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Old May 7th 07, 02:47 AM posted to rec.aviation.piloting
Luke Skywalker
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Posts: 102
Default Mystery turn control device on older jets

On May 6, 8:23 pm, Mxsmanic wrote:
Luke Skywalker writes:
Well not remembering which jet leaves the field wide open...but if it
was on the pedestal of a B737 200 series or a B727 or a B707 you were
looking at the rudder trim knob.


I thought of that, but this was larger ... and you wouldn't normally use
rudder trim to turn the aircraft.

I guess it could be a manual turn controller for the autopilot, as Bob said,
but I wonder how it was used and why it's gone now. Maybe it was something
like control wheel steering (also apparently not used much in practice).

--
Transpose mxsmanic and gmail to reach me by e-mail.


In a Boeing I doubt it was Control Wheel steering. CWS (in a older
boeing at least...and even in the -300 series 737) was done by the
Actual Control wheel...IT with a certian force you moved the control
where and it then "froze" whereever you left it. I find/found it
useful in turbulence...but you had to recognize that in that mode it
didnt recognize any pitch or roll commands. It has been so long since
I flew a -200 737 but I seem to recall that aileron trim was also a
"large" knob on the pedastal...

I've never seen ANY autopilot controls on the pedestal for two
reasons. First they are out of "normal line of sight" which the FAA
requires and second they are vunerable (at least in the 737) to jump
seat riders putting their feet on the pedestal.

The early 737/300's had a "blade" knob for the electric Rudder trim.
This caused at least one accident when a person (on the ground) put
their foot on the pedestal and part of their shoe inadvertantly moved
the knob and ran the rudder trim full deflection.

Now it is a knurled knob to prevent that and there is a two inch guard
around the pedestal...

Sorry I cant help more

Robert