Narrative:

On B737 periodic service (P/south) check (and maybe other job cards); step 2 (east) tells to check tire step wear and lists figure-1 for explanation. Figure-1 doesn't clearly explain what step wear actually is. Note-2 seems to say that only when I see fabric; there is step wear; is this correct? I've always thought when the shoulder side tread wears more quickly than the crown; that is step wear. I; later the next day; had a heated argument with another mechanic on this; and need final and clear explanation; as one of us is clearly not reading the requirement correctly. Does it mean that the outboard shoulder side of the tread must have 3/32' of an inch of tire tread left; or that either side of the tire groove; crown or shoulder; can have that 3/32' of an inch [remaining] for the tire to be good?[recommend] our air carrier clearly explain in the ps check and general procedures manual (gpm) if the shoulder side tread requires 3/32' tread or not; and also explain if the tire is serviceable with the shoulder side to be below 3/32' of an inch; if the crown side is still above 3/32' of an inch.

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Original NASA ASRS Text

Title: Two Aircraft Maintenance Technicians (AMTs) request clarification in their Periodic Service Check and Procedures Manual for measuring Tire Tread Wear Limits on their B737-800 Main Landing Gear (MLG) tires. Also noted were the different interpretations of what STEP WEAR actually was and whether the inboard; outboard; or both shoulder side treads required 3/32 of an inch of tread remaining; for the tire to be considered serviceable.

Narrative: On B737 Periodic Service (P/S) Check (and maybe other Job cards); Step 2 (E) tells to check tire Step Wear and lists Figure-1 for explanation. Figure-1 doesn't clearly explain what STEP WEAR actually is. Note-2 seems to say that only when I see fabric; there is Step Wear; is this correct? I've always thought when the shoulder side tread wears more quickly than the crown; that is Step Wear. I; later the next day; had a heated argument with another Mechanic on this; and need final and clear explanation; as one of us is clearly not reading the requirement correctly. Does it mean that the outboard shoulder side of the tread must have 3/32' of an inch of tire tread left; or that either side of the tire groove; crown or shoulder; can have that 3/32' of an inch [remaining] for the tire to be good?[Recommend] our air carrier clearly explain in the PS Check and General Procedures Manual (GPM) if the shoulder side tread requires 3/32' tread or not; and also explain if the tire is serviceable with the shoulder side to be below 3/32' of an inch; if the crown side is still above 3/32' of an inch.

Data retrieved from NASA's ASRS site 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.