SHERWOOD, OR, USA
N9297F
Hughes 269C
The commercial pilot and pilot rated passenger were practicing a pinnacle approach, terminating to a hover, over a gravel pile in the confines of a rock quarry. The commercial pilot stated that during the transition to a hover the helicopter continued to settle and the aircraft's left skid collided with the top of the pile. The pilot added full collective and left cyclic without a notable response. The helicopter continued to roll to the right and down the embankment. After the accident, the pilot reported that a dynamic roll over had occurred. Examination of the helicopter and associated system components revealed no evidence of a mechanical malfunction or failure.
On January 18, 2000, about 1530 Pacific standard time, a Hughes 269C Helicopter, N9297F, registered to and operated by Helicopter Specialists, Inc., was substantially damaged after colliding with terrain three miles south of Sherwood, Oregon. Visual meteorological conditions prevailed and no flight plan was filed. The helicopter was being operated as a visual flight rules (VFR) local flight under Title 14, CFR Part 91, when the accident occurred. The commercial pilot and private pilot rated passenger were uninjured. The flight originated from Stark's Twin Oaks Airpark, Hillsboro, Oregon, approximately 15 minutes prior to the accident. There was no fire and no report of ELT activation. The pilot-in-command (PIC) reported that he planned to execute a pinnacle approach, terminating to a hover, over a rock pile in the confines of a rock quarry. He stated "I had made the approach and transitioned to a hover but the helicopter settled further and touched the pile." The helicopter's left skid contacted the gravel pile and rolled to the right. The pilot stated he pulled full collective and increased left cyclic without a notable response. The helicopter continued to roll to the right and down the embankment. After the accident, the pilot reported to the Federal Aviation Administration (FAA) that a dynamic rollover had occurred. Initially, the FAA Inspector who responded to the accident site reported that the aircraft's mixture control cable was broken and was not properly adjusted. The helicopter was then recovered and transported to the operator's hangar facility in Hillsboro, Oregon. On March 8, 2000, the helicopter was examined by representatives from the FAA and National Transportation Safety Board. The main cabin of the aircraft was intact, but sustained substantial impact damage and the tail boom was severed. The aircraft's three main rotor blades displayed signs of impact damage, including leading edge damage, aft bending and scratch marks radiating from the leading edge to the trailing edge of the blades. With the cockpit mixture control in the full-rich position, the mixture control bell crank was marked referencing the broken off piece of mixture cable and the still attached section of mixture control cable (Reference Photographs 15 and 2A). The fuel servo unit, mixture control cable and cable housing were then removed from the helicopter. The mixture control cable, including both fracture surfaces and the control cable housing were shipped to the National Transportation Safety Board, Materials Laboratory Division in Washington, D.C. A Senior Metallurgist from the lab reported that a series of wear marks were noted both on the inside diameter of the control cable housing and on the outside diameter of the mixture control cable. The specialist reported that the separation of the mixture control cable was through the area of the wear marks. Examination of the fracture surfaces revealed features typical of overstress bending separation. No evidence of fatigue cracking or other types of progressive separation was noted (Reference Materials Lab Report 00-079). The fuel flow servo (Model RSA-7AA1) was removed from the helicopter and shipped to Precision Airmotive Corporation, Everett, Washington for examination. Inspection and testing of the servo, in the marked position, revealed no evidence of pre-impact anomalies or failures. The helicopter was released to Helicopter Specialties, Inc., Hillsboro, Oregon, on March 8, 2000.
The pilots failure to arrest the helicopter's descent rate during a planned approach to a hover. Factors include uneven terrain.
Source: NTSB Aviation Accident Database
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