Aircraft Type: Hughes OH-6 Cayuse
The Hughes OH-6 Cayuse (nicknamed "Loach", after the requirement acronym LOH—Light Observation Helicopter) is a single-engine light helicopter with a four-bladed main rotor used for personnel transport, escort and attack missions, and observation. Hughes Helicopters also developed the Model 369 as a civilian helicopter, and the Hughes Model 500, currently produced by MD Helicopters as the MD 500.
A heavily modified pair of OH-6As were utilized by the CIA via Air America for a covert wire-tapping mission in 1972. The aircraft, dubbed 500P (penetrator) by Hughes, began as an ARPA project, codenamed "Mainstreet", in 1968. Development included test and training flights in Culver City, California (Hughes Airport) and at Area 51 in 1971. In order to reduce their acoustic signature, the helicopters (N351X and N352X) received a four-blade 'scissors' style tail rotor (later incorporated into the Hughes-designed AH-64 Apache), a fifth rotor blade and reshaped rotor tips, a modified exhaust system and various performance-boosts. Deployed to a secret base in southern Laos (PS-44) in June 1972, one of the helicopters was heavily damaged during a training mission late in the summer. The remaining helicopter deployed a wiretap near Vinh, Vietnam on the night of 5–6 December 1972, which provided the United States with useful information during the Linebacker II campaign and Paris Peace Talks. Shortly thereafter, the aircraft were returned to the U.S., dismantled and quietly found new homes as the now-standard 500s.
964 out of the 1,422 OH-6As built for the US Army were destroyed in Vietnam, mostly from hostile ground fire.