Step-Up P-Twins

Budget and pressurized twin don't exactly go together, but Cessnas 337 and 340 and the Beechcraft P-Baron are possibilities.

by Marc Cook

Although there are a few more choices than this, in reality, if you want a pressurized single-engine aircraft, you’ll be looking at a Cessna P210 or a Piper Malibu. End of story. Thanks for coming.

But expand your horizons into twins-more to the point, prepare your accountant for the red ink to come-and your coffee-or-cake choices turn into a veritable French bakery.

It only makes sense: The addition of pressurization hardware represents a smaller weight increase on a 7000-pound twin than on a 4000-pound single. New-airplane economics have favored pressurization at the top of the twins class, too; if youre popping for the turbos anyway, it doesnt make sense to pass on pressurization.

No question, this part of the fleet is weighted toward the high end. The notion of a step-up pressurized twin is vaguely ridiculous, given the price, capability and cost of operating two engines and a blow-up cabin. Nonetheless, if you need to carry the weight or volume and you want to go high to avoid weather without fussing with oxygen, you have to start somewhere. With that in mind, weve divided the pressurized twin options into two segments, the low-end of the market and the upper end, which are all cabin-class twins. we’ll look at those airplanes in a future issue.

In the low end, the only cabin class model in our grouping is the Cessna 340, which is a good choice for stepping up to higher performance that also happens to be pressurized.

The Cessna P337 Skymaster is the sole budget P-twin, if there is such a thing, but it stands alone. Acquisition and upkeep costs in this class start high and go up from there. As we observed with the singles in our analysis in the July, 2004 issue, youre buying more hardware and supporting an engine (now two) that will see more of its life carried out in thin air at high power. You probably already know this, but its worth reiterating: A pressurized twin is no place for cheapskates.

But for a knowledgeable owner who is willing to spend wisely on ongoing (and even proactive) maintenance, a pressurized twin can be just the right airplane-fast, comfortable and reassuring with its redundant systems. Here, then, is a look at the pressurized twin selection for buyers with budgets in the $110,000 to under $500,000 range, with an emphasis on the lower end of that price spectrum. we’ll explore the pricier twins in a future article. we’ll also see how turboprops stack up.

Cessna P337
Cessnas everymans twin, the 337 Skymaster, was a guinea pig in many ways. On that model, Cessnas engineers worked out the dynamics of a centerline-thrust design and used it to define (and refine) a simplified pressurization system that would eventually find a home on the P210.

Debuting in 1973, just a year after Cessnas other popular pressurized twin, the 340, the G-model Skymaster used a strengthened version of the T337s fuselage and uprated versions of the Continental TSIO-360. With boost running 37 inches, they were rated for 225 HP, a lot of juice from a small engine.

Like the P210 to come after, the maximum pressure differential was 3.35 PSI, good for a 10,000-foot cabin at 20,000 feet. Arriving late to the 337 family, the P337G received the benefit of a simplified landing-gear system (electro-hydraulic, no longer with an engine-driven pump) and a more rational fuel system. Through the production run, the P337 could be had with a total long-range fuel capacity of 118 gallons for 1973 and 1974 and 148 gallons after.

you’ll want lots of fuel because the P337 is not terribly efficient, despite having relatively small displacement engines. Maximum cruise speeds are in P210-land, at 165 knots at low altitude to as much as 204 knots at 20,000 feet on nearly 27 gallons per hour total. Thats not bad economy as twins go, but its not good economy for an airplane cruising at 180 knots when measured against, say, the P210 or T210.

Moreover, few P337 owners run the engines at maximum cruise because they tend to be fragile and somewhat hot-running. In general, TCMs IO-360 have proven to be smooth engines but they arent noted for longevity. (We hear that hangar tales of the 337s rear engine running so much hotter is more a case of improper maintenance and gauge errors.) Climb performance is good, as youd expect with 450 horses on tap, with the usual weight-defined poor single-engine climb found on most twins. However, the P337 will climb high on one engine with a minimum of fuss for the pilot.

Indeed, making life easy for the left seater is what the 337 series is all about. Particularly in P337 form, the airplane is stable and nice handling, with surprisingly light ailerons and a rock-solid ride in weather. Visibility is good, thanks to the wing being so far back of Row 1. You can see up and down without lifting a wing or growing a triple-jointed neck.

