THE DALLES, OR, USA
N51657
ENSTROM 280C
THE PILOT WAS BLOWING CHERRY TREES DRY WITH ROTOR DOWNWASH FROM AN ALTITUDE ABOUT 5 TO 8 FEET ABOVE THE TREETOPS. DURING THE FLIGHT, ONE SET OF POINTS IN THE ENGINE'S DUAL-POINT MAGNETO BECAME LOOSE AND STOPPED OPERATING. THE ENGINE SUFFERED A PARTIAL LOSS OF POWER DUE TO THE RESULTING LOSS OF IGNITION FROM THIS SET OF POINTS. DUE TO THE LOW ALTITUDE FLIGHT AND MANEUVERING REQUIRED FOR THE OPERATION, SUFFICIENT ALTITUDE WAS NOT AVAILABLE TO AVOID A FORCED LANDING IN THE CHERRY ORCHARD.
On June 14, 1995, approximately 1300 Pacific daylight time (PDT), an Enstrom 280C helicopter, N51657, registered to ATR Services, Inc., Veneta, OR, and operated by Conquest Helicopters, Troutdale, OR, received substantial damage in a forced landing in a cherry orchard approximately 5 miles south of The Dalles, OR, following a loss of engine power. Neither the commercial pilot nor his passenger were injured. The helicopter had been operating from a field adjacent to the cherry orchard. Visual meteorological conditions existed and no flight plan had been filed for the 14 CFR 91 flight. In his report on the accident, the pilot reported that he was flying "at a fast walk [or] slow jog", about 5 to 8 feet above the treetops (reported as 15 to 20 feet tall by FAA on-scene investigators) to blow them dry with rotor downwash. He reported that he "had just looked at RPM" and that it was "in the green." The pilot reported that the "engine (sputter) went rough", and that he noted a "slight yaw (left to right)" and "saw RPM dropping." He stated that he "lowered collective (bumped)" and increased throttle, but the helicopter "continued [sinking]." He stated that he "pulled up full collective before impact" and that impact then occurred. In a letter to the operator dated July 23, 1995, the passenger stated: ...all of a sudden, the helicopter had a tremendous loss of power with no warning at all....I'd guess we were between ten and fifteen feet above the top of the trees. [The pilot] took the helicopter over three or four rows of trees and into an opened area in one of the rows. It was the only opened area that we could have possibly landed in... Enstrom Helicopters, Inc. supplied a Model 280C height/velocity (H/V) diagram to the NTSB investigator. The flight regime comprising an airspeed of approximately 5 MPH and altitude of 25 to 35 feet above ground level falls in an area of the diagram annotated "AVOID OPERATION IN THIS AREA." In a post-accident examination of the wreckage, FAA inspectors discovered that one set of points on the dual-point magneto was completely loosened and that the loose set of points would not open or close. They further noted in an attempt to run the engine after the accident that the engine would not run with the ignition switch in the "right" position. The loose points were also noted by Flightcraft, Inc. of Portland, OR in a post-accident teardown of the magneto. Aircraft maintenance records indicate that the helicopter was delivered disassembled from Columbia Helicopters, Inc. of Aurora, OR to Conquest Helicopters on April 7, 1995. The maintenance record entry on this date indicated that Columbia had replaced the "left hand mag points and capacitor", and had also replaced a missing inspection plug on the right hand side of the magneto. The helicopter was subsequently reassembled and was signed off as airworthy in an annual inspection on April 26, 1995. The most recent maintenance documented in the aircraft log was a 50 hour service inspection on May 25, 1995.
A PARTIAL LOSS OF ENGINE POWER DUE TO ONE SET OF IGNITION POINTS BECOMING LOOSE DURING FLIGHT. FACTORS INCLUDED THE LOW ALTITUDE FLIGHT AND MANEUVERING REQUIRED TO CONDUCT THE OPERATION AND THE RESULTING LACK OF SUITABLE TERRAIN FOR A FORCED LANDING.
Source: NTSB Aviation Accident Database
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