ROBINSON HELICOPTER R22 BETA II near Olalla, WA — 2008-08-17
- Date
- 2008-08-17
- Location
- Olalla, WA, USA
- Aircraft
- ROBINSON HELICOPTER R22 BETA II
- Registration
- N301MA
- Category
- Helicopter
- Highest injury
- Fatal
- Fatalities
- 1
- Phase of flight
- Maneuvering
Probable cause
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.
NTSB narrative
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.
Analysis
- Primary failure mode
- Mechanical failure
- First missed decision gate
- Pilot should have ensured mixture control was properly secured before flight.
NTSB coding
Evidence available
- Photos
- 17 docket documents
Docket documents17
- Release of Aircraft Wreckage, NTSB Form 6120.15form
- Statement of Party Representatives to NTSB Investigationinterview
- Carburetor Icing Probability Chartother
- Image 1. Looking west across back yard at impacted fence and tree.photos
- Image 10. Upper portion of center pedestal.photos
- Image 11. Mixture control knob with bent shaft.photos
- Image 12. Mixture control cable at carburetor.photos
- Image 2. Impacted fence, and tree impacted by main rotor (on right just behind fence).photos
- Image 3. Ground impact site as viewed through impacted fence.photos
- Image 4. Belly of helicopter as viewed from rear.photos
- Image 5. Tail rotor assembly and gearbox.photos
- Image 6. Main rotor assembly and swashplate.photos
- Image 7. Mixture control knob (red).photos
- Image 8. Carburetor heat control knob and knob lock.photos
- Image 9. Lower portion of center pedestal.photos
- Materials Laboratory 15 - Materials Laboratory Factual Report 09-032report
- Toxicological Reportreport
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