PLT OF EC120 HELI MAKES FORCED OFF FIELD LNDG NEAR SBP AFTER COWLING LEFT UNLATCHED BEFORE TKOF COMES OFF AND CONTACTS MAIN ROTOR.

Narrative

I TOOK OFF ON AN FAR PART 91 FLT FROM SBP FOR THE BIG SUR COASTLINE WITH THE OWNER OF THE ACFT. APPROX 6 MI NW OF THE ARPT; WE HEARD A THUNK. I LOOKED INTO THE MIRROR AND SAW THAT THE STARBOARD ENG COWLING WAS LOOSE. I IMMEDIATELY MADE AN EMER LNDG ON TOP OF A HILLTOP THAT IS PART OF A HORSE PASTURE. THE LNDG WAS NORMAL. ROTOR RPM NEVER DROPPED AND PWR AND VIBRATION LEVELS WERE NORMAL. UPON SHUTDOWN; I COULD SEE THAT THE LOWER THIRD OF THE COWLING HAD BEEN TORN AWAY AND THAT THE ROTOR BLADES HAD BEEN SCRATCHED NEAR THE BLADE ROOT; PRIMARILY ON THE STAINLESS STEEL LEADING EDGE. THERE WAS NO EVIDENCE OF ANY CONTACT OR DAMAGE TO THE TAIL; HORIZ OR VERT STABILIZERS OF THE ADJACENT COWLINGS. THERE WAS NO EVIDENCE OF FOREIGN OBJECT INGESTION INTO THE ENG. THE INTAKE WAS CLEAN AND THE SCREEN WAS UNDAMAGED. I KNOW WHY THIS INCIDENT HAPPENED. WHEN WE WERE GOING THROUGH THE START PROB AND HIT THE STARTER; NOTHING HAPPENED. WE RAN THROUGH THE PROC AGAIN AND ONCE MORE IT DIDN'T CRANK. I CHKED THE CIRCUIT BREAKERS AND THEN REMEMBERED SOMETHING I HAD LEARNED IN THE EC120 COURSE. THERE IS A MICROSWITCH ON THE ROTOR BRAKE THAT WILL NOT LET THE STARTER ENGAGE IF THE ROTOR BRAKE IS ON. THEY HAD TOLD US THAT IT OCCASIONALLY STICKS. SO; I TOOK THE PLASTIC END OF A SCREWDRIVER AND TAPPED THE SWITCH. THEN; I LOWERED THE COWLING WITHOUT LATCHING IT BECAUSE I WASN'T PLANNING TO START. I JUST WANTED TO TAP THE STARTER SWITCH TO SEE IF IT WOULD ENGAGE. IT DID. THE TAP HAD SOLVED THE PROB. I WAS EXCITED THAT I HAD FOUND THE PROB. I THEN GOT OUT OF THE SHIP AND LOOKED AFT TO BE SURE THE COWLING WAS CLOSED AND FORGOT THAT I HAD LEFT IT UNLATCHED. I BROKE A FUNDAMENTAL RULE OF MINE; WHICH IS TO ALWAYS WALK AROUND THE ACFT JUST BEFORE YOU GET IN TO CHK OBVIOUS THINGS SUCH AS LATCHES; FUEL CAP; TIE-DOWNS; COVERS; AND ROTOR BLADE CONDITIONS. AS OF THIS WRITING; THE HELI IS STILL ON THE HILLTOP.