A Line Mechanic describes the events and environment that led to his signing for a # 4 Main tire installation that was accomplished by a Mechanic who had not been qualified to sign-off their company tire write-ups. The Main tire installed was not rated for the heavier B737.
Synopsis
A Line Mechanic describes the events and environment that led to his signing for a # 4 Main tire installation that was accomplished by a Mechanic who had not been qualified to sign-off their company tire write-ups. The Main tire installed was not rated for the heavier B737.
Narrative
Signed-off Release of tire change; due to Mechanic not Qualified to do so on the type of B737 aircraft. Turns out tire was not the proper tire for our heavier rated B737 series. I did assist sliding the tire on with the help of two other Mechanics; the tire and equipment were brought to the aircraft by the Lead on duty.I was assigned this aircraft to perform securing back in its place... Blood Pressure 'BP' Cuffs. I was met by a Mechanic who signed the Non-routine Write-up; who (also) wrote the tire up; telling me he had a tire. I went to tell the Duty Lead of his find; and when I got to the plane to do the oil service; I showed the Lead; then I went to write oils in the Log. When I came out of the aircraft; the Lead was bringing over a tire; and equipment to change the tire assembly.I will not sign for anyone's action; if they do not read serviceable tags for tires of the type of equipment they are to be used. Communication between Technicians is a factor. I assumed the proper tire was brought over; and the person filling out the tag; knew the tire was correct for this type of aircraft.
NASA callback
Reporter stated their company Mechanics are not allowed to sign-off tire write-ups until they go through one of their information classes for tire changes.Reporter stated that although he was distracted by trying to accomplish re-installing a new Medical Kit in the cabin; because the Blood Pressure Cuffs had been used; his biggest mistake was assuming the Lead had brought over the correct tire to the B737. The Lead had relied on the Main tire wheel cover color as an indication of the correct tire. No one; including himself (Reporter); seemed to have verified the tire Serviceable Tag information with the type of B737 the tire was going on.Reporter stated they use different colored wheel covers to indicate which type of aircraft the tire can be installed on. The color of the tire wheel cover indicated the Main tire they were installing was rated for a heavier aircraft; but that was not correct.Reporter stated that approximately seventeen days and forty-nine flights later; a Line Mechanic had written-up the tire for low pressure and then also noticed the stenciling on the inside of the tire; indicating the tire was not rated for that model aircraft.Reporter stated he was able to show the conflict between their General Maintenance Manual about Mechanics responsibility to Sign for their own work and then; in a different section of the same manual; Mechanics who are assigned work are directed not to sign-off that work unless they are qualified.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.