The pilots of a Cessna Citation CJ2+ on the last leg of an international ferry flight on April 29 from Zurich, Switzerland, to Harrisburg, Pa., initially experienced a single engine control system fault on the number-two Williams FJ44 turbofan as they were descending through 15,000 feet. The 2009 CJ was being vectored for an ILS approach to Harrisburg International Airport (MDT), where the cloud base was about 500 feet.

The PIC, Eric Norber of ELJ Aviation, told AIN the indication meant one of the Fadec channels had failed and the unit had switched to a backup. At this point, the CJ was approximately 50 nm from Harrisburg. After running the appropriate checklists and being unable to bring the faulty Fadec back online, Norber, who is a designated pilot examiner in the Hawker 125 series, elected to continue the approach to MDT rather than divert to another airport.

As the aircraft was approaching minimums in the bumpy, ice-laden clouds, the second Fadec apparently failed and “the right engine shut itself down,” Norber said. The aircraft broke out of the clouds at about the same time and Norber continued to a safe touchdown at Harrisburg.

The engine data was uploaded to Williams, and the faults clearly appeared in the time line, although the engine manufacturer has no idea yet what caused the uncommanded engine shutdown.

According to Norber, the Williams technicians told him this is the first such dual Fadec failure in eight million flight hours on the FJ44.The FJ44’s system redundancy at the time the engine was certified was considered robust enough that the engine was certified without a manual method of controlling the engine in the event of this kind of failure.