Originally Posted by
bsieker
And while a "split elevator" condition arising from both pilots pushing/pulling on the yokes against each other may occur in the
767 (see the
final report for Egypt Air Flight 990), I have never heard of this for the 737.
Originally Posted by
bsieker
Sorry to say so, but your say-so is not what I meant by "authoritative source". It would require some other document contradicting the 737 FCOM and mine and hec7or's reading of it. For example some documentation explaining that the torque tube between the two elevator surfaces is frangible and supposed to be broken by the override mechanism for dealing with a jammed control column.
Here is a good explanation of the B737 Aircraft Control Override Devices (in agreement with Olasek in
#969):
«
B737 Aircraft Control Override Devices: There are two devices that allow you to control the aircraft in case of a malfunctioning or jammed control system.
One concerns roll control. When one of the yoke cables (or aileron PCU/spoilers) becomes jammed or moves freely, the opposite control is still available to roll the aircraft. The two yokes are interconnected at the base of the co-pilots control column by the Aileron Transfer Mechanism through torsion spring friction and a “lost motion device”. If the FO control jams, the spring force can be overcome by the Captain thereby controlling the aileron PCU through cables. If the Captain control jams, the FO can control roll by use of the flight spoilers. Note that this only happens when the yoke has been turned ± 12° which engages a so called “lost motion device” which in turn operates the flight spoilers.
The second is related to pitch control.
When one of the control columns becomes jammed, the crew can override (breakout) the failing control. The control columns are interconnected below the cockpit floor by a torque tube with a device that enables the controls to be separated from each other. The Elevator Breakout Mechanism connects both control columns by two springs which will separate the columns when ± 30Lbf/13Kgf is used to overcome them. When applied, the control columns are mechanically separated from each other. Note that deflection of the elevators is significantly reduced and a higher force is needed to move the elevators. (even higher than with manual reversion) »