Helicopter UH-1H 68-15464

 THE PURPOSE OF THE FLIGHT WAS TO PERFORM A VIBRATION CHECK OF A NEW ENGINE INSTALLED BY THE 79TH TRANS. CO. AT QUI NHON, RVN. THE 79TH HAD PERFORMED A TEST FLIGHT BUT FAILED TO INCLUDE THE RESULTS OF THE VIBRATION CHECK AND ENGINE TOPPING CHART IN THE TEST FLIGHT THEY PERFORMED. WO1 EDWARDS MADE THE RUN-UP AND GROUND CHECK OF THE AIRCRAFT. CW2 GROCE SUPERVISED THE ENGINE MAN INSTALLING THE LEADS ON THE VIBRATION METER. WO1 EDWARDS WAS THE PILOT IN CONTROL OF THE AIRCRAFT THROUGHOUT THE ENTIRE FLIGHT. AFTER RECEIVING CLEARANCE FROM THE TOWER HE TOOK OFF USING THE 03 TAXIWAY. WHILE CLIMBING OUT AT 180' AGL AND 70 KNOTS IAS WO1 EDWARDS ELECTED TO MAKE A HYDRAULIC CHECK. THIS MANEUVER WAS NOT CONDUCTED IN ACCORDANCE WITH STANDARD TEST FLIGHT PROCEDURES. WO1 EDWARDS INSTRUCTED CW2 GROCE TO TURN OFF THE HYDRAULIC SWITCH. CW2 GROCE INFORMED WO1 EDWARDS HE WAS TURNING OFF THE HYDRAULIC SWITCH AT THAT TIME AND WO1 EDWARDS PUT THE COLLECTIVE FULL DOWN AND DISCOVERED HE STILL HAD HYD ASSIST AND INFORMED CW2 GROCE HE STILL HAD HYDRAULICS. AT THIS TIME WO1 EDWARDS PULLED IN COLLECTIVE PITCH AND CW2 GROCE REACHED TO RECYCLE THE HYDRAULIC SWITCH AND NOTED THE RPM PASSING THROUGH 6200 AND INFORMED WO1 EDWARDS TO BOTTOM COLLECTIVE PITCH. AT APPROXIMATELY 80' AGL AND 70 KNOTS IAS, WO1 EDWARDS STARTED A DECELERATION TO SLOW HIS FORWARD AIRSPEED, AT APPROXIMATELY 20' AGL 45 KNOTS IAS PULLED INITIAL COLLECTIVE PITCH. DUE TO THE LOW ROTOR RPM, APPROXIMATELY 225, THE AIRCRAFT HAD A HIGH SINK RATE AND HIT IN A TAIL LOW ATTITUDE AND LEVELED SKIDS. THE TAIL BOOM AND STINGER HAD CONTACT WITH THE TAXIWAY FOR 28'7" BEFORE THE SKIDS MADE CONTACT. THE SKIDS ON CONTACT SPREAD AND THE BELLY OF THE AIRCRAFT CONTACTED THE TAXIWAY SLIDING FOR 45 FEET, THEN WENT AIRBORNE FOR 42 FEET, SLID 44 FEET ALIGNED WITH TAXIWAY AND STARTED A SLOW TURN TO THE LEFT. WHEN THE AIRCRAFT STARTED A SLOW TURN WO1 EDWARDS APPLIED FULL LEFT CYCLIC CAUSING THE MAIN ROTOR TO STRIKE THE PAVEMENT AND MAST BUMPING TO OCCUR. THE AIRCRAFT CONTINUED SLIDING ALIGNED ON THE TAXIWAY IN A SLOW TURN AND 2( FEET FROM INITIAL MAIN ROTOR BLADE CONTACT, THE SECOND STRIKE OCCURRED AND THE MAIN ROTOR STRUCK THE TAIL BOOM SEVERING A PORTION OF THE TAIL BOOM AND TAIL ROTOR DRIVE SHAFT WHICH WAS FOUND 124 FEET FROM THIS POINT. AT 215 FEET FROM THE INITIAL POINT OF CONTACT A WHIRD MAIN ROTOR BLADE STRIKE OCCURRED COMPLETELY SEVERING THE TAIL BOOM, THE VERTICAL FIN AND TAIL ROTOR FELL TO THE GROUND AT THAT POINT AND SLID FOR 78 FEET AND STOPPED. THE AIRCRAFT CAME TO REST UPRIGHT HEADED 280 DEGREES AND 353 FEET 2 INCHES FROM THE INITIAL CONTACT POINT. WHEN THE ROTOR BLADES STOPPED TURNING WO1 EDWARDS TURNED OFF THE BATTERY AND NOTED THE MAIN FUEL SWITCH WAS TURNED OFF. THE CREW THEN EXITED THE AIRCRAFT.\\