Date: 201304
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: DC-10 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Mission: Cargo / Freight / Delivery
Flight phase: Parked
Aircraft component: Main Gear Tire
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Powerplant; Maintenance Airframe
Human factors: Communication Breakdown; Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Other During Maintenance
Result: General Maintenance Action
Contributing factors: Human Factors; Incorrect / Not Installed / Unavailable Part
Primary problem: Human Factors

Narrative: April 2013 at Station ZZZ1; Mechanics changing # 8 Main Wheel Assembly reported Tang Washer was missing when they removed the wheel. Back in December 2012; Mechanic Y and myself (Mechanic X) changed the # 8 Main Wheel Assembly. Installing and removal procedures [were] done in accordance with Maintenance Manual (MM) 32-41-01-2. It was late at night finishing; and the MM procedure was followed and no discrepancies were found. On short notice of the findings by ZZZ1; I was notified [approximately] five days later and I investigated to see if we may have missed the Tang Washer as found in the MM 32-41-01-2; page 19; Item 8. I called our Air Carrier Company Representative who works with the Vendor concerning [landing] gear assemblies. He gave me our Company's Receiving Report which showed no abnormalities from the Contract Tire/Wheel Vendor as to the Tang Washer being left with the removed Main Wheel Assembly. He informed me that I would need to check the Shop Report that the Contract Vendor keeps; that documents everything they found during the Shop visit.I then contacted the Contract Vendor Representative to get a copy of the Shop report. The report on the tire wheel assembly was at an off-location and had to be retrieved. The following afternoon the Vendor Representative informed me that there was nothing mentioned about finding a Tang Washer during disassembly of the Tire/wheel assembly [we had removed in December]. As a precaution; I had him check the Shop report for the tire/wheel assembly just removed in ZZZ1; to make sure that somehow the Tang washer was not left with the tire [that ZZZ1 mechanics had removed]. The wheel assembly we had installed in December also had a clean report. I do not remember the exact details of the main wheel change on the DC-10 in December 2012; but I do follow the MM on all work accomplished on any aircraft I work. It is not only required and company policy; but all aircraft have differences in the way they are built that it is necessary to consult the MM to keep the aircraft safe.  I am answering this due to the incident brought up by Management; I do not know exactly what happened to the missing part in question; however I will attempt to answer what may have happened somewhere. The Tang Washer probably stuck to the wheel bearing grease being removed and would end up on the wheel going into disassembly. [Recommend] when removing the old Wheel assembly; the wheel bearings should be wiped off and an inspection done to the wheel prior to installation of shipping caps. This would help to identify any other problems with the aircraft that may contribute to wheel change. Such as; flat spots on tire beyond normal wear; discoloration of heat shield; loose or broken beam rotator keys.




Synopsis: A Line Mechanic describes his efforts to locate a Tang Washer found missing from a # 8 Main Tire/Wheel Assembly he had previously changed on a DC-10 aircraft.