MD-83
Maintenance Airframe; Maintenance Powerplant
Maintenance Technician 35
Communication Breakdown; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Chart Or Publication; Company Policy; Human Factors; Incorrect / Not Installed / Unavailable Part
I was working the B-Check on Aircraft X; an MD-83 aircraft. I always work the tail [section]. We were performing the Horizontal Stabilizer Task Cards and noticed the elliptical motion on the [Horizontal Stab] Jackscrew. I told my Lead about it. I told the Line Engineer Mr. X about it. He called Maintenance Control to report it. They said they would check the Manuals for Run-Out information. They called back to report that the Maintenance Manual (M/M) did not have any information. They found in the unit [Component] Overhaul Manual that [jackscrew] run out of .004' of an inch; is maximum allowed. Mr. X and I performed a Dial Indicator run out on the jackscrew and it was .070' of an inch. When Mr. X told Maintenance Control; they planned a jackscrew replacement. The following evening on my entering work I noticed Aircraft X was gone. An Engineer; Mr. Y; had given Aircraft X a Line Engineering Order to allow .070' run out on Aircraft X. This was done after our Air Carrier realized that they did not have a jackscrew in stock; or have access to one. In my opinion this aircraft is unairworthy. I believe our Air Carrier is not willing to 'Ground' an aircraft; or buy an expensive part for an aging aircraft that might be parked in less than two years. It strikes me very strange that they were planning to change the jackscrew until they realized that they did not have one.I am an Airframe and Powerplant Mechanic with an IA [rating]. I expect [my] Air Carrier to comply with airworthiness issues properly; as I am expected to do. What did the Engineer Mr.Y have for documentation to allow the Line Engineering Order [to be issued]? I think possibly the FAA should revise Air Directive AD-2000-15-15 to include inspection of [Horizontal Stab] Jackscrew for out of round or elliptical movement.
Reporter stated he could visually see the Horizontal Stab Jackscrew [shaft] wobble; even from a distance. If the jackscrew shaft were to shear from the stab drive gearbox with an airload on the tail; the horizontal stab leading edge would most likely move full up and the aircraft's nose would go down. He doubts the elevators could compensate for the extreme nose down pitch angle. He was told by another company Engineer; that the aircraft's Manufacturer had approved the .070' thousandths of an inch wobble; but that same Engineer had not actually seen the approval paperwork yet. Since the crash of a different Operator's MD-80 off the California coast; due to horizontal stab jackscrew failure; he is very upset his Air Carrier continues to allow that MD-80 to fly with that amount of wobble of the jackscrew. He has thirty-five years aircraft maintenance experience.
An Aircraft Maintenance Technician (AMT) suggests that FAA should revise Airworthiness Directive (AD) 2000-15-15 to include inspection of the Horizontal Stabilizer Jackscrew (J/S) shaft for an out of round; or elliptical run-out movement. His company engineering had released an MD-83 aircraft for service with an excessive; visible; wobble of the Horizontal Stabilizer Jackscrew (J/S) that was noticed during a B-Check.