Downloaded from https://www.everyspec.com AMCP 706-0N , must be established by careful analysis of great detail and with extensive use of hook- drift data, but it usually can be set initially to up diagrams, They should include data correspond with the shortest recallbration sheets that require recording both the as- interval of any standatl equipment installed received and as-adjusted readings, and the in the system.' Detailed procedures, in- Instrumont errors.
The as-received readings cluding before and after data sheets, are are essential to permit studies of drift rates esential to calibrate tach equipment prop- for the purpose of adjusting recalibratlon erly, Audit responsibilities should be aw- periods to suit individual usage conditions signed to an unbiased Inspection group to en- and specific drift factors. Calibration pro- sure that the procedures are meticulously cedurea- prepared by instrument manufac- followed. turers are not always detailed enough and must frequently be rewritten. Standards can be calibrated in two ways:
(1) by cross-checking of like standards held 9.0 TEST EQUIPMENT RUGGEQIZATION by a laboratory, and (2) by comparison of the standard with a standard of higher ac- Test equipment must be ruggedized to curacy traceable to a comparison with a minimize the loss of accuracy In laboratory standard held by the National Bureau of or field use, Measurements made with"in- Standards. Cross-checking is relatively easy adequately ruggedized test equipment may and inexpensive, and its use roducei the fre- introduce errors in the test data. In addition, quency with wlhch the standards must be the inadequate test equipment may be in- referred to a higher-accuracy standard:.
capable of performing continuously and Certification of standards is a comamon consistently, thus destroyinp the effective- practice.
Inspection departments should be ness o1' the test program, Therefore, it is glwrii the responitbility of auditing all the important that considerable attention is standards in the chain from the local-ievel paid to ruggedizing the test equipment, When standard bick to NBS to ernsure that floor test equipment is ruggedized at a point in the measurements are within the specified ac- program after some tests have been run, curacy, great care must be taken that the new equip- ment does not Introduce undetected changes Detailed calibration procedures for both into the system, A convenient check on commercial standard measuring eqtipment this problem can be made by making corn- and special test equipment must be pre- patibility runs and testing the same hard- pared and used.
Calibration usually is per- ware on both the old and the new test equip- formed by highly skilled technicians who ment arid carefully comparing the results may believe that they can dispense with before the new test equipment is released for written instructions because tfiey know all production use, tre steps.
The errors and mistakes which re- sult rrom this overconfidence are frequently To minimize the ruggedizing cost, the catastrophic, particularly since other project reliabilitr group should review the initial personnel assume that the calibrations have R&D test equipment designs to ena'ure that been properly performed, as much MIL-Spec quality material as pos- sible is specified and that the original Auditing responsibilities should be as- drawings are as detailed and complete as signed to a "disinterested" group to ensure possible. Although this approach will in- that detailed procedures are prepared and crease the cost of the R&D test equipment, followed by calibration laburatory personnel.
it will result in considerable net savings to These procedures should be prepared in the project by reducing the amount of re- . . .