Narrative:

We had a Q400 main wheel returned with a 'bad from stock' tag to the shop; with two outboard bearings. Fearing that the mechanics on the floor might have put in two inboard bearings on the aircraft; maintenance was called and asked to remove the tire off the aircraft and route it back to the shop for inspection. During this time mr. X and mr. Y went to stores to inspect all wheels built in that same batch and found a second wheel with two outboard bearings installed. They also found three wheels in the batch with correct bearings; but on the wrong side. The wheel returned and had the correct bearings and installment. The 'bad from stock' wheel came from the hanger floor; never made it on an aircraft; and couldn't have; due to it having a smaller inner diameter bearing. This would have prevented it from being able to slide onto the axle in the inboard spot. All other wheels were found and corrected in stock. The Q400 inboard and outboard bearings for the main wheel are the same size; unlike all other wheel type configurations. Once they are greased up; it is impossible to tell one from the other. I believe that I must have inadvertently mixed up bearings during the greasing process. Inspected all other Q400 main wheels turned out that day for correct bearing installment. Then corrected any errors found.working with inspection; we've determined a better process where inspection has a more active role. They will now verify all part numbers of bearings in the stack before and after greasing. After checking the part numbers; the inspector will now place the outboard seal on the outboard bearing prior to installation. This ensures that the outboards are correctly identified while greased and installed correctly.

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Original NASA ASRS Text

Title: A Mechanic reported a main landing gear tire was returned to their wheel shop with two outboard wheel bearings. Fearing that Mechanics on the floor might have installed two inboard wheel bearings on one of their DHC-8-400; the tire was removed.

Narrative: We had a Q400 main wheel returned with a 'bad from stock' tag to the shop; with two outboard bearings. Fearing that the Mechanics on the floor might have put in two inboard bearings on the aircraft; Maintenance was called and asked to remove the tire off the aircraft and route it back to the shop for inspection. During this time Mr. X and Mr. Y went to stores to inspect all wheels built in that same batch and found a second wheel with two outboard bearings installed. They also found three wheels in the batch with correct bearings; but on the wrong side. The wheel returned and had the correct bearings and installment. The 'bad from stock' wheel came from the hanger floor; never made it on an aircraft; and couldn't have; due to it having a smaller inner diameter bearing. This would have prevented it from being able to slide onto the axle in the inboard spot. All other wheels were found and corrected in stock. The Q400 inboard and outboard bearings for the main wheel are the same size; unlike all other wheel type configurations. Once they are greased up; it is impossible to tell one from the other. I believe that I must have inadvertently mixed up bearings during the greasing process. Inspected all other Q400 main wheels turned out that day for correct bearing installment. Then corrected any errors found.Working with Inspection; we've determined a better process where inspection has a more active role. They will now verify all part numbers of bearings in the stack before and after greasing. After checking the part numbers; the Inspector will now place the outboard seal on the outboard bearing prior to installation. This ensures that the outboards are correctly identified while greased and installed correctly.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.