# Reduction gear and shaft - Type: NTSB finding subsection - Path: [Aircraft](https://openairdocs.org/ntsb-findings/01) › [Aircraft power plant](https://openairdocs.org/ntsb-findings/0105) › [Engine (turbine/turboprop)](https://openairdocs.org/ntsb-findings/010572) › Reduction gear and shaft - NTSB code: 01057210 - Cases: 8 - In the probable cause: 8 - Fatal cases: 0 - All cases: https://openairdocs.org/ntsb-findings/01057210/cases.md - Cases with it in the probable cause: https://openairdocs.org/ntsb-findings/01057210/cases.md?cause=1 - Page: https://openairdocs.org/ntsb-findings/01057210 ## Cases per year (in the probable cause / all) - 2009: 2 / 2 - 2010: 1 / 1 - 2011: 2 / 2 - 2012: 1 / 1 - 2023: 2 / 2 ## Defining events in these cases - [Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340): 4 cases - [Uncontained engine failure](https://openairdocs.org/ntsb-events/343): 2 cases - [Loss of engine power (total)](https://openairdocs.org/ntsb-events/341): 2 cases ## Aircraft models (registry) - [Dehavilland DHC-6-300](https://openairdocs.org/model/dehavilland-dhc-6-300): 1 cases - [Cessna 208](https://openairdocs.org/model/cessna-208): 1 cases - [Bell Helicopter Textron Canada 412EP](https://openairdocs.org/model/bell-helicopter-textron-canada-412ep): 1 cases - [Ayres S2R-T34](https://openairdocs.org/model/ayres-s2r-t34): 1 cases - [Hall Lester R LEGACY](https://openairdocs.org/model/hall-lester-r-legacy): 1 cases - [Air Tractor AT-502B](https://openairdocs.org/model/air-tractor-at-502b): 1 cases - [Air Tractor AT-301](https://openairdocs.org/model/air-tractor-at-301): 1 cases ## Other findings in the same cases - [Turbine section](https://openairdocs.org/ntsb-findings/01057250) (Aircraft): 2 cases - [Not determined, general](https://openairdocs.org/ntsb-findings/05000000) (Not determined): 1 cases - [Support/oversight/monitoring, general](https://openairdocs.org/ntsb-findings/04030000) (Organizational issues): 1 cases - [Equipment manufacture](https://openairdocs.org/ntsb-findings/04013010) (Organizational issues): 1 cases - [Manufacture/production, general](https://openairdocs.org/ntsb-findings/04013000) (Organizational issues): 1 cases - [Equipment design](https://openairdocs.org/ntsb-findings/04011010) (Organizational issues): 1 cases - [Maintenance, general](https://openairdocs.org/ntsb-findings/02062000) (Personnel issues): 1 cases - [Intentional act, general](https://openairdocs.org/ntsb-findings/02051000) (Personnel issues): 1 cases - [Power plant, general](https://openairdocs.org/ntsb-findings/01057100) (Aircraft): 1 cases ## Newest cases - [NTSB ERA23LA327](https://openairdocs.org/ntsb/ERA23LA327), Aug 4, 2023: Air Tractor AT502 (N5048S), Leipsic, OH, substantial damage. Probable cause: The incorrect assembly of the turbine engine’s reduction gear box second-stage ring gear, which resulted in an internal failure of multiple engine components and a total loss of power. - [NTSB ENG23LA034](https://openairdocs.org/ntsb/ENG23LA034), Jul 20, 2023: Hall Lester R Legacy (N707MM), Rochester, MN, incident, minor damage. Probable cause: Mechanically distressed reduction gears causing an engine overspeed and turbine blade tensile overload and subsequent uncontainment. Contributing to the uncontainment was the operator’s use of the… - [NTSB DCA12IA114](https://openairdocs.org/ntsb/DCA12IA114), Jul 28, 2012: Boeing 787 (VT-ANJ), Charleston, SC, incident, minor damage. Probable cause: The separation of the fan mid shaft resulted from environmentally assisted cracking under static load. Contributing to the incident was the combination of dry film lubricant applied to the fan… - [NTSB CEN11LA404](https://openairdocs.org/ntsb/CEN11LA404), Jun 16, 2011: Ayres S2R-T34 (N30902), Athleimer, AR, substantial damage. Probable cause: Failure of the first stage planetary gearset in the propeller reduction gearbox, which resulted in catastrophic engine failure. Contributing to the failure was the misrepresentation of the gearset… - [NTSB ENG11IA032](https://openairdocs.org/ntsb/ENG11IA032), May 21, 2011: Dehavilland DHC-6-300 (N178GC), Peach Springs, AZ, incident, no damage. Probable cause: A quality control failure in the Sungear, Inc. manufacturing and quality control process allowed sungears with surface finishes of the root fillet radius of the spline that did not conform to the… - [NTSB ERA10TA493](https://openairdocs.org/ntsb/ERA10TA493), Sep 22, 2010: Bell 412 (N412PD), Brooklyn, NY, substantial damage. Probable cause: The fatigue fracture of the reduction gearbox output drive gear, which resulted in the loss of power output from the engines to the helicopter rotor blade system and a subsequent forced landing. The… - [NTSB ERA09LA523](https://openairdocs.org/ntsb/ERA09LA523), Sep 15, 2009: Cessna 208 (N336DN), Sheffield, MA, destroyed. Probable cause: A total loss of engine power due to a failure of the 1st stage sun gear output splines for unknown reasons, which resulted in a power turbine overspeed condition, with subsequent blade… - [NTSB CEN09LA602](https://openairdocs.org/ntsb/CEN09LA602), Aug 22, 2009: Air Tractor AT-301A (N3651R), New Miner, WI, substantial damage. Probable cause: A total loss of engine power due to the fatigue failure of the engine torsion shaft. Contributing to the accident was the chrome plating of the shaft by an undetermined maintenance/overhaul facility. NTSB has coded findings and defining events since 2008; earlier cases used its older occurrence and cause codes and aren't counted. Findings: https://openairdocs.org/ntsb-findings.md. Defining events: https://openairdocs.org/ntsb-events.md. Phases of flight: https://openairdocs.org/ntsb-phases.md. Every investigation, filtered by finding, event, phase, state, year or model: https://openairdocs.org/ntsb.md (for example ?state=MI&fatal=1). NTSB's definitions: Accident and incident, 49 CFR 830.2 (https://www.ecfr.gov/current/title-49/subtitle-B/chapter-VIII/part-830/subpart-A/section-830.2), CICTT occurrence categories (PDF) (https://www.ntsb.gov/safety/data/Documents/datafiles/OccurrenceCategoryDefinitions.pdf), CICTT phases of flight (PDF) (https://www.ntsb.gov/safety/data/Documents/datafiles/PhaseofFlightDefinitions.pdf), and NTSB coding manual, before 2008 (PDF) (https://www.ntsb.gov/GILS/Documents/codman.pdf). NTSB publishes no definitions for its findings, only their names. --- 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.