TS Equipment Calibration & Maintenance 3 — Questions and Answers
Question 1: What is the meaning of 'traceability' in the context of calibration?
- The ability to locate equipment in a facility
- An unbroken chain of comparisons linking measurements to national or international standards (Correct answer)
- Tracking who last used a piece of equipment
- A record of all maintenance performed
Correct answer: An unbroken chain of comparisons linking measurements to national or international standards
Metrological traceability means each calibration is linked through an unbroken chain of comparisons to a recognized national metrology institute such as NIST.
Question 2: A torque wrench calibration shows it over-reads by 3% at all tested values. This type of error is best described as:
- Random error
- Systematic error (Correct answer)
- Resolution error
- Hysteresis error
Correct answer: Systematic error
A consistent offset across all values indicates a systematic error, which can often be corrected with an adjustment or correction factor.
Question 3: In preventive maintenance, the term 'MTBF' stands for:
- Mean Time Between Failures (Correct answer)
- Minimum Test Bench Frequency
- Measured Tolerance Baseline Factor
- Maximum Time Before Fixing
Correct answer: Mean Time Between Failures
Mean Time Between Failures (MTBF) is a reliability metric representing the average time a repairable system operates between failures.
Question 4: Which standard governs the general requirements for the competence of testing and calibration laboratories?
- ISO 9001
- ISO/IEC 17025 (Correct answer)
- MIL-STD-45662
- ANSI Z540
Correct answer: ISO/IEC 17025
ISO/IEC 17025 is the international standard specifying requirements for competence, impartiality, and consistent operation of calibration and testing laboratories.
Question 5: During a calibration of an oscilloscope, the technician notices the 1kHz timebase reading is consistently 2% fast. The best corrective action is to:
- Replace the oscilloscope immediately
- Apply a correction factor to all future measurements
- Adjust the internal timebase reference and verify (Correct answer)
- Increase the calibration interval to monitor the trend
Correct answer: Adjust the internal timebase reference and verify
A consistent systematic error in a timebase can typically be corrected by adjusting the internal reference and then verifying the correction with the standard.
Question 6: What is the recommended minimum accuracy ratio (Test Accuracy Ratio) for a calibration standard relative to the unit under test?
- 1:1
- 2:1
- 4:1 (Correct answer)
- 10:1
Correct answer: 4:1
A 4:1 Test Accuracy Ratio (TAR) is the widely accepted minimum, meaning the reference standard should be at least four times more accurate than the instrument being calibrated.
Question 7: Which maintenance approach schedules service based on actual condition indicators rather than fixed time intervals?
- Corrective maintenance
- Preventive maintenance
- Predictive (condition-based) maintenance (Correct answer)
- Scheduled overhaul maintenance
Correct answer: Predictive (condition-based) maintenance
Predictive or condition-based maintenance uses real-time data (vibration, temperature, performance trends) to trigger service only when indicators suggest impending failure.
TS Equipment Calibration & Maintenance 3
What is the meaning of 'traceability' in the context of calibration?