# NTSB CEN10IA438: Bell 206, N317RL, Gulf of Mexico, LA, July 26, 2010 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: July 26, 2010, 14:42 local (19:42 UTC) - Place: Gulf of Mexico, LA - Coordinates: 31.170183, -91.868186 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=31.1702&lon=-91.8682&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report October 4, 2012 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Transportation Safety Board of Canada, Rotorcraft Leasing Company LLC, Rolls-Royce Corporation, Bell Helicopter - Textron, FAA Baton Rouge FSDO - NTSB case key (mKey): 76760 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN10IA438 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/76760/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=76760 - Page: https://openairdocs.org/ntsb/CEN10IA438 ## Probable cause The loss of main rotor rpm during takeoff for reasons that could not be determined because postaccident examination of the airframe and engine did not reveal any anomalies. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Main rotor system](https://openairdocs.org/ntsb-findings/01046200): Aircraft › Aircraft propeller/rotor · Capability exceeded (probable cause); cases with it: [All aircraft, 25 cases](https://openairdocs.org/ntsb-findings/01046200/cases.md) - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Autorotation: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Post-impact: Cabin safety event](https://openairdocs.org/ntsb-events/110); cases with it: [All aircraft, 151 cases](https://openairdocs.org/ntsb-events/110/sequence.md) ## Analysis During takeoff from an offshore oil platform, the pilot reported a loss of main rotor rpm. The pilot activated the emergency float system and initiated an autorotation to the water. Upon touchdown, the engine was still operating. The pilot shut down the engine and prepared the passengers to evacuate. All three occupants safely evacuated the helicopter (which was upright on its skid-mounted float system) and boarded the emergency life raft that the pilot had inflated. The helicopter remained upright floating on the water and was later recovered and transported to the operator’s on-shore maintenance facility. The operator did immediate fuel quality tests at the facility where the helicopter had most recently been refueled and found no problems. An examination of the helicopter drive systems and a test run of the engine did not reveal any preincident anomalies that would have precluded normal operation of the main rotor system. The cause of the loss of main rotor rpm could not be determined. ## Factual narrative On July 26, 2010 about 1442 central daylight time, a Bell 206L4 helicopter, N317RL, had a loss of main rotor rpm and the pilot executed an autorotation to the water about 63 miles southwest of Houma, Louisiana in the Gulf of Mexico (GOM). The commercial pilot and his two passengers were not injured. The helicopter was registered to and operated by Rotorcraft Leasing Company LLC, Broussard, Louisiana. Visual meteorological conditions (VMC) prevailed in the vicinity and a company flight plan was filed for the Title 14 Code of Federal Regulations Part 135 on-demand passenger flight. The helicopter had just taken off from the South Timbalier 178A offshore oil platform and its intended destination was another nearby offshore platform. The pilot reported that during takeoff from the platform he heard what seemed to be loud banging from the rear of the helicopter and noted a loss of main rotor rpm. The pilot activated the emergency float system and initiated an autorotation to the water. Upon touchdown, the engine was still running. The pilot shut down the engine and prepared the passengers to evacuate. All three occupants safely evacuated the helicopter (which was upright on its skid mounted float system) and boarded the emergency life raft that the pilot had inflated. A nearby surface vessel came to their aid and transported the three occupants to a nearby platform. A Coast Guard helicopter later transported them to an on-shore location for a medical evaluation. The helicopter remained upright floating on the water and was later recovered and transported to the operator’s on-shore maintenance facility. The operator did immediate fuel quality tests on the facility where the helicopter had most recently been refueled and found no problems. An examination of the helicopter drive systems did not reveal any preincident anomalies which would have precluded normal operation. The engine was removed intact and was operated within normal parameters during an engine test cell run. The reason for the pilot’s report of a partial loss of main rotor rpm could not be determined. ## Aircraft - Registration: N317RL (not matched to a registry record) - Reported make and model: BELL 206 (L4) - Category: Helicopter - Serial number: 52317 - Airframe hours: 5544 - Engines: ALLISON 250 650 horsepower turbo shaft - Damage: Minor damage - Flight: Part 135 - Operator: Rotorcraft Leasing Co LLC - Registered owner: Rotorcraft Leasing Co LLC - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, June 26, 2010, 127 hours before - Departed: NONE, Gulf of Mexico, LA - Destination: NONE, Gulf of Mexico, LA - Flight plan: Company VFR - Airport: NONE, South Timbalier 178A ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; injuries: none; commercial; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review July 16, 2010; seat: right; flight hours: 1,297 total, 239 in this make and model, 39 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 130° at 8 knots - Visibility: 7 statute miles - Lowest ceiling: 5,000 ft broken - Temperature: 86 °F, dew point 84 °F - Altimeter: 30.00 inHg - Observed at: HUM, 63 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20100726051689I](https://openairdocs.org/incident/20100726051689I), Jul 26, 2010: Bell 206-L4, Minor damage. While departing a offshore platform in the gulf of Mexico just after takeoff, the pilot reported hearing the low rotor RPM alarm and observed the low rotor… ## Docket (6 files) The files NTSB released with the investigation on August 7, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=76760. 3.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374418&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Passenger Statements (item 2, .PDF, 183 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374293&FileExtension=.PDF&FileName=Passenger%20Statements-Redacted.PDF - Record of Conversations (item 3, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374535&FileExtension=.PDF&FileName=Record%20of%20Conversations-Master.PDF - Map (item 4, .PDF, 426 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374298&FileExtension=.PDF&FileName=Map-Master.PDF - Helicopter Accident/Incident Supplemental Checklist (item 5, .PDF, 23 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374384&FileExtension=.PDF&FileName=Helicopter%20Accident%2FIncident%20Supplemental%20Checklist-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 6, .PDF, 512 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374301&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF 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.