1、 MIL-PRF-7726K INCH POUND20 February 2007 SUPERSEDING MIL-PRF-7726J 29 January 2001 PERFORMANCE SPECIFICATION RETREAD TIRES, RIBBED TREAD, PNEUMATIC AIRCRAFT Beneficial comments (recommendations, additions, and deletions) any pertinent data, which may be used in improving this document, should be ad
2、dressed to: 984 CSUG/GBCLE, 6040 Gum Lane, Bldg 1216, Hill AFB, UT 84056-5825 or CSUG.GBCL.WorkflowHILL.af.mil. Since contact information can change, you may want to verify the currency of this address information using the ASSIST Online database, http:/assist.daps.dla.mil. AMSC: N/A FSC 2620 Provid
3、ed by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-7726K 1. SCOPE 1.1 Scope. This specification covers the requirements for a retreaded bias ply or radial ply aircraft tire, which has had a worn casing restored by renewing the tread material or the tr
4、ead and sidewall material. A rebuilt aircraft pneumatic tire may be a tube-type or tubeless ribbed and is intended for use on an aircraft wheel. The drawing and slash sheet matrix (shown as Table I) identifies these retreaded tires by size and ply rating. 2. APPLICABLE DOCUMENTS 2.1 General. The doc
5、uments listed in this section are specified in Sections 3, 4, and 5 of this specification. This section does not include documents cited in other sections of this specification or recommended for additional information or as examples. While every effort has been made to ensure the completeness of th
6、is list, document users are cautioned that they must meet all specified requirements of documents cited in Sections 3, 4, and 5 of this specification, whether or not they are listed. 2.2 Government documents.2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and
7、 handbooks form a part of this document to the extent specific herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-PRF-5041 Tires, Ribbed Tread, Pneumatic, Aircraft DEPARTMENT OF DEFENSE STANDARDS
8、 MS 14113 Tape, Identification, Color Coded, for Aircraft Tires (Copies of these documents are available from the Standardization Document Order Desk, 700 Robbins Avenue, Bldg 4D, Philadelphia, PA 29222-5094 or http:/assist.daps.dla.mil. 2.2 Other Government documents, drawings, and publications. Th
9、e following other Government documents, drawings, and publications form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. FEDERAL AVIATION ADMINISTRATION (FAA) PUBLICATIONS TSO-C62 Techni
10、cal Standard Order Tires AC 145-4 Inspection, Retread, Repair, and Alterations of Aircraft Tires 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-7726K (Copies of these documents are available from U.S. Department of Transportation, Federal
11、Aviation Administration, 800 Independence Avenue, SW, Washington DC 20591 or www.firstgov.gov.) DRAWINGS (See Supplement 1 of this document for the Air Force Drawings) 2.3 Non-Government publications. The following documents form a part of this document to the extent specified herein. Unless otherwi
12、se specified, the issues of these documents are those cited in the solicitation or contract. AMERICAN SOCIETY OF QUALITY (ASQ) ANSI/ASQ Z1.4 Sampling Procedures and Tables for Inspection by Attributes (Application for copies of this document should be addressed to American Society of Quality (ASQ),
13、611 East Wisconsin Avenue, P.O. Box 3005, Milwaukee, WI 53202 or www.asq.org.) AMERICAN SOCIETY OF TESTING AND MATERIALS (ASTM) ASTM D413-98 Standard Test Method for Rubber Property 175 Montrose West Avenue, Suite 150, Copley, OH 44321 or www.TRAUS-TRA.org.) 2.4 Order of precedence. In event of a co
14、nflict between the text of this document and the references cited herein, the text of this document takes precedence. Nothing in 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-7726K this document, however, supersedes applicable laws and re
15、gulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 Qualification. The retreaded tires furnished under this specification shall be products that are authorized by the qualifying activity for listing on the application Qualified Products List (QPL) before contract award (see
16、paragraphs 4.2 and 6.3). Changes in plants, construction, materials, or processes that affect performance of the retreaded tire shall require re-qualification per this specification. Qualification testing is only required with the first (R-1) application of a new tread or as otherwise specified in t
17、his document. Design and construction differences between radial tires of different manufacturers dictate that retread qualification (dynamometer) testing be conducted on each radial tire manufacturers casing. Qualification of bias tire retreads on a single manufacturers casing qualifies the retread
