Jeff Guzzetti Lubrication and End Play Inspection Lubrication and End Play Inspection

Lubrication: The Procedure Gain access to the tail Remove access panels Gain access to the tail Remove access panels

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

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

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 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

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

Lubrication: Manufacturer’s Recommended Interval

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

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 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

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 to 0.010

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) Move stabilizer to the 1 deg. ANU position Remove fairings Install restraining fixture between horizontal and vertical stabilizer (Continued)

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) 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)

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

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

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

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

The End Play Check: Observations Working conditions can be adverse

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

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