# NTSB LAX08LA097: Bell 47G-3B-1, N24SD, Denio, NV, April 11, 2008 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 11, 2008, 09:00 local (16:00 UTC) - Place: Denio, NV - Coordinates: 41.049999, -118.333335 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.0500&lon=-118.3333&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report May 6, 2009 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 67806 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX08LA097 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/67806/pdf - Page: https://openairdocs.org/ntsb/LAX08LA097 ## Probable cause The pilot's inadvertent hard landing induced by a perceived loss of power and a main transmission anomaly while maneuvering at low altitude. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Aircraft](https://openairdocs.org/ntsb-findings/01020000): Aircraft › Aircraft systems · Not specified (probable cause); cases with it: [Bell 47G-3B-1, 2 cases](https://openairdocs.org/ntsb-findings/01020000/cases.md?model=1181028), [All aircraft, 63 cases](https://openairdocs.org/ntsb-findings/01020000/cases.md) - [Personnel issues](https://openairdocs.org/ntsb-findings/02040000): Personnel issues › Action/decision · Flight crew (probable cause); cases with it: [Bell 47G-3B-1, 1 case](https://openairdocs.org/ntsb-findings/02040000/cases.md?model=1181028), [All aircraft, 56 cases](https://openairdocs.org/ntsb-findings/02040000/cases.md) - [Terrain: sloped/uneven terrain](https://openairdocs.org/ntsb-findings/03021017): Environmental issues › Physical environment · Effect on operation (probable cause); cases with it: [Bell 47G-3B-1, 1 case](https://openairdocs.org/ntsb-findings/03021017/cases.md?model=1181028), [All aircraft, 270 cases](https://openairdocs.org/ntsb-findings/03021017/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [Bell 47G-3B-1, 3 cases](https://openairdocs.org/ntsb-events/900/sequence.md?model=1181028), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Landing-flare/touchdown: Hard landing](https://openairdocs.org/ntsb-events/092); cases with it: [Bell 47G-3B-1, 2 cases](https://openairdocs.org/ntsb-events/092/sequence.md?model=1181028), [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) - [Landing-flare/touchdown: Roll over](https://openairdocs.org/ntsb-events/097); cases with it: [Bell 47G-3B-1, 2 cases](https://openairdocs.org/ntsb-events/097/sequence.md?model=1181028), [All aircraft, 261 cases](https://openairdocs.org/ntsb-events/097/sequence.md) ## Analysis After the passenger shot a coyote during the predator control flight, the helicopter pilot circled the injured coyote. While maneuvering at 15 miles per hour and about 20 feet above the hilly terrain, the pilot heard a grinding noise, which he opined originated from the transmission. The pilot believed the helicopter was losing power, and he opted to immediately land on sloping terrain. The helicopter touched down hard, the main rotors severed the tail boom, and the helicopter rolled over. During the subsequent examination of the airframe, transmission, and engine, no evidence of a mechanical malfunction was found. One of the two cooling fan drive belts was not found seated, and may have rolled over on its pulley, producing the noise that the pilot may have misinterpreted as relating to a loss of power. ## Factual narrative On April 11, 2008, about 0900 Pacific daylight time, a Bell 47G-3B-1, N24SD, made a hard landing on hilly terrain about 25 miles south of Denio, Nevada. Following impact, the helicopter's skids collapsed, the main rotor blades severed the tail boom, and the substantially damaged helicopter rolled over. Neither the commercial pilot nor the passenger was injured during the aerial observation flight. The helicopter was operated by Helicopter Roundup Service, LLC, Nephi, Utah. Visual meteorological conditions prevailed at the time, and no flight plan was filed. The flight was performed under the provisions of 14 Code of Federal Regulations Part 91, and it originated from a private ranch near Denio, about 0700. The pilot reported to the National Transportation Safety Board investigator that the purpose of the flight was predator control, and the passenger-gunman had just shot a coyote. The pilot opined that a mechanical malfunction occurred as he was circling the injured coyote about 20 feet above ground level, and while nearly in a hover. According to the pilot, while maneuvering he heard a grinding noise emanating from the transmission, which was immediately followed by a loss of power to the main rotors. Prior to hearing the noise, there had not been any problem with the helicopter. The pilot stated that, at the time, the helicopter's airspeed was about 15 miles per hour, and he was unable to perform a successful autorotative descent. The helicopter was recovered from the accident site and examined by Federal Aviation Administration (FAA) and Bell Helicopter personnel. In pertinent part, the swashplate and centrifugal clutch for the main rotor system showed no indication of failure, the engine and turbocharger rotated freely, the tail rotor drive shaft and tail rotor gear box rotated freely, and no signs of abnormal wear or failure were found. No evidence of any abnormal wear, failure, or anomalies with the transmission was found. The FAA noted that the only discrepancy that was possibly pertinent to the pilot's report of hearing unusual noise may have related to the fact that one of the helicopter's two cooling fan drive belts was not found seated; although it was found at the accident site. The FAA reported that the belt may have rolled over on its pulley and made a noise that the pilot heard just before it broke. ## Aircraft - Registration: [N24SD](https://openairdocs.org/deregistered/N24SD-2008-07-14), registration cancelled 2008-07-14, S/N 3671, built 1967 (OpenAirDocs) - Reported make and model: BELL 47G-3B-1 - Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs) - Registry engine: [Lycoming TVO-435-GIA](https://openairdocs.org/engine/lycoming-tvo-435-gia) (registry code 41526, turbo-prop) (OpenAirDocs) - Category: Helicopter - Serial number: 3671 - Airframe hours: 9476 - Engines: Lycoming TVO-435-B1A 270 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial observation, Part 91 - Operator: Helicopter Roundup Service, LLC - Registered owner: Helicopter Roundup Service, LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, February 27, 2008 - Departed: NONE, Denio, NV - Destination: NV ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; injuries: none; commercial; medical: class 2, without waivers/limitations; last flight review August 10, 2007; seat: left; flight hours: 4,153 total, 2,746 in this make and model, 4,081 as pilot in command, 67 in the last 90 days, 13 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 30 statute miles - Lowest ceiling: none - Temperature: 46 °F ## 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 20080411836879A](https://openairdocs.org/incident/20080411836879A), Apr 11, 2008: Bell 47, Dinio, NV, Substantial damage. (-23) Accident occurred on a predator eradication flight (coyote). After culling a coyote they returned to the carcass to determine status of same when at… ## Other investigations on N24SD (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 DEN05LA137](https://openairdocs.org/ntsb/DEN05LA137), Sep 13, 2005: Bell 47G-3B-1 (N24SD), Rock Springs, WY, substantial damage. Probable cause: the pilot's failure to maintain control of the helicopter during the attempted autorotation after he experienced an engine overspeed that occurred for reasons undetermined. 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.