What was found
SAP - FLT 220 - DURING CLIMB, LEFT AND RIGHT MLG DID NOT SECURE IN UPLOCK POSITION. THE AIRCRAFT RETURNED TO SAP FOR MX. A FERRY FLT PERMIT WAS GRANTED. AFTER LANDING AT EL SALVADOR, MX TECHS PERFORMED RETRACTION AND EXTENSION OF THE LANDING GEARS AS PER AMM 32-32. FOUND INCORRECT OPERATION OF THE SELECTOR VALVE. THE UNIT WAS REPLACED AND TESTED AS PER AMM 32-31-51. ALSO, THE FILTER ELEMENTS OF THE MODULAR PACKAGES 'A' AND 'B' WERE REPLACED AS PER AMM 29-11-71 AND AMM 29-12-41. LANDING GEARS RETRACTION AND EXTENSION WERE PERFORMED ON GROUND AS PER AMM 32-32. NORMAL RESULTS WERE OBSERVED. TEST FLIGHT WAS PERFORMED. THE LANDING GEAR RETRACTION AND EXTENSION SYSTEM SHOWED NORMAL. THE AIRCRAFT RETURNED T