WACO, Texas — Blackhawk Modifications is developing a Supplemental Type Certificate (STC) that will allow the installation and operation of the Pratt & Whitney Canada PT6A-67A engine to replace the existing PT6A-60A engines on the King Air 350 model.
The Blackhawk program, called the XP67A Engine+ Upgrade, is currently installed on Blackhawk’s King Air 350 that will be used as the STC test aircraft during the experimental flight process. Blackhawk anticipates receiving the STC in the second quarter of 2017.
The PT6A-67A engine is a 1200 SHP powerplant that will replace the existing 1050 SHP PT6A-60A engine currently certified on the King Air 350. Blackhawk’s STC will flat rate the 1200 SHP to the airframe limit of 1050 SHP allowing an owner to take advantage of more than 400 thermodynamic shaft horsepower per engine in climb and cruise settings (1825 ESHP).
This higher thermodynamic rating will also improve takeoff and climb performance in high altitude and hot ambient temperature conditions, company officials said.
The initial performance results have exceeded forecast projections, officials add. In hot climate conditions, the XP67A will climb from sea level to its service ceiling of FL350 in 18 minutes, more than doubling the rate of climb.
Typical cruise speeds are increased by up to 37 KTAS and can settle in at up to 340 KTAS if a pilot chooses to fly at maximum engine power limits.
Blackhawk’s STC will include a new Flight Manual Supplement with full performance for flight planning purposes.
The PT6A-67A engine will require a more robust propeller assembly than what the PT6A-60A currently turns. Blackhawk has selected, and is now flying with, the German-designed 5 blade natural composite propeller from MT. The blades have a diameter of 102 inches allowing for more ground clearance, have unlimited blade life that are field reparable and employ large nickel alloy leading edges for superior erosion protection. The ground RPM restrictions are removed as well as the Ground Idle Solenoid to allow smooth taxi operations.
The Hartzell 105 inch diameter 5 blade composite propeller is also likely be included in the initial certification plan as an option, company officials said.
Raisbeck Engineering is working on a migration path to upgrade their newly certified Swept 4 blade aluminum propeller assembly to be compatible with the PT6A-67A installation.
The XP67A initial certification plan will include all Proline II equipped King Air 350’s with the steam powered engine instruments. Blackhawk is working jointly with Garmin and anticipates G1000 compatibility as part of the initial STC. A separate certification program will capture the Proline 21 avionic package along with the 16,500 lbs. increased gross weight kit with extended range tanks.
Precertification orders are now being accepted for the XP67A. A $50,000 refundable deposit will secure an initial delivery position and lock in a precertification pricing rebate. Blackhawk has contracted with Pratt & Whitney to offer the XP67A under the Converter Exchange Program (CEP) and requires the core PT6A-60A engines to be returned. Qualifying core engines will be issued credit at $70 per hour/per engine for time remaining to the 3600 TBO.