Page 23 - Volume 15 Number 12

Going Up, FastWe climbed into the cockpit, pulled up the boarding ladders and went through the routine PT6A starting procedure; master on and fuel pump to normal, engage start switch and watch rotation begin on the Ng gauge, waiting for 15% Ng to introduce fuel. The lightoff and rise in rpm caused no more than a 750 C. indication on the ITT (start limit is 975 C). Once stabilized, we confirmed that the starter had been switched into generator mode and the avionics were flipped on.The cooperative Hartford, Connecticut tower offered to arrange for VFR flight following service as we exited their airspace to the east; Dunkin’s plan was to execute a max-performance climbout above Providence’s Class C environment. We quickly taxied to runway 21 for a prop governor test and advanced to high idle condition, extended ten degrees of flap and took the inertial separator handle out of “bypass” position. With the APE kit, extreme short-field takeoffs are approved with 30 degrees of flap, versus 20 degrees for an unmodi- fied airplane.The propeller wound up to 2000 rpm while we held the brakes, and we advanced the power lever to about 2150 pounds of torque on the roll. The torque built to 2200 as we lifted off at a leisurely 80 knots, halfway down the 4400-foot runway.Once past 95 knots, the flaps were brought up and I quickly accelerated the aircraft to 120 knots. Dunkin advised me to hold 115 in the climb; by doing so, visibility over the nose was nil. The VSI read 2000 fpm initially, finally settling in at 1600 to 1700 fpm. Blackhawk’s brochure says the XP42A has double the climb rate of a standard Caravan, and when we compared numbers with the standard and modified charts, it appeared to be true; under similar conditions, a 675-hp 208B would manage around 850 fpm.With torque tweaked occasionally to keep 2200 pounds pulling us upward, the ITT started out at 730 degrees C. and rose to no more than 750 at the top of our climb, 11,500 MSL. Only about 8 minutes had elapsed since our sea-level liftoff. The -42A Pratt had kept its 2200 pounds of torque until 10,500 feet. Temperature was about 16 degrees over standard ISA and takeoff weight was estimated at 7700 pounds.As we leveled off with 2100 pounds of torque and 750 degrees on the ITT, the airspeed settled at 165 knots IAS, computing to a TAS of 202, while burning 460 PPH of Jet-A. The standard 208B’s book showed that only 1370 pounds of torque would have been available at 12,000 feet, providing a TAS of about 158 knots. In all fairness, Dunkin pointed out, our TAS would have been ten knots or so less if we had been at full gross weight.DECEMBER 2011TWIN & TURBINE • 21