Examination and Recommended Action 1. Tread NORMAL TREAD WEAR...................................................................................................................... 02 UNEVEN TREAD WEAR (SHOULDER)...............................................................................................03 UNEVEN TREAD WEAR (CENTER).................................................................................................... 04 IRREGULAR WEAR: ABRASION.........................................................................................................05 SPOT WEAR...........................................................................................................................................06 TREAD RUBBER REVERSION............................................................................................................07 TREAD SEPARATION.......................................................................................................................... 08 CUTS....................................................................................................................................................... 09 RIB UNDERCUTTING...........................................................................................................................10 CHEVRON CUTTING............................................................................................................................ 11 PEELED RIB........................................................................................................................................... 12 BULGE ON THE CROWN SURFACE (DEFLATED TIRE).................................................................13 GROOVE CRACKING........................................................................................................................... 14 CONTAMINATION.................................................................................................................................15 OPEN TREAD-SPLICE.......................................................................................................................... 16 CHIPPING AND CHUNKING............................................................................................................... 17 RIB TEARING.........................................................................................................................................18 CORD EXPOSURE IN TREAD GROOVE...........................................................................................19 IMPACT BREAK.....................................................................................................................................20 SKID BURST.......................................................................................................................................... 21 BULGE/BLISTER................................................................................................................................... 22 2. Sidewall SIDEWALL CUTS...................................................................................................................................23 SIDEWALL CRACKING (Upper side and lower side) Circumferential cracks.............................. 24 WEATHERING & RADIAL CRACKING................................................................................................ 25 INNERLINER WRINKLING................................................................................................................... 26 CASING BREAK UP (CBU)..................................................................................................................27 3. Bead OVERHEATING FROM EXCESSIVE BRAKING................................................................................. 28 CHAFER DAMAGE................................................................................................................................29 HEAT BURST..........................................................................................................................................30 1
NORMAL TREAD WEAR PHENOMENON Rubber is worn out evenly across the tire tread. Even tread wear indicates that tire pressure has been maintained at the correct inflation level during service. RECOMMENDATION Tire should be removed at the following condition whichever comes first across the tread; i) When the wear level reaches the bottom of any groove at one point up to 1/8 of the circumference. ii) The reinforcing fabric (bias) or aramid cord protector (radial) is exposed. If it is necessary to continue the tire in service beyond the limit i), the tire should be removed either at the next maintenance base or the limit ii) happens, whichever occurs first. Important Notice: As written in “General” on 1st page of this manual, specific removal criteria shall be defined by instruction of airframe manufacturers, such as AMM. Such document takes precedence over this manual. 2
UNEVEN TREAD WEAR (SHOULDER) PHENOMENON Rubber wearing is much progressed at “shoulder area” of tread. POSSIBLE CAUSES Underinflation will lead to excessive tread shoulder wear. It will also lead to high tire deflection and subsequent heat build-up which may result in tire damage. RECOMMENDATION If the tire wear limit has been or soon will be reached, remove the tire. If the wear limit has not been reached, check the pressure and adjust it to the recommended value. If shoulder wear is more pronounced on one side, this type of wear could result from axle flexing. Tire can be kept in service until normal wear removal criteria is reached. 3
UNEVEN TREAD WEAR (CENTER) PHENOMENON Rubber wearing is much progressed at “center area” of tread. POSSIBLE CAUSES Overinflation accelerates center tread wear, reduces tire traction and makes the tread more susceptible to cutting by foreign objects. RECOMMENDATION If the tire wear limit has been reached or soon will be reached, remove the tire. If the wear limit has not been reached, check tire pressure and adjust in accordance with maintenance manual standards. 4
IRREGULAR WEAR: ABRASION PHENOMENON Tread surface becomes quite rough, or slightly melted. Side Force POSSIBLE CAUSES Refers to abrasive wearing of the tread caused by sudden, strong side forces. RECOMMENDATION If the reinforcing fabric (bias) or aramid cord protector (radial) is exposed, remove the tire. 5
SPOT WEAR PHENOMENON Quite deep rubber wearing happens at singular location of tire. POSSIBLE CAUSES Skid burns result from brake malfunctions or locking of the wheel, most often during landing. RECOMMENDATION If the spot wear reaches the reinforcing fabric (bias) or aramid cord protector (radial), remove the tire from the aircraft. If the spot wear does not reach the reinforcing fabric (bias) or aramid cord protector (radial), if there is sufficient groove depth in the whole spot wear area, if there is not incipient separation and if vibration is not detected while rolling, leave the tire on the aircraft. 6
TREAD RUBBER REVERSION PHENOMENON A patch of tread rubber is melted or scorched. POSSIBLE CAUSES An oval shaped burn on the tread most often is caused by hydroplaning on wet or frozen runways during landing. RECOMMENDATION If the tread rubber reversion reaches the reinforcing fabric (bias) or aramid cord protector (radial), remove the tire from the aircraft. If the tread rubber reversion does not reach the reinforcing fabric (bias) or aramid cord protector (radial), if there is sufficient groove depth in the whole tread rubber reversion area, if there is not incipient separation and if vibration is not detected while rolling, leave the tire on the aircraft. 7
TREAD SEPARATION PHENOMENON Internal separation happens between tire components at tread area. Part of tread rubber and / or fabrics are lost and internal construction is exposed. POSSIBLE CAUSES Separation of the tread or fabric is caused by overloading, cuts, abnormal heat built-up, etc. RECOMMENDATION A tire with tread or fabric separation must be removed immediately and be checked by the tire manufacturer. If tread separation is serious, part of most of the tread (often including the reinforcing fabric in bias tires) may peel off, which in turn may lead to damage to the aircraft. Therefore, remove the tire immediately. Early signs of tread separation can manifest themselves in the form of a tread bulge, local uneven wear (depression) or a local tread/sidewall rubber split. Remove the tire immediately. If the tire is still inflated after aircraft is at parking position, record the pressure after it has cooled down (allow 3 hours). Then deflate the tire before removing the wheel assembly. 8
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