Date: 201205
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: A300
Operator: Air Carrier
Operating under: Part 121
Mission: Cargo / Freight / Delivery
Flight phase: Parked
Aircraft component: Fan Reverser
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Powerplant; Maintenance Airframe
Human factors: Communication Breakdown; Distraction; Situational Awareness; Troubleshooting; Workload
Second reporter function: Lead Technician
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Other Post Aircraft Departure
Result: General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: An A300 aircraft assigned to ZZZ Line due to # 2 Engine Thrust Reverser inoperative. [I performed] reactivation and troubleshooting of # 2 Engine Thrust Reverser. Removed all sleeve and Center Drive Unit (CDU) Lockout tabs and placed them in parts box. [I] secured electrical connectors and pneumatic lines; troubleshoot to Right-Hand Reverser Sleeve. After maintenance per Trouble Shooting Manual and Aircraft Maintenance Manual (AMM) procedures; no further faults [noted]. [I] began safety wire installation and returning sleeve and CDU lockout tabs to the stowed (not in use) positions. I had done most of the work except when fellow AMT Lead Mechanic x in cockpit was needed for operation of Thrust Reverser. He had been doing other maintenance and pulling additional manual references for me. He joined me on Thrust Reverser and installed sleeve and right-hand CDU lockout and assisted in closure of cowlings.I closed MEL deferral Write-up 78-30-XX (Thrust Reverser) and Write-up 71-10-XX (# 2 Engine cowling). At beginning of next shift Lead Mechanic X said he awoke in the middle of the night thinking he had installed right-hand CDU Lockout in the locked in the 'Forward Thrust' position rather than in the 'Stowed' and not in use position. We looked up in electronic Logbook for the A300 aircraft and found that Thrust Reverser had not deployed on landing in ZZZ1 and had Write-up 78-30-XX assigned. He immediately called Maintenance Control and ZZZ1 Line Maintenance to explain what problem with Thrust Reverser was. ZZZ1 Maintenance confirmed that was problem; stowed lockout tab; conducted Operational Check and cleared maintenance display. [Contributing factor] was second AMT coming onto job near the end to assist after completing other duties he was performing. [Recommend] reducing multiple write-ups simultaneously in work. Increase cross-task vigilance on single maintenance action with multiple AMTs.


Second narrative: What happened was Mechanic X and myself (Lead Mechanic X) were working the # 2 Engine Thrust Reverser that was deferred on an A300 aircraft; reference Write-up 78-30-XX. We had restored aircraft to normal operational reverser configuration to troubleshoot the Thrust Reverser. We had actuated the Thrust Reverser and performed maintenance in accordance with (in accordance with) applicable Maintenance Manual. After all checks were completed; Mechanic X installed the left-hand Center Drive Unit (CDU) lockout tab in the correct position and I had unintentionally installed the lockout tab on the right-hand CDU in the incorrect (locked-out) position. Thrust Reverser failed to deploy in ZZZ1. I called Maintenance Control first thing this morning and coordinated with them and ZZZ1 Line [Maintenance] to go directly to # 2 Engine Thrust Reverser CDU and look for a lockout tab installed incorrectly. ZZZ1 Line Lead Aircraft Maintenance Technician (AMT) contacted me and informed me that the lockout tab was indeed installed in the locked-out configuration. I informed him to write-up exactly what he had found and informed him that I was preparing to submit a report. They have signed the item off as Operational Check OK. I was performing other maintenance and helping Mechanic X as needed in the cockpit for operational checks of #2 Engine Thrust Reverser. I specifically was performing Engineering Orders on the landing gear attach lugs and as I completed the Engineering Orders went on to pull up Trouble Shooting Manual (TSM) paperwork for troubleshooting of the inoperative Thrust Reverser. As Mechanic X had completed the troubleshooting on the Thrust Reverser and it was in the final stages of safetying lines; plugs; fittings and caps; I came back in on the job in which the only items remaining were to install lockout plates on CDU's and close and secure engine cowling. I feel that since I was performing other maintenance and not fully involved from start to finish I had unintentionally installed [the] lockout tab incorrectly. [Would recommend] increased cross vigilance; decrease maintenance multi-tasking that is involved in more than one maintenance tasks at a time.


Synopsis: A Line Mechanic and Lead Mechanic report about a # 2 Engine Thrust Reverser that failed to deploy on landing on a company A300 aircraft after they had cleared an MEL reverser deferral. Lead Mechanic notes that multi-tasking and lack of adequate communication contributed to his installing the Lockout tab in the Reverser Lock-out position.