In the light-twin world, there’s Cessnas 337 Skymaster push-me/pull-you design-plus a handful of Adam 500s-and then there’s everything else. Eliminating asymmetric thrust from the single-engine handling equation was what Cessna had in mind when it brought the Skymaster to market. It succeeded, since the airplane handles pretty much the same when one or both engines are turning. But some compromises were made along the way, many of which can hike maintenance costs. In an engine-out situation, conventional piston twins generally need to be handled with kid gloves lest the airplane get too slow and roll over on its back. Close to the ground, that can be very bad. Which is one reason Cessna aligned the Skymasters two engines with the airframe centerline, offering pilots the safety of a second engine without the penalty of adverse handling. If one quits, identify it, feather it and don’t worry about the dead-foot, dead-engine drill. The FAA even granted the 337 its own class rating, limiting pilots to centerline-thrust twins only. That part of Cessnas plan worked, since there’s little question the Skymaster is easier to fly on a single engine than a conventional twin. But, since the VMC rollover accident doesnt happen that often in the real world, the airplanes overall accident record isn’t that much better than conventional twins. A pilot looking to improve redundancy by stepping up from a single to a twin certainly will achieve it with a Skymaster. But in the bargain of gaining redundancy, pilots can be forced to accept a platform with more cabin noise, a set of operating peculiarities all its own and tightly packaged systems presenting more of a challenge to maintenance personnel than if each engine resided on its own wing. All of which might argue in favor of the single. Until the singles engine fails, that is.
The 337 Skymasters front/rear engine layout and high wing started out as the fixed-gear Model 336 in 1964, powered by Continental IO-360-A engines of 195 HP apiece. Widely acknowledged as a slug, Cessna sold only 195 336s in one year of production; 86 remain on the FAAs registry today. In 1965, the company folded the gear and upgraded powerplants to a pair of Continental IO-360-Cs pumping out 210 HP, resulting in the 337 Skymaster. Cessna sold 239 copies that year. (Not really learning from its 336 experience, Cessna flew a cantilever-winged, lower-powered version, the 327, in late 1967, but it proved too slow and the project was dropped the next year.)
To make the original 336 a retractable, Cessna borrowed the complex and troublesome hydraulic landing gear system from the 210. In 1973, it was upgraded to a simpler and more reliable electro-hydraulic system. While less complex and easier to maintain, the system still isn’t as robust as, say, a Barons or Senecas.
Early models also came with multiple fuel tanks, another system proving problematic in the field. It, too, was replaced in 1973 by a superior, less complicated system. A turbocharged version-the T-337B, powered by 210-HP TSIO-360-A or -B engines from Continental-appeared in 1967, but was dropped in 1972 with the addition to the Skymaster line of the almost-revolutionary pressurized 337 version, the T-337 G-P, powered by TSIO-360-C engines up-rated to 225 HP.
The turbo reappeared in 1978, with TSIO-360-H powerplants, but Skymaster sales had begun slipping by then. Cessna pulled the plug following the 1980 model year, after a total production run of 2058, plus 332 pressurized versions. In addition, Cessna built slightly more than 500 Skymasters for the U.S. Air Force, which saw action in Vietnam as the O-2A. It boasts structural beefups, hard points and extra windows. These airplanes frequently appear on the used market and may we’ll be the least expensive warbirds available. Additionally, some civilian models were converted to an O-2B configuration for the military to use in psychological warfare.
Major tweaks were few, but there were many designation changes. Beginning in 1970, some inspection panels were added-making maintenance easier-and the airframe was lightened a bit, increasing useful load. The interior arrangement also changed through the years, with various combinations of seat mounting.
As is not uncommon with any aircraft, the non-pressurized 337s gross weight crept up during its years in production. Early models started at around 4200 pounds; late ones weighed 4630 pounds, with max landing weight limited to 4400 pounds. Meanwhile, the P-337, with its 30 extra horsepower, had a takeoff weight of 4700 pounds and max landing weight of 4465 pounds.
These days, piston-twin prices are as soft as ever, and the 337 is no exception. On the up side, most of the depreciation has been squeezed out of these airframes. The downside? Cessna 337s cant be counted on to increase much in value. But a Skymaster is a lot of airplane for the money. Besides current fuel prices and future uncertainties, other factors depressing prices are that the 337 has a reputation for being a maintenance hog-one largely undeserved as twins go-and they arent all that fast.
Buyers should be aware, however, that buying a cheap twin is not the same as operating a twin cheaply. A hangar queen will eat through a bunch of money if it needs remedial work and, in any case, you’ll need to find a shop familiar with the breed to do the pre-buy and maintain the airplane going forward. The Skymaster doesnt perform much better than a Cessna 210, and it has two of everything to maintain and replace, driving up ownership costs. But, of course, it has two of everything.
Skymasters arent speed-demons, though the turbocharged models do respectably we’ll for pilots willing to take them into the teens. Owners of normally aspirated models can plan on between 155 and 165 true knots, depending on altitude and how much fuel they want to burn. The turbocharged and pressurized models will push 190 to 200 knots at 20,000 feet, their maximum certified altitude. At middle altitudes, 170 to 180 knots is typical for the turbo models, which aint bad.
Since Skymasters have relatively small displacement six-cylinder engines, fuel burn tends to be reasonable, ranging from 15 GPH to 22 GPH total, with 19-20 GPH typical for a 150- to 160-knot cruise. For comparison, a Twin Comanche will do