1、MILR-55231 (EL) 12 APRIL 1963 MILITARY SPECIFICATION RELIABILITY REQUIREMENTS, GENERAL; FOR PRODUCTION ELECTRONIC EQUIPMENT 1. SCOPE 1.1 Scope. This specification covers the general reliability procedures for use on production contracts for electronic equip- ment. Detail requirements will be specifi
2、ed in the individual equipment specification. in case of conflict, the equipment specification shall govern. 1.2 Phases. This specification covers the following three phases of contractual eff Ort, which mill be prescribed individually or col- lectively : Preproduction Teliability measwement: The me
3、asurement of reliability of a preproduction sample of one or more units, sets, or systems. Plot-prodzcctioIt reliability hnspection: The measurement or acceptance in- spection of the reliability of a pilot production sample of two or more units, sets, or systems. Q.titlJ-production Teliability inspe
4、c- Zion: The acceptance inspection, by sampling, of quantity production of units, sets, or systems. 1.3 Classification. This specification is ap- plicable when either of the following pro- cedures is to be employed : 1.3.1 Procedwe I. A mean-time-between- failures (MTBF) is not specified. The con- t
5、ractor conducts specified reliability testing on preproduction and pilot production items. A minimum MTBF for production is then established by analysis (statistical and other) of the test data. 1.3.2 Procedwe II. A MTBF is cited in the equipment specification or in the con- tract. 2. APPLICABLE DOC
6、UMENTS 2.1 The following documents, of the issue in effect on the date of invitation for bids or request for proposal, form a part of this specification to the extent specified herein: SPECIFICATION MILITARY MIL-P-9853 -Paper, Diazo-Sepia, Re- producible, Interfile- able. (Copies of specifications r
7、equired by contractors in connection with specific procurement functions should be obtained from the procuring activity or as directed by the contracting officer,) PUBLICATION Reliability of Military Electronic Equip- ment: Report by Advisory Group on Reliability of Electronic Equipment- Office of t
8、he Assistant Secretary of De- fense (Research and Engineering), 4 June 1957. For sale by Superintendent of Documents, U. S. Government Print- ing Office, Washington 25, D. C. (Supplement 1 to this specification extracts verbatim the essential portions of the above report, and is intended to serve as
9、 a convenient reference in lieu of the entire report.) 3. REQUIREMENTS 3.1 General. The contractor shall establish a comprehensive reliability assurance pro- gram, which will be subject to approval and monitoring by authorized representatives of Licensed by Information Handling Services-_-_ _-_17- M
10、IL-R-55231 NI m 7777706 0404503 2 9 NILR-55231( EL) the contracting officer. Except as otherwise specified, the reliability program shall be in accordance with the report of Task Group 3, Pilot Production and Production Model Tests, dated 15 January 1957, and 3.2 herein. The Task Group 3 report is i
11、ncluded in the docu- ment listed in section 2 above, and will be referenced hereinafter as “The TG-3 Re- port”. (See Supplement i.) 3.2 Reliability program. The contractor shall submit for approval a reliability assur- ance program, as specified in 3.1, to include but not be necessarily limited to 3
12、.2.1 through 3.2.5. 3.2.1 Rehbiiitg organization. The de- scription of the reliability organizational structure shall indicate areas of responsi- bilities, personnel, operating procedures, and plans for implementation of this specifica- tion. 3.2.2 Facitities. The contractor shall de- scribe the fac
13、ilities for testing, adjusting, and repairing items subjected to reliability testing. The calibration techniques to be employed for tools and test facilities shall be described. 3.2.3 Procurement functions. This section shall describe the contractors procedures for review and evaluation of its suppl
14、iers quality and reliability organization, quality controI and reliability liaison activities with its suppliers, and data feedback system to correct and improve vendors product quality and reliability, 3.24 Analgses and evaluation. When pro- cedure I is specified, the contractor shall perform an an
15、alysis and evaluation of the existing equipment design to determine if marginal stresses exist in circuit and com- ponent applications. If such stresses exist, recommended changes to alleviate these con- ditions shall be presented, 3.2.5 Reliability test propam. The follow- ing elements of the relia
16、bility test program shall be described: (a) Tests and examinations to be per- formed. (See 4.3.) (b) Failure criteria. (See 4.3.) (c) Frequency of performing inspec- (d) Debugging period. (See 4.6.) (e) Preventive maintenance schedules, when applicable. (See 4.7.) (f) Sampling plan to be utilized, w
17、hen applicable. (9) Temperature cycling conditions. (See 4.5.) (h) Vibration conditions. (See 4.5.) (i) On-off cycling conditions. (See 4.5.) (j) Input voltage conditions. (See 4.6.) (k) Data recording procedures. (See (1) Forms to be utilized. (See 4.4.) (m) Corrective action definitions. tions. 4.
