Cessna's Pressurized Centurion

knob at lower right. which shows 2,300 feet as the desired cabin altitude. CENTURION continued Grasch, in his preflight briefing, stressed the importance of advance planning in use of this aircraft. With ground speed during a descent in the 200- to 220-knot range, the pilot needs to plan his descent to pass through 10,000 feet 30 miles from the destina- tion. So a descent from 18,000 feet might start 80 miles out. Grasch sug- gests that an altitude of 20,000 would be impractical for most flights unless they are at least 600 miles long. The pressurization system of the P210 allows for a maximum pressure differential of 3.35 pounds per square inch (psi). So at 10,000 feet, where the outside standard pressure is 10.10 psi, the pressure in the cabin could be as high as 13.45, equivalent to the pressure down near 2,000 feet. If the plane is at 20,000 feet, its cabin can be maintained at a pressure level of 10,000 feet. A dial on the instrument panel is used to set the altitude you'd like to hold in the cabin. Once that dial is set, the altitude will be held automatic- ally, until the craft climbs above an altitude that causes the pressurization to reach 3.35 psi maximum. Then the cabin starts to climb. but at a rate less than the airplane itself. An inner scale on the altitude select dial shows the altitude at which the maximum dif- ferential will be reached. There is a gauge to show the rate of climb or descent in the cabin, and another that shows both the cabin altitude and the pressure differential that exist at any given moment. Though no 600-mile flight was en- visioned. I took the craft up to 20,000 feet. Cabin altitude was set for 2,300 feet. As the craft passed through that level its cabin climb needle went to zero. Then the differen tial began to increase toward 3.35 psi, which was reached at 10,300 feet. At that point the plane was climbing at 900 to 1,000 fpm, and the cabin began a 700 fpm climb. To- gether. the cabin and plane climbed to 20,000. where the cabin altitude had reached almost 10,000 feet. Time to altitude from Cessna's 1,384-foot-high field in Wichita was just about 20 minutes. At that altitude, the Continental en- gine was set for 79% power, which took 33 inches manifold pressure and 2,500 rpm. The outside temperature was -23°C and the altimeter was set to 29.92 (standard since we were at a flight level). The speed indicator showed 145 knots, which computed to 198 knots true, with fuel consumption at 1] 5 pounds per hour (19.2 gallons per hour). A more conservative power set- ting was 55% -25 inches manifold pressure and 2,300 rpm-where a speed of 171 knots true was achieved with fuel consumption reduced to 75 pounds per hour (12.5 gph). At the higher power setting. in level flight with mod- erate tailwinds (for that altitude), the DME showed a modest 244 knots, or 40 THE AOPA PILOT I JUNE 1978 281 mph. At any of the selected power settings, the noise levels inside the P210 are very low, due to the extra structure and thick windows envelop- ing the craft's occupants. Brief experiments with potential mis- takes a pilot could make showed the consequences of mishandling the con- trols of this craft. Since pressurization depends on operation of the turbo- charger, a manifold pressure of not much lower than 20 inches must be held to maintain cabin pressure. A quick rotation of the altitude select dial, or too much of a power reduc- tion, will bring about a discomforting surprise to the ear drums, for cabin response to pressurization change is almost instantaneous. If you quickly rotate the cabin pressure dial from 8,000 to 10,000, your ears will climb 2,000 feet before you can say "two- thousand." Besides these cabin controls, the pilot needs to stay closely tuned to cabin temperature. A good amount of jockeying of heater and defroster con- trols is required to adjust for changing temperatures resulting from the rapid climbs and descents this airplane is capable of. And speaking of rapid descents, the craft's handbook specified emergency letdown procedures, and we gave them a try. First the gear is extended (at an airspeed below ]40 knots IAS), and power is pulled back. With flaps re- maining up, the craft's nose is lowered to attain speeds up to 200 knots indi- cated (in smooth air). In this config- uration but holding 180 knots, our P210 was dropping earthward from 18,000 feet at a rate of 1,000 feet every 20 seconds. No adjustment to the pressurization system is necessary for such a descent. However, for any landing the pilot must make sure that the selected cabin altitude is higher than the field eleva- tion at the destination so the airplane does not arrive at the ramp in a pres- surized condition. The emergency descen t exercise was ended at 15,000 feet and we continued downward at more normal rates. The overall feel of this aircraft, particularly during takeoff and landing, is that this is not a light airplane. Well, for cer- tain, it's not. The Pressurized Cen- turion weighs in at 4,016 pounds maxi- mum ramp weight, which puts it in the ring with the heavyweights. In flight, the plane is readily controllable, however, and the operating speeds for gear (140 knots) and flaps (10 degrees at 150 knots) allow for added maneu- verability approaching airfields. Takeoffs from Cessna field and near- by EI Dorado were found to be a little sluggish. With temperatures in the low 40s, a takeoff from Cessna's airport used up almost 1,500 feet of the 3,800- foot strip. There were two of us aboard with full fuel (89 gallons), meaning the plane still had carrying capability for another 540 pounds of people or baggage. The 210's reputation as an excep- tional load carrier has been main- tained. The P210's allowable gross weight was raised to more than over- come the weight penalty added by pres- surization gear. The airplane flown for this check, besides all its other equipment, also carried a full complement of deicing equipment, including electric prop heat, boots on the wings and tail lead- ing edges, and a windshield anti-ice plate. However, the plane was not cer- tified for flight in icing conditions. Re- portedly, there is still resistance on the part of the FAA to approve a single- engine airplane for flight in icing con- ditions. And being a single, it lacks some of the system redundancy found in twins. Nevertheless, this P210 would have to be termed the complete single, for it has all primary features available to any aircraft. With its pressurization, turbocharging, radar, ice protection, extensive avionics, and stereo, there can be only one conclusion about the true identity of this craft. It's a six- seat airliner, with a propeller on the front. D Length Height Wing area Wing loading Passengers and crew Empty weight Useful load Gross weight Power loading Fuel capacity Oil capacity Baggage capacity Engine Propeller Wing span CESSNA P210N Basic price $94,500 Specifications Continental TSIO· 520·P 285 hp @ 2,600 rpm (continuous) McCauley CS, 3·blade 80·in dia 36 ft 9 in 28 ft 2 in 9 ft 5 in 175 sq ft 22.9 Ib/sq ft 6 2,345 Ib 1,671 Ib 4,000 Ib 12.9 Ib/hp 90 gal (89 usable) 11 qt 200 Ib Porthole·like windows are required for better cabin·sealing capability, but reduce all-around visibility. The half-sized emergency exit on the plane's starboard side at lower left. Performance The extent of instrumentation on this single is measured by the array on its panel. Besides full avionics, an RDR-160 weather radar fits in at right. Fuel gauges are moved to the base of the center pedestal. Takeoff distance (ground roll) 1,300 ft Takeoff over 50 ft 2,160 ft Rate of climb (sea level) 930 fpm Maximum level speed 204 kt Normal cruise speed (80% power, 20,000 ft) 196 kt Economy cruise speed (55% power, 20,000 ft) 158 kt Range at normal cruise (with 45·min reserve) 815 nm Maximum range (with 45·min reserve) 960 nm Certified maximum altitude 23,000 ft Stall speed-C.A.S. (clean) 67 kt Stall speed-C.A.S. (gear and flaps down) 58 kt Landing distance (ground roll) 765 ft Landing over 50 ft 1,500 ft JUNE 1978 I THE AOPA PILOT 41