What was found
AIRCRAFT RETURNED FROM FLIGHT WITH CABIN BLOWER OPERATING BUT NOT MOVING ANY AIR. GAINED ACCESS TO BLOWER ASSEMBLY UNDER CO-PILOT FLOOR. FOUND ALL FAN BLADES TO BE BROKEN OFF. THIS IS THE SECOND TIME THIS HAS HAPPENED IN LESS THAN TWO MONTHS. CHECKED MOTOR FOR SECURITY AND LOOSENESS, CHECKED GOOD. CHECKED FAN HUB FOR SECURITY AND LOOSENESS ON MOTOR SHAFT AND FOUND THAT IT WAS TIGHT. INSTALLING TECHNICIAN SAID THAT HE SPECIFICALLY CHECKED FOR BLADE CLEARANCE AROUND HOUSING WHEN THIS FAN WAS INSTALLED AND IT WAS FINE. HIGHLY SUSPECT DEFECTIVE FAN BLADE AT MANUFACTURE. RECOVERED ALL BROKEN BLADES AND INSPECTED. FOUND ONE WITH WHAT APPEARED TO BE A CLEAN BREAK AT BASE. SUSPECT THAT ONE DEFECTIVE BLADE BRO