REPORTEDLY, THE PLT & PASSENGERS HAD GONE TO A LOCAL ESTABLISHMENT, WHERE THE ENTIRE PARTY HAD CONSUMED AN UNSPECIFIED AMOUNT OF ALCOHOLIC BEVERAGES. ONE PASSENGER REPORTED THAT AFTER ARRIVING AT THE ARPT, THE PLT MADE A WALK-AROUND INSPECTION OF THE HELICOPTER, & BEFORE TAKING OFF, HE PERFORMED AN ENG RUN-UP. SHORTLY AFTER THE ACFT HAD DEPARTED, THE LEFT CHIP DETECTOR LIGHT ILLUMINATED & THE PLT PROCEEDED TO RETURN TO THE ARPT. ALMOST IMMEDIATELY, THE RIGHT CHIP DETECTOR LIGHT ALSO ILLUMINATED, THEN BOTH ENGS LOST POWER. THE PLT ENTERED AN AUTOROTATION, BUT WHILE AVOIDING POWER LINES, AVAILABLE LIFT WAS EXPENDED & THE HELICOPTER LANDED HARD. THE OCCUPANTS RECEIVED SERIOUS BACK INJURIES DURING THE LANDING. AN INVESTIGATION REVEALED THAT THE HELICOPTER HAD BEEN PARKED OUTSIDE THE HANGER FOR CONTINUING REPAIRS & THE OIL SUPPLY LINES TO THE SENSORS HAD BEEN DISCONNECTED. SUBSEQUENTLY, OIL WAS LOST THRU THE DISCONNECTED LINES & BOTH ENGS HAD FAILED. A CHECK OF THE PLT'S BLOOD SHOWED AN ALCOHOL LVL OF 0.04%