Cessna 340

As a generality, the Cessna 340 is a pressurized, turbocharged 310. Cessna put a lot of effort into its styling and the results are particularly attractive both inside and out.

The Cessna sales’ effort placed great weight on the pitch that the 340 is a “300 series plane,” and not one of the 400 series. But to look at it, you see more of the 400 series than you do the pressurized 310. Not only that, Cessna’s detailed engineering report on the 340 says the wing is the same as 414, as are the flaps and ailerons. The landing gear is the same as the 414, but the horizontal and vertical stabilizer, elevator and rudder are the same as the 310; minor changes in the 310 tail make it interchangeable with the 340.

The 340 has a gross weight of 5,975 pounds, and an empty weight of 3,697 pounds. But any discussion of an airplane – any airplane – must balance all the heavily publicized features to some practical use. The customary advertising claims throw all the seats, gross weight, maximum fuel, and maximum performance into one arena. But hardly any plane can do all those things, and carry all that weight, at one and the same time.

The trend appears to be more reasonable these days. Cessna, for example, lists a variety of combinations, up to a maximum of six people, but with greatly reduced fuel load and range. With up to four people, for example, the 340 can carry its maximum of 180 gallons of fuel, although maximum range drops off slightly as the weight goes up. With six people, the fuel load must be reduced to some 112 gallons.

The 340’s pressurization system maintains a differential of 4.2 psi. The day I flew N4001Q for this preliminary report, the cabin pressure remained at 3,000 feet, with the plane at 13,000. On takeoff, we used 33 inches and 2,700 rpm; both engines have a double set of safety stops to prevent over boosting the turbochargers. All you do is leave the throttles at takeoff position, and climb right up to 13,000 feet.

Stalls are simple and straightforward. At zero thrust on the left engine, with the right engine at cruising power at 12,000 feet, the 340 stalled at 80 mph indicated with flaps and gear up, and was easily controllable in level flight. In the short time we were in the air we didn’t have time to make significant checks on climb and speed. But we did try descending – airline-style – at rates up to 4,000 fpm, to see if the cabin pressurization follows such a steep descent. It does, and very well.

The 340 doesn’t land like the 310. You get the approach speed stabilized at 117 indicated with flaps and gear down, then hold it in that position until just over the runway, when you ease off the power. The plane lands itself. No flaring nose-up and sitting it on the back wheels.

Unless some unexpected defects show up, the 340 should prove a most significant addition to the general aviation fleet. It does what I felt had to be done a few years ago after flying a Cessna 320 on a high altitude flight to Mexico City, using oxygen mask. The conclusion then was clear: No matter how you turbocharge engines, they won’t be practical until the cabin itself is pressurized. Now Cessna’s done it.

A Pair of Newcomers
Max Karant, AOPA Pilot, January 1972

The 340 is an all metal, six-place, low wing, pressurized, twin engine airplane and is equipped with retractable tricycle landing gear.
This airplane is certificated in the normal category. Spins and aerobatic maneuvers are not permitted in normal category airplanes. The airplane is approved for day and night VFR/IFR operations when equipped in accordance with F.A.R. 91 or F.A.R 135.

The airplane is powered by two horizontally opposed, six cylinder, direct drive, turbocharged, air cooled, fuel injected engines. The engines are Continental Model TSIO-520-Ns and are rated at 310 horsepower each.

The fuel system consists of two main tanks, two optional auxiliary tanks, two optional wing locker tanks, fuel selectors for selection of main, auxiliary or crossfeed fuel and other necessary components to complete the system. The main tanks are integrally sealed aluminum tanks mounted on each wing tip. Each tank contains an auxiliary fuel pump and transfer pump. The optional auxiliary tanks are available in two sizes. These tanks are bladder type cells located between the spars and the outboard wing. Optional wing locker tanks are installed in the forward portion of each wing locker area. A fuel flow gauge, fuel quantity gauge and a fuel low level warning light is located in the cockpit.

The airplane has a 28-volt, negative ground, direct current electrical system powered by an alternator on each engine and a 24-volt battery.