Manchester, NH, USA
N169JS
Stump Rotorway Exec 90
The amatuer-built helicopter was about 45 minutes into its flight when the pilot heard a "pop," and saw a puff of blue smoke. He also noticed an odor of "burning" oil, and heard "crackling" in the engine compartment on the pilot's side of the helicopter. He selected a forced landing site and entered autorotation as the engine "sputtered" and stopped producing power. The helicopter touched down on an upslope with forward motion, then rolled over on to its side. A split engine oil suppy line was identified at the site, and examination revealed that beneath the torn fire sleeve and damaged outer braiding material, there was longitudinal cracking about 1 inch in length due to fatigue. Positioning of the oil line on the accident helicopter was different than a factory-assembled version that was examined, but because the helicopter was amateur built, there was no standard. Photographs of the oil line installation on the 23 year-old accident helicopter suggested the oil line was curved more tightly than the manufacturer's suggested minimum radius, and showed the oil line in close proximity to a source of high heat; the engine exhaust.
On November 18, 2006, at 1430 eastern standard time, an amateur-built Rotorway Exec 90 helicopter, N169JS, was substantially damaged during a forced landing following a loss of engine power near Manchester, New Hampshire. The certificated private pilot and the passenger were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight conducted under 14 CFR Part 91. The pilot provided a written statement and was interviewed by telephone. He said that about 45 minutes into the flight, while flying about 1,000 feet above ground level, he heard a "pop," and saw a puff of blue smoke. He also noticed an odor of "burning" oil, and heard "crackling" in the engine compartment on the pilot's side of the helicopter. The pilot scanned the gauges, which appeared "normal." He then contacted the air traffic control tower at Manchester Airport (MHT), Manchester, New Hampshire, and announced that the helicopter was experiencing "oil pressure problems." The tower controller issued a landing clearance, but the pilot felt that he could not reach the airport. Instead, he elected to make an off-airport landing in a clearing, about a mile from his position, due to unsuitable terrain below. Once over his selected forced landing site, the pilot entered autorotation as the engine "sputtered" and stopped producing power. The helicopter touched down on an upslope with forward motion, then "tilted up on the left skid until the main rotor hit," and the helicopter rolled over on to its side. The helicopter was moved from the site, and examined at Boire Field (ASH), Nashua, New Hampshire, by a Federal Aviation Administration (FAA) aviation safety inspector. Examination of the engine compartment revealed a damaged oil supply line with an opening in the firesleeve and damaged braiding. The line was removed, and forwarded to the Safety Board Materials Laboratory in Washington, D.C. According to FAA records, the helicopter was manufactured in 1984, and had accrued approximately 173 total hours of operation. Its most recent condition inspection was completed in September 2006, at 160 total hours. The pilot held a private pilot certificate with ratings for airplane single engine land, instrument airplane, and rotorcraft-helicopter. The pilot had 1,350 total hours of flight experience. He had accrued 178 total hours of helicopter experience, 175 hours of which were in make and model. At 1451, the weather reported at Boire Field, about 5 miles to the south, included clear skies with 10 miles of visibility. The wind was from 010 degrees at 3 knots. On March 1, 2007, the oil line was examined at the Safety Board's materials laboratory in Washington, D.C. Examination revealed that beneath the split fire sleeve, and the damaged outer braiding material, was longitudinal cracking about 1 inch in length due to fatigue. Positioning of the oil line on the accident helicopter was different than a factory-assembled Rotorway helicopter that was examined, but because the helicopter was amateur built, there was no standard. Photographs of the oil line installation on the accident helicopter indicated the oil line was curved more tightly than the manufacturer's suggested minimum radius, and showed the oil line in close proximity to a source of high heat; the engine exhaust.
An improperly installed oil line, which resulted in oil line fatigue failure and a subsequent loss of oil to the engine. A contributing factor was the sloping terrain at the forced landing site.
Source: NTSB Aviation Accident Database
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