Passengers in the P337 have it somewhat better than in the lesser Skymasters because there are only five seats. There’s no emergency exit, only the heavily reinforced clamshell door on the right, which is how Cessna was able to construct a workable pressure vessel without weight going through the roof.

The center seat up to 1976 didnt track back and forth, but later versions did; perhaps one reason to look for a later airplane. Regardless of how they sit, passengers will have to endure a lot of noise, just one side effect of placing engines at either end of the fuselage. The P337s pressurization cuts noise a lot, but Aunt Mabel will never mistake the Cessna for, say, a Malibu.

Its hard to say if the P337s limited numbers (just 334 were built), reputedly cranky engines, decidedly un-macho configuration or lackluster performance has hurt it most, but examples have comparatively little value on the used market. An early one retails for $103,000, with the prices climbing only as high as $141,000 for the last-year (1980) model. As a result, many 337s-more often the normally aspirated and turbo models than the Ps-have been through tight-budget or don’t-care owners.

The best advice from Skymaster boosters is to find a maintenance facility thats conversant in the airplane and to shop with your skepticism turned all the way up. A P337 is a tantalizingly inexpensive way to buy into pressurization but a deferred-maintenance dog will eat you alive over time. If you go into the buying decision with the idea of fixing everything thats broke, no exceptions, you can probably get into the P337 for $150,000, with change left over.

Thats not a bad value, provided you can (a) afford the fuel costs and (b) youre willing to keep ahead of the maintenance curve to have decent dispatch rates.

Beech 58P
Its said Beech customers are notoriously conservative. Change the Bonanza one bit and youre in for enough complaints to choke the mail room. This attitude explains the King Airs success and may even extend to the Beech Dukes relative lack of same. It also explains why Beech elected to pressurize the long-body 58 Baron and offer it only six years after the burly Duke appeared.

The P-Baron shares much with its un-pressurized brethren, including most systems, wing, cabin shape and superb flying qualities. Out on the wing are Continental TSIO-520-Ls, rated at 310 horsepower-although troublesome in their own way, theyre easier to live with than the thirsty, extraordinarily expensive-to-overhaul Lycomings on the Duke. (Even so, youre looking at around $27,000 per for a major overhaul.)

Early versions are straight L-suffix engines with light crankcases; the LB version arrived later, accompanied by a 200-hour-higher TBO, now 1600 hours. Most have been updated with the heavier case, but its worth double checking the logs to make sure. If the airplane has the L-engine, youve got a large cudgel to beat the price back.

With a cabin rated initially at 3.7 PSI (and later raised to 3.9 PSI for the 1979 model), the pilot and his five passengers have the benefit of a 10,000-foot cabin at FL220. They sit club-style in the back, having arrived through a smaller single door on the left aft fuselage-replacing the non-pressurized 58s dual cargo doors-and a conventional looking over-wing door on the right. There’s a generous baggage compartment in the nose but not much space inside the cabin; remember, too, that the forward bay is unpressurized and unheated.

P-Baron buyers outnumbered those lining up for the similar-performing 58TC Baron that debuted at the same time and they continued writing checks until 1986. Beech made incremental changes to the airplane until 1984, when the old-style panel with a throwover yoke was banished to usher in a taller, more spacious panel featuring conventional controls-that is, dual yokes–the gear and flap switches in the now expected locations and considerably more room for avionics.

Speaking of which, most P-Barons are we’ll equipped, with radar and de-ice. Full-fuel payload clocks in at just over 700 pounds, a bit less than a regular 58 because of the heavier airframe, but reasonable in this class of twin.

P-Barons are considered a modest step-up, from a care-and-feeding perspective, from the more common long-body Barons, thanks in part to lots of shared components and a big fleet. Beechs parts can be, as ever, breathtakingly expensive, but they are at least available.

The 58Ps Continental 325-HP TSIO-520-WBs are considered good powerplants, if somewhat odd in having Bendix fuel injection in place of the traditional TCM system. Pressurization hardware adds a bit to the bundle-of-snakes look in the engine bays.

Although decidedly lacking in ramp appeal-and speed-compared to its stablemate, the Duke, the P-Baron is nonetheless a fast, sensible P-twin. Like all Beechcraft airplanes, it has the panache of good handling and good construction, especially in fit and finish. For that reason, Beech airplanes generally don’t take the warm bath on declining value that other types suffer when gas prices spike or the market tanks.

