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ASN Wikibase Occurrence # 20393
Last updated: 29 July 2020
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Date:25-MAY-2008
Time:19:21
Type:Silhouette image of generic H500 model; specific model in this crash may look slightly different
McDonnell Douglas MD 500E (369E)
Owner/operator:Private
Registration: N686F
C/n / msn: 0524E
Fatalities:Fatalities: 1 / Occupants: 5
Aircraft damage: Substantial
Category:Accident
Location:Lake of the Ozarks, Sunrise Beach, MO -   United States of America
Phase: Landing
Nature:Private
Departure airport:Sunrise Beach, MO
Destination airport:Sunrise Beach, MO
Investigating agency: NTSB
Narrative:
According to the pilot, he was approaching his personal helipad when the helicopter started rotating rapidly to the right. Multiple witnesses reported that the helicopter approached the landing zone from the north and maneuvered to land, at which time the helicopter began spun to the right four or five times before impacting the water. The pilot and three passengers were able to egress from the helicopter. One passenger drowned. No passenger briefing was conducted and none of the occupants were shown how to use their seatbelts or doors as required in 14 Code of Federal Regulations Part 91.107. The victim, who was sharing a seatbelt with another passenger, had never flown in the helicopter before and was unfamiliar with the exits in the helicopter and how to operate them. According to one passenger and multiple witnesses, thunderstorms and lightning were observed at the time of the accident. Extreme weather radar echoes containing thunderstorms were recorded southwest through the east of the accident site. An analysis conducted by Safety Board meteorologists indicates that turbulence, including vertical and horizontal wind changes, would have been associated with this thunderstorm activity. The terrain would have enhanced the intensity of these parameters, resulting in an encounter of a strong convective outflow of approximately 45 knots from the south. Toxicology testing of blood drawn within an hour after the accident detected butalbital (a prescription barbiturate typically used for severe headaches) and diphenhydramine (an over-the-counter antihistamine commonly known by the trade name Benadryl). The drug levels suggest that the butalbital was likely taken more than 24 hours prior to the accident and that the diphenhydramine was likely taken much more recently (probably on the day of the accident). The pilot had a history of diabetes diagnosed in 1993, with no documentation in his Federal Aviation Administration medical records since 1994 regarding treatment or control of the disease. It is possible that the diphenhydramine, the conditions for which the detected medications were used, or complications or side effects from long-standing diabetes may have contributed to the pilot's decision to fly and/or his inability to control the helicopter in the prevailing conditions; however, the investigation could not definitively determine this. An examination of the helicopter's systems and structure revealed no preimpact anomalies.
Probable Cause: The loss of tail rotor effectiveness and the pilot's failure to regain aircraft control. Contributing to the accident was the pilot's decision to fly in known adverse weather conditions and the gusty winds generated from convective outflow. Contributing to the severity of the injuries was the pilot's failure to provide a safety briefing to his passengers in accordance with Federal Aviation Regulations.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20080529X00752&key=1


Revision history:

Date/timeContributorUpdates
01-Jun-2008 11:34 Fusko Added
10-Aug-2008 01:09 RobertMB Updated
08-Sep-2014 19:26 Aerossurance Updated [Operator, Location, Departure airport, Destination airport, Source, Narrative]
21-Dec-2016 19:14 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
21-Dec-2016 19:16 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
21-Dec-2016 19:20 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
03-Dec-2017 10:51 ASN Update Bot Updated [Other fatalities, Departure airport, Destination airport, Source, Narrative]

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