Safety & Survivability
The AVX team has significant experience providing survivability with a range of rotorcraft including the V-22, AH1Z, UH1Y and OH58D. The OH-58D/AVX retains the airframe survivability of the Kiowa Warrior. The existing armor protection for the crew, engine and fuel controls will be maintained. The main rotor hubs and blades for the OH-58/AVX are of all composite laminated construction designed to withstand ballistic impacts equal to the system on the current OH-58D helicopter, which has proven to absorb hits by small arms fire up to .50 Cal without catastrophic failure.
The OH-58D/AVX helicopter shall be capable of operation in adverse conditions such as extreme heat and cold (-40 to +40 degrees C), IFR meteorological flight conditions (including rain and inadvertent light icing), blowing sand and dusty landing zones, and salt water environment. The engine will utilize the same air filtration system as the Engine Barrier Filter (EBF) on the OH-58D helicopter. The laminated composite main rotor hubs and blades will have similar ballistic tolerance to the OH-58D rotor system. The rotor blades will incorporate a leading edge abrasion strip to minimize wear during flight in rain, sand and dust, and the composite material will be immune to the affects of operation in a salt water environment.
The drive system and rotating controls have been designed with sealed bearings to minimize intrusion by foreign particles and thereby provide for long life and safe operation in any type hostile environment where military operations may be conducted.
Drive System and Ducted Fans
The Drive System survivability is integrated with the aircraft design to allow continued aircraft operation with one fan operating or with both fans inoperative with the main gearbox functioning normally. The fans may be damaged or the center and/or either fan gearbox may be damaged or have the lubrication lost and the main gearbox can power the aircraft back to a safe landing site using the main rotor controls and power to the main gearbox.
The main transmission is designed to continue to rotate without lubrication but the gearbox may lose power. The gearbox is designed so it will not jam if lubrication and power is lost so the aircraft can operate similar to a gyrocopter with the fans providing the propulsion and the main rotors providing the lift. This allows the aircraft to find a suitable landing site and auto rotate to the ground.
Brownout
The AVX fans can be used to decelerate while approaching a landing with a 5-10° nose down approach, eliminating the need to flare to a hover, which could dramatically decrease the risk of “brownout”. AVX hired Continuum Dynamics, Inc (CDI) to perform an analysis differentiating the modified OH-58D/AVX and the unmodified (OH-58D) aircraft to evaluate the standpoint of brownout in representative fields of sand/dust. CDI’s initial studies concluded that the AVX configuration will decrease the susceptibility of brownout with a 5-10° nose down approach. Additional studies are being performed.