FLIGHT TEST:BLACKHAWK 350

THE ULTIMATE KING AIR

Blackhawk Modifications have built an enviable reputation taking excellent turboprops and making them even better. This is particularly evident in the spectacular gains they have achieved with the Beechcraft King Air range.

THE OLD ADAGE THAT ‘you can never have too much power’ is the core of Blackhawk’s modifications. But it’s not just a matter of swopping the standard engines for more modern higher-powered versions – you have to be able to use that power, and so the engine conversion includes new props which are quieter and more efficient.

Blackhawk established its reputation as the leading turboprop modifier by upgrading the King Air 200. It was then a natural outgrowth for it to expand its range of upgrades to include the top of the range King Air 300/350 series.

BETTER THAN NEW

The heart of an aircraft is its engines. The Blackhawk upgrade of the King Air 350/350ER features Pratt & Whitney Canada PT6A-XP67A engines (-67s), producing 1,050 shaft horsepower (shp) up to 25,000 feet.

AOPA reports that Blackhawk’s latest offering is a package for the King Air 350 and 350i that the company calls its XP67A Engine+ Upgrade. It swops out the stock Pratt & Whitney PT6A-60A (dash 60) engines for PT6A-67A (dash 67) powerplants—the same engines used in the Pilatus PC–12NG turboprop single.

Interestingly Blackhawk does not change the standard rated power of the King Air 350. Both the -60A and -67A engines are rated at 1,050 shaft horsepower—the 350’s originally certified airframe limitations—but the -67A has a big advantage: Its thermodynamic rating is 1,200 shaft horsepower. In other words, the -67A has higher interstage turbine temperature (ITT) redlines than the -60A. This essentially gives the upgraded engines about 150 more shaft horsepower per side.

The King Air is much loved in Africa and the Blackhawk upgrade makes it even more versatile.

THE BENEFITS OF A HIGHER FLAT RATING

Flying a turboprop means managing a balancing act between torque (the twisting force exerted on the propeller shaft) and ITT limits.

At lower altitudes, where air is denser, it’s easy for pilots to advance power during takeoff and climb and reach—or exceed, if they’re ham handed—torque limits, but dense air keeps ITTs cool. As the plane climbs into the thin air at altitude, torque falls off, but ITTs creep up because that same thin air does a poor job of cooling internal engine components. If you try to make up for a loss of torque by pushing up the power levers you’re likely to exceed ITT redline, which is bad because expensive engine damage can occur.

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