NIST FORCE CALIBRATIONS ENSURE PROPER OPERATION OF AIRCRAFT ENGINES

摘要

The NIST Force Metrology Laboratory completed calibration of a secondary standard load cell system consisting of a 222.4 kN (50.000 lbf) capacity load cell and a dedicated indicator for Rolls Royce Canada Limited of Quebec, Canada. Rolls Royce Canada performs numerous jet engine thrust measurements for worldwide I customers to verify the proper operation of the engine under test following "overhaul or repair/The company provides service for more than 123 different types of engines powering commercial and military aircrafts around the world. The load cell system calibrated at NIST serves as the "master" used to calibrate two other "working" load cell systems that are installed in one of two jet engine test stands in their laboratory. This test stand will service engines in the maximum thrust capacity range of 311 kN (70,000 lbf), which, typically, are found on a Boeing 747 type of aircraft. To accommodate seasonal weather changes in Canada, the Rolls Royce procedure is to heat the load cells within the test stands by use of a heating blanket wrap around the load cell. The load cells are maintained at 35 degrees Celsius while in use and during calibration in the NIST force deadweight machine. The uniqueness of using this blanket while in use in the test stand helps to minimize any thermal gradients within the load cell that would affect the Rolls Royce specification of ensuring 0.25 percent repeatability for the overall system.