Beechcraft Baron 55 (E55, IO-520-C)

Beech introduced the Baron in 1961 as a refined twin to replace the Travel Air. The original Baron 55 had two Continental IO-470-L engines at 260 horsepower each, an all-metal swept-tail design, and a four-seat cabin. The airplane was instantly successful. Beech sold over 800 Barons in the first three years of production, which was huge for the early-1960s twin market.

Production then ran through serial improvements rather than redesigns. The A55 (1962-1964) added minor refinements. The B55 (1964-1982) was the volume seller and stayed in production for nearly two decades with the IO-470-L engine. The C55 (1966-1968) and D55 (1968-1969) introduced the larger IO-520-C engines at 285 horsepower. The E55 (1970-1982) was the final big-engine variant and the one most buyers focus on today. The E55 received the same fuselage stretch as the Baron 58 family while keeping the smaller 55 cabin. The 55 series ended in 1982 when Beech focused production on the larger 58.

Many Baron 55s have been upgraded over the years. The most common upgrade is conversion to IO-550 engines via STC, which adds horsepower (300 each) and improves TBO numbers (1,700 to 1,900 hours instead of 1,700 for the IO-520). Other common upgrades include modern Garmin avionics, Hartzell Top Prop or three-blade scimitar propellers, and tip-tank STCs to extend range. A clean Baron 55 with all these upgrades approaches the speed and capability of a Baron 58 at a substantial price discount.

Performance numbers depend on which engine is in the airplane. A B55 with the 260 hp IO-470-L cruises at about 175 KTAS on 25 gph total. An E55 with the 285 hp IO-520-C cruises at 185 to 190 KTAS on 28 to 32 gph total. Aircraft with IO-550 STC conversions add another 5 to 8 knots and pick up climb performance, especially at altitude.

Useful load on a typical Baron 55 is about 1,500 pounds. That's roughly 300 pounds less than a Baron 58 due to the shorter fuselage and smaller cabin. Full fuel (136 gallons usable on most variants, less on others) leaves about 700 pounds for people and bags. That's four adults with light bags or two adults with full overnight gear. Range with reserves is about 1,000 nm at long-range cruise.

The Continental IO-470-L (B55) is a six-cylinder, fuel-injected, direct-drive piston engine with a 1,500-hour TBO (1,700 hours for serial numbers 1006000 and later) per Continental Service Information Letter SIL 98-9E. It runs on 100LL. Field overhauls at Western Skyways or Gann Aviation run about $38,000 to $50,000 per engine in 2026 prices. The IO-470-L has a long fleet history with predictable maintenance patterns.

The Continental IO-520-C (C55, D55, E55) is the same engine family as the early Baron 58. TBO is 1,700 hours regardless of serial number per SIL 98-9E. Field overhauls run $50,000 to $60,000 per engine. The IO-520-C has the same light-crankcase history as the engine in the Baron 58, with documented case cracks in the fleet. A pre-buy must include thorough case inspection on any C55, D55, or E55.

Oil consumption on a healthy IO-470 or IO-520 runs about 0.3 to 0.5 quarts per hour per engine. Cylinder work at top-overhaul intervals (around 1,000 to 1,300 hours on hard-flown engines) runs $3,500 to $5,000 per cylinder. Both engines have six cylinders per side. Owners who can afford it tend to convert to IO-550 at overhaul time via STC, which adds about $30,000 to $50,000 over a straight overhaul but improves the airplane's performance and TBO.

Plan on $320 to $480 per flight hour at 150 hours a year of utilization, all-in. The Baron 55 is meaningfully cheaper to own than the Baron 58 mainly because the acquisition price is lower (which reduces insured hull value and the proportional insurance premium), the cabin is smaller (which slightly reduces airframe maintenance), and the older airframes have already absorbed depreciation that newer aircraft are still working through.

Fuel and oil run about $150 to $200 per hour on a B55 at 25 gph and $5.50 to $7 fuel. The E55 with bigger engines runs $170 to $230 per hour. Engine overhaul reserve is about $50 to $70 per hour for two engines on a B55 ($38,000 to $50,000 each over 1,500 to 1,700 hour TBO) and $60 to $80 per hour on an E55 ($50,000 to $60,000 each over 1,700 hour TBO). Airframe maintenance reserve is $40 to $60 per hour. Annual fixed costs (hangar, insurance, annual inspection) add another $60 to $110 per hour at 150 hours a year.

Acquisition cost in mid-2026 ranges by variant. A B55 with mid-time engines and steam gauges trades at $90,000 to $150,000. A clean B55 with engine overhauls done in the last few years and modern Garmin panel sits at $150,000 to $200,000. C55 and D55 examples are limited and trade $100,000 to $200,000. An E55 in flyable condition runs $150,000 to $250,000. IO-550 STC conversions add $40,000 to $70,000 to comparable IO-520 examples.

Insurance is the wildcard. First-time twin owners pay $10,000 to $20,000 a year. Established Baron pilots with American Bonanza Society transition training and 200-plus hours in type pay $5,000 to $9,000 a year. Insurance on the smaller Baron is typically about 70% to 80% of comparable Baron 58 premiums due to the lower hull value.