Narrative:

I was the sole occupant of the aircraft. The takeoff and entry into cruise flight was normal. The ceiling had lowered and I needed to stay at an altitude of 600-700 ft AGL to remain in VFR conditions. I checked the radar altimeter shortly after liftoff and estimated the ceiling to be ragged at approximately 800-900 ft. Approximately 4 mins into the flight, I noticed that the scattered clouds ahead of my path were appearing to become broken and also appeared to be lowering. I remained in VFR conditions, however, it quickly became apparent to me that I could not remain VFR if I continued on a direct flight path back. I realized that I was needing to descend to remain clear of the clouds. I glanced at the radar altimeter and noticed that it read approximately 425 ft. I decided that I could no longer continue and elected to start a shallow left turn. I could still see VFR to the left, but IFR to my right. As I turned the aircraft to the left, I obviously allowed the aircraft to descend inadvertently. A second or two later, I believe that I noticed the alert light on the radar altimeter flash on, the bug on the radar altitude was set for 300 ft. At the same moment I saw 2 bright flashes, one above and right and the other to my left. I also heard a loud 'pop' sound. The aircraft jerked slightly but continued to fly. I never saw any wires but immediately realized that I must have struck power wires. After the initial jerk, I realized that the aircraft was still flying. I immediately began an assessment of the health of the aircraft and its system. All of the engine instruments appeared to be normal and in the green. The rotor RPM's stayed normal, torque was normal and both turbines remained matched. Upon realizing that the aircraft was apparently functioning normally, my next concern was to get the aircraft over a suitable landing area in the event that things began to go wrong and I would be forced to make a precautionary landing. I continued to fly southwest. I contacted approach and advised them that I had possibly struck power wires and wished to proceed directly to ZZZ airport. I did not declare an emergency or ask for rescue equipment. I did, however, ask the control tower personnel to contact company personnel to meet me by the ramp in front of our hangar so that they could visually inspect the underside of the aircraft prior to my setting the aircraft down. I was concerned that the landing gear may have been damaged, causing it to collapse upon set-down. Upon inspection, the landing gear appeared normal. The set-down was uneventful. A cursory inspection of the aircraft revealed damage to the radar dome at the nose of the aircraft, damage to upper edge of the copilot windshield, also damage to the lower wire strike brace. Human performance considerations: I feel that I should have realized earlier and, therefore, turned the aircraft earlier, prior to the need to descend. I was well rested and alert at the time of the incident, so I do not believe that fatigue was the problem.

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Original NASA ASRS Text

Title: BK117 PLT TURNS TO AVOID LOWERING CEILING AND INADVERTENTLY DSNDS, STRIKING A PWR LINE. AFTER ASSESSING CTLABILITY, PLT RETURNS TO HOME BASE WHERE MINOR DAMAGE IS NOTED.

Narrative: I WAS THE SOLE OCCUPANT OF THE ACFT. THE TKOF AND ENTRY INTO CRUISE FLT WAS NORMAL. THE CEILING HAD LOWERED AND I NEEDED TO STAY AT AN ALT OF 600-700 FT AGL TO REMAIN IN VFR CONDITIONS. I CHKED THE RADAR ALTIMETER SHORTLY AFTER LIFTOFF AND ESTIMATED THE CEILING TO BE RAGGED AT APPROX 800-900 FT. APPROX 4 MINS INTO THE FLT, I NOTICED THAT THE SCATTERED CLOUDS AHEAD OF MY PATH WERE APPEARING TO BECOME BROKEN AND ALSO APPEARED TO BE LOWERING. I REMAINED IN VFR CONDITIONS, HOWEVER, IT QUICKLY BECAME APPARENT TO ME THAT I COULD NOT REMAIN VFR IF I CONTINUED ON A DIRECT FLT PATH BACK. I REALIZED THAT I WAS NEEDING TO DSND TO REMAIN CLR OF THE CLOUDS. I GLANCED AT THE RADAR ALTIMETER AND NOTICED THAT IT READ APPROX 425 FT. I DECIDED THAT I COULD NO LONGER CONTINUE AND ELECTED TO START A SHALLOW L TURN. I COULD STILL SEE VFR TO THE L, BUT IFR TO MY R. AS I TURNED THE ACFT TO THE L, I OBVIOUSLY ALLOWED THE ACFT TO DSND INADVERTENTLY. A SECOND OR TWO LATER, I BELIEVE THAT I NOTICED THE ALERT LIGHT ON THE RADAR ALTIMETER FLASH ON, THE BUG ON THE RADAR ALT WAS SET FOR 300 FT. AT THE SAME MOMENT I SAW 2 BRIGHT FLASHES, ONE ABOVE AND R AND THE OTHER TO MY L. I ALSO HEARD A LOUD 'POP' SOUND. THE ACFT JERKED SLIGHTLY BUT CONTINUED TO FLY. I NEVER SAW ANY WIRES BUT IMMEDIATELY REALIZED THAT I MUST HAVE STRUCK PWR WIRES. AFTER THE INITIAL JERK, I REALIZED THAT THE ACFT WAS STILL FLYING. I IMMEDIATELY BEGAN AN ASSESSMENT OF THE HEALTH OF THE ACFT AND ITS SYS. ALL OF THE ENG INSTS APPEARED TO BE NORMAL AND IN THE GREEN. THE ROTOR RPM'S STAYED NORMAL, TORQUE WAS NORMAL AND BOTH TURBINES REMAINED MATCHED. UPON REALIZING THAT THE ACFT WAS APPARENTLY FUNCTIONING NORMALLY, MY NEXT CONCERN WAS TO GET THE ACFT OVER A SUITABLE LNDG AREA IN THE EVENT THAT THINGS BEGAN TO GO WRONG AND I WOULD BE FORCED TO MAKE A PRECAUTIONARY LNDG. I CONTINUED TO FLY SW. I CONTACTED APCH AND ADVISED THEM THAT I HAD POSSIBLY STRUCK PWR WIRES AND WISHED TO PROCEED DIRECTLY TO ZZZ ARPT. I DID NOT DECLARE AN EMER OR ASK FOR RESCUE EQUIP. I DID, HOWEVER, ASK THE CTL TWR PERSONNEL TO CONTACT COMPANY PERSONNEL TO MEET ME BY THE RAMP IN FRONT OF OUR HANGAR SO THAT THEY COULD VISUALLY INSPECT THE UNDERSIDE OF THE ACFT PRIOR TO MY SETTING THE ACFT DOWN. I WAS CONCERNED THAT THE LNDG GEAR MAY HAVE BEEN DAMAGED, CAUSING IT TO COLLAPSE UPON SET-DOWN. UPON INSPECTION, THE LNDG GEAR APPEARED NORMAL. THE SET-DOWN WAS UNEVENTFUL. A CURSORY INSPECTION OF THE ACFT REVEALED DAMAGE TO THE RADAR DOME AT THE NOSE OF THE ACFT, DAMAGE TO UPPER EDGE OF THE COPLT WINDSHIELD, ALSO DAMAGE TO THE LOWER WIRE STRIKE BRACE. HUMAN PERFORMANCE CONSIDERATIONS: I FEEL THAT I SHOULD HAVE REALIZED EARLIER AND, THEREFORE, TURNED THE ACFT EARLIER, PRIOR TO THE NEED TO DSND. I WAS WELL RESTED AND ALERT AT THE TIME OF THE INCIDENT, SO I DO NOT BELIEVE THAT FATIGUE WAS THE PROB.

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.