Cessna 340
If there ever was proof that Cessna could market its way into any category worth picking, the 340 is it. Debuting in 1972 as a downsized, cabin-class twin, it found instant success using what amounted to a Cessna 414 wing-and-engine combo mated to a compact, six-place cabin. Bracketed by the larger, more expensive 414 from above and the non-pressurized 310 from below, the 340 found itself the perfect middle ground and sold we’ll from the start.

For owners who don’t have to carry a lot, the 340 is nearly the ideal personal P-twin. It shares wing, landing gear, engines and many systems with the 414 (including the 4.2-PSI pressurization set-up), which debuted two years earlier, so its well-known an d understood on the shop floor. Thanks to a lower gross weight and smaller cabin, the 340 is faster than a 414 on the same fuel. (Or go the same speed and save some gas.)

Generally speaking, there arent any must-have model years for the 340, as it never got the longer wing of the later 414. Throughout production, the 340 had the traditional tip-tank wing and multiple-tank fuel system. Cessna started the model with Continental TSIO-520-K engines, rated at 285 HP each, but replaced them with a 310-HP variant in 1976 as the 340A.

Early airplanes can be updated to the 310-HP engine and, with a RAM conversion, to even more powerful versions of the TSIO-520. The later engines were fitted with intercoolers, which help keep temperatures down and to raise the critical altitude. Initial TBO was 1400 hours but was later raised to 1600 with the NB version of the engine. Most aircraft in the field have been updated to the longer TBO.

Owners describe the 340 as having no bad habits and aside from dealing with a different kind of (high-altitude) weather, flying one shouldnt be a huge step up from an unpressurized, high-performance twin. It would help prospective 340 buyers to have some 310 time, if only to help decipher the complex fuel system. The system, which uses the tip tanks as mains, can hold up to 203 gallons, but requires considerable pilot attention to where the fuel is in the airplane.

The engines can feed from the mains or auxes, but so-called locker tanks are designed to feed directly into the mains. But first you have to move enough fuel out of the mains to make room. Experienced 340 pilots soon work out a system or a rhythm with the fuel system, but its a baited trap for the uninitiated. The insurer will likely specify training at Flight Safety, SimCom or another training company which will give the owner an opportunity to get the fuel system down pat.

Plenty of fuel capacity is generally good, but the 340 is payload limited, with nominally 1600 to 1700 pounds available for gas and goods. Full tanks can force you to leave four of the six seats empty. Vortex generators are available-and probably already fitted to any 340 offered for sale-that boost gross weight by as much as 300 pounds.

Many 340 owners moved up to the 414 largely to get more payload. But if your carrying needs are modest-or the stage lengths short-the 340 might be just the right P-twin for you. Its easy to fly, affordable to operate-at least as this category of airplane goes-and has the added appeal of being a cabin class cruiser.

There’s little question that owning a twin is an expensive proposition, often more than twice the cost of a single. Add pressurization to the mix and you have further potential for fiscal mayhem. Still, a few of these P-twins offer excellent utility and the comfort of no-mask flying for what wed consider not-outlandish costs.

In the overall realm of pressurized twins, the three step-up models we describe here are all winners, in our view. They are all reasonable to operate, can be bought at affordable prices in the current market and have a nice combination of range, speed and utility.

Our top pick in this group? The Cessna 340. Prices on the used market are good, inventory is available and many of these airplanes have been upgraded with newer avionics, autopilots and interiors. Owners seem to uniformly have good things to say about 340s. A budget of $250,000 will buy an early 1980s version and more and more of the inventory is upgraded with newer avionics.

Second pick, the P-Baron. Its a fine-handling P-twin with a stable maintenance record and good parts availability. Its not cheap on the used market so for the dollar spent, we don’t think it represents quite the value that the 340 does. On the other hand, for the dollar invested, it also holds value better when prices get soft, which they may be about to do again.

Our last choice is the P337 but not because its not a worthy airplane. The P337 has been long overlooked by macho pilot types, which explains its bargain prices on the used market. But its actually quite a good airplane if properly maintained. The catch is that not a lot of shops are familiar with the airframe, which can lead to high maintenance bills.

Without the right maintenance, an airplane bought at a dream price could become a nightmare of airplanes that we think a prospective owner should begin his shopping with the maintenance facility that will keep the thing flying. If there isn’t a competent one close by or convenient, be wary of purchasing one.

Also With This Article
“The Twin Cessna Spar Scare”
“Charts and Specs”

-Marc Cook is an Aviation Consumer contributing editor. He lives in Long Beach, California.