IDAHO HELICOPTERS, INC.

MADE AN UNSCHEDULED LANDING AFTER DEPARTURE, PILOT NOTICED A CAS MESSAGE "ROTOR BRAKE". THERE WERE NO ADVERSE INDICATIONS THAT THE ROTOR BRAKE HAD ACTUALLY INADVERTANTLY ENGAGED. MX INSPECTED THE ROTOR BRAKE SYS AND MADE ADJUSTMENTS TO THE SENSOR THAT CALCULATES THE DISTANCE BETWEEN THE BRAKE DISK AND PAD. ACFT WAS RETURNED TO SERVICE.

BROKEN FUEL SCREEN MOUNTING BRACKET, DISCOVERED BY INSP WHEN INSTALLING FUEL CELL, REF ITEM 66 OF FIG 28-1003, BHT 430-MM-4, PN 222-066-624-101. THE MOUNTING BRACKET IS 2 PART AND ATTACHED TO THE SCREEN HOUSING BY SPOT WELDING, THE SPOT WELDS ON THE SECOND PAR OF THE BRACKET APPEAR TO HAVE CRACKS IN THE AREA OF THE SPOT WELDS AS WELL. THIS BRACKET AND HOUSING HOLD THE ENGINE FUEL SUPPLY HOSE IN PLACE, COMPLETE FAILURE OF THE BRACKET COULD ALLOW THE SUPPLY LINE INLET TO DRIFT UP IN THE FUEL CELL AND LEAD TO ENGINE FLAME OUT. PROBABLE CAUSE: DESIGN OR BAD WELD.

WHILE IN CRUISE FLIGHT, MAIN ROTOR TRANSMISSION OIL PRESSURE FLUCTUATION OCCURRED RESULTING IN A FLUCTUATION BETWEEN 65-80 PSI., WITH AN ILLUMINATION OF THE LOW OIL PRESSURE WARNING LIGHT. PILOT LANDED IMMEDIATELY AT HELIPAD. TWO QUARTS OF TRANSMISSION OIL WAS ADDED TO MOBIL SHC 626, CAUSING FOAMING AND THE ABOVE OIL PRESSURE FLUCTUATION. RE-PLACARD TRANSMISSION NEAR SIGHT GLASS IN PLAIN VIEW TO PREVENT MIXING OF OILS. DUE TO PLACARD BEING OBSTRUCTED BY NACA INLET AND FLT MANUAL WORDING. UNLESS PILOT AND/OR MECH WAS POSITIVE OF TRANS PN, IT IS EASY TO ADD WRONG TYPE OF OIL. FLUSHED TRANSMISSION TWICE AND RESERVICE WITH APPROXIMATELY 10 QUARTS OF CORRECT OIL, SYSTEM OPS NORMAL AND AIRCRAFT RETURNED TO SERVI

SERVICE ABOUT 1415 HOURS. AFTER A NORMAL START PROCEDURE AND RUN-UP A DEPARTURE WAS MADE. ABOUT 10 MINUTES INTO FLIGHT, ACID SMELL WAS NOTICED. SCANNED THE INSTRUMENT PANEL ALL INSTRUMENTS WERE IN THE GREEN THERE WERE NO CAUTION LIGHTS. MASTER CAUTION LIGHT FLASHED, TURNED OFF THE MAIN GENERATOR. PLACED THE BUS SWITCH FROM NORMAL TO MANUAL AND TURNED THE AIRCRAFT BACK TO THE AIRPORT. AFTER THE TURN TO THE AIRPORT, THE FIRE LIGHT BEGAN TO FLASH. AFTER LANDING FOUND THE MAIN WIRING HARNESS FROM THE GENERATOR THROUGH THE ENGINE DECK TO BE MELTED AND SMOLDERING.

DEPARTED AIRPORT ABOUT 1415 HOURS. AFTER A NORMAL START PROCEDURE AND RUN-UP A DEPARTURE WAS MADE TO AIRPORT. ABOUT 10 MINUTE INTO THE FLIGHT, ACRID SMELL WAS NOTICED. SCANNED THE INSTRUMENT PANEL ALL INSTRUMENTS WERE IN THE GREEN. THERE WERE NO CAUTION LIGHTS. ABOUT THE TIME I FINISHED MY SCAN THE MASTER CAUTION LIGHT FLASHED, TURNED OFF THE MAIN GENERATOR. PLACED THE BUS SWITCH FROM NORMAL TO MANUAL AND TURNED THE AIRCRAFT BACK TO THE AIRPORT. AFTER THE TURN TO THE AIRPORT, THE FIRE LIGHT BEGAN TO FLASH. AFTER LANDING, FOUND THE MAIN WIRING HARNESS FROM THE GENERATOR THROUGH THE ENGINE DECK TO BE MELTED AND SMOLDERING.