SYNTHETIC ROPE FOR HELICOPTER RESCUE HOISTS

SINCE HELICOPTERS WERE FIRST USED FOR RESCUE ACTIVITIES AND AIR CARGO LIFT OPERATIONS, THERE HAS ALWAYS BEEN A POTENTIAL HAZARD ASSOCIATED WITH THE HIGH ELECTROSTATIC POTENTIAL OF THE AIRCRAFT RELATIVE TO THE EARTH GROUND BELOW DURING MISSIONS CONDUCTED IN SNOW, RAIN OR DUST. THE PRESENCE OF THESE ELEMENTS IN THE FLIGHT ENVIRONMENT CREATES A SEVERE CHARGING PROBLEM AS STATIC POTENTIAL ACCUMULATES RAPIDLY AND REACHES LEVELS GREAT ENOUGH TO CAUSE SEVERE BURNS OR DEATH TO PERSONNEL, SHOULD THEY PROVIDE A DIRECT GROUND PATH FROM THE AIRCRAFT TO EARTH. RECENT ADVANCES IN THE DEVELOPMENT OF HIGH MODULUS MULTIFILAMENT MATERIALS PROVIDE THE OPPORTUNITY TO DESIGN A NON-METALLIC ALTERNATIVE TO THE WIRE ROPE HOIST CABLE. WE PROPOSE TO DESIGN AND FABRICATE HOIST CABLES WITH EACH OF THREE CANDIDATE FIBERS (KEVLAR, TECHNORA AND SPECTRA) WITHIN THE PRESENT HOIST CABLE HARDWARE ENVELOPE. BY TEST, WE WILL DETERMINE THE FATIGUE PROPERTIES OF THESE CABLES. MICROSCOPIC EXAMINATION OF FILAMENT DAMAGE WITHIN THESE CABLES AFTER CYCLING WILL BE CORRELATED WITH EACH CABLE'S COMPOSITION AND LOAD HISTORY TO SELECT THE BEST MATERIAL/DESIGN COMBINATION. RELIABLE INSPECTION AND RETIREMENT CRITERIA FOR SYNTHETIC HOIST CABLES WILL BE DEFINED TO ASSURE THE RELIABILITY AND MINTAINABILITY OF THIS NEW HARDWARE.