# NTSB DFW05CA072: Robinson R44 II, N7535S, Woodward, OK, April 13, 2005 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: April 13, 2005, 11:30 local (16:30 UTC) - Place: Woodward, OK - Coordinates: 36.436668, -99.520835 - Nearby events: https://openairdocs.org/map.md?lat=36.4367&lon=-99.5208&mi=10 - Phase of flight: [Standing](https://openairdocs.org/ntsb-phases/150) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report July 7, 2005 - Report: Approved by Office Director - Parties: Oklahoma City, Oklahoma - NTSB case key (mKey): 61028 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DFW05CA072 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/61028/pdf - Page: https://openairdocs.org/ntsb/DFW05CA072 ## Probable cause the pilot's encounter with adverse weather conditions. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - On ground/water encounter with weather, standing - idling rotors - weather condition - high wind (cause) - weather condition - gusts (cause) ## Analysis After touching down on a portable helipad in a single-engine helicopter, the 10,500-hour pilot started "cool down procedures." After "sufficient time", the pilot disengaged the clutch, waited 30-45 seconds, and then turned the engine off. With the cyclic locked in the center position, the clutch light went out, and the rotor was winding down slowly. As the pilot reached back to apply the rotor brake, "a strong wind gust caused the rotor to lift and strike the tail boom. At the time of rotor blade impact, the engine was turned off and the clutch was totally disengaged." The reported wind at the time of the accident was from 350 degrees at 11 knots, gusting to 15 knots.. ## Factual narrative On April 13, 2005, approximately 1130 central daylight time, a Robinson R44 II single-engine helicopter, N7535S, was substantially damaged during engine shut-down at the West Woodward Airport (WWR), near Woodward, Oklahoma. The private pilot and his passenger were not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the personal flight, which was being conducted under the provisions of 14 Code of Federal Regulations Part 91. The flight departed from the Purcell Municipal Airport (3O3), near Purcell, Oklahoma, approximately 1100, with WWR as its intended destination. In a written statement, the pilot reported that upon arrival to WWR, he elected to land the helicopter into the prevailing "strong northerly wind". Immediately after touching down on the portable helipad, the pilot initiated the prescribed "cool down procedures." After "sufficient time", the pilot disengaged the clutch, waited 30-45 seconds, and then shut-down the engine. With the cyclic locked in the center position, the clutch light went out, as the rotors were slowly winding down. As the pilot reached back to apply the rotor brake, "a strong wind gust caused the rotor to lift and strike the tail boom." The pilot further reported that at the time of rotor blade impact, "the engine was turned-off and the clutch was totally disengaged." A review of photographs that were provided to an NTSB investigator revealed structural damage to the tail boom, as well as the main rotor blade. At 1130, the automated weather observing system at WWR reported wind from 350 degrees at 11 knots, gusting to 15 knots, 10 statute miles visibility, a clear sky, temperature 15 degrees Fahrenheit, dew point 6 degrees Fahrenheit, and a barometric pressure setting of 30.13 inches of Mercury. ## Aircraft - Registration: [N7535S](https://openairdocs.org/deregistered/N7535S-2020-05-01), registration cancelled 2020-05-01, S/N 10496, built 2004 (OpenAirDocs) - Reported make and model: Robinson R44 II - Registry model: [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii) (registry code 7640122) (OpenAirDocs) - Registry engine: [Lycoming IO-540 series](https://openairdocs.org/engine/lycoming-io-540-series) (registry code 41530, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 10496 - Airframe hours: 74.8 - Engines: Lycoming IO-540-AE1A5 reciprocating - Damage: Substantial damage - Flight: Business, Part 91 - Registered owner: Haines Capital Group, LLC - Airworthiness certificate: Standard, Normal - Departed: 3O3, Purcell, OK - Destination: WWR, Woodward, OK - Airport: WWR, West Woodward Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; injuries: none; private; airplane ratings: single-engine land, multi-engine land; medical: class 3, with waivers/limitations; last flight review January 1, 2005; seat: right; flight hours: 10,500 total, 1,400 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 350° at 11 knots, gusting 15 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 59 °F, dew point 43 °F - Altimeter: 30.12 inHg - Observed at: WWD ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20050413004839A](https://openairdocs.org/incident/20050413004839A), Apr 13, 2005: Robsin R44RAVENII, Woodward, OK, Substantial damage. (-23) Pilot stated that during shutdown of the aircraft, and during application of the rotor brake, the retreating main rotor blade flexed downward and struck… ## Other investigations on N7535S (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB GAA19CA103](https://openairdocs.org/ntsb/GAA19CA103), Dec 18, 2018: Robinson R44 (N7535S), Strykersville, NY, substantial damage. Probable cause: The structural failure of the home-built landing platform during landing, which resulted in the helicopter rolling over. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.