ARMY AVIATION SYSTEMS TEST ACTIVITY EDWARDS AFB CA
A limited performance evaluation was conducted to determine the effects of increasing the tolerances on contour, inboard twist and outboard twist on the OH-6A helicopter main rotor blades. The performance areas investigated were hovering performance, level flight performance and blade stall onset airspeeds. The tracking effort required for each set of blades was also investigated. Four blades with expanded contour tolerances, four blades with expanded inboard twist tolerances and four blades with expanded outboard twist tolerances were flown during this program. An additional blade configuration consisting of three blades with a different tolerance deviation on each blade and a standard production blade were flown to determine the blade stall onset airspeeds. The airspeeds for the expanded tolerance blades compared closely to the same blade stall airspeeds for a set of master blades. The hovering and level flight performance for the expanded tolerance blades compared closely to the hovering and level flight performance for standard production blades used on the Phase D test program and the LOH Competition. The tracking effort was acceptable for the expanded tolerance blades that had been pre-tracked on a whirl tower.