Looking to step up from a high-performance single into the world of cabin-class piston twins? Of course you’d 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, flexible and capable airplane that well serves business missions while serving double duty for loading up the family for go-places traveling.
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.
From 1972 through 1975 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 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, of course, but known icing didn’t come until 1977. In 1989, a maximum ramp weight of 6025 pounds was approved and max weight for takeoff and landing was set at 5990 pounds for the 340A, compared with 5975 pounds for the 340. The last significant change in the line came in 1979, with the switch to TSIO-520-NB 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 1400 to 1600 hours in 1983.
With a total of about 1297 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 8000-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 of course 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 8000 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 9000 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.
Still, Jerry Temple, our go-to twin-Cessna sales pro at Jerry Temple Aircraft Sales, said, “The fuel system is no big deal. 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 be running to get cool air. Parts for this system can be challenging to get and we’ve seen big invoices for AC repairs. Look carefully at the system’s health before buying.
Performance, 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 true between 190 and 205 knots on about 30 gallons per hour at 65 percent power, and 200 to 217 knots on 32 to 34 GPH using 75 percent power.
Rate of climb at sea level is a respectable 1650 FPM, but climb performance tapers above 20,000 feet to a dawdling 300 to 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’s and 4.5 inches wider than a P-Baron’s. 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
“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. True airspeeds at FL180 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,” John Taylor told us. He has a 1981 340A II (pictured below) and logically transitioned to it from a Cessna T210. His 340A has RAM engines, VGs, stock air conditioning and mix of new and older avionics.
“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),” he said. 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 to 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 amount of time plodding along in icing conditions. Change altitude and course as needed,” Taylor told us.
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. Whatever you do, 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 type organization. Find them at www.twincessna.org.
And 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.
Cessna 340 Accidents: Other
Looking over the 100 most recent Cessna 340-series accidents we were struck by how few were caused by a mechanical failure of an engine, only five. That indicated to us that 340 owners are maintaining their engines, or that if an engine does shell out, most are able to successfully manage the ensuing single-engine descent and landing.
In the years that we’ve flown 340s we’ve found that they provide a lot of performance but also demand a lot of skill and judgment on the part of their pilots.
We also think that some credit for the low rate of engine failure accidents is due, in part, to the demanding training requirements for owners/pilots on the part of the insurance companies.
We were also pleasantly surprised to see only one inadvertent gear-up landing. On the other side of the coin, there were a boatload of mishaps due to a mechanical problem with the gear—a total of 13 gear collapses or inability to extend all three Firestones—and all were due to maintenance that had not been performed or improperly performed. The electromechanical gear of the 340 debuted with the 310 in the 1950s. It’s been around and is, in our opinion, a reliable system; however, it must be maintained in accordance with Cessna’s guidance.
That takes time and is expensive. In our experience, rigging the landing gear takes two people who know what they are doing eight hours and involves working from the center of the system outward. One leg of the gear cannot be rigged by itself. There are no shortcuts.
With the gear down and locked, it provides very stable and predictable ground handling. There were only six runway loss of control (RLOC) events, and one of those was on a snow- and ice-covered runway. In our experience 340s handle crosswinds well. However, they are not exactly short-field machines. Two pilots hit obstructions at the end of a runway on high and hot takeoffs. Six pilots went off the end on landing and three did so after aborting a takeoff.
One of those went off of a 6000-foot runway after discovering, at rotation speed, that the control lock was still in. The pilot then used an additional 3000 feet of runway, at full power, attempting to remove it before trying to stop.
We noted two accidents in IMC shortly after significant glass avionics upgrades. The flight profiles strongly implied that the pilots weren’t up to speed on the new panels.
There was one accident in VFR immediately after an autopilot upgrade. The airplane impacted vertically with full nose-up trim.
Where we think we saw problems was with pilot judgement and overall skill levels. There were eight VFR into IMC events, and 10 IMC LOC accidents, some involving going well below minimums before losing it during an attempted missed approach. Fifteen pilots stalled or otherwise lost control in VFR conditions, some after barely getting off of a short runway.
A student pilot bought a 340 and had a private pilot with only a single-engine rating give him dual. They had almost three successful lessons—losing control and crashing on final during the third.
