Accident Hughes 500 N3766Z, Friday 19 August 1988

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Date:	Friday 19 August 1988
Time:	08:10 LT
Type:	Hughes 500
Owner/operator:	Trafficopters, Inc.
Registration:	N3766Z
MSN:	440588S
Year of manufacture:	1974
Total airframe hrs:	4635 hours
Engine model:	Allison 250-C20
Fatalities:	Fatalities: 0 / Occupants: 2
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Accident
Location:	Riviera Beach, FL - United States of America
Phase:	En route
Nature:	Survey
Departure airport:	West Palm Beach, FL
Destination airport:
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
THE TRAFFIC WATCH HELICOPTER WAS CRUISING NORTHBOUND ALONG THE INTERSTATE AT 450 FT AGL & 85 KTS AIRSPEED. A GRINDING NOISE WAS HEARD & THE TAIL ROTOR SEPARATED FROM THE ACFT. THE ACFT BEGAN AN UNCOMMANDED RIGHT TURN WHICH WAS ARRESTED IN ABOUT 1/4 TURN. THE PLT ATTEMPTED TO AUTOROTATE INTO AN OPEN FIELD JUST EAST OF THE HWY, BUT STRUCK A 25 FT TREE AT THE EDGE & CRASHED. AN EXAM REVEALED THE TAIL ROTOR GEAR BOX HOUSING, P/N 369A5400-607, HAD FAILED. A PORTION OF THE HOUSING, DRIVEN GEAR, TAIL ROTOR BLADES & RELATED COMPONENTS SEPARATED FROM THE ACFT IN FLT. THE MISSING PARTS SANK IN A LAKE ABOUT 1/2 MI FROM THE CRASH SITE & WERE NOT RECOVERED. THE REMAINING SECTION OF THE BOX WAS EXAMINED BY NTSB LAB & FAILURE WAS DUE TO OVERLOAD WITH NO EVIDENCE OF FATIGUE OR CORROSION. A WITNESS SAW 2 OBJECTS FALL FROM THE HELICOPTER. ONE OBJECT WAS WHITE AND LOOKED LIKE A BIRD, PROBABLY A SEAGULL. THE OTHER OBJECT LOOKED LIKE A STICK OR A 2X4 PIECE OF WOOD.

Probable Cause:

Accident investigation: