# Hydraulic power system - Type: NTSB finding section - Path: [Aircraft](https://openairdocs.org/ntsb-findings/01) › [Aircraft systems](https://openairdocs.org/ntsb-findings/0102) › Hydraulic power system - NTSB code: 010229 - Cases: 65 - In the probable cause: 56 - Fatal cases: 7 - All cases: https://openairdocs.org/ntsb-findings/010229/cases.md - Cases with it in the probable cause: https://openairdocs.org/ntsb-findings/010229/cases.md?cause=1 - Page: https://openairdocs.org/ntsb-findings/010229 ## Cases per year (in the probable cause / all) - 2008: 5 / 6 - 2009: 6 / 8 - 2010: 3 / 4 - 2011: 5 / 6 - 2012: 4 / 4 - 2013: 2 / 2 - 2014: 4 / 6 - 2015: 4 / 4 - 2016: 2 / 2 - 2017: 2 / 2 - 2018: 3 / 3 - 2019: 2 / 2 - 2020: 5 / 5 - 2021: 4 / 4 - 2022: 3 / 3 - 2023: 1 / 2 - 2024: 1 / 2 ## Findings - [Hydraulic, main system](https://openairdocs.org/ntsb-findings/01022910): 27 cases, 23 in the probable cause - [Hydraulic power system, general](https://openairdocs.org/ntsb-findings/01022900): 22 cases, 20 in the probable cause - [Pump, main](https://openairdocs.org/ntsb-findings/01022913): 7 cases, 7 in the probable cause - [Accumulator, main](https://openairdocs.org/ntsb-findings/01022911): 3 cases, 2 in the probable cause - [Reservoir, main](https://openairdocs.org/ntsb-findings/01022916): 3 cases, 3 in the probable cause - [Hydraulic, auxiliary system](https://openairdocs.org/ntsb-findings/01022920): 2 cases, 2 in the probable cause - [Hydraulic, indicating system](https://openairdocs.org/ntsb-findings/01022930): 2 cases, 2 in the probable cause - [Pressure relief, main](https://openairdocs.org/ntsb-findings/01022915): 1 cases, 0 in the probable cause - [Pressure regulator, main](https://openairdocs.org/ntsb-findings/01022917): 1 cases, 1 in the probable cause - [Handpump, auxiliary](https://openairdocs.org/ntsb-findings/01022924): 1 cases, 0 in the probable cause - [Pressure sensor](https://openairdocs.org/ntsb-findings/01022932): 1 cases, 0 in the probable cause - [Hyd pwr sys wiring](https://openairdocs.org/ntsb-findings/01022997): 1 cases, 1 in the probable cause ## Defining events in these cases - [Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330): 25 cases - [Loss of control in flight](https://openairdocs.org/ntsb-events/240): 12 cases - [Landing gear collapse](https://openairdocs.org/ntsb-events/094): 9 cases - [Fire/smoke (non-impact)](https://openairdocs.org/ntsb-events/150): 3 cases - [Landing gear not configured](https://openairdocs.org/ntsb-events/095): 3 cases - [Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333): 2 cases - [Electrical system malf/failure](https://openairdocs.org/ntsb-events/332): 2 cases - [Runway excursion](https://openairdocs.org/ntsb-events/300): 2 cases - [Birdstrike](https://openairdocs.org/ntsb-events/901): 1 cases - [Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241): 1 cases ## Aircraft models (registry) - [Eurocopter AS 350 B2](https://openairdocs.org/model/eurocopter-as-350-b2): 4 cases - [Eurocopter AS 350 B3](https://openairdocs.org/model/eurocopter-as-350-b3): 3 cases - [Piper PA 46-350P](https://openairdocs.org/model/piper-pa-46-350p): 2 cases - [Fairchild SA227-AC](https://openairdocs.org/model/fairchild-sa227-ac): 2 cases - [Cessna 210](https://openairdocs.org/model/cessna-210): 2 cases - [Cessna 172RG](https://openairdocs.org/model/cessna-172rg): 2 cases - [Aerospatiale AS350 B2 ECUREUIL](https://openairdocs.org/model/aerospatiale-as350-b2-ecureuil): 1 cases - [Sikorsky S-61N](https://openairdocs.org/model/sikorsky-s-61n): 1 cases - [Sikorsky S55B](https://openairdocs.org/model/sikorsky-s55b): 1 cases - [Rockwell International 112](https://openairdocs.org/model/rockwell-international-112): 1 cases ## Other findings in the same cases - [Gear extension and retract sys](https://openairdocs.org/ntsb-findings/01023230) (Aircraft): 10 cases - [Not determined, general](https://openairdocs.org/ntsb-findings/05000000) (Not determined): 9 cases - [Hydraulic fluid](https://openairdocs.org/ntsb-findings/01071015) (Aircraft): 9 