N456CL
Operators of this aircraft
Who operated this tail, and how firmly we know it.
No operator established for this aircraft.
Accident & incident history
No NTSB accidents or incidents on file for this aircraft.
Maintenance disclosures
ACFT DEPARTED, EN ROUTE THE FL180 CHECKS WERE COMPLETED, ALL NORMAL. AT FL340, THE CREW NOTICED THE CABIN WAS AT 8,000 FEET AND CLIMBING. TURNED THE CABIN PRESSURE CONTROL TO MANUAL AND TRIED TO DRIVE THE CABIN DOWN, WITH NO SUCCESS. THE CABIN CLIMBED TO 9,000 FEET AND THE LT EMERGENCY PRESSURIZATION VALVE OPENED AS IT SHOULD. THEY DESCENDED, THE EMERGENCY PRESSURIZATION RESET AFTER THE CABIN DESCENDED. MX INVESTIGATED THE ISSUE, AND FOUND THAT THE PRESSURE REGULATOR THAT SUPPLIES THE FLOW CONTROL VALVE, IT`S REF PRESSURE WAS NOT REGULATING THE PRESSURE CORRECTLY. THE PRESSURE IS SUPPOSED TO 15 PSI +-2, BUT WENT AS HIGH AS 28 PSI DURING GROUND RUNS. THE HIGHER THE REF, THE MORE THE FLOW CONTROL VALVE DRIVES TO CLOSED, STARVING THE CABIN OF INFLOW. NO RECOMMENDATION OR PREVENTION.
AFTER LEVEL OFF, HEARD A BANG, NOTICED AC STARTED TO DUTCH ROLL AND AP DISCONNECTED. INITIATED EMER DESCENT AND AC FLIGHT STABILIZED. NOTICED AFCS YAW CIRCUIT BREAKER WAS POPPED AND PRI AND SEC YAW DAMPER WAS INOPERATIVE, CREW ELECTED TO NOT RESET THE CIRCUIT BREAKER, SO AS NOT TO INDUCE FURTHER COMPLICATIONS, RETURN TO DEPARTURE. MX REPRODUCED DISCREPANCIES. FOUND 3 BROKEN OR PARTIALLY BROKEN WIRES AT THE PRI YAW DAMPER COMPUTER CONNECTOR NR AP200. THE CAUSE OF THE BROKEN WIRES IS DUE TO AGING ACFT ISSUES. LACK OF STRAIN ON THE PRIMARY YAW DAMPER CONNECTOR FROM ORIGINAL PRODUCTION ALLOWING WIRES TO BE FLEXED CAUSING WORK HARDENING AND SUBSEQUENT BREAKAGE.