TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
Excessive or low force required to move control columns. Power on. (Determine forces with elevator force checks per 27-31-0, Adjustment/ Test) Column force below minimum tolerance and Autopilot travel excessive.  NOTE: If excessive force is only in certain portions of elevator travel, probable cause is interference in system or binding due to defective or worn parts. If excessive force is through the entire travel range, probable cause is in the artificial feel system or high system friction due to worn parts. 1) Air pressure leakage in pitot system and/or test equipment. 2) Feel computer misrigged due to misindexed feel computer input arm.  Test pitot lines for leakage (Ref 27-31-212, Adjustment/Test). Inspect input arm alignment with shaft in feel computer by removing input arm retaining bolt. Index pin in shaft should align with missing spline tooth on input arm.  Repair or seal leaking part. Replace feel computer. 

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27-31-0  Nov 01/73 
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TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
Column force below minimum tolerance and autopilot travel excessive. (Cont) Column force excessive Column force excessive and autopilot travel below minimum tolerance.  3) Hydraulic pressure from feel computer low. 4) Defective feel actuator 5) Defective feel and centering unit. Bad check valve in the flight controls hydraulic modular package 1) Feel computer misrigged due to misindexed feel computer input arm.  Disconnect flexible hydraulic pressure lines and return lines from feel actuator located on feel and centering unit. Attach a hydraulic pressure gage to each of the four lines (Range 0-1500 psi). Plug open ports in feel actuator. Set stabilizer B dimension at 41.57 ±0.01 inches. Pressurize pitot system to 0.50 ±0.05 psi. Pressure at pressure lines should be 435 ±35 psi above return line pressure. Pressurize pitot system to 3.5 ±0.05 psi. Pressure at pressure lines should be 1320 ±150 psi above return line pressure. Remove pressure from pitot system. Pressure at pressure lines should be 200 ±20 psi above return line pressure. Replace and rerun test per 27-31-0, Elevator and Tab Control System -A/T. Replace and rerun test per 27-31-0, Elevator and Tab Control System -A/T. Do a check of hydraulic leakage from the flight controls hydraulic modular package Same as 2), trouble shooting item: Column force below minimum tolerance and autopilot travel excessive.  Replace feel computer. Replace feel actuator. Replace feel and centering unit. Replace the flight controls hydraulic modular package (AMM 27-09-200/4) Replace feel computer. 

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TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
Column force  2) System friction  Check elevator centering per 
excessive and  excessive.  27-31-0. If elevator does not 
autopilot  return to neutral, system friction 
travel below  may be excessive. Refer to 
minimum  trouble-shooting item: Faulty 
tolerance.  elevator centering. Check for 
(Cont)  3) Hydraulic pressure from feel computer high. 4) Stabilizer trim brake control linkage jammed or binding. 5) Defective feel actuator. 6) Defective feel and centering unit.  chafing cables, misaligned or defective pulleys or fair leads, foreign objects interfering with cable or control linkage movement. Check for excessive stiffness in the elevator input Torque Tube/Feel and centering unit support bearings. Cycle control column through its full travel. Operation shall be smooth without binding or rough spots. Same as 3), trouble shooting item: Column force below minimum tolerance and autopilot travel excessive. Check for interference in operation of stabilizer trim brake or foreign object in trim brake linkage. Disconnect rod between stab trim brake and control column and recheck column force. Replace and rerun test per 27-31-0 A/T. Replace and rerun test per 27-31-0 A/T.  Repair or replace defective parts. Remove foreign objects. Replace feel computer. Repair or replace defective parts. Remove foreign objects. Replace feel actuator. Replace feel and centering unit. 
　
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