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Hