Light Observation Helicopter

The Light Observation Helicopter (LOH) program was a United States Army program to evaluate, develop and field a light scout helicopter to replace the Army's aging OH-13 Sioux. The program gained impetus with the advent of the Vietnam War and was aided by advances in helicopter technology, specifically the development of the turboshaft engine. Three of the aircraft evaluated for the program would eventually enter military service, one as a training helicopter and two as observation helicopters used for battlefield reconnaissance missions.

In July 1953, the Office of Lieutenant General John Dahlquist, Chief, Army Field Forces (AFF), forwarded desirable military characteristics for a two-place reconnaissance helicopter to Army Headquarters. Nearly a year later, in May 1954, Dahlquist's office once again emphasized the need for replacement aircraft and recommended procurement of troop test quantities of the YH-32. Preliminary evaluation of the YH-32 design revealed that the aircraft was unsuitable for the mission, and the tests were canceled.

In 1955, the Army Field Forces were transformed into the Continental Army Command (CONARC). Dahlquist, who had been promoted to 4-star General on 18 August 1954, continued in command. On 11 October 1955, CONARC recommended that the Department of the Army initiate a program to develop a replacement observation helicopter for the aging OH-13 Sioux and OH-23 Raven. Army's Chief of Research and Development agreed to include the requirement for a new helicopter in the budget for fiscal year 1957 on 19 March 1956, after CONARC highlighted the continued lack of development for replacement aircraft.

During the course of the next three years, three helicopters would be evaluated as candidates to replace the OH-13 and OH-23; the Sud-Ouest Djinn, the Hughes 269, and the Brantly B-2. The aircraft were designated the YHO-1 DJ, YHO-2 HU, and YHO-3 BR, respectively. By October 1958, service testing of Sud Aviation YHO-1 DJ was completed. The following year saw the completion of the desert and temperate temperature testing of the YHO-2 HU. The YHO-3 BR did not complete user testing after engineering evaluations revealed significant deficiencies. Service testing demonstrated that the YHO-2 had been the most capable, but due to a limited load capability, it was deemed not suitable to replace the OH-13.

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