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Jackscrew Lubrication and End Play Inspection Procedure

This guide outlines lubrication steps and end play checks for jackscrews on aircraft. Learn the manufacturer's intervals and observations for effective maintenance.

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Jackscrew Lubrication and End Play Inspection Procedure

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  1. Jeff Guzzetti Lubrication and End Play Inspection

  2. Lubrication:The Procedure • Gain access to the tail • Remove access panels

  3. FAIRING ACCESS PANELS GREASE GUN Lubrication:The Procedure • Apply grease to acme nut fitting with grease gun until grease exits out top of acme nut

  4. Lubrication:The Procedure • Brush application of “light coat of grease” onto jackscrew threads • Operate jackscrew “through full range of travel” BRUSH

  5. Lubrication:Observations • Differences with method of application • Small access panel • Lube of nut fitting only is not adequate • No inspection req’d • Recommendations issued, and more proposed

  6. Jackscrew Lubrication:Alaska Airlines Interval Extension Alaska Airlines Interval Manufacturer's Recommended Interval

  7. Lubrication:Manufacturer’s Recommended Interval

  8. Maintenance Intervals:Issues • Process is deficient • Does not account for design assumptions • Not supported by data • Does not account for lack of task accomplishment

  9. The End Play Check:Background • DC-9 jackscrew life:30,000 hrs. - No Inspection • 1965 Sampling program: Premature wear found during bench checks • Changes to acme screw & wear limits • On-wing End Play Check developed in 1967

  10. The End Play Check:Background • Ad Hoc procedure developed using tools already available to airlines: • Horizontal Stabilizer Restraining Fixture • Dial Indicator • Torque Wrench • Purpose: To check amount of thread wear without jackscrew removal GAP 0.003 to 0.010

  11. The End Play Check:The Procedure • Move stabilizer to the 1 deg. ANU position • Remove fairings • Install restraining fixture between horizontal and vertical stabilizer • (Continued)

  12. The End Play Check:The Procedure (Continued) • Clamp dial indicator to torque tube nut (below nut) • Preload dial indicator • Apply 250 – 300 in-lbs torque to shorten restraining fixture • Record dial indicator reading (interpretation required)

  13. The End Play Check:The Procedure (Continued) • Relieve torque and ensure indicator returns to initial • Repeat steps several times • Check end play is “between 0.003 and 0.040 inch.”

  14. End Play Check:Alaska Airlines Interval Extension Manufacturer's Recommended Interval

  15. The End Play Check:Observations • Installation of dial indicator can affect end play reading

  16. The End Play Check:Observations • Dial indicator can be difficult to read

  17. The End Play Check:Observations • Working conditions can be adverse

  18. The End Play Check:Observations • Restraining fixture condition, torque, and rotation direction can affect reading • Jackscrew rotation during check can affect reading

  19. The End Play Check:Observations • Differences w/ Alaska Airline fabricated restraining fixture ALASKA AIRLINES TOOL BOEING TOOL

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