1、d MIL-T-28816(EC) AMENDMENT 1 25 April 1975 MILITARY SPECIFICATION TIME-FREQUENCY STANDARD, DISCIPLINED, AN/URQ-23, GENERAL SPECIFICATION FOR This amendment forms a part of Military Specification MIL-T-28816(EC), dated 4 April 1975. Page 1 , 1.2.1, line 1: 1.2.2, line 1: Delete “class 4“ and substit
2、ute “Range 4“. Delete “class 2“ and substitute “Range 2“. Page 2 2.1, STANDARDS, MILITARY: After “MIL-STD-1364“ add “MIL-STD-1472 - Human Engineering Design Criteria for Military Systems, Equipments, and Facilities“. 2.1, .HANDBOOKS, MILITARY: Delete “Ma-HDBK-472 - Maintainability Prediction“. Page
3、4 3.5: Delete and substitute: “3.5 Reliability requirements. “3.5.1 Reliability. The standard shall have a specified mean-time- between-failure (MTBF), eo, as defined by MIL-STD-781, of 2500 hours under shipboard conditions. “3.5.2 Equipment conditioning. Ail equipment shall be subjected to a temper
4、ature burn-in with the environment temperature equal to or greater than those specified in 1.2 with the equipment operating in the worst case mode for a cumulative operating time of 48 hours. the last 24 hours shall be repaired and the burn-in resumed with a minimum of 24 hours of equipment conditio
5、ning without further failure. monitoring during burn-in shall include as a minimum the functional checks to assure proper operation under the worst case operating mode. ments of the equipment (for example, manual compensation for drift in VCOs) , other than normal operating mode changes, shall be al
6、lowed during burn-in. Failures occurring during Equipment No adjust- Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL -T-2 881 6 (E C) AMENDMENT 1 Page 10 Table IV, Aging rate column, 5th line: Delete “0.661d.o“ and substi- tute “O. 66PP1010“. Pag
7、e 12 3.7.9, line 4 : After “MIL-STD-454“ add “and MIL-STD-1472“. Page 18 3.17: Delete and substitute: “3.17 Maintainability. The standard shall have a median corrective maintenance time (fict) not exceeding 15 minutes when repair is accomplished at the organizational level (see 6.4.7) of maintenance
8、 by the replacement of subassemblies (including modules and printed circuit boards) and chassis- mounted parts (electronic, electrical, electromechanical, and mechanical parts) . Corrective maintenance time shall include localizational, isolation, disassembly, interchange, reassembly, alignment, and
9、 checkout for all main- tenance tasks .“ Page 32 4.4.2.3: Delete “One out of every ten standards shall be subjected to the following tests.“ Page 41 4.4.2.4: Delete. Page 43 4.4.3.2.2, line 2: After “environmental“ add “equipment conditioning (burn-in) I. Page 44 4.4.4, 4.4.4.1, and 4.4.4.1.1: “4.4.
10、4 Reliability demonstration. Reliability demonstration shall be Delete and substitute: performed in accordance with MIL-STD-781, except as hereinafter specified. Reliability shall be performed as part of first article inspection only. “4.4.4.1 -Reliability testing. as required by 4.4.4.1.1 and 4.4.4
11、.1.2. Reliability testing shall be conducted Page 2 of 4 pages %- “I Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1 . MIL-T-28816 (1) bb 977770b 0136404 7 W MIL -T-2 881 6 ( EC) AMENDMENT 1 “4.4.4.1.1 First article testing. Reliability demonstrati
12、on testing shall be performed to test level E in accordance with test plan IV except as specified in 4.4.4.2. with the specified criteria in MIL-STD-781 for test plan IV. shai be performed during first article. Testing shall proceed to a decision in accordance This testing “4.4.4.1.2 Production samp
13、ling testing. Reliability sampling tests shall be conducted throughout production to ensure continued manufacture of acceptable equipment. plan IVA of MIL-STD-781 except as specified by 4.4.4.2. to be randomly selected from each months production for reliability samp- ling tests shall be in accordan
14、ce with Table 5 of MIL-STD-781. shall proceed to a decision in accordance with the criteria specified in MIL-STD-781 for test plan IVA. Sampling testing shall be at test level C to test The number of units Testing “4.4.4.1.3 Equipment conditicning. Debugging and burn-in of equip- A performance check
15、 shall be ments, assemblies, or parts prior to performance of the reliability testing shall be limited to that required by 3.5.2. conducted a minimum of twice every 24 hours and just prior to the end of burn -in. 4.4.4.2.2: Delete and substitute: “4.4.4.2.2 Temperature. Testing shall be performed at
16、 a temperature equal to or greater than those specified in 1.2.“ Add new paragraphs: “4.4.4.2.6 Preventive maintenance, Except for normal battery replace- ment in equipments powered by self-contained batteries, no preventive main- tenance shall be performed during the reliability test. “4.4.5 Mainta
17、inability demonstration, Conformance with the equipment maintainability requirement shall be demonstrated in accordance with Method 4 of MIL-STD-471 by replacement of subassemblies and chassis-mounted parts corresponding to- organizational level corrective maintenance. contractor shall determine 30
18、candidate faults for the maintainability dem- onstration in accordance with Appendix A of MIL-STD-471. activity shall select 20 faults to be used for the demonstration. For fault simulation, a number shall be assigned to each part, including those that are contained in subassemblies. Faults for the
19、demonstration shall be cre- ated by introduction of faulty parts or simulation of such faults in parts corresponding to the number selected, The The procuring “4.4.5.1 Rejection, If a reject decision is reached, the procuring activity shall be immediately notified. The contractor, at no additional P
20、age 3 of 4 pages Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- MIL-T-28816 (1) 66 = 9777706 0136405 7 MIL-T-28816 (EC) AMENDMENT 1 cost to the Government: (a) develop an approach for redesign or correction of all deficiencies, and (b) upon approva
21、l of a documented approach, the con- tractor shall repeat the demonstration until an accept decision is reached. “4.4.5.2 Technical documentation. Technical documentation to be used in the demonstration shall be limited to the technical manual.“ Preparing activity: Navy - Ex: (Project No. 6625-N663) * U. S GOVERNMENT PRINTINO OFFICE: 1975 -aOS118/4755 Page 4 of 4 pages Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
