What was found
PASSING 10K ACFT FAILED TO PRESSURISE, CABIN ALT INDICATES NEGATIVE IAW DEBRIEF OF CREW. CREW FLEW UP TO 11,700 FT & STATED THAT THEY NEVER GOT A POSITIVE CABIN ALTITUDE, ALWAYS NEGATIVE. THE LARGE NEEDLE INDICATED 3, WHILE SMALL NEEDLE INDICATED NEGATIVE, BTWN 50 & ZERO PSI. PERFORMED BITE OF CABIN PRESSURE CONTROLLER, NO FAULTS DISPLAYED IAW AMM 21-31-00. PRESSURISATION PANEL WAS LEFT IN AUTO AT ALL TIMES. CREW NEVER GOT AN AUTO FAIL LIGHT. SINCE THE FLIGHT ALTITUDE WAS A LITTLE OVER 10,000 FT, IAW 21-00 TASK 807 SUSPECTED LAND ALTITUDE MAY BE INCORRECTLY SET BELOW DEPARTURE FIELD ELEVATION, PRESSURIZED CABIN IAW AMM 05-51-91 TO 4 PSI, FOUND BOTTOM OF R1 FLAP SEAL LEAKING, WHICH IS NOTICABLE FROM INSIDE. BELOW 15,000 FT IS NORMAL TO SHOW 0 PSI CABIN PRESSURE IAW SDS 21-30-00-109. SEE REF. FOR R1 DOOR LEAK LOG PAGE 3453645