Narrative:

Katama (1b2) to hfd. Estimated flight time 1 hour 10 mins with fuel 2 hours 20 mins. On engine start, noted that after clutch engaged it required more than 10 seconds for helicopter's blades to begin to swing -- indicating that clutch limiter stop should be adjusted. Prior to liftoff, turned on panel lights and map light anticipating landing at night. Flight following from cape approach and pvd approach proceeding directly to hartford. 5-10 mins after passing jamestown bridge, I noticed a low level glow in the clutch warning light. A low level constant dim light -- described as a dim buzz, can mean that the drive belts are beginning to fail in the R22 and that loss of power to the rotor system may be imminent. The emergency procedure is to pull the clutch circuit breaker and land as soon as possible while anticipating possible need for autorotation. I pulled the breaker, and called mayday requesting nearest airport location from pvd approach. Richmond was 6 mi south with quonsey 7 or 8 mi east. Over woods at the time, initiated a right 270 degree turn to locate a place for immediate landing if required before proceeding to richmond. Proceeded to richmond on vectors from approach, reporting 'airport in sight' and 'landing assured.' landed without incident and taxied to ramp to check the belts -- saw no problem. By now it was dark enough so that when I got back in the aircraft I noticed the map light was pointing at the panel, not down at my kneeboard. When the map light was adjusted to point downwards, the glow in the warning light dimmed. The glow disappeared altogether when shielded from the maplight by my hand. Departed richmond to resume flight to hartford brainard. Rest of trip was uneventful. During the start- up, I had listened carefully, watching for any indication of a belt not tightening properly on the sheave. So the condition of the belt system was on my mind at the start of the flight. I was still 'pre-wired' to assume when the glow in the clutch light appeared that something was indeed amiss, and did not hesitate to declare an emergency. In retrospect, the warning light 'glow' was steady - not 'buzzing' or flickering on and off, which is the key to the actually potentially dangerous condition. Lessons learned: in spite of the fact that the glow in the warning light was misinterped as an extremely hazard warning -- declaring the emergency and getting the aircraft on the ground where the problem could be assessed safely was the right thing to do. On the next flight, excess slack, if any, will be taken out of the belts by engaging the clutch prior to engine start until the factory specified limits are achieved. The first step will be to have the clutch limit stop adjusted to allow for further stretching as the belts continue to break in.

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Original NASA ASRS Text

Title: A ROBINSON 22 HELI PLT CALLS FOR A FLT ASSIST TO NEAREST ARPT WHEN HE SEES A WARNING LIGHT THAT INDICATES AN IMMINENT PWR LOSS TO HIS ROTOR DRIVE.

Narrative: KATAMA (1B2) TO HFD. ESTIMATED FLT TIME 1 HR 10 MINS WITH FUEL 2 HRS 20 MINS. ON ENG START, NOTED THAT AFTER CLUTCH ENGAGED IT REQUIRED MORE THAN 10 SECONDS FOR HELI'S BLADES TO BEGIN TO SWING -- INDICATING THAT CLUTCH LIMITER STOP SHOULD BE ADJUSTED. PRIOR TO LIFTOFF, TURNED ON PANEL LIGHTS AND MAP LIGHT ANTICIPATING LNDG AT NIGHT. FLT FOLLOWING FROM CAPE APCH AND PVD APCH PROCEEDING DIRECTLY TO HARTFORD. 5-10 MINS AFTER PASSING JAMESTOWN BRIDGE, I NOTICED A LOW LEVEL GLOW IN THE CLUTCH WARNING LIGHT. A LOW LEVEL CONSTANT DIM LIGHT -- DESCRIBED AS A DIM BUZZ, CAN MEAN THAT THE DRIVE BELTS ARE BEGINNING TO FAIL IN THE R22 AND THAT LOSS OF PWR TO THE ROTOR SYS MAY BE IMMINENT. THE EMER PROC IS TO PULL THE CLUTCH CIRCUIT BREAKER AND LAND ASAP WHILE ANTICIPATING POSSIBLE NEED FOR AUTOROTATION. I PULLED THE BREAKER, AND CALLED MAYDAY REQUESTING NEAREST ARPT LOCATION FROM PVD APCH. RICHMOND WAS 6 MI S WITH QUONSEY 7 OR 8 MI E. OVER WOODS AT THE TIME, INITIATED A R 270 DEG TURN TO LOCATE A PLACE FOR IMMEDIATE LNDG IF REQUIRED BEFORE PROCEEDING TO RICHMOND. PROCEEDED TO RICHMOND ON VECTORS FROM APCH, RPTING 'ARPT IN SIGHT' AND 'LNDG ASSURED.' LANDED WITHOUT INCIDENT AND TAXIED TO RAMP TO CHK THE BELTS -- SAW NO PROB. BY NOW IT WAS DARK ENOUGH SO THAT WHEN I GOT BACK IN THE ACFT I NOTICED THE MAP LIGHT WAS POINTING AT THE PANEL, NOT DOWN AT MY KNEEBOARD. WHEN THE MAP LIGHT WAS ADJUSTED TO POINT DOWNWARDS, THE GLOW IN THE WARNING LIGHT DIMMED. THE GLOW DISAPPEARED ALTOGETHER WHEN SHIELDED FROM THE MAPLIGHT BY MY HAND. DEPARTED RICHMOND TO RESUME FLT TO HARTFORD BRAINARD. REST OF TRIP WAS UNEVENTFUL. DURING THE START- UP, I HAD LISTENED CAREFULLY, WATCHING FOR ANY INDICATION OF A BELT NOT TIGHTENING PROPERLY ON THE SHEAVE. SO THE CONDITION OF THE BELT SYS WAS ON MY MIND AT THE START OF THE FLT. I WAS STILL 'PRE-WIRED' TO ASSUME WHEN THE GLOW IN THE CLUTCH LIGHT APPEARED THAT SOMETHING WAS INDEED AMISS, AND DID NOT HESITATE TO DECLARE AN EMER. IN RETROSPECT, THE WARNING LIGHT 'GLOW' WAS STEADY - NOT 'BUZZING' OR FLICKERING ON AND OFF, WHICH IS THE KEY TO THE ACTUALLY POTENTIALLY DANGEROUS CONDITION. LESSONS LEARNED: IN SPITE OF THE FACT THAT THE GLOW IN THE WARNING LIGHT WAS MISINTERPED AS AN EXTREMELY HAZARD WARNING -- DECLARING THE EMER AND GETTING THE ACFT ON THE GND WHERE THE PROB COULD BE ASSESSED SAFELY WAS THE RIGHT THING TO DO. ON THE NEXT FLT, EXCESS SLACK, IF ANY, WILL BE TAKEN OUT OF THE BELTS BY ENGAGING THE CLUTCH PRIOR TO ENG START UNTIL THE FACTORY SPECIFIED LIMITS ARE ACHIEVED. THE FIRST STEP WILL BE TO HAVE THE CLUTCH LIMIT STOP ADJUSTED TO ALLOW FOR FURTHER STRETCHING AS THE BELTS CONTINUE TO BREAK IN.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.