NTSB Identification: SEA08FA185
14 CFR Part 91: General Aviation
Accident occurred Sunday, August 17, 2008 in Olalla, WA
Probable Cause Approval Date: 09/30/2009
Aircraft: ROBINSON HELICOPTER R22 BETA II, registration: N301MA
Injuries: 1 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The pilot, who had not flown his helicopter for about one year, took off and flew about seven to ten minutes to the location of his personal residence. Once at that location, he flew around the local area while waiting for the person who drove him to the airport to return to the newly constructed helipad at the residence before he made his first landing there. After about ten minutes of maneuvering around the area, the helicopter experienced a complete loss of engine power, and the pilot attempted an autorotation to the backyard of a residence about one-half mile from his own. During the last part of the attempted forced landing, the helicopter collided with a tree and a wood fence. The investigation did not reveal any anomalies or malfunctions that would have prevented the engine from operating normally, and the engine underwent a successful post-accident dynamometer test run. The investigation revealed that the flight took place during ambient conditions that would be expected to produce carburetor icing, and under which the pilot would need to constantly monitor the carburetor temperature gauge and make adjustments to the carburetor heat. The pilot had a history of seasonal allergies, and toxicology test results were consistent with the recent use of diphenhydramine, a sedating and impairing over-the-counter antihistamine often known by the trade name of Benadryl. The extent to which impairment from the medication may have played a role in the accident could not be determined.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The complete loss of engine power due to the accumulation of ice in the carburetor as a result of the pilot's failure to use carburetor heat.

Full narrative available

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