? Etc, etc.)Anyway, it's already an interesting mental excercise :-)Thanks.Cheers.Ian.

[marcom 139]

Hi Ian! I have had a couple of aileron failures using 767PIC (which were generated by the failure generator) and you get no warning message whatsoever. No EICAS status message, none of the 3 AP's work, they don't disconnect either even if the FD commands a bank angle of 25

[Guest Martin]

Mark summed it up pretty well - basically the ailerons just fail, with no indications of it whatsoever. I didn't try aileron trim, so I don't know if it would have had any effect.I guess we can come to the conclusion that a full aileron failure (including spoilerons) like that is not very realistic, but obviously it was good practise. I really didn't expect that it would be so easy to land the plane anyway (I've never tried using only rudder for directional control before).>Anyway, it's already an interesting mental excercise :-)I try! :-)Martin767 fetishistIt's a lot like life and that's what's appealing

[Guest Ian_Riddell]

> Only rudder and assymetric thrust will turn yaWith the symptoms you mentioned, Mark... I'd be on the phone to Boeing quicksmart.... Doesn't sound like your "average" double aileron failure (grin). Sounds like every cable in the aileron system has snapped... along with the failure of the airplane and A/P warning systems (You weren't doing aerobatics in a thunderstorm shortly before this were you?).I really don't think we can put this one down to a "Neutron Single Event Upset" :-lolCheers.Ian.P.S. Sorry.... I think I'd also have to leave the aerodynamics to the experts, too. I do find it hard to believe that it was that easy to control the aircraft with just rudder and thrust.

[marcom 139]

Nah I blame cosmic radiation for that one, Ian :-lolNow that you mention aerobatics, hmmm, well I only tried the barrel roll Tex Johnston did with the Dash 80 a couple decades ago... Now don't tell me the Dash 80 is more stable than the 767-300??Greetings,Mark