Maintenance Airframe; Maintenance Powerplant
Confusion; Communication Breakdown
Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Procedure; Manuals; Human Factors; Chart Or Publication
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.
Reference Procedures Manual (PM) 7-02-4. I have recently observed two very heated arguments between mechanics regarding interpretation of Tire Tread Wear limits. The topic has both times been about measuring wear on the outermost tread; the tread between the crown and shoulder. The disputes were whether the crown side and the tread side [of the tire] both require 2/32' of an inch (3/32' for B737) tread [remaining]; or more; to be considered a Serviceable Tire.My understanding is both tread sides require 2/32' of an inch (or 3/32') in order to be Serviceable.  Request answer: Are the shoulder and crown tread sides BOTH expected to be above the 2/32' (3/32') minimum in order for the wear to be serviceable?[Recommend] clarification in the Procedures Manual (PM) what the wear expectation is; as some seem to understand the PM expectation is the shoulder side [of the tire] isn't actually a 'tread' when looking at Figure 7-02-3.  Figure 7-02-2 shows both RIB and TREAD locations. Suggest replace word RIB with TREAD;  Figure  7-02-3 shows word TREAD RIB for inner treads; but nothing for the shoulder tread; suggest adding arrow and identifying SHOULDER TREAD.
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.