What was found
(CAN) AIRCRAFT LOST CABIN PRESSURE WHILE IN CRUISE AT FL 210. PILOT DESCENDED AND RETURNED TO BASE. MAINTENANCE DISCOVERED AIR DISTRIBUTION TUBE (P/N 46504-00) AND HOSE (P/N 49990-06) CONNECTION HAD COME APART. FURTHER INVESTIGATION DETERMINED THE WRONG SIZE STRAP HAD BEEN INSTALLED UNDER THE CLAMP THAT SECURES THE HOSE/TUBE CONNECTION. THE SUSPECT STRAP IS USED ON THE PARALLEL TUBE ADJACENT TO THE FAILED CONNECTION. THIS PARALLEL TUBE HAD ONE INCORRECT STRAP INSTALLED AS WELL. STRAPS SWITCHED TO PROPER TUBE/HOSE ASSEMBLIES AND TIGHTENED. NOTE: CAUTION WHEN REMOVING BOTH TUBES AT SAME TIME TO PREVENT INCORRECT STRAP INSTALLATION.