18、 on other manufacturers compatible casings of the same size, ply rating, speed rating and National Stock Number (NSN). 3.1.1 Qualification casing requirements. Unless otherwise specified in Table I, referenced drawings or specification sheets, hereinafter referred to as slash sheets, maximum damage
19、(e.g. cuts, fatigue, casing ply exposure, etc) to candidate tire casing (see paragraph 6.5) used for retread qualification shall be in accordance with FAA publication AC 145-4. Each retread manufacturer shall provide a “Process Specification” document detailing the maximum permissible repairs that h
20、ave been validated by tests, or analysis, or both for approval by the qualifying activity prior to being applied in service. The casings selected for qualification testing shall have no less than 80% of their new molded skid depth (see paragraph 6.4.4.11) removed by wear (e.g. worn by aircraft usage
21、). 3.1.2 Retread level escalation. Following successful qualification of retreaded tires at the first retreaded level (see paragraph 6.4.4.8) each part number shall be escalated in accordance with AC 145-4. The qualification test requirements of this document take precedence over those specified by
22、AC 145-4. 3.2 General requirements. Unless otherwise specified (see paragraph 6.2), retreaded tires shall be suitable for use on military aircraft, on all types of improved and unimproved runways, including ships (usually aircraft carrier decks), under all weather conditions. For retreaded tires not
23、 found in Table I, referenced drawing or slash sheet, performance or interface requirements shall be provided by the qualifying activity (see paragraph 6.2). 3.2.1 Ambient temperature range. The ambient temperature range over which the retreaded tire is required to operate is -58F to 125F (-50C to 5
24、2C). All retreaded tire compounds maintain their fracture toughness and strength characteristics within this temperature range. 3.2.2 Tire sizing. The retreaded tire size, inflated to rated inflation pressure and allowed to stretch due to inflation for 12 hours, must meet the grown tire dimensional
25、envelope established for that size by the TRA Aircraft Yearbook. In addition, the retreaded tire, when inflated to its rated pressure and rotated at its rated speed, must meet the “grown and thrown” dimensional envelope established for that size by the TRA Aircraft Yearbook. 4 Provided by IHSNot for
26、 ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-7726K 3.2.3 Tire dimensions and weight. Dimensions and weight of the retreaded tire shall be as specified in Table I referenced drawing or slash sheet. All lettering, decorative ribs and designs shall be included in
27、the dimensions. The definition of the tire shoulder (for use in should height and width requirements found in the drawing or slash sheet) is found in the TRA Aircraft Yearbook. 3.2.3.1 Tire dimensions for helicopters. The maximum allowable increase in dimensions for helicopter application of a tire
28、given that the maximum allowable inflation pressure for this application is 1.80 times rated inflation pressure (see paragraphs 6.5) is 4 percent. 3.2.3.2 Tire bead width. The tire bead width shall not exceed the minimum wheel ledge width as specified in the TRA Aircraft Yearbook. 3.3 Rim interface.
29、 Each retreaded tire shall interface with the rim as specified in Table I referenced drawing or slash sheet. 3.4 Materials. Materials shall be of a quality that will meet the performance requirements specified in paragraph 3.5 or in Table I referenced drawing or slash sheet. 3.5 Performance.3.5.1 Ba
30、sic tire performance. Unless otherwise specified (see paragraph 6.2), tires shall have a retread buff line (RBL) (see paragraph 6.5) visible in the cross sectional cut. 3.5.2 Tire speeds. Unless otherwise specified in Table I referenced drawing or slash sheet, the retreaded tire shall have a minimum
31、 velocity capability of 120 mph at the rated load and rated inflation pressure (see paragraph 6.5). 3.5.3 Tread pattern. The tread pattern shall be ribbed, having a minimum of three grooves for tires with a cross sectional width greater than 6.0 inches and a minimum of two grooves for tires with a c
32、ross sectional width of 6.0 inches or less. The grooves shall be continuous and circumferential. 3.5.4 Retreadability. Unless otherwise specified (see paragraph 6.2), tires shall have a RBL (see paragraph 6.4.4.8) visible in the cross sectional cut. 3.5.5 Sidewall. The sidewall shall protect the cas
33、ing against abrasion and weathering. 3.5.6 Venting. Means shall be provided to vent any trapped gases from the casing. If vent holes are used, there shall be at least eight functioning vent holes per sidewall located above the rim flange. 3.5.6.1 Tube type tires. If vent holes are used, they shall b
