B. Balance panels may be replaced without altering the control surface balance. The aileron balance tab adjust weights fasten to the lower aft edge of the aileron balance panel.
5.  Aileron Trim Control Unit
A.  The aileron trim control unit is used to initiate motion in the aileron trim control system. The unit consists of a cable drum attached to a shaft, and a control knob. (See figure 4.) The cable drum is located within the control stand and is rotated by the trim control knob on the aft part of the control stand. Access to the drum is available by removing the right access panel on the control stand.
B.  The trim control knob can be manually rotated about 3.55 turns in either direction from neutral. Stops within the trim knob mechanism regulate the amount of cable that may be wound on or off the drum. The aileron trim indicator is part of the trim control knob. The indicator dial is marked in units trim on either side of neutral. The action produced by rotating the control knob to the right raises the right aileron and lowers the left aileron, turning the control knob to the left raises the left aileron and lowers the right aileron.

G03085 G03087
500  Aileron Balance Panel 
May 15/68  Figure 3 B
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Aileron Trim Control Unit  500 
27-11-0Page 8   Figure 4 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  May 15/68 

6.  Aileron Centering Spring and Trim Mechanism
A.  The aileron centering spring and trim mechanism provides aileron control system centering, trim, and artificial feel. The aileron centering spring mechanism consists of a cam, roller arm support, and two springs. (See figures 1 and 5.) The centering cam is bolted to the control quadrant shaft. The roller is mounted on the roller arm and the roller arm is mounted on the support. Two springs are attached between the roller arm and the support to provide the force necessary to hold the roller against the cam; thus providing aileron control system centering and artificial feel. The support is positioned by a trim gearbox through a trim drive rod.
B.  The aileron trim gearbox contains a worm and a sector gear which positions a trim arm in response to the aileron trim system. The worm is splined to an aileron trim input shaft which is connected to the aileron trim drum located in the floor beam space adjacent to the aileron control quadrant. The trim gearbox is mounted to structure by two forks and a safety tie bar and is connected to the centering mechanism by two bosses which are concentric with the aileron quadrant shaft. The trim arm connects to the centering mechanism by the trim drive rod.

G03089
500  Aileron Control Spring and Trim Mechanism 
May 01/76  Figure 5  27-11-0 
Page 9 
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7.  Aileron Transfer Mechanism
A.  A transfer mechanism is located at the base of the first officer's column. It incorporates both the transfer mechanism and the lost motion device. The transfer device consists basically of a preloaded torsion spring whose ends are held against two identical halves of a spring container. (See figure 6.) The two halves of the spring container are locked to preload the spring.
B.  The aileron control bus drum is attached to the upper half of the spring container and the spoiler control drum is attached to the lower half of spring container. In normal operation, motion is transmitted between the two drums through the preloaded torsion spring. If a malfunction occurs, which jams either the aileron or the spoiler control system, the other system could be operated independently. In this case, the captain or the first officer, depending on the jammed system, will have to exert a maximum force of 117 pounds to overcome the spring preload in the transfer mechanism and operate the other system to maintain lateral control of the airplane. In case the aileron cables are jammed, the first officer will have to exert a force to overcome the spring preload in the transfer mechanism and operate the spoilers. When the first officer's control wheel starts turning, it will turn through 12 degrees before motion is picked up by the spoiler control drum through the lost motion device. The control drum then operates the spoilers through the right hand aileron control cables AA and AB (figure 2) to the spoiler mixer.
　
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