Used Aircraft Guide: Cessna 340 Boasts Cabin-Class Comfort and Pleasing Handling

Looking to step up from a high-performance single into the world of cabin-class piston twins?

Of course, you would consider the Cessna 340. With a biz-aircraft-like presence on the ramp—and generating big invoices at the shop—the 340 series is a sizable leap in complexity and high-flying performance.

Although not without its shortcomings—most notably certain loading limitations and a complex fuel system—the 340 is nevertheless an impressive and flexible airplane capable of  business missions while serving double duty for loading up the family for go-places traveling.

This Article First Appeared in FLYING Magazine

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When shopping, start with a good prepurchase evaluation and lots of upkeep money in the operating account—especially for 340s with higher-time engines and neglected maintenance. Save for training, too.

Smaller than a 414, and much larger than a 310, the 340 came around 1972 as a lower-cost alternative to the Cessna 414, which had arrived in 1970.

Look closely at the two airframes. While it carries a 300-series number, the 340 and 414 share the same wing, flaps, ailerons, landing gear, and engines. The 340 has an airstair door, thus you don’t need a ladder to get into it, as some have jokingly complained about the long-legged Cessna 310. The 340 carries less than the 414, but it’s faster on the same fuel burn.

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From 1972 through ’75 the engines were Continental TSIO-520-Ks, which produce 285 hp at 33 inches manifold pressure from sea level to 16,000 feet. However, most of the K engines in the early 340s have been converted to Js or Ns. The TSIO-520-J engine, used on early 414s, produces 310 hp at 36 inches manifold pressure. The N engine, installed on later 414s and 340As, produces 310 hp at 38 inches.

The major difference between the K engine and the J and N variants is that the latter are equipped with intercoolers, which wash the heat out of the induction air as it flows to the cylinders. This yields better power and efficiency without stressing the jugs, something that can be good for longevity, but only if you know how to properly set the power.

The N engines produce their rated 310 hp up to 20,000 feet and provide higher cruise speeds performance. Three-blade McCauley propellers, formerly an option, also became standard equipment in 1976. Earlier 340s came with puny two-blade McCauleys.

These are all-weather machines, but known icing didn’t come until 1977. In 1989, a maximum ramp weight of 6,025 pounds was approved, and max weight for takeoff and landing was set at 5,990 pounds for the 340A, compared with 5,975 pounds for the 340.

The last significant change in the line came in 1979, with the switch to TSIO-520NB engines—the B denotes a heavier crankshaft. Subsequent modification of cylinders, valve lifters, and piston pins by Continental increased TBO of the NB engines from 1,400 to 1,600 hours in 1983.

With a total of about 1,297 aircraft made, last we checked there were just under 900 still registered.

Complex Systems

But that’s typical of all big Cessna twins. In fact, the pressurization system is the same as that found in Cessna’s 400-series twins, with a maximum differential of 4.2 psi providing an 8,000-foot cabin up to 20,000 feet.

Above that, the cabin climbs with the airplane. Initial training will focus heavily on the pressurization system and high-altitude ops. Though, as pressurization goes, the 340 is relatively easy, requiring just a quick check and set for each flight. The pilot merely dials in field elevation plus 500 feet before takeoff and landing and selects desired cruise cabin altitude on initial climb. The rest is simply monitoring the system to make sure it’s delivering as commanded.

Cessna offered an automatic pressurization control, which activates and deactivates while climbing or descending through 8,000 feet, but twin-Cessna pros tell us more buyers opted for the variable-control system. 

The variable system maintains a sea-level cabin up to 9,000 feet, then delivers the pilot-selected cabin altitude until a 4.2 psi differential is reached.

While the pressurization is easy, the same can’t be said for the fuel system.

Start with the 100-gallon-usable tip tanks, which are the mains in this airplane. Add up to four auxiliary wing tanks, two holding 40 gallons, the other two holding 23 gallons. Throw in locker tanks, which add another 40 gallons. That’s up to 203 gallons in tanks peppered throughout the length of the wings.

Where things get tricky for the uninitiated is which tank to use when.

Use the mains, alone, for takeoff and landing. The engines can feed directly from the auxiliary tanks, but fuel in the lockers has to be transferred to the mains, which are the tip tanks. You have to make room in the mains first, otherwise you’ll vent the pumped fuel over the side.

“The fuel system is no big deal,” said Jerry Temple, our go-to twin-Cessna sales pro at Jerry Temple Aviation in North Texas. “I prove it twice a month to new twin Cessna owners. It can be mastered in one 2.5 hour cross-country.”

We say pay attention.

The majority of 340s have what is called full deice. This usually means boots on the wing and tail (with the exception of the wing stubs), heated props, and alcohol spray for both sides of the windshield. This is adequate for many 340 owners. The few 340s out there with hot props only are tough to sell, but can be ideal for owners in warmer locations.

Air conditioning might be the factory system, which requires the right engine to be running to get cool air. Parts for this system can be challenging to acquire, and we’ve seen big invoices for AC repairs. Look carefully at the system’s health before buying.

