ADS-79D-HDBK Downloaded from https://www.everyspec.com should be designed to simulate on-aircraft operating conditions so fault progression and condition indication tracking can proceed as it would in a normal environment. However, at times it may be necessary to exceed normal component operating conditions to achieve a reasonable time limit on the experiment. It is important, though, that test conditions do not specify operation outside of the test fixture safety limits. SFT design should not call for exceeding test stand operating thresholds which expose equipment or personnel to a safety risk.
Also, if possible, automated monitoring equipment should be designed into the test fixture to maintain continuous, real-time observation and monitoring of not only the condition indicators but damage progression in the test specimen. During the course of test stand development, a progressive review process should be used to ensure the testing agency will be able to meet the goals and objectives of the test. These progressive reviews the US Army uses are Preliminary Design Review (PDR), Critical Design Review (CDR), and Test Readiness Review (TRR). Through these progressive reviews all stakeholders are involved and provide approval at predetermined developmental criteria. b.
Physics of failure model – A complete SFT analysis would include development of a physics of failure model. This would include the use of the best available modeling and analytical tools to predict fault initiation, fault growth, and component failure under specified test conditions. A rigorous mathematical characterization of the experiment also enables a complete post-test analysis of all observable fault symptoms. In addition, the modeling effort could help explain any unexpected, observed failure phenomenon encountered during the test. c. Test plan preparations / review / approval – The SFT Plan should be written using Data Item Description DI-NDTI-80566A as a guide.
To synopsize, the SFT Plan should clearly identify the: (1) Test Stand & Component configurations, (2) Calibration requirements (3) Baseline measurements, (4) Fault(s) under test, (5) Condition Indicators being evaluated, (6) Data Format/Requirements, (7) Component Failure Modes, (8) Intended Testing Milestones, (9) Government & Contractor Participation Roles, (10) Test Facilities/Locations, (11) Anticipated Schedule, (12) Safety & Security Guidelines & Responsibilities, (13) Number of Cycles, (14) Success/Failure Criteria and(15) Reporting Requirements/Responsibilities.
The test plan should incorporate all stakeholder inputs as to ensure the most comprehensive plan that meet the testing goals and objectives. The overall SFT Plan should be reviewed by associated CBM peers prior to execution. This review should confirm the faulted condition(s) to be induced in the part, the manner in which the fault(s) is generated in the laboratory, and the condition(s) the faulted component will operate under. Therefore, the review should cover both the selected test specimen and the configured test fixture as well as any conducted pre-test analysis, such as physics of failure. d.
Pre-test inspections – Both the test specimen part and the test fixture should be carefully inspected prior to test start. It should be confirmed that the test part is of acceptable quality and that the controlled deformity is the only compromise to integrity so that the part will either produce anticipated results, or fail as expected in the test. Also, a final inspection of the test fixture should be performed to ensure it will operate properly over the entirety of the test and impose the controlled stress needed to induce the expected fault and monitor fault progression/component failure. The US Army uses a review called a Test Stand Verification (TSV).
The purpose of the TSV is to document and review the items required to verify the 180