Model 7704M7 vibration sensors
San Juan Capistrano, CA
On August 8, 2007, three Space Shuttle Main Engines (SSMEs) from Pratt & Whitney Rocketdyne lifted the space shuttle Endeavor into orbit and on its way to the International Space Station. The three SSMEs were fitted with Advanced Health Management (AHMS) controllers, using Endevco Model 7704M7 vibration sensors, to actively monitor engine health and performance.
The new AHMS controllers monitor engine turbopump vibration and, if conditions warrant, they can automatically shut down an engine. This was the first mission in which all three controllers were in active mode. If unacceptable vibration levels were detected during the eight-and-a-half-minute firing of the engines during launch, the controllers were enabled to prompt action. The AHMS controllers can also track a history of key performance parameters.
The Model 7704M7 Series Isoshear® piezoelectric accelerometers used in the AHMS controllers are designed to be extremely stable and insensitive to environmental inputs such as base bending and thermal transients. The series has been tested in a radiation environment up to 108 rads without performance degradation. Also featured in the series is Endevco’s Piezite® Type P-8 crystal element, operating in shear mode. The self-generating accel-erometers require no external power source for operation.