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Helicopter Technology From Naval Air Warfare Center Aircraft Division

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Two fundamental but very important improvements to helicopter operations have been developed and patented at Naval Air Warfare Center Aircraft Division Patuxent River (NAWCAD). One relates to rotor blade monitoring, and the other involves illumination of the messenger cable during nighttime or marginally optimum operations. Both technologies offer low-cost solutions to current helicopter operating hazards that could also benefit other industries. [caption id="attachment_13542" align="alignleft" width="300" caption="Sailors aboard the forward-deployed aircraft carrier USS George Washington attach "legs" to an MH-60S Seahawk with the "Sea Knights" of Helicopter Combat Squadron 25 during an at-sea ammunition on-load with the Military Sealift Command dry cargo and ammunition ship USNS Charles Drew. (Photo: U.S. Navy, Mass Communication Specialist 3rd Class Paolo Bayas)"][/caption] Civilian and military pressurized helicopter blades have a finite operating life, with factors such as fatigue and damage through use rendering blades unserviceable. The early indication of loss of blade pressure, damage, or fatigue cracking is an important safety advisory to the helicopter crew, which can determine the flight worthiness of the helicopter and to avoid blade associated in-flight hazards. The United States Navy and Marine Corps currently use an inspection system called In-Flight Blade Inspection System (IBIS) to detect loss of pressurization, damage and blade condition. However, the current system uses a radioactive isotope (strontium 90) to communicate to a sensor in the aircraft when the ideal pressure goes below a safe threshold. Disposal of the radioactive isotope must be handled as hazardous material, driving up costs for logistic support, disposal, repair, replacement, as well as the impact of radioactive materials to the environment and the possible exposure of personnel to radiation in the event of a flight or ground mishap. NAWCAD’s Wireless Blade Monitoring System provides real-time, in-flight advisory of the blade pressurization and structural condition of a helicopter’s rotor blade(s) without using hazardous material. The system uses inexpensive and commonly available digital sensors and modern battery and wireless communication technologies in a unique manner that produces a highly reliable advisory information system capable of enhancing flight safety while reducing operating costs. The new system meets form, fit and function requirements, and is easy to use, relatively simple to manufacture, and economical to install on both military and commercial helicopters. The components are controlled by nonproprietary, open architecture software. In addition to indicating blade health on a cockpit display, the wireless device can communicate with a laptop or handheld PC for ground safety checks. The labor and skill required to install the wireless monitoring system in place of currently used systems is minimal since the new system is designed to plug directly into existing sockets and sensor holders. Since the new system is easy to modify with software and other components, the technology would be advantageous in various applications where gas pressure and temperature need to be monitored, e.g., chemical plants, nuclear power plants, refineries, and other remote monitoring of sensors, particularly in dynamic/rotating systems where wired systems are inappropriate. In the United States, shipboard landing for some helicopters is achieved through a system called RAST (recovery assist, secure and traverse) and utilizes a haul-down device that involves attaching a cable to a probe on the bottom of the aircraft prior to landing. The secondary purpose of the haul-down device is to equalize electrostatic current between the helicopter and ship, as the rotor blades of a helicopter can cause large charges to build up on the airframe that would be serious enough to cause injury to ship personnel if they touch any part of the helicopter as it approaches the helicopter deck. During night landings or inclement weather, the ship’s helicopter deck is marginally lit and, as a result, the ship’s deck crew may not be able to see the haul-down device, known as the messenger cable, to capture it for hookup operations as it dangles from the helicopter. Dangerous operational situations can occur if the cable becomes snarled with the ship’s hardware or entangled with a crewman. The delay of recovery of the helicopter resulting from possible hookup difficulties could also occur, especially during emergency situations. NAWCAD’s simple solution to low visibility of a helicopter’s messenger cable is to affix a short piece of luminescent “glow” cover to the cable spanning the distance from the top of the messenger probe to the pulley. A bracket with a halogen or UV charging light is added near the cable adjacent to the cable sheave, allowing this light to charge the luminescent material so that it retains a visual glow for at least ten minutes and be visible to the ship’s crew when lowered during the helicopter recover evolution. The Helicopter Messenger Cable Illumination allows the flight deck crew to maintain eye contact with the messenger cable to the ship’s flight deck, resulting in increased shipboard safety. Along with Department of Defense helicopters, NAWCAD’s Helicopter Messenger Cable Illumination should be attractive to first responders, firefighters, forest and rescue services, as well as the rock climbing enthusiast. [caption id="attachment_13543" align="alignright" width="300" caption="A MH-60S from Helicopter Sea Combat Squadron Two One approaches the flight deck of amphibious transport dock USS New Orleans during night flight operations. New Orleans is underway earning its amphibious warfare certification and aviation readiness qualification. (Photo: U.S. Navy, Mass Communication Specialist 2nd Class Gary Granger Jr.)"][/caption] In addition to the helicopter technologies detailed, NAWCAD’s Naval Aviation Center for Rotorcraft Advancement (NACRA) operates the Department of Defense’s only maritime vertical lift test bed capability. Available to government agencies, industry, and academia through research vehicles such as a CRADA (cooperative research and development agreement) or work with private party agreement, the facilities offer a wide range of rotor wing technology and expertise. NACRA’s T-Rex (testbeds for rapid warfighter response and experimentation) facility and team are centered on two UH-1N Huey flying test bed helicopters and offer a small, multi-disciplined team working across the rotorcraft community to help identify and develop technologies beneficial to the current and future rotorcraft fleet. The test beds feature modern communication, navigational and survivability equipment including a 1553 data bus, ARC-210 radios and embedded GPS. Additional capability includes an external sensor with in-dash display and reconfigurable component racks allowing for rapid flight clearance approval. For more information on these two technologies or NACRA’s T-Rex facilities, please contact the NAWCAD Technology Transfer Office at (301) 342-1133.
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