34、e marked with a white or aluminum colored dot. Vent holes may penetrate the liner of the tire (see paragraphs 6.5). 3.5.6.2 Tubeless tires. If vent holes are used, they shall be marked with a bright green dot. Vent holes shall not penetrate the liner of the tire. (see paragraphs 6.4.4.5). 5 Provided
35、 by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-7726K 3.5.7 Maximum wear limit (MWL) indicator. The tire shall be provided with a MWL indicator (e.g. ply count indicator) to specify the maximum number of fabric layers to the outermost structural ply
36、that may be exposed before the tire must be removed from service. A colored MWL indicator may be incorporated in addition to the ply count indicator. Retreaded tires for the Department of Navy use do not require a MWL indicator. 3.5.8 Burst pressure. The retreaded tire shall be designed to withstand
37、 a minimum burst pressure as specified in Table I referenced drawing or slash sheet. If the tire is not listed in Table I, the tire shall be designed to withstand a minimum burst pressure of three times the rated inflation pressure for land-based aircraft or four times the rated inflation pressure f
38、or carrier-based aircraft. 3.5.9 Dynamic durability. Unless otherwise specified (see paragraphs 4.6.6), excluding wear, retreaded tires for fighters, attack, and trainer aircraft shall withstand a minimum of 50 cycles of taxi, takeoff, and landing; and retreaded tires for other aircraft shall withst
39、and a minimum of 100 cycles of taxi, takeoff, and landing. In addition, for the Department of Navy aircraft with carrier based requirements, retreaded tires shall withstand normal catapults, landing arrestments, and cable strikes without failure. 3.5.9.1 Cord fraying. During dynamic life (as defined
40、 in paragraph 3.5.9) of the retreaded tile, cord fraying, if present in the groove of the tire, shall be only of the outer layer or cord. 3.5.9.2 Tread chunking. During the dynamic life (as defined in paragraphs 3.5.9) of the retreaded tire, any tread chunk shall not exceed 1 square inch in area or
41、75 percent of the skid depth (see paragraph 6.4.4.11), any void in the bottom of the groove shall be no deeper than a void caused by the outer layer of cord being pulled through the rubber stock in the bottom groove. There shall be not rib undercutting. 3.5.9.3 Groove cracking. During the dynamic li
42、fe (as defined in paragraph 3.5.9) of the retreaded tire, there shall be no groove cracking in retreaded tires having all rubber tread. In retreaded tires with fabric tread (see paragraphs 6.4.4.4), any void in the bottom of the groove shall be no deeper than a void caused by the outer layer of cord
43、 being pulled through the rubber stock in the bottom of the groove. There shall be no rib undercutting. 3.5.9.4 Bead separation. Retreading of the tire shall not adversely affect the bead bundle (see paragraph 6.4.4.1). During the dynamic life (as defined in paragraph 3.5.9) of the retreaded tire, t
44、he bead bundle shall not show evidence of separating from the casing plies (see paragraphs 6.4.4.3). If bead wires are used, individual wires shall not show evidence of separating from each other, or of being kinked, broken, or exposed. 3.5.10 Wheel/tire slippage. A mounted retreaded tire, inflated
45、to rated inflation pressure, shall not slip on the wheel rim to such an extent that would damage the tube or valve in the tube type tire or the inflation seal of the tubeless tire. 3.5.11 Inflation pressure retention tubeless tire. After an initial 12 hour growth, starting at rated inflation pressur
46、e, the pressure loss from rated inflation pressure in a tubeless, retreaded tire assembly during the subsequent 24 hour period shall not exceed 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-7726K 5 percent of rated inflation pressure spec
47、ified in Table I referenced drawing or slash sheet. 3.5.12 Balance. Retreaded tires shall be balanced, when not inflated; within tolerance specified in Table I referenced drawing or slash sheet. Out-of tolerance conditions may be corrected by utilizing balance pads affixed to the inside of the tire.
48、 In tube type retreaded tires, the pads shall not chafe the tubes. Balance pad adhesion values shall be as follows: 8 pounds force per inch-width minimum for tubeless tires and 1.5 pounds force per inch-width minimum for tube type tires. 3.5.13 Tread adhesion. Retreaded tires shall have a minimum of 30 pounds force per inch-width adhesion at the interface between the tread or under tread and the outermost structural ply (casing, breaker, or belt ply). 3.6 Product identification and marking.3.6.1 Original tire identification data. Unless otherwise specified (see para
