What was found
EXPERIENCED LOSS OF PRESSURIZATION DURING DESCENT INTO KPHX. DESCENDING THROUGH FL270 VIA THE EAGUL6 ARRIVAL A CABIN ALT WARNING OCCURRED. OXYGEN MASKS WERE DONNED AND CHECKLIST WAS ACCOMPLISHED. PRESSURIZATION WAS REGAINED AND FLIGHT RESUMED NORMALLY. NO OTHER ACTION WAS REQUIRED. THE PRESSURIZATION AUTO CONTROLLER WAS SET ON AUTO 2 WHEN LOSS OF PRESSURIZATION OCCURRED. AUTOMATIC SWITCHOVER TO AUTO 1 DID NOT OCCUR. CABIN ALT AUTO 2 WAS DISPLAYED IN STATUS MESSAGE. AIRCRAFT LANDED WITH OUT FURTHER INCIDENT. MAINTENANCE GROUNDED AIRCRAFT. MAINTENANCE PERFORMED BITE TEST OF AUTOMATIC CABIN PRESSURE CONTROLLERS IAW B767 AMM 21-31-00 NO FAULTS FOUND. AIRCRAFT RETURNED TO SERVICE.