Date: 201206
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: B757-200
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Routine Inspection
Result: General Maintenance Action
Contributing factors: Chart Or Publication; Human Factors; Manuals; Procedure; Aircraft
Primary problem: Human Factors

Narrative: Suspect possible damage to the Nose Wheel Tiller Shaft during test per Aircraft Maintenance Manual (AMM) 32-51-00-735 Test Tiller Handle Steering. We set up to perform the test while the rest of the [Maintenance] crew was at break so that we could have hydraulics off. While trying to do the test during the crews break time; I forgot to raise the [Nose Gear] Upper Torsion Link to be parallel with the ground position per Step-G during the test; but didn't realize it at the time. When the Mechanic in the cockpit used the Torque Wrench to move the Tiller; I was watching the Load Limiter. I heard a noise as he applied the torque but assumed it was normal since it was the first time I had performed the test. The cam rollers didn't move and he said the torque wrench jumped so he was unable to get a good reading. The second time we tried to perform the test it was at the end of our shift. I had the Upper Torsion Link up at that time and was able to see the cam rollers move from the detent as they should. I was on my way home about midnight and thinking about the job when I realized that the cam rollers didn't move the first time we performed the test; probably because the torsion link was not up. I called and notified the Lead on the next shift. He said they would check and make sure everything was OK. But after looking at the [Shaft] tube and [Shaft] couplings the next day in the Illustrated Parts Catalog (IPC) and realizing they couldn't see the rivets that hold the coupling at the upper end of the Tiller Shaft; I talked to the Supervisor and requested that they do a Maintenance set-up to inspect the Tiller Shaft between the Load Limiter and the Tiller Handle; reference IPC 32-51-01-05. The Shaft is set up to be inspected tonight in ZZZ1.

Callback: Reporter stated he works as an Aircraft Mechanic for a major Air Carrier in their company hangars. The Torque Limiter; which is below the Lower Torque Shaft for the Nose Wheel Steering Tiller; had been robbed (cannibalized) for another B757 aircraft. A new Torque Limiter had been installed and he was trying to accomplish the Tiller Handle Steering Shaft Torque Test with the help of an Avionics' Mechanic in the cockpit. The rollers he was referring to; ride up on a cam inside the Torque Limiter. The Shaft Torque Test verifies the Torque Limiter spring and two rollers will 'break-over'; ride-up on a cam; to prevent excessive Tiller input to the Forward Cable Drum. He was under the cockpit floor to observe the 'break-over' motion.Reporter stated the Tiller Shaft Upper Torque Shaft coupling attach rivets are the 4-D type rivets. They were inspected the following night and found to be secure; not loose or partially sheared. That was his concern; especially since he had failed to disconnect the Upper Torsion Link on the nose gear when they had initially attempted to apply the Torque Limiter Test procedures.



Synopsis: A Mechanic requests his Supervisor initiate a maintenance follow-up to inspect the Nose Wheel Handle Steering; Upper Torque Shaft coupling attach rivets for damage on a company B757-200 aircraft. He had initially applied a Torque Test on the Torque Limiter without disconnecting the nose gear Upper Torsion Link first.