Narrative:

I and two other mechanics replaced a set of nose tires on aircraft X. While the two mechanics did the right&right; I took care of the parts tags and logbook. Somehow we all failed to notice if there were markings on the tires indicating bias tires. The store inventory number and procedures manual number is identical for both bias and radial tires. Our air carrier does not issue separate inventory numbers or procedures manual numbers or any other type of marking on the parts tags; like what you will find on a parts tag for a part that's CAT III sensitive. After the aircraft flew for four days and had gone through a maintenance visit; the error was discovered by a mechanic. Contributing factors: three mechanics worked together to minimize delay time; air carrier parts tags not having different procedures manual numbers for different type parts. No identifying marks on parts tag to remind the mechanic; bias and radial tires stored in the same tire rack; lack of markings in tire storage area. This event did not affect the safety of the aircraft. The procedures manual suggest that when possible tires especially nose tires be installed in pairs of new tires of same make or retread.callback conversation with reporter revealed the following information: reporter stated installing different ply type tires; radial and bias; on the nlg is the issue. The same type of wheel halves are used; with the same part number in their inventory system and on the parts tag when building-up either a radial or bias ply tire. This part number in their inventory system does not discriminate between a radial or bias ply tire. The only difference is a white lettering on the sidewall of the nose tire indicating 'bias ply' and a color coded DOT on the same wheel half. Although the tire racks they use do separate the -300's from the -700's tires; his company stores their radial and bias ply tires together in the same racks. In the rush to meet departure schedules; they just did not notice the difference between the two tires when they were installed. Reporter also stated the radial and bias ply tires have the same height and same tread pattern and the same tire vendor. Reporter has suggested to his carrier to put some kind of identifier next to the part number and serial number on the parts tag to help prompt the mechanic; who uses these numbers from the tags; when signing off the logbook; that he may have different ply tires installed on the same nlg.

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Original NASA ASRS Text

Title: A B737-700 ACFT WAS FOUND WITH ONE RADIAL AND ONE BIAS PLY TYPE TIRE ON NLG. TIRES WERE PREVIOUSLY REPLACED FOR WEAR AT UP-LINE STATION.

Narrative: I AND TWO OTHER MECHANICS REPLACED A SET OF NOSE TIRES ON ACFT X. WHILE THE TWO MECHANICS DID THE R&R; I TOOK CARE OF THE PARTS TAGS AND LOGBOOK. SOMEHOW WE ALL FAILED TO NOTICE IF THERE WERE MARKINGS ON THE TIRES INDICATING BIAS TIRES. THE STORE INVENTORY NUMBER AND PROCS MANUAL NUMBER IS IDENTICAL FOR BOTH BIAS AND RADIAL TIRES. OUR ACR DOES NOT ISSUE SEPARATE INVENTORY NUMBERS OR PROCS MANUAL NUMBERS OR ANY OTHER TYPE OF MARKING ON THE PARTS TAGS; LIKE WHAT YOU WILL FIND ON A PARTS TAG FOR A PART THAT'S CAT III SENSITIVE. AFTER THE ACFT FLEW FOR FOUR DAYS AND HAD GONE THROUGH A MAINT VISIT; THE ERROR WAS DISCOVERED BY A MECHANIC. CONTRIBUTING FACTORS: THREE MECHANICS WORKED TOGETHER TO MINIMIZE DELAY TIME; ACR PARTS TAGS NOT HAVING DIFFERENT PROCS MANUAL NUMBERS FOR DIFFERENT TYPE PARTS. NO IDENTIFYING MARKS ON PARTS TAG TO REMIND THE MECHANIC; BIAS AND RADIAL TIRES STORED IN THE SAME TIRE RACK; LACK OF MARKINGS IN TIRE STORAGE AREA. THIS EVENT DID NOT AFFECT THE SAFETY OF THE ACFT. THE PROCS MANUAL SUGGEST THAT WHEN POSSIBLE TIRES ESPECIALLY NOSE TIRES BE INSTALLED IN PAIRS OF NEW TIRES OF SAME MAKE OR RETREAD.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED INSTALLING DIFFERENT PLY TYPE TIRES; RADIAL AND BIAS; ON THE NLG IS THE ISSUE. THE SAME TYPE OF WHEEL HALVES ARE USED; WITH THE SAME PART NUMBER IN THEIR INVENTORY SYSTEM AND ON THE PARTS TAG WHEN BUILDING-UP EITHER A RADIAL OR BIAS PLY TIRE. THIS PART NUMBER IN THEIR INVENTORY SYSTEM DOES NOT DISCRIMINATE BETWEEN A RADIAL OR BIAS PLY TIRE. THE ONLY DIFFERENCE IS A WHITE LETTERING ON THE SIDEWALL OF THE NOSE TIRE INDICATING 'BIAS PLY' AND A COLOR CODED DOT ON THE SAME WHEEL HALF. ALTHOUGH THE TIRE RACKS THEY USE DO SEPARATE THE -300'S FROM THE -700'S TIRES; HIS COMPANY STORES THEIR RADIAL AND BIAS PLY TIRES TOGETHER IN THE SAME RACKS. IN THE RUSH TO MEET DEP SCHEDULES; THEY JUST DID NOT NOTICE THE DIFFERENCE BETWEEN THE TWO TIRES WHEN THEY WERE INSTALLED. RPTR ALSO STATED THE RADIAL AND BIAS PLY TIRES HAVE THE SAME HEIGHT AND SAME TREAD PATTERN AND THE SAME TIRE VENDOR. RPTR HAS SUGGESTED TO HIS CARRIER TO PUT SOME KIND OF IDENTIFIER NEXT TO THE PART NUMBER AND SERIAL NUMBER ON THE PARTS TAG TO HELP PROMPT THE MECHANIC; WHO USES THESE NUMBERS FROM THE TAGS; WHEN SIGNING OFF THE LOGBOOK; THAT HE MAY HAVE DIFFERENT PLY TIRES INSTALLED ON THE SAME NLG.

Data retrieved from NASA's ASRS site as of January 2009 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.