Narrative:

While performing [horizontal] jackscrew installation on an md-88 aircraft 'X'; june 2010; orientation of the jackscrew gimbal nut came into question. I performed the same installation procedure on a [different] md-88; aircraft 'Y' two weeks earlier. The md-88 maintenance manual (M/M) 27-40-01-401 step 9-B states: 'position the acme screw and nut; support; and gimbal ring in vertical stabilizer with upper stop on nut facing forward'. My interpretation was to have the face of the upper stop facing forward; not have the stop assembly on the forward side of the gimbal/acme nut when installed in the aircraft. A consensus was taken of fellow amt's; lead amt's; and an inspector; the findings confirmed that I did install the jackscrew gimbal nut assembly 180 degrees out from proper orientation.maintenance control and operations were contacted and informed of the situation. Aircraft 'Y' was immediately grounded in ZZZ. Company line maintenance in ZZZ1 sent an amt/crew to investigate the issue. After confirmation of improper installation a crew from company hangar in ZZZ2 was dispatched to correct the problem. To my knowledge no damage occurred to the aircraft or components in question. To prevent further installation confusion I believe a clarification of that M/M step should be performed to alleviate any gray areas.

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Original NASA ASRS Text

Title: A Mechanic and Inspector report about an incorrectly installed horizontal stab jackscrew gimbal/ACME nut on an MD-80 type aircraft. The gimbal assembly is symmetrical and had been installed 180 degrees out of proper orientation; preventing proper lubrication of the ACME nut for the jackscrew. Maintenance diagrams were reported to be unclear.

Narrative: While performing [horizontal] jackscrew installation on an MD-88 aircraft 'X'; June 2010; orientation of the jackscrew gimbal nut came into question. I performed the same installation procedure on a [different] MD-88; aircraft 'Y' two weeks earlier. The MD-88 Maintenance Manual (M/M) 27-40-01-401 step 9-B states: 'Position the ACME screw and nut; support; and gimbal ring in vertical stabilizer with upper stop on nut facing forward'. My interpretation was to have the face of the upper stop facing forward; not have the stop assembly on the forward side of the gimbal/ACME nut when installed in the aircraft. A consensus was taken of fellow AMT's; Lead AMT's; and an Inspector; the findings confirmed that I did install the jackscrew gimbal nut assembly 180 degrees out from proper orientation.Maintenance Control and Operations were contacted and informed of the situation. Aircraft 'Y' was immediately grounded in ZZZ. Company Line Maintenance in ZZZ1 sent an AMT/Crew to investigate the issue. After confirmation of improper installation a crew from company hangar in ZZZ2 was dispatched to correct the problem. To my knowledge no damage occurred to the aircraft or components in question. To prevent further installation confusion I believe a clarification of that M/M step should be performed to alleviate any gray areas.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.