Performance and Payload

The airplane owes its speed to a relatively slick airframe, and because it has flap and gear operating speeds that are on the low side, it can be a handful to go down and slow down at the same time.

For example, flaps can be extended 15 degrees at 160 knots—the limit is 156 knots for the first 300 airplanes built—to help slow the airplane to max-gear-extension speed, a pitiable 140 knots. But slowing the airplane to 160 knots without stressing the engines can be a problem, if you believe in the shock cooling genie. Owners say descents and approaches require planning and occasional persistence with ATC if a slam dunk is in the offing.

Once the airplane is slowed down with gear and flaps deployed, however, it tends to sink like a rock, and some power must be maintained right into the flare. This is due in part to the split flaps, which are great for drag, but not so good for lift.

With a service ceiling of nearly 30,000 feet, most owners wisely operate in the high teens to mid-20s, where the airplane can be expected to travel true between 190 and 205 knots on about 30 gph at 65 percent power, and 200 to 217 knots on 32-34 gph using 75 percent power.

Rate of climb at sea level is a respectable 1,650 fpm, but climb performance tapers above 20,000 feet to a dawdling 300-400 fpm in the mid-20s. Not bad as twins go, but it’s no turboprop.

The 340’s claimed single-engine rate of climb is 315 fpm, better than the 414 (290 fpm), Beech P58 Baron (270), and the Piper 601P (240) and 602P (302) Aerostars. Single-engine minimum control speed is 82 knots. Stall speeds are 79 knots, clean, and 71 knots in landing configuration.

The 340’s cabin is 46.5 inches wide and 49 inches high, about the same size as an Aerostar and 4.5 inches wider than a P-Baron.

Payload isn’t much to brag about.

Load enough gas for a 4.5-hour flight with reserves, and you can take along only two passengers and their bags. Fill all the seats with 170-pounders and pack away their 30 pounds of baggage each, and you can carry enough fuel for less than two hours of flying.

Among the cabin, nose, and locker compartments, there’s a cavernous 53 cubic feet of space in which a maximum of 930 pounds can be crammed.

Owning Them

John Taylor owns a 1981 340A II and logically transitioned to it from a Cessna T210. His airplane also has RAM engines, VGs, stock air conditioning, and a mix of new and older avionics.

“The airplane is thirsty, guzzling approximately 30 gph of fuel at 65 percent power lean of peak, or 36 gph rich of peak, in cruise,” Taylor said. “True airspeeds at FL 180 to 230 are between 195 to 210 knots, depending on atmospheric temperatures and gross weights. Higher speeds are available above 65 percent power, but cylinder head temperatures and fuel flow increases both outweigh the gains in my opinion.” 

“As an AP/IA I’ve made a number of modifications to the engines and airframe, most aimed at improving reliability and reducing empty weight (family of five, plus the dog). All lighting has been changed to LEDs, and the Hartzell Q-tip propellers were changed out for the McCauley 515 Sabretips. The propeller change resulted in approximately 20 pounds of useful load and 3-5 knots more speed in the flight levels. Additionally, the pressurized Slick magnetos were discarded and exchanged for one Bendix 1200 series and one SureFly SIM6C on each engine—which removed nine pounds of excess wiring.

“The airplane is equipped for flight in known-icing conditions (FIKI), but it does not carry ice well. The boots lose their effectiveness above 10,000 feet msl, and I would caution any pilot planning to spend any time plodding along in icing conditions: Change altitude and course as needed.”

Installing a Garmin autopilot? Taylor put one in his plane and said to look out for the required inspection of the roll servo mounting brackets for cracks (and repair if necessary) pursuant to Garmin’s SB 22107 Rev A.

When it comes to 340 upkeep, hold onto your wallet. Like any high-performance airplane, a 340 won’t tolerate skimpy maintenance, and owners we spoke with overwhelmingly agree that annual inspections and most any major work must be done by a shop with twin Cessna expertise.

TAS Aviation in Defiance, Ohio, continues to reel in high marks.

Make sure you do a thorough prepurchase evaluation, looking hard at upkeep, and especially on the airframe as these machines are aging—some not so graciously.

One important FAA AD to check for is 82-26-05, which requires visual checks for cracks in the rudder balance weight rib every 100 hours until a new rib is installed. Such cracks have been the subject of numerous service difficulty reports.

To help with maintenance decisions, training, and just about anything else to do with these birds, we think any potential owner should join the Twin Cessna Flyer (TTCF) type organization. Find it at www.twincessna.org.

As we always advise, check on insurance rates—especially older pilots and those new to twins—and plan on the rigors of good specialized transition and recurrent training. It’s a must for piloting a 340. 

Editor’s note: The Aviation Consumer (aviationconsumer.com), a Firecrown Media Inc.  brand, features in-depth technical reviews on everything from headsets to avionics to new and used aircraft. We have incorporated its popular Used Aircraft Guide (UAG) into FLYING Magazine to bring greater resources to our readers. The above article was originally published in September 2024.

This column first appeared in the November Issue 964 of the FLYING print edition.