EDEN PRAIRIE, MN, USA
N6269R
Culver-Revolution MINI 500
The kit-built helicopter was hover-taxiing for about ten minutes according to the pilot/builder. He said '...the engine stopped unexpectedly [and the helicopter] settled to the runway and rolled over.' The on-scene investigation revealed a silicon-type sealant had completely blocked the supply side of the fuel filter. The builder said he had used this material to seal the fuel tank filler neck's flange to the fuel tank. According to the manufacturer's instruction manual, the builder is to 'Place a 1/8-inch bead of MA300 from the adhesive kit around [the] hole circle through the centerline of [the mounting] holes.' MA300 is an epoxy-type glue/sealant that does not break down when contacted by gasoline. The silicon-type material dissolves when it comes in contact with gasoline, according to the helicopter's kit manufacturer.
On September 8, 1998, at 1900 central daylight time (cdt), a Culver-Revolution Mini 500, N6269R, piloted by a private pilot, was substantially damaged when it collided with the ground shortly after a total loss of power while hovering. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 personal flight was not operating on a flight plan. The pilot reported no injuries. The flight departed Eden Prairie, Minnesota, at 1850 cdt. The pilot said he had been hover-taxiing the helicopter between the approach end of runway 36 and the south taxiway for runway 09R. He said he had been hover-taxiing for about 10-minutes when "...the engine stopped unexpectedly [and it] settled to the runway and rolled over." The on-scene investigation revealed no anomalies with the airframe, engine or control system that would prevent flight. Examination of the fuel system revealed a silicon-type sealant had completely blocked the supply side of the fuel filter. According to the pilot/builder, he had used this material as a seal between the helicopter's fuel tank filler neck flange and fuel tank body. The helicopter's kit manufacturers instruction states that the builder is to "Place a 1/8-inch bead of MA300 from the adhesive kit around [the] hole circle through the centerline of [the mounting] holes." A copy of these instructions are appended to this report. The kit manufacturer was contacted regarding the accident and pilot/builders use of the silicon-type material. The manufacturer representative was asked if there were any warnings in the construction manual against the use of the silicon-type sealant as the builder had done. He said there were no warnings, only instructions to use the MA300 material. He said the MA300 is an epoxy- type glue/sealant that does not break down when contacted by gasoline. He said the silicon-type sealant will dissolve when contacted by gasoline. The IIC suggested the company publish a manual change or communicate the need to use only the sealant recommended by them. The company representative agreed and said they would put a notice in the next builder's newsletter. A copy of the company's December 1998 newsletter is appended to this report.
a design change to the fuel tank filler neck sealant made by the owner/builder of the helicopter. Factors associated with this accident were an improper sealant material used by the owner/builder and an autorotation was not possible by the pilot due to the hover-taxis low altitude.
Source: NTSB Aviation Accident Database
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