The Cessna 402 A Versatile Cabin-Class Twin

The Cessna 402 A Versatile Cabin-Class Twin

The Cessna 402 A Versatile Cabin-Class Twin

By the mid-1960s, Cessna Aircraft Company was on a growth spurt, bringing out new aircraft models to fill every possible marketing opportunity. Recognizing that business aircraft was the key to the company’s future, it was obvious that expanding the twin-engine line was vital. The Model 310 was over ten years old and had seen its share of upgrades, but Beech Aircraft had introduced the cabin-class Queen Air in 1960. To compete, Cessna needed a bigger plane.

What the engineers came up with was something called the “Cessna 411”. Originally, it was one of Cessna’s few design mistakes, but it did serve as the foundation for a successful family of rear-door twins, extending for the next 20 years. The 411 utilized the 310/320 wing, complete with wingtip fuel tanks, split flaps and electrically-operated landing gear, but with an entirely-new “wide oval” fuselage. Unlike Beech’s taller, but narrower, “bread loaf” cross-section, the new Cessna twin sacrificed headroom in favor of a wider cabin, since most of the trip is spent in a seated position. A split entrance door behind the wing offered folding entrance steps in its lower portion and a windowed upper portion. Nominally set up for four club-facing seats in the rear plus two cockpit chairs, two additional passengers could be accommodated if desired.

Certificated in August 1964, the 411 made use of turbocharged 520 cubic-inch Continentals, similar those of the late model 320 Skyknight, but with a 3:4 gear ratio behind the propeller to generate 340 horsepower, turning the engine at 3,200 rpm and props at 2,400. The vertical fin and rudder turned out to be undersized for the task of opposing engine-out predicaments; Vmc was published as 90 knots. The 411 was produced for four years and 300 units; with oval windows and turbocharger bleed air available, it was obviously designed for pressurization, and thus the 421, with a larger tail and 375-hp GTSIO-520 engines turning propellers at a 2:3 ratio, was certified on May 1, 1967.

000002750002 copyMeanwhile, Back at the Drawing Board…

Shortly after the 411’s introduction, it was obvious that the fuselage had utilitarian possibilities, and on September 20, 1966, Cessna gained certification for Models 401 and 402, using direct-drive TSIO-520 engines of 300-hp. The airplanes were basically identical, with the 401 supposedly a more-opulent executive configuration and the 402 slated for utility service, much like the two versions of the 206 single that had been offered a year earlier. Most importantly, the 401/402 had a bigger tail than the 411, dropping Vmc to 83 knots with the smaller engines.

The 402 proved to be the clear winner, and the 401 version was dropped after six years. Although both grossed at 6,300 pounds, the 402 had 1.6 inches more aft c.g. allowance and could carry an additional passenger, for a total of nine occupants.

For the 1969 model year, a 401A and 402A were offered; the 401A was certificated in October 1968 and the 402A in January 1969. With the 402A designation, up to 10 seats could be installed. The major change occurred with the 401B and 402B, approved November 12, 1969. The – B model had an extended nose with a second forward baggage door, allowing as much as 600 pounds to be carried in the snozzola. However, the maximum takeoff weight of 6,300 pounds remained.

Cessna continued development of the 400-series twins in the 1970s, introducing a less-expensive pressurized 414 for the 1970 model year, powered by direct-drive 310-hp engines, and in 1976 the 421 got its makeover with a bonded, wet-wing fuel system and hydraulic landing gear, abandoning the tip-tanks that required auxiliary cells larger than the tips. No one missed the labyrinthine fuel lash-up. Accordingly, the clean-wing 414A came along in 1978 and in 1979 it was the 402’s turn for the new wing.

The restyled 402C was built until 1985, and it remains a popular load-hauler for charter and business use. More than just a removal of the tip tanks and change to hydro gear, the engines’ output was boosted to 325 hp each and max gross weight went to 6,850 pounds, creating a much more useful airplane. Even with the weight increase, single-engine performance went up and the stall speed went down a couple of knots. The 402C remained in production through the decline in general aviation manufacturing in the 1980s, finally succumbing to the triple threats of product liability costs, a bad economy and an oversupply of slow-selling aircraft. Cessna wisely abandoned propeller twins to concentrate on jets.

000002750001 copyThe Three Cessna 402s

There are three variations of the Cessna 402; the original short-nose 401/402, the long-nose 402B, and the wet-wing 402C. The latter is the most sought-after, with its greater payload and simpler fuel system, but the older tip-tanked airplanes offer a lot of capability and value.

The walkaround inspection reveals an imposing aircraft, with a huge vertical tail and an equally-significant proboscis. So extensive is the forward baggage area that it requires four swing-up doors to access it, and 600 pounds can be carried, less any installed avionics. A 45,000-BTU combustion heater is in the nose. Not that other baggage space is lacking; wing lockers, aft of the nacelles, can take 200 pounds each, although air conditioning normally installed behind the right engine cuts 80 pounds off that side’s allowance. And a swing-open cargo door behind the air-stair entrance allows loading of bulky items, with baggage adjacent to the aft seats. Loading should be accomplished in front-to-back order.

The 402C’s landing gear is hydraulically actuated, powered by pumps on both engines, rather than electrically-driven like the earlier airplanes. The maingear, carrying 6.50 x 10 tires, stows into open wells, instead of behind the sequencing doors used previously; the nosegear has a 6.00 x 6 tire. A standby blow-down bottle in the nose backs up the hydraulic system.

