What was found
BETWEEN 9,000 AND 11,000 FT EXPERIENCED FOUR SEPARATE INCIDENCES OF CABIN PRESSURE RELEASE. CABIN ALTITUDE INDICATOR SPIKED TO GREATER THAN 2,000 FPM CLIMB. RETURNED TO SLC. CHECKED AUTO PRESSURIZATION USING TEST EQUIPMENT. ALL FUNCTIONS CHECKED NORMAL. ALSO MANUAL PRESSURIZATION CHECKS GOOD. UNABLE TO DUPLICATE CONDITIONS ON GROUND.