cases - [Use of equip/system](https://openairdocs.org/ntsb-findings/02063015) (Personnel issues): 7 cases - [Decision making/judgment](https://openairdocs.org/ntsb-findings/02041520) (Personnel issues): 7 cases - [Main landing gear](https://openairdocs.org/ntsb-findings/01023210) (Aircraft): 7 cases - [Aircraft control](https://openairdocs.org/ntsb-findings/02063040) (Personnel issues): 6 cases - [Incorrect action performance](https://openairdocs.org/ntsb-findings/02041015) (Personnel issues): 6 cases - [Forgotten action/omission](https://openairdocs.org/ntsb-findings/02041035) (Personnel issues): 5 cases - [Scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010) (Personnel issues): 4 cases ## Newest cases - [NTSB WPR24LA157](https://openairdocs.org/ntsb/WPR24LA157), May 16, 2024: Cessna P210 (N4769K), Daggett, CA, substantial damage. Probable cause: The pilot’s failure to detect the tripped alternator circuit breaker in flight, which resulted in a drained battery that prevented the landing gear from fully extending to the down-and-locked… - [NTSB DCA24LA095](https://openairdocs.org/ntsb/DCA24LA095), Feb 11, 2024: Boeing 737-823 (N991AN), Dallas, TX, incident, minor damage. Probable cause: Improper maintenance due to human error during a braking system modification diminished braking performance. Contributing to the diminished braking performance was the lack of a functional check to… - [NTSB DCA24FA002](https://openairdocs.org/ntsb/DCA24FA002), Oct 5, 2023: Boeing 757-236 (N977FD), Chattanooga, TN, substantial damage. Probable cause: The failure of the alternate gear extension system, which prevented the landing gear from being lowered. The cause of the system failure was a broken wire, due to tensile overload, between the… - [NTSB ERA23LA202](https://openairdocs.org/ntsb/ERA23LA202), Apr 18, 2023: Rockwell International 112 (N12RX), Miami, FL, substantial damage. Probable cause: Failure of the right main landing gear due to inadequate hydraulic pressure as result of a torn O-ring that was installed on the hydraulic pack’s check valve during overhaul. - [NTSB WPR22LA341](https://openairdocs.org/ntsb/WPR22LA341), Sep 7, 2022: Cessna 750 (N15TZ), Mesa, AZ, substantial damage. Probable cause: The pilot’s improper decision to depart on the accident flight with a known hydraulic leak, resulting in an in-flight hydraulic system failure, and the pilot’s attempt to land during an unstabilized… - [NTSB CEN22LA378](https://openairdocs.org/ntsb/CEN22LA378), Aug 9, 2022: Cessna 210B (N9637X), Clinton, AR, substantial damage. Probable cause: A fatigue crack in the hydraulic actuator, which resulted in the loss of hydraulic fluid and the pilot’s inability to fully extend the landing gear. - [NTSB ERA22LA148](https://openairdocs.org/ntsb/ERA22LA148), Mar 7, 2022: Cessna 525 (N22AU), Middle River, MD, substantial damage. Probable cause: And undetermined failure of the brake system. Contributing to the accident was the failure of the pilots to locate and operate the emergency brake control, which resulted in a runway excursion and… - [NTSB ERA22LA005](https://openairdocs.org/ntsb/ERA22LA005), Oct 5, 2021: Cessna 210 (N6318B), Columbia, SC, substantial damage. Probable cause: A failure of the landing gear hydraulic power pack for reasons that could not be determined. - [NTSB DCA21LA229](https://openairdocs.org/ntsb/DCA21LA229), Sep 1, 2021: Boeing 767-332 (N196DN), Seattle, WA, no damage. Probable cause: The flightcrew’s failure to set the hydraulic panel correctly during the execution of the pushback checklist, and when the hydraulic panel setting was corrected, that resulted in the airplane coming… - [NTSB WPR21LA323](https://openairdocs.org/ntsb/WPR21LA323), Aug 15, 2021: Cessna 177RG (N8029G), Albuquerque, NM, substantial damage. Probable cause: The failure of the nose gear hydraulic flex line, which resulted in a loss of hydraulic fluid which prevented the main landing gear from fully extending and locking into place during landing. 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.