18、4.) 3.3 Mean-Time-Between-Failures (MTBF) . 3.3.1 Preproduction phase. When this phase is specified, the contractor shall per- form reliability testing on preproduction quantities of equipment. The number of items to be tested and the number of hours of operating time (up-time) required shall be as
19、specified in the contract, Testing shall be in accordance with 4.9.1. 3.3.2 Pilot production phase. When this phase is specified, the contractor shall per- form reliability testing on pilot production quantities of equipment. 3.3.2.1 Procedure I, When procedure I is specified in the contract, the nu
20、mber of items to be tested and the number of hours of operating time required will be specified therein. After review of the pilot production report (3.4), the Government and the con- tractor will establish a contract MTBF for use when the Government invokes the quan- tity production phase of proced
21、ure I. The MTBF shall be derived as follows : 2 /-=, _ I_- . Licensed by Information Handling ServicesMIL-R.55231( EL) SUPPLEMENT 1 2rm - ports shall encompass the reliability tests specified in section 4 and shall describe the following : (a) L*C.L* = xX(1-c) (2r+2j where L.G.L. =lower confidence l
22、imit P =number of failures m =observed mean-time-between- failures X =Chi square value for 2r+2 de- grees of freedom (Chi square tables are included in most standard statistical textbooks.) C 0.90 (This is the 90 percent con- fidence level, and means that there is a 90 percent confidence that the tr
23、ue MTBF is at least equal to the L.C.L.) (b) The contract MTBF will be deter- mined by adding 50 percent to the L.C.L., in accordance with TG-3 principles. .- (a) Debugging period. (b) Sampling plan utilized, when ap- plicable. (c) Preventative maintenance sched- ules, when applicable, (d) Temperatu
24、re cycling conditions. (e) Vibration conditions. (f) On-off cycling conditions. (g) Input voltage conditions. (h) Data recording procedures. (i) Failure rules. (j) Corrective action definitions. (k) Forms utilized, and distribution of forms when failure occurs. (i) Failure distribution bar chart. (m
25、) Failure analysis and corrective ac- tion taken. (n) Component part failure rates. (o) Description of each .failure, analysis made and corrective action taken, (p) Censored failures described. (9) MTBF calculations, (r) Recommendations for reliability 3.3.2.2 Procedure II. When procedure IT is spec
26、ified in the contract, and the Govern- ment invokes the quantity production phase, the Government may review the pilot pro- duction test reports to insure that the de- tailed equipment design has the inherent capability of meeting the contract MTBF. improvement. 3.3.3 Quantity production phase. When
27、 the Government invokes the quantity produc- tion phase, the mean time between inde- pendent failures shall be not less than that derived in accordance with 3.3.2.1 (pro- cedure I) or not less than that specified in the individual equipment specification or the contract (procedure II) whichever is a
28、p- plicable. 3.4 Final test reports. Separate, final test reports, in accordance with the TG3 Report and this paragraph, shall be furnished by the contractor on the preproduction, the pilot-production, and the quantity-production reliability testing. All pages of these test reports shall be produced
29、 on full-size, direct- reading, positive-print, moist-process sepias, type II in accordance with Specification MILPP-9853, and shall be capable of making completely legible diazo copies. Original test data shall be copied photographically; tran- scribed data will not be acceptable. The re- 3.5 Perio
30、dic reports, pilot production. At regular intervals, the contractor shall fur- nish summary reports on the pilot-produc- tion reliability testing. These summary reports shall be produced in conformance to the process specified in 3.4, except that the data may be transcribed. These reports shall be f
31、urnished as required by the invitation for bids or request for proposal, in a format that is satisfactory to the Government, and shall include the following : (a) Accumulated up-time at end of the reporting period. (b) Pertinent failure data, including total up-time to the failure, analy- sis of the
32、 failure, and description of corrective action taken or to be taken. 4. QUALiTY ASSURANCE PROVISIONS Licensed by Information Handling Services_ - -_-I_- NIL-R-55231 NI - 977770b 0404505 b - MIL-R,-55231( EL) 4.1 Responsibility for inspection. Unless otherwise specified in the contract or pur- chase
33、order, the supplier is responsible for the performance of all inspection require- ments as specified herein. Except as other- wise specified, the supplier may utilize his own facilities or any commercial laboratory acceptable to the Government. The Govern- ment reserves the right to perform any of t
34、he inspections set forth in the specification where such inspections are deemed neces- sary to assure that supplies and services conform to prescribed requirements. 4.2 Classification of tests. Testing of the equipment for reliabiilty shall be classified as follows: (a) Preproduction reliability tes
35、ting. (b) Pilot-production reliability testing. (e) Quantity-production reliability test- ing. 4.3 Measurements. Measurements during reliability testing, and criteria of satisfactory performance, shall be as described in the in- dividual equipment specification or the con- tract. Reliability testing
36、 shall be entirely separate from preproduction evaluation and from quality-conformance inspection of sup- plies for Government acceptance. 4.4 Data handling. The contractor shall collect data in accordance with the provi- sions of The TG-3 Report, for inclusion in the test reports specified by 3.4.
