# Mast bumping - Type: NTSB defining event - NTSB code: 245 - CICTT category: Loss Of Control (Inflight) - Defining event in: 9 cases - In the sequence of: 18 cases - Fatal cases: 7 - All cases: https://openairdocs.org/ntsb-events/245/cases.md - Cases with it anywhere in the sequence: https://openairdocs.org/ntsb-events/245/sequence.md - Page: https://openairdocs.org/ntsb-events/245 ## Cases per year (defining / in the sequence) - 2010: 0 / 1 - 2011: 1 / 1 - 2012: 0 / 1 - 2013: 0 / 2 - 2014: 0 / 1 - 2015: 0 / 1 - 2016: 2 / 2 - 2017: 0 / 1 - 2018: 1 / 1 - 2019: 1 / 1 - 2021: 0 / 2 - 2023: 1 / 1 - 2024: 2 / 2 - 2026: 1 / 1 ## Phase of flight - Enroute: 3 cases - Maneuvering: 2 cases - Enroute-cruise: 2 cases - Maneuvering-low-alt flying: 1 cases - Taxi-to runway: 1 cases ## In the probable cause of these cases - [Main rotor mast/swashplate](https://openairdocs.org/ntsb-findings/01046230) (Aircraft): 3 cases - [Terrain induced turbulence](https://openairdocs.org/ntsb-findings/03032010) (Environmental issues): 2 cases - [Main rotor blade system](https://openairdocs.org/ntsb-findings/01046210) (Aircraft): 2 cases - [Convective turbulence](https://openairdocs.org/ntsb-findings/03032020) (Environmental issues): 1 cases - [Aircraft control](https://openairdocs.org/ntsb-findings/02063040) (Personnel issues): 1 cases - [Use of equip/system](https://openairdocs.org/ntsb-findings/02063015) (Personnel issues): 1 cases - [Identification/recognition](https://openairdocs.org/ntsb-findings/02041510) (Personnel issues): 1 cases - [Incorrect action performance](https://openairdocs.org/ntsb-findings/02041015) (Personnel issues): 1 cases - [Incorrect action selection](https://openairdocs.org/ntsb-findings/02041010) (Personnel issues): 1 cases - [Prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052) (Aircraft): 1 cases ## Aircraft models (registry) - [Robinson Helicopter R66](https://openairdocs.org/model/robinson-helicopter-r66): 1 cases - [Robinson Helicopter R44](https://openairdocs.org/model/robinson-helicopter-r44): 1 cases - [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta): 1 cases - [Fairchild Hiller FH-1100](https://openairdocs.org/model/fairchild-hiller-fh-1100): 1 cases - [Faber Vincent L SCORPION 133](https://openairdocs.org/model/faber-vincent-l-scorpion-133): 1 cases - [Bell OH-58A](https://openairdocs.org/model/bell-oh-58a): 1 cases - [Bell 206B](https://openairdocs.org/model/bell-206b): 1 cases - [CSP Leasing CAVALON](https://openairdocs.org/model/csp-leasing-cavalon): 1 cases ## Newest cases - [NTSB ERA26LA324](https://openairdocs.org/ntsb/ERA26LA324), Aug 30, 2026: CSP Leasing Cavalon (N203AG), Ronkonkoma, NY, substantial damage, investigation ongoing - [NTSB ANC24FA063](https://openairdocs.org/ntsb/ANC24FA063), Jul 11, 2024: Robinson Helicopter R44 (N144KW), Kekaha, HI, substantial damage, 3 fatal. Probable cause: An encounter with turbulence due to downdraft winds that resulted in mast bumping and an in-flight breakup. - [NTSB CEN24FA248](https://openairdocs.org/ntsb/CEN24FA248), Jul 5, 2024: Rotorway Scorpion 133 (N51017), Andale, KS, destroyed, 1 fatal. Probable cause: The pilot’s abrupt control inputs, which resulted in a low-G condition, main rotor mast bumping, and subsequent severing of the tailboom by the main rotor blades. - [NTSB WPR23LA313](https://openairdocs.org/ntsb/WPR23LA313), Aug 9, 2023: Bell OH-58A (N861CC), Guernsey, CA, substantial damage. Probable cause: The pilot’s overpitching of the main rotor blades while maneuvering at low altitude in a high-temperature environment at high gross weight, which resulted in a reduction of engine and rotor speed,… - [NTSB WPR19FA109](https://openairdocs.org/ntsb/WPR19FA109), Apr 16, 2019: Bell 206 (N61PH), Fort McDowell, AZ, destroyed, 2 fatal. Probable cause: The separation of the main rotor head from the mast as a result of a sudden displacement of the cyclic stick during a low-G maneuver, leading to mast bumping. Contributing to the accident were the… - [NTSB CEN18WA402](https://openairdocs.org/ntsb/CEN18WA402), Apr 5, 2018: Rotorway Exec (F-PFBJ), Crestet, France, destroyed, 1 fatal - [NTSB CEN17FA012](https://openairdocs.org/ntsb/CEN17FA012), Oct 6, 2016: Fairchild Hiller FH 1100 (N4035G), Lino Lakes, MN, destroyed, 2 fatal. Probable cause: The separation of the main rotor assembly due to mast bumping. - [NTSB WPR16FA130](https://openairdocs.org/ntsb/WPR16FA130), Jun 23, 2016: Robinson Helicopter R66 (N117TW), Wikieup, AZ, destroyed, 2 fatal. Probable cause: An encounter with turbulence due to updrafts and/or dust devils that resulted in mast bumping and an in-flight break-up. - [NTSB CEN11FA422](https://openairdocs.org/ntsb/CEN11FA422), Jun 27, 2011: Robinson R22 Beta (N7779M), Del Valle, TX, substantial damage, 1 fatal. Probable cause: The divergence of the main rotor from its normal plane of rotation for reasons that cannot be determined because the pilot’s control inputs leading up to the event are unknown, resulting in mast… 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.