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Show MES MEASURING up, MAY 20 On National Metrology Day don't look to the skies, the 'stars' are in the measurements "PMEL is the one, single foundational element of each and every item produced at the Ogden Air Logistics Center. No item leaves this center that PMEL hasn't touched in some way, either directly or indirectly." 'Metrology' — what is it? Metrology is the science of weights and measures, according to Webster's New World College Dictionary. Metrology is the science that deals with measurements or a system of measurement, according to the American Heritage Dictionary. 5257A TRANSFER OSCILLATOR HEWLETT - PAC (CARD FREQUENCY MHz RANGE GHz MODE .05 - .2 .2 - 1 PULSED RF TRANSFER STANDARD NO. APC LEVEL AD) 9 May 19, 2011 1 1-4 4-18 — Don Hallford, 527th Equipment Maintenance Squadron director INPUT .05-18 GHZ 1 2 CAUTION +10 dBm MAX Hill Air Force Base Precision Measurement Equipment Lab w orld Metrology Day celebrates the signature by representatives of seventeen nations of The Metre Convention on May 20, 1875. The convention set the framework for global collaboration in the science of measurement and in its industrial, commercial and societal application. The original aim of the Metre Convention — the worldwide uniformity of measurement — remains as important today, in 2011, as it was in 1875. World Metrology Day has become an established annual event during which more than eighty countries celebrate the impact of measurement on our daily lives, no part of which is untouched by this essential, and largely hidden, aspect of modern society. WITH 100:1 DIVIDER mV dBm 3000 +20 1000 +10 300 100 - 10 30 -20 -30 R MODEL 92A-52 TRANSFER STANDARD NO. -40 PROBE 1 PWR 100 -50 U I Standard-Examiner graphics Precision in the process BY STEVE CRAGO HILL AFB PMEL F rom a technician's viewpoint, calibration involves three main parts: research, calibration and certification. Research is the detailed study of a subject, and in this case, the subject is the equipment to be calibrated. Technicians research a variety of items prior to each calibration such as fuse data, operational procedures, technical orders, commercial publications, engineering drawings, software, and specifications. Hill Air Force Base has many one-of-a-kind items, and some are 40 or more years old so finding detailed information can be daunting. A 33-point checklist is used as a guide, and technicians must be diligent in tracking down information. This often requires consulting with manufacturers and engineers. The precision demanded by today's aerospace equipment requires the use of the best standards available. As a rule, PMEL equipment standards must have an accuracy that is four times better than the equipment being calibrated, and technicians use indepth math to prove accuracy. The standards must also meet traceability requirements. This means the accuracy of PMEL's own standards must be traceable back to NIST (our highest national standard) through a chain of unbroken measurements. So even though you may not immediately see technicians at your work site for a given calibration, rest assured that they are working behind the scenes to ensure they know as much as possible about your equipment before they calibrate it. After the initial research is complete, technicians can finally start the hands-on portion of calibration. First, a FOD and safety See TECHNICIAN I page 13 527th Electronic Maintenance Squadron/PMEL The 527th Electronic Maintenance Squadron (EMXS) is the Precision Measurement Equipment Laboratory (PMEL) for the Ogden Air Logistics Center (OO-ALC). The 527th EMXS PMEL is comprised of three distinct functional areas. They are the Organic Lab, the Type IIA Lab, and the Resource Support Flight. The Organic Lab provides on-site calibration for test stations used for intermediate and final functional testing of assets. The Organic Lab performs calibrations on all on-site non-portable Test Measurement and Diagnostic Equipment (TMDE). This lab also supports peculiar TMDE in the following catego- ries: • Proprietary TMDE • One of a kind TMDE that differs significantly from common TMDE in length of calibration, difficulty of calibration or requiring special training • Commercial off-the-shelf TMDE no longer commercially supported that must be maintained due to its use in a production line or other direct core support • Equipment critical to a one of a kind test stand or production line • Equipment imbedded in test stands that is time prohibitive to remove for submission to the See PMEL I page 10 — A Of Royal Cubit Masters, pharoah's forearms and Air Force missile failures ON BOONTONIII ELECTRONICS CQiiPQRATIQIV Air Force and the use of metrology Metrology is the science of measurement. Metrology is required to ensure that Air Force systems are accurate and can reliably perform their designated missions. Every system in the Air Force inventory requires some type of accurate and reliable measurement to be made in development or operation. For example, when landing a plane, the pilot counts on the Instrument Landing System to tell him if he's centered on the runway and making his approach at the proper angle. A laser-guided bomb requires both the target designator and the guidance sensor on the bomb to operate at the proper wavelength and at correct power levels for the successful munitions delivery. Finally, the weight of aircraft must be known to ensure that they are not overloaded and that they have the proper amount of fuel for safe flights. The accuracy and reliability of all of these systems can be directly traced to measurements made at the Air Force Primary Standards Laboratory (AFPSL) and/or the National Institute of Standards and Technology (NIST). One element of metrology is calibration. Calibration is the comparison of an instrument of unconfirmed accuracy to another instrument of known and even greater accuracy. The instrument of unconfirmed accuracy is referred to as the unit under test and the instrument of known accuracy is known as a measurement standard. Calibrations are performed to ensure Air Force instruments are accurate enough to meet the performance requirements of Air Force systems. Instruments requiring calibration range from weighing scales and tire pressure gauges to laser targeting devices and complex communication systems. One squadron at Hill Air Force Base is tasked with the calibration responsibility. FULL SCAL RF MILLIVOLTMETER Hill Air Force Base PMEL T he desire for a fair and honest system of weights and measures has been around for thousands of years. The Egyptians studied the science of geometry and understood the importance of weights and measurements. They used a cubit to construct the pyramids. The "Royal Egyptian Cubit" was decreed to be equal to the length of the forearm from the bent elbow to the tip of the extended middle finger plus the width of the palm of the hand of the pharaoh ruling at the time. The "Royal Cubit Master" was carved out of a block of granite to endure for all times. Workers engaged in building tombs, temples and pyramids were supplied with cubits made of wood or granite. The royal architect or foreman of the construction site was responsible for maintaining and transferring the unit of length to workers' instruments. They were required to bring back their cubit at each full moon to be compared to the Royal Cubit Master. Failure to do so was punishable by death. Although the punishment was severe, the Egyptians had anticipated the spirit of the present day system of legal metrology, standards, traceability and calibration recall. With this standardization and uniformity of length, they achieved a surprising accuracy of 0.05 percent. In roughly 756 feet they were within 4.5 inches. We have a difficult time achieving that accuracy today. Metrology has been around throughout history. The Romans used metrology and even Moses mentioned weights and measures. See HISTORY I page 13 3 |