The T-45 project office has been conducting a flutter test program, gradually expanding the stabilator freeplay to ensure that the aircraft does not encounter flutter throughout the envelope. The goal of the flight test effort is to expand the freeplay envelope to 0.30o without restrictions in an effort to reduce unnecessary down time and save on the cost of replacement parts. Pilots and engineers from Pax have completed approximately half of the program and have not encountered flutter or limit cycle oscillations. Environmental Control System Fog and Ice by LCDR Don Parker, USN An excessive amount of water enters the Goshawk cockpit through the ECS system in the forms of liquid, fog, snow and ice. Ice chunks frequently navigate the defog ducts and impact the pilot's visor.
Water also falls from the eye vents onto the consoles, potentially promoting corrosion.
I testing discovered that a pressure relief valve opened unexpectedly following a pressure build up in the water separator and coalescer sock. Additionally, temperature and flow oscillations were observed that appeared unrelated to any pilot activity. The tests also demonstrated that the ECS turbine outlet temperature was too cold, resulting in temperatures of 19o F in the coalescer. The temperature in the coalescer must be above freezing to prevent ice build up. The testing also discovered that the current temperature controller has an extremely high variability in the temperature of the air being discharged from the ECS system.