Preliminary Airworthiness Evaluation (PAE 1) of the YCH-47D Helicopter

The Preliminary Airworthiness Evaluation of the YCH-47D helicopter was conducted between 11 September and 6 December 1979. Seventeen flights were required for a total of 41.4 hours, of which 32.8 hours were productive. Testing was conducted at the Boeing Flight Test Facility at Wilmington, Delaware. The YCH-47D exhibits improved lift capability at a hover (both in and out of ground effect) when compared to the CH-47C with fiberglass rotor blades and T55-L-712 engines. Higher airspeeds are also possible at high gross weights. The AFCS was found to be an enhancing characteristic. Twenty shortcomings and one deficiency were also documented during the test. The deficiency of delay in power steering activation should be corrected prior to operational deployment. The noise level in the cockpit and cabin showed no apparent improvement over previous models and was of sufficient magnitude to induce temporary hearing loss without adequate protection. The vibration levels became excessive above 145 KIAS, increasing to unacceptable prior to V sub H, with 6 per rev vibrations being predominent.