In a most-welcome departure from the tip-tanked 402, the wet-wing fuel system is a simple on/off/crossfeed system, normally requiring no management, holding 206 usable gallons, but seldom filled unless extreme range is required. About 900 pounds of payload can be carried with full fuel. There is a 6,515-pound zero-fuel weight to be observed, so there’s no reason to depart with less than 30 gallons per side. Maximum landing weight is the same as max takeoff weight.

The electrically-driven flaps are split-type panels, retained from the earlier twin Cessnas.

The TSIO-520-VB engines are cowled in slim nacelles with screwdriver accessible drop-down doors and removable panels. Cowl flaps are installed. The engines can put out 325 hp for takeoff and single-engine operation; normal rated power is 310 hp. The three-blade McCauley props are housed in polished spinners.

The big tail stretches 12 feet into the air, with a single trim tab on the right elevator, along with trim tabs on the rudder and left aileron. A clever optional rudder gust-lock lever on the left side of the tailcone pins the rudder in neutral. If overlooked during preflight, it will disengage with application of up-elevator.

The early 401 designation for passenger accommodation and 402 for utility hauling was replaced in the 1973 402B by simply offering “Businessliner” and “Utililiner” packages, the latter having extra seating and plainer furnishings. These offerings were carried over into the 402C. If used for cargo hauling, a forward crew door and wingwalk were offered.

For business flying, the cabin would normally have club seating plus two crew and two aft seats, with foldaway work tables and cabinetry. After entering via the airstair, the lower door is raised by its support cables and secured in place, followed by pulling down the upper portion and latching it. The wide aisle gives enough room to wiggle forward in a low crouch, and the cockpit is spacious, once seated. Because most electrical controls are on the sidewalls, there’s little overhead but some lights and rheostats. Fuel selectors are on the floor, and everything else is handy at waist level.

The pedestal has the power stalks and cowl flap handles, along with trim and autopilot controls. Power gauges are at eye-level under the glareshield and there’s plenty of room for avionics plus right-side gauges. Starting and electrical switches are on the left sidewall, with a priming toggle between the starter buttons to actuate the high boost pump. One quickly learns to catch a faltering engine with primer, starting with mixture rich and pumps off. Once running, the boost pumps go “on”, which is a low-speed vapor-purge setting unless the engine-driven pump fails, causing the boost pump to automatically go to “high”.

MDC Cessna 402 at Jefferson City Airport hangar.
MDC Cessna 402 at Jefferson City Airport hangar.

Taxiing is a pleasure, with light pedal pressures and prompt steering. Visibility isn’t bad, despite the long nose; the maingear span is almost 18 feet, so it pays to watch taxiway radius and centerlines. There’s a heavy elevator down-weight and a slight aileron/rudder bungee interconnect, neither of which are objectionable. Runup is conducted at a sedate 1,700 rpm, trims and controls are checked, boost pumps are verified on, cowl flaps are open and air conditioner turned off for departure. The prop synchrophaser can be left on.

Line-up and go involves the usual spool-up for the turbochargers, and regard for the single-engine operation numbers. Vmc is 80 knots, but Vyse is 104 knots. A compromise of 95 knots gives Vxse, so rotation is scheduled for about 90 knots, at which point liftoff and gear retraction would put one in safe territory. Flaps are not used, since they are primarily a drag device.

Acceleration is quick, given that the power-loading is around 10 pounds per horsepower, and 2,000 feet of runway is sufficient to reach Vxse, climbing away at 1,500 fpm. Normal cruise-climb power is 29.5 inches and 2,450 rpm, which yields around 1,000 fpm at 125 knots. Boost pumps off and props synched, there’s little to do but watch the airplane climb; the 402C is stable and solid, even flown manually.

Leveled out and leaving the power at 29.5 and 2,450, about 70%, the TAS at 9,000 to 10,000 feet works out to 200 knots, burning about 18 gph per side. Coming back to 28 inches and 2,300 rpm, roughly 65% power, TAS drops by six or seven knots and fuel is down to 17 gph each, and at a fuel-saving 56% power of 26/2,200 the TAS is 183 knots on 14 gph per engine. At cruise, the big 402C rides like a bus, trimmed up with yaw damper on.

Slowing down, both first-flaps and landing gear can be extended below 180 knots, which is basically anytime, with additional flaps allowed below 149 knots. Motoring along at the 104-knot Vyse blueline, there’s none of the flywheel effect of the 300-pound tip tanks on the 402B, and the stall warning horn doesn’t come on until reaching 80 knots. A clean stall is achieved at 74 knots, and in full-dirty configuration the stall break comes at 10 knots slower.

Single-engine performance is not the hallmark of a loaded 402C, but it’s possible to manage 300 fpm with an engine zero-thrusted, pulling full 325 hp out of the good engine. As with any piston-powered light twin, loading, technique and atmospherics influence performance greatly, and density altitude must be respected if any single-engine capability is to be expected.

In the pattern, 17 to 18 inches m.p. works well for maneuvering power, riding down the glideslope at 100 knots or so. With experience, one can fly a 90-knot approach and cross the threshold at 85 to get down and turned off in 1,500 feet of runway. For a three-ton people hauler, it’s a pretty good short-field airplane.

The old 402 developed into a dependable, capable utility twin during its 20 years of production, and it’s still a very useful tool for business and personal travel. Early examples can be obtained cheaply, but do not ignore the expense of maintaining two turbocharged Continentals and keeping up a complex airplane. As always, the 402 does its job, without muss or fuss.

000002750003

About the Author

Leave a Reply