ARNOLD AIR FORCE BASE, Tenn. -- Members of the Enterprise Data System team at Arnold Air Force Base implemented a proactive maintenance action to prevent a calibration interval dropping to under six months for digital temperature scanners (DTS), thus preventing an estimated cost of $96,000 in additional man hours for AEDC.
According to Randy Prince, an instrumentation, data and controls engineering tech at Arnold AFB, mitigating this calibration interval change was essential in maintaining current test operations.
“If the calibration interval had changed from the current six months interval down to three months, it would’ve had an extensive impact on test support availability and maintainability, which would adversely impact the AEDC Data Acquisition System’s temperature measurements,” he said.
Prince explained what calibration is and why it’s important at Arnold AFB.
“Calibration is a maintenance action that is required to ensure instrumentation supporting Air Force systems is accurate and can reliably perform its mission,” he said. “Every measurement application at Arnold AFB and across the globe requires some type of accurate and reliable measurement to support research, development, test and evaluation (RDT&E).
“The only way to validate that instrumentation is accurate and reliable is to compare it to an instrument of a known value and even greater accuracy commonly referred to as a measurement standard. The Air Force measurement traceability chain begins with the National Institute of Standards and Technology (NIST). NIST transfers measurements to the Air Force Primary Standards Laboratory which in turn transfers measurements to the Precision Measurement Equipment Laboratory at Arnold.”
These measurements are later transferred to the rest of Team AEDC to support RDT&E.
Prince noted that the instrumentation for developmental test and evaluation is required to provide accurate, reliable and traceable measurements.
“Consider you are flying on a commercial plane,” he said. “The altimeter is not calibrated and you are getting ready to land at Nashville in dense fog. The altitude of the Nashville International airport is 600 feet. The pilot is using his altimeter to land the plane but the plane crashes. A review of the crash reveals the altimeter at 600 feet was actually reading 1,000 feet. The plane crashed because the instrumentation used to make critical decisions was not properly maintained.
“Without calibration maintenance, AEDC could not meet its mission statement and would be putting our warfighters in harm’s way and our nation at risk.”
Maintenance data is collected on each instrument that is supported by the Arnold AFB PMEL. Prince mentioned the maintenance data history for the DTSs resulted in a degradation in the calibration interval required to maintain the manufacturer’s stated accuracy requirement.
“Once the calibration interval reached six months, concerns were voiced by Team AEDC, including the Test and Communications Branch, the Test Operations and Sustainment (TOS) contractor, Technical and Management Advisory Services (TMAS) and PMEL. Their concerns were regarding the potential availability and maintainability of the DTSs to support temperature testing at Arnold.”
Under the direction of David Rollins, Carl Shetters and Jensie Castleman with the Enterprise Data System Item Management group, ID&C engineer Scott Howard, and AEDC Data System architect Mike Bennett, with oversight from Bill Bridges, Air Force project manager of the AEDC Test and Communications Branch, a plan was developed.
“Together, we implemented a proactive maintenance action to evaluate what would be required to mitigate the calibration interval from dropping to under six months for the DTSs,” Prince said. “I saw two options – staff up to support the DTSs to maintain the current accuracy requirements or re-evaluate the accuracy requirements.”
He added that when looking at options, he knew that maintaining the current accuracy requirements would be extremely expensive.
“After evaluating calibration data for every DTS in inventory at Arnold, I determined an accuracy from reviewing the last year of calibration data that would allow the DTS to maintain a 12-month calibration interval,” he said. “I then coordinated with the Test and Communications Branch, TMAS, and TOS Engineering for each of the AEDC Combined Test Forces to determine if this revised DTS accuracy would be sufficient to meet their individual testing requirements.”
Bridges provided final approval on taking this approach, and Prince then coordinated with the engineering staff at Air Force Metrology and Calibration Program and Greg Earp, PMEL manager, and his team to implement the calibration interval mitigation.
Prince mentioned that with approximately 200 DTSs in inventory having a six-month calibration interval, it takes an estimated 1,600 man hours to perform the two calibrations a year.
“If the DTSs required four calibrations a year, this would jump to 3,200 man hours, which doubles the cost of the requirement,” he said. “So, not only did we prevent the cost from doubling, but also prevented testing downtime and the coordination efforts that would have otherwise been required to keep the test cells operational and ready for testing.
“Our long term goal is to get the DTSs back on a 12-month calibration interval based on the updated temperature accuracy requirements and implementation of those requirements. If the historical data holds true, the DTSs this time next year could be at a 12-month interval resulting in an estimated cost avoidance of $144,000.”
Prince added that this accomplishment shows the true team-oriented nature of AEDC.
“I am always humbled when I look around at all the individuals that support our mission at AEDC,” he said. “Integrity, service before self, and excellence in all we do is the first thing that comes to mind when I look around at the amazing team I am privileged to work with. We are all gifted with different talents… Everything we do is a team effort and I’m very proud to be a member of Team AEDC.”
Bridges, who oversaw the calibration interval mitigation effort, also noted how all groups were able to come together to determine a solution.
"The teamwork and communication exhibited by all parties in this effort has been exemplary in resolving this critical issue that was threatening to impact AEDC's test mission,” he said. “They did not simply roll over and accept the shrinking interval for the calibration of the aging Digital Temperature Scanners, and they put forth the extra effort. Randy Prince and the team took immediate action and interfaced with the proper offices and gained the appropriate approvals, allowing AEDC to continue testing with minimal impact. This was a true application of Operational Risk Management and demonstrated how organizational cooperation (between AEDC, PMEL, TOS, & AFMETCAL) can, and should, occur for the benefit of the greater good."