37、4.5 Environmental and stress conditions. Environmental and stress conditions during reliability testing shall be in accordance with The TG-3 Report and as specified in the individual equipment specification or the con- tract. 4.6 Debugging. In order to exclude the early failure period, each item sub
38、jected to reliability testing shall first have been sub- jected to a suitable run-in period which is satisfactory to the authorized representative of the contracting officer. 4.7 Preventive maintenance and repair. _- No preventive maintenance shall be per- formed during reliability testing except th
39、at scheduled before initiation of the testing. The schedule shall be subject to approval by the authorized representative of the contract- ing officer. In addition, no adjustment or re- pair shall be made on a test item except that necessary to enable a failed item to meet the measurements specified
40、 during reliability testing ; however, except as otherwise speci- fied, adjustment of operator controls shall be permitted at any time. 4.8 Related inspection. Items used for re- liability testing shall first undergo and pass the normal, short-time inspection (usually called “Group A”) cited in the
41、individual equipment specification, as well as any other inspection required by that specification to be performed in connection with the relia- bility testing. Such inspection shall be re- peated after completion of reliability testing, before the test items are offered for accept- ance on contract
42、. 4.9 Reliability testing. Reliability testing shall be performed in accordance with The TG3 Report and as follows : 4.9.1 Preproduction relhbility testing. When preproduction reliability testing is specified, it shall be performed concurrently with other preproduction testing on addi- tional items
43、as specified in the contract. 4.9.1.1 Procedure I. When procedure I is specified, the contractor shall conduct in- formatory testing for the number of oper- ating hours specified in the contract. 4.9.1.2 Procedure II. When procedure II is specified, preproduction reliability testing shall continue u
44、ntil pilot production testing for reliability is initiated or decision is reached, whichever occurs first. If the test ends in a reject decision, necessary correc- tions shall be made in all the items on pre- production reliability test and the test shall be started over again. No other modifica- ti
45、ons shall be made except as agreed to by the authorized representative of the contract- ing officer. Licensed by Information Handling Services4.9.2 Plot-prodzcctioIt reliability testing. When the pilot production phase is specified, the procedure shall be as described in this paragraph. The test ite
46、ms shall be in addition to those used for pilot-production quality- conformance inspection. Pilot-production re- liability testing shal be initiated as soon as pilot production items become available. If any test item is modified during this test, al1 remaining items in the test group shall be modif
47、ied at the same time, to incorporate the change. The nature of the modification shall be evaluated by the contractor and the authorized representative of the contracting officer, and agreement reached as to whether or not the modification has invalidated data already generated during the pilot-produ
48、c- tion reliability test. If it is determined that the data have been invalidated, the con- tractor shall return to time zero and start the pilot-production reliability test over again. 4.9.2.1 PTocedure I. When procedure I is specified, the number of items to be sub- jected to reliability testing a
49、nd the total operating time (“up”-time) shall be as speci- fied in the contract. 4.9.2.2 PTocedwe II. When procedure II is specified, the contractor shall test a suffi- cient number of items from pilot production to complete the pilot-production reliability testing within the time schedule cited in the contract. (Table 2 of The TG-3 Report shows the maximum operating time required for a decision.) Test schedules shall allow for time when the test items are not in operation (cooling time, repair time, etc.) 4.9.3 Qzutntity-p.i.oduction Teltbility test- hg. Whe
