Date: 201306
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Light: Night
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight phase: Parked
Aircraft component: Main Gear Tire
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Powerplant; Maintenance Airframe
Human factors: Situational Awareness; Distraction; Communication Breakdown; Workload
Second reporter function: Technician
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Routine Inspection
Result: General Maintenance Action
Contributing factors: Human Factors; Incorrect / Not Installed / Unavailable Part
Primary problem: Human Factors

Narrative: I was working B737-800 aircraft with Mechanic Y; we had a Number 3 [Main] tire change. While replacing Number 3 tire; we were interrupted several times by my Lead mechanics and co-workers. Some of these interruptions included work reassignments and personnel reassignments. There was so much confusion from this it created verbal altercations amongst us; leading me to miss the installation of washer... task focus was lost during installation of Number 3 tire. [Recommend] to stop; access situation and continue when ready to complete task. Graveyard [shift].  A-Check. Maintenance Supervisor generated a Maintenance item [for the washer]. Complacency.


Second narrative: I was assigned two airplanes that both arrived late. I was working an A-Check on a B737-800 aircraft on Gate X. After completing the A-Check and Special Items [Job] Cards; my partner Mechanic X notified me that the Number 3 [Main] tire required changing. After gathering the required tooling; paperwork and parts; we began the tire change. During the tire change we were interrupted several times by two Lead mechanics; and two mechanics; one of which was a verbal altercation. Apparently during the process of the tire change and the disruptions we forgot to check the old tire for the washer; and did not install it with the new tire. I feel that the event occurred because of the interruptions and altercation during the Maintenance Procedure. My suggestion would be to stop work and notify the persons causing the interruption that the matters at hand would have to wait until the maintenance tasks are complete; and then retrace the steps of the maintenance task to insure they are all completed. Graveyard [shift]. Complacency.

Second callback: Reporter stated he has eighteen years Maintenance experience with his current Air Carrier. The # 3 tire was the inboard tire on the right Main Landing Gear (MLG) on the B737-800 aircraft. Their Tire Shop found a washer stuck to the old tire they had removed. That washer is actually an axle nut washer that has a centering tang on the washer. The tang alignes with a groove in the MLG axle to prevent the tang washer from rotating when pressed up against the wheel bearing; as the axle nut is installed and tightened. A Technical Supervisor generated a carry over maintenance item; not a logbook or maintenance write-up; to have the washer installed the following night; since the same aircraft was scheduled to return to their Station.

Synopsis: Two Line mechanics report how interruptions and a verbal altercation during a right Main Landing Gear (MLG) tire change resulted in the axle nut tang washer not being installed on a B737-800 aircraft.