# NTSB DEN00LA045: Bell 212, N212HQ, Mt Pleasant, UT, January 29, 2000 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: January 29, 2000, 15:00 local (22:00 UTC) - Place: Mt Pleasant, UT - Coordinates: 39.550868, -111.390251 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.5509&lon=-111.3903&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report July 2, 2001 - Report: Approved by Office Director - ADs cited in the narratives: [AD 98-24-15](https://openairdocs.org/ad/98-24-15) (OpenAirDocs) - NTSB case key (mKey): 48553 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN00LA045 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/48553/pdf - Page: https://openairdocs.org/ntsb/DEN00LA045 ## Probable cause Failure of the main rotor mast due to fatigue that resulted from inadequate quality assurance during the manufacturing process. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, maneuvering - rotor drive system,main rotor mast(drive shaft) - fatigue (cause) - rotor drive system,main rotor mast(drive shaft) - failure,total (cause) - inadequate quality control, manufacturer (cause) ## Analysis While in level flight approximately 120 feet above ground level, carrying an external load of logs, the main rotor mast separated from the helicopter. The fuselage descended into a tree covered slope and broke into three sections. The pilot received serious injuries. Laboratory examination of the main rotor mast provided evidence the mast failed in fatigue at the lower ring groove of the damper splines where burrs were left during machining of the part. Retirement requirements for the mast were 15,000 flight hours or 300,000 RIN (retirement index number). The mast had 5,644.4 hours with the last overhaul being done at 3,660.8 hours. The FAA calculated the RIN number to be 291,065. ## Factual narrative On January 29, 2000, at 1500 mountain standard time, a Bell 212 helicopter, N212HQ sustained substantial damage when it impacted the ground after the main rotor system separated from the aircraft during logging operations near Mount Pleasant, Utah. The commercial pilot, who was the sole occupant, received serious injuries. The flight was operating under Title 14 CFR Part 133 and no flight plan was filed. Visual meteorological conditions prevailed for this local area flight that departed Mount Pleasant at 1410. The helicopter was in level flight approximately 120 feet above the ground, over down sloping terrain carrying an external load of logs, when the main rotor mast failed. The fuselage descended nose down into trees with the load of logs attached. On impact with the ground, the fuselage inverted and broke into three pieces. The pilot remained in the aircraft and the seat remained attached. Examination of the main rotor mast was conducted at the facilities of Bell Helicopter Textron, Inc., (BHTI) Hurst, Texas, under the direction of a Safety Board investigator from the Arlington, Texas, office. The examination provided evidence that the main rotor mast P/N 204-011-450-007, S/N N9-19783, failed in fatigue at the lower ring groove of the damper splines. The origin was in a burr area left after machining of the part. (See attached NTSB and BHTI reports) According to information provided by the Federal Aviation Administration (FAA), BHTI, and the operator, the rotor mast had accumulated 5,644.4 hours since its manufacture in 1978, and had been overhauled four times, with the latest being at an accumulated time of 3,660.8 hours. The retirement requirement for the rotor mast at the time of the accident was either 15,000 flight hours or 300,000 RIN (retirement index number). The operator calculated the RIN to be approximately 264,000; the FAA calculated it to be 291,065 and BHTI calculated it to be 463,000. The operator and FAA used recorded data to calculate RIN and BHTI used data from service bulletins and past Airworthiness Directives pertaining to RIN count. For an explanation of RIN calculation requirements see Airworthiness Directives (AD) 98-24-15 and AD 20-00-08-52. Based on the results of the accident investigation, the FAA issued Emergency AD 20-00-08-52 on April 21, 2000. The AD reduced the allowable RIN life limit, clarified the RIN calculation method, and required a one time special inspection of main rotor masts on the BHTI models 204B, 205A, 205B, and 212. Compliance was required prior to further flight. ## Aircraft - Registration: [N212HQ](https://openairdocs.org/deregistered/N212HQ-2010-04-07), registration cancelled 2010-04-07, S/N 30646, built 1974 (OpenAirDocs) - Reported make and model: Bell 212 - Registry model: [Bell 212](https://openairdocs.org/model/bell-212) (registry code 1181420) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PT6T-3](https://openairdocs.org/engine/pratt-whitney-canada-pt6t-3) (registry code 52102, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 30646 - Airframe hours: 8118 - Engines: P&W PT-6-3 900 horsepower turbo shaft - Damage: Substantial damage - Flight: Part 133 - Registered owner: Heliqwest International, Inc. - Airworthiness certificate: Standard, Utility - Last inspection: Continuous airworthiness, January 22, 2000, 18 hours before - Departed: 43U ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 39; commercial; airplane ratings: single-engine land, multi-engine land; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 7,370 total, 90 in this make and model ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 43 °F, dew point 10 °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 20000129005699A](https://openairdocs.org/incident/20000129005699A), Jan 29, 2000: Bell 212, Mount Pleasant, UT, No damage. (-23) On January 29, 2000, at approximately 1347 MST, a bht 212 helicopter piloted by daniel d. gauthier, certificate 2590780, was demolished when the main… 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.