What was found
(WO 16155440) DURING CLIMB AT FL 250, THE CAB ALT BEGAN TO RISE RAPIDLY,A RAPID DESCENT WAS STARTED TO FL 150. CAB ALTITUD DID NOT REACHED 14000 FT. THE VENT EXTRACT VALVE WAS FULL OPEN. THE MEL CREW OPERATIONAL PROCEDURE WAS ACCOMPLISHED ACCORDING TO THE MANUAL. IN ACCORDANCE WITH AMM 21-26-57-000-801-A REMOVE OF THE OVERBOARD EXTRACT VALVE WAS PERFORMED AS PER AMM 21-26-57-400-801-A OVERBOARD EXTRACT VALVE WAS INSTALLED, OPERATIONAL TEST OF THE AVIONICS WAS PERFORMED SATISFACTORY. NOTE: FOR COMPONENTS INFO SEE WO 16155422. IAW TSM 21-23-00-810-813-A STEP 4.A.2 AND AMM 21-26-57-000-801/21-26-34-400-001 THE AEVC WAS REMOVED AND REPLACED. DFDR AND CVR WERE REMOVED FOR READING. DFDR AND CVR WERE INSTALLED IN ACCORDANCE WITH AMM 31-33-55-400-801-A AND AMM 23-71-35-400-001-A OPERATIONAL TEST SATISFACTORY. IN ACCORDANCE WITH AMM:05-53-00-780-803-A01 THE PRESSURIZATION RETEST AND LEAKAGE RATE MEASUREMENT (WITH ACMS) WAS PERFORMED SATISFACTORY.