Known by Helio as the model H-500 this STOL aircraft mounted twin Lycoming engines on top of the high-set wing, close to the fuselage. With the engines mounted in this manner, lateral and over-the-nose visibility were much improved while the propellers were kept clear of cabin doors and away from possible debris damage during rough field operations. This was a tail-wheel design, so the vertical component of propeller thrust assisted STOL take-off performance from rough fields. Fully automatic full-span, leading-edge slats were fitted along with high-lift flaps.
In 1967 or 68, work was started on a redesign of the Twin Courier in a tricycle-gear configuration for the commercial market, since many firms which desired STOL capability had regulations which required multi-engine aircraft. The company ran out of money and the project was terminated.
The aircraft structure of the Helio Stallion, a single-engine turboprop version of the more successful Helio Courier, was based on the design of the Twin Courier.
The Twin Courier could seat six and first flew in April 1960, being awarded FAA certification on June 11, 1963. (The Twin Courier met FAA requirements marginally and was certificated to meet immediate needs for service in Vietnam, on the understanding that the design would not be marketed commercially. Thus, the redesign.) Only seven examples were built, these receiving the United States Armed Forces designation U-5A. One was reported to have been evaluated by US Army Special Forces.
U-5A Twin Courier
Official Air America records preserved at the Air America Archives do not mention such an aircraft, but there are three ways to explain why Twin Couriers were mentioned to have been in service with Air America:
In the summer of 1965, Air America pilot William Andresevic, who had flown the regular Helio extensively in Laos, was ordered to fly a Helio Twin Courier to Bolivia for evaluation by the US Embassy.
After some operational use in Bolivia, it was returned to an airstrip in Virginia.
In 1962, the USAF evaluated 2 U-5A Twin Couriers, 59-5955 and 59-5956, at Hulburt for use by the air commandos. “90336” is possibly a fake serial for 59-5956.
Operators were Aviation Research Centre, India, Indian Intelligence Bureau, Air America, CIA and United States Air Force.
U-5A Twin Courier
Powerplant: 2 × Lycoming O-540-A2B or -C2C air-cooled flat-six, 250 hp (190 kW) each
Propellers: 2-bladed Hartzell, 7 ft 0 in (2.13 m) diameter
Length: 32 ft 0 in (9.75 m)
Wingspan: 41 ft 0 in (12.50 m)
Height: 8 ft 10 in (2.69 m)
Wing area: 242 sq ft (22.5 m2)
Empty weight: 3,126 lb (1,418 kg)
Max takeoff weight: 5,850 lb (2,654 kg)
Maximum speed: 185 mph (298 km/h; 161 kn) at sea level
Cruise speed: 166 mph (144 kn; 267 km/h) (econ cruise, 60% power) at 10,000 ft (3,050 m)
Range: 1,500 mi (1,303 nmi; 2,414 km) (max fuel)
Service ceiling: 19,500 ft (5,944 m)
Rate of climb: 1,640 ft/min (8.3 m/s)
Capacity: 5 passengers