2. TRAILING EDGE FLAP SYSTEM TROUBLE SHOOTING CHART
TROUBLE  PROBABLE CAUSE ISOLATION PROCEDURE REMEDY 
Flaps will not extend hydraulically or electrically in Flaps 0-25 range inflight Flaps will not extend hydraulically or electrically in Flaps 25-40 range inflight  Structural failure and/or interference Visually inspect all flap and flap drive components where relative motion occurs, for structural failure or foreign object damage Repair as required Power unit gearbox binding Disconnect gearbox and check for free rotation Replace gearbox if binding Angle gearboxes binding Disconnect gearboxes and check for free rotation Replace gearbox if binding Right angle gearboxes binding Disconnect gearboxes and check for free rotation Replace gearbox if binding Transmission internal jam Disconnect transmissions from torque tubes and jackscrews and check for free rotation Replace transmission if binding The following items are listed in descending order of effectiveness for causing flap drive system lockout but also weighted in order of probability of occurrence. The flap system should be inspected in the sequence listed. The items 1 thru 8 will cause lockout if found discrepant, therefore, if condition discovered and corrected, no further checks are required. Items 9 thru 15 will not cause lockout when acting alone but require some combination with other items. The possible combinations of these items to cause lockout are: Items 9 + 10, 11, 12 or 14 Items 9, dual roller jam Items 10 + 9, 11, 12 or 14 Items 11 + 9, 10, 12 or 14 Items 12 + 9, 10, 11 or 14 Items 14 + 9, 10, 11, 12 1. Midflap carriage forward and aft flight rollers jammed and skidding at flap jackscrews 2, 3, 4, 5, 6, 7 (single roller) Inspect rollers for free rotation. Inspect tracks for evidence of skidding. Inspect roller OD for signs of skipping/skidding Replace roller if binding or there are signs of the roller skipping/skidding. Lubricate all midflap carriage rollers. See Chapter 12 

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TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
Flaps will no extend hydraulically or electrically in Flaps 25-40 range inflight (Cont.)  2. Outboard flap drive transmission output bearing jammed and/or excessively corroded 3. Jackscrew ball nut jammed or binding 4. Structural failure and/or interference 5. Power unit gearbox binding 6. Transmission internal jam  Disconnect transmission from torque tubes and jackscrews and check for free rotation by rotating the output shaft with a small side load on it. Check that bearing ID does not rotate relative to shaft. Check for signs of rust at the edges of the bearing seal. Inspect in this order: 2,7,1,8 Disconnect ball nuts. Clean ball screws. Check for free rotation and signs of gouging in ball nut grooves Visually inspect all flap and flap drive components where relative motion occurs, for structural failure or foreign object damage Disconnect gearbox and check for free rotation Disconnect transmissions from torque tubes and jackscrews and check for free rotation  Replace transmission if bearing defective Replace jackscrew assembly if binding Repair as required Replace gearbox if binding Replace transmission if binding 

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27-51-0  May 15/73 
Page 104 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
Flaps will not extend hydraulically or electrically in Flaps 25-40 range inflight (Cont)  7. Angle gearboxes binding 8. Right angle gear box binding 9. Midflap carriage forward and aft flight rollers jammed and skidding at flap jackscrews #1 and #8  10. Outboard aftflap drive mechanism failure or jam  11. Outboard foreflap sequencing carriage toggle failure (unsequenced foreflap) plus galled or damaged floreflap carriage rub strips  12. Outboard aftflap track rollers jammed  13. Inboard aftflap drive mechanism jam or failure  Disconnect gearboxes and check for free rotation Disconnect gearboxes and check for free rotation Inspect rollers for free rotation. Inspect tracks for evidence of skidding. Inspect roller OD for signs of skipping/skidding Inspect drive mechanism in outboard screw fairings Inspect outboard foreflap toggles and sequencing carriages for failure or binding and rub strips for galling Inspect rollers for free rotation. Inspect tracks for evidence of skidding Inspect mechanism for failed parts. Check drive clutch setting  Replace gearbox if binding Replace gearbox if binding Replace roller if binding or there are signs of the roller skipping/skidding, relube all main carriage rollers Repair or replace damaged partsReplace damaged partsReplace roller if binding Replace parts or readjust clutch 
　
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