Pilatus Aircraft is working with engine supplier Pratt & Whitney Canada and Woodward Governor of Rockford, Ill., to roll out an “aggressive campaign” to retrofit the entire fleet of more than 500 PC-12s with improved fuel control units (FCUs).

The PC-12, a single-engine turboprop, has been involved in six full or partial engine failures in recent months, apparently due to fuel leakage. Two of the four incidents that occurred in flight resulted in successful deadstick landings (AIN, March, page 3). The other two managed to regain full or partial power.

Modified pneumatic systems will use a “double-walled, double sealed bellows design” to prevent fuel leaking, according to a spokesman at Pilatus Business Aircraft in Broomfield, Colo. P&WC plans to issue a Service Bulletin “within the next several weeks,” pending successful completion of flight testing, which is currently under way in Stans, Switzerland.

Pilatus expects to have all PC-12s flying with the new FCU “within three months of program launch,” the spokesman said. “All costs will be covered by Pilatus and our suppliers.”

In the interim, Pilatus reiterated the importance of operators’ “thoroughly understanding the proper use of the engine MOR [manual override] procedures” as published in Temporary Revision No. 42 of the PC-12 Pilot’s Operating Handbook. “Adherence to these procedures will ensure continued control of engine power in the event of an FCU failure.” To date, the FAA has not issued ADs or special airworthiness information bulletins.