BK117 helicopter makes precautionary landing in response to strong vibration. Pilot accomplishes tem...

Attributes
ACN	580354
Time
Date	200304
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : gge
State Reference	SC
Altitude	msl single value : 800
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : myr.tracon
Operator	common carrier : air taxi
Make Model Name	MBB-BK 117A-1
Operating Under FAR Part	Part 135
Flight Phase	cruise : level
Flight Plan	VFR
Person 1
Affiliation	company : air taxi
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 45 flight time total : 5200 flight time type : 2100
ASRS Report	580354
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper documentation maintenance problem : improper maintenance non adherence : far
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : landed as precaution
Consequence	other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

I was flying on a north easterly heading at approximately 800 ft MSL. Indicated airspeed was 122 KTS. I heard a loud slap like a large bug had impacted some portion of the airframe or windscreen. Nothing could be observed from the cockpit, and flight was continued. In less than 2 mins, the helicopter started to exhibit a pronounced vertical vibration. Within a few seconds, the vibration became moderate and airspeed was reduced. The vibration also diminished. I was on radar with myrtle beach approach control, and declared with them that I was making a precautionary landing, because of moderate vertical vibrations. The approach and landing were uneventful. After normal shutdown, the postflt revealed a small tear on the leading edge of the yellow blade tape. A flap of tape was protruding just enough to interfere with the airfoil on this blade. I then trimmed this small piece of tape off by just tearing where it had already started to tear. I removed the torn tape measuring about 1 inch by 1/2 inch from the blade. I felt I had a smooth enough blade surface to return to base and have repairs made, and let the a&P mechanic look at it. I then ran the aircraft up to full RPM, set for about 1 min, then hovered for 30-40 seconds, and took off accelerating slowly. All seemed normal, and the aircraft flew as smooth as before. I declared that my maintenance flight check was good and that the aircraft was airworthy and svcable. The aircraft was flown back to base for further inspection uneventfully.

Original NASA ASRS Text

Title: BK117 HELI MAKES PRECAUTIONARY LNDG IN RESPONSE TO STRONG VIBRATION. PLT ACCOMPLISHES TEMPORARY REPAIR OF LOOSE TAPE ON MAIN ROTOR, AND RETURNS TO BASE FOR INSPECTION AND REPAIR.

Narrative: I WAS FLYING ON A N EASTERLY HDG AT APPROX 800 FT MSL. INDICATED AIRSPD WAS 122 KTS. I HEARD A LOUD SLAP LIKE A LARGE BUG HAD IMPACTED SOME PORTION OF THE AIRFRAME OR WINDSCREEN. NOTHING COULD BE OBSERVED FROM THE COCKPIT, AND FLT WAS CONTINUED. IN LESS THAN 2 MINS, THE HELI STARTED TO EXHIBIT A PRONOUNCED VERT VIBRATION. WITHIN A FEW SECONDS, THE VIBRATION BECAME MODERATE AND AIRSPD WAS REDUCED. THE VIBRATION ALSO DIMINISHED. I WAS ON RADAR WITH MYRTLE BEACH APCH CTL, AND DECLARED WITH THEM THAT I WAS MAKING A PRECAUTIONARY LNDG, BECAUSE OF MODERATE VERT VIBRATIONS. THE APCH AND LNDG WERE UNEVENTFUL. AFTER NORMAL SHUTDOWN, THE POSTFLT REVEALED A SMALL TEAR ON THE LEADING EDGE OF THE YELLOW BLADE TAPE. A FLAP OF TAPE WAS PROTRUDING JUST ENOUGH TO INTERFERE WITH THE AIRFOIL ON THIS BLADE. I THEN TRIMMED THIS SMALL PIECE OF TAPE OFF BY JUST TEARING WHERE IT HAD ALREADY STARTED TO TEAR. I REMOVED THE TORN TAPE MEASURING ABOUT 1 INCH BY 1/2 INCH FROM THE BLADE. I FELT I HAD A SMOOTH ENOUGH BLADE SURFACE TO RETURN TO BASE AND HAVE REPAIRS MADE, AND LET THE A&P MECH LOOK AT IT. I THEN RAN THE ACFT UP TO FULL RPM, SET FOR ABOUT 1 MIN, THEN HOVERED FOR 30-40 SECONDS, AND TOOK OFF ACCELERATING SLOWLY. ALL SEEMED NORMAL, AND THE ACFT FLEW AS SMOOTH AS BEFORE. I DECLARED THAT MY MAINT FLT CHK WAS GOOD AND THAT THE ACFT WAS AIRWORTHY AND SVCABLE. THE ACFT WAS FLOWN BACK TO BASE FOR FURTHER INSPECTION UNEVENTFULLY.

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.

BK117 helicopter makes precautionary landing in response to strong vibration. Pilot accomplishes temporary repair of loose tape on main rotor, and returns to base for inspection and repair.