Re: Two DC-9 aileron questions from a student pilot

Date:         27 Dec 96 04:41:05 
From:         D Snow <dougie@mama.indstate.edu>
References:   1
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Quoting from a Republic Airlines DC-9 Flight manual, page 7-30 (7-1-79):

"A takeoff warning system is provided.  When the throttles are advanced
for takeoff and the flaps, slats, spoliers, or stabilizer are not in the
correc tposition, and on the -50s, if the parking brakes are on, a warning
horn will sound intermittently."

LATERAL CONTROL:

"Conventional control wheels are cable connected to control tabs on the
ailerons.  Aerodynamic force on the control tabs moves the ailerons.  The
control wheels are linked together by a torque tube arrangement that
drives an independent cable system to each aileron control tab.  Should
any part of the system become jammed between the torque tube and the
control tab, the torque tube mechanism will allow either control wheel to
drive the remaining unjammed tab.  Left and right ailerons are bussed
together by cables so that they always move together on the proper
direction.  Each aileron contains a conventional trim tab connected to a
trim knob on the pedestal.

FLIGHT SPOILERS:

Aileron lateral control is aided by a flight spoiler system.  Aileron
control tab cable movement is linked to a mechanical mixer assembly that
provided variable actuation of the flight spoiler hydraulic control valve.
The flight spoilers consist of two extendable surfaces on each wing.  The
flight spoiler surfaces start to extend only after 5 degrees of control
wheel throw.  Flight spoilers remain retracted with a down aileron.  the
mixer assembly provided the proper amount of flight spoiler extension in
relation to aileron movement.  The inner and outer flight spoiler surfaces
are powered by separate hydraulic systems, so that with one hydraulic
system inoperative, one-half of the flight spoiler system effectiveness is
reduced.

For the CONTROLS check in the normal operations section, p. 2-57
(2-28-89):

CONTROLS - FREE AND NORMAL

This is a check to determine that the flight controls are free and
normal.

1.  The F/O will first check the elevators by pulling the control column
to the full aft position while noting that the aunnunciator ELEVATOR PWR
ON light is OFF and then pushing the control coliumn full forward noting
that the blue ELEVATOR PWR ON light illuminates indicating the elevator
augmentation system is working.  While still holding the control column
full forward and making sure the captains knees arent in the way, deflect
the wheel full eft and right noting hydraulic fluctuations on the
HYDRAULIC PRESSURE indicators and a SPOILER EXTEND annun. light.  The last
check is to note that the ELEVATOR PWR ON and SPOILER EXTEND lights go
out after releasing the control column.

Incidentally, I was on a NWA DC9-50 from MSP-DTW back in 4-95 when I
worked there, and had the same reaction to the aileron deflection when we
took the active runway, by 40-50 kts, the ailerons evened out.  As for the
continuous deflection in flight, more than likely the aircraft was out of
rig, and the crew had some trim dialed in.

-----
Douglas Snow                                dougie@mama.indstate.edu
http://mama.indstate.edu/users/dougie