Cessna 337 Skymaster

Overview

The Cessna 337 Skymaster is a twin-engine civil utility aircraft produced from 1965 to 1980, distinguished by its push-pull centerline thrust configuration: one engine faces forward as a tractor, the other faces aft as a pusher, both on the fuselage centerline. Twin booms extend aft of the high wing to the tail, with the horizontal stabilizer mounted between them behind the rear propeller. The design eliminates asymmetric thrust entirely. When one engine fails, there is no yaw, no V_mc hazard, and no critical engine. This was Cessna’s answer to the most dangerous phase of conventional twin-engine flying: the engine failure on or shortly after takeoff.

The FAA recognized the Skymaster’s fundamental difference from conventional twins and created a separate multi-engine rating for centerline-thrust aircraft. A pilot rated in the 337 is not automatically rated in a conventional twin, and vice versa. The aircraft was also adopted by the U.S. Air Force as the O-2A forward air control platform, flying extensively in Vietnam.

The 337G and 337H (1973 to 1980) are the most refined and most commonly traded variants, featuring the electrohydraulic gear system, improved fuel system, and Continental IO-360-G engines. The earlier models used IO-360-C/D engines and a more complex hydraulic gear system inherited from the Cessna 210.

Key Features for GA Buyers

Centerline thrust safety. The Skymaster’s defining feature is the complete absence of asymmetric thrust on engine failure. A single-engine emergency in the 337 is a workload and performance problem, not a control problem. The aircraft has a published single-engine climb rate of approximately 300 FPM: modest, but positive and predictable. For pilots who want genuine twin redundancy without the V_mc exposure of conventional twins, the Skymaster makes a compelling case.

Twin-engine redundancy at near-single-engine operating cost. Two IO-360-G engines running at reduced power each burn roughly 11 GPH, for a combined 22 GPH. That is more than a single-engine 210 but less than most conventional light twins. Purchase prices for late-model examples are substantially lower than comparable conventional twins, reflecting the aircraft’s niche appeal and smaller buyer pool.

Visibility and cabin. The high wing and absence of wing-mounted engines provide outstanding downward and lateral visibility. This was a significant factor in the O-2’s selection for forward air control duty. The cabin seats up to six, though four with baggage is the practical mission.

Useful load. The 337G/H carries approximately 1,500 lbs of useful load, competitive with the Cessna 210 and meaningfully better than most four-seat singles.

Trade-offs

• Maintenance complexity. Two engines, two propellers, a complex gear system, and the rear engine’s difficult access make the 337 a genuine maintenance challenge. Expect annual inspection costs of $4,000 or more. The rear engine in particular requires a specialist and runs hotter than the front due to its enclosed cowl position.
• Rear engine TBO. Both IO-360-G engines carry a 1,500-hour TBO, shorter than most IO-360 variants in single-engine applications. The rear engine typically reaches TBO first. With two engines to overhaul at roughly $20,000 each, the total reserve is significant.
• Not fast. Cruise speed of 144 KTAS at sea level is unimpressive for a twin. The 337 trades speed for its safety concept. Pilots seeking cross-country performance should look at the turbocharged or pressurized variants (T337, P337).
• Noise. The rear pusher propeller operates in disturbed air from the front propeller and airframe, producing a distinctive and loud cabin environment. Owners widely cite this as the aircraft’s most fatiguing characteristic on long flights.
• Niche rating. The separate centerline-thrust multi-engine rating limits the pool of qualified pilots and instructors, which can complicate training, insurance, and resale. Finding a current CFII familiar with the type requires planning.
• Parts and specialist knowledge. With production ending in 1980, some 337-specific components require sourcing through specialists. A shop experienced with the type is strongly recommended.

See Also

• Cessna P337 Pressurized Skymaster – pressurized and turbocharged variant; adds cabin pressurization and altitude performance at substantially higher cost and complexity
• Piper PA-34 Seneca – conventional twin in the same class; faster cruise and a larger buyer pool, with the V_mc considerations the Skymaster avoids
• Beech Baron 55 – lighter and more affordable Baron variant; a common alternative for buyers weighing the Skymaster’s safety concept against conventional twin performance
• Beech 58 Baron – the larger, more capable Baron; stronger cruise performance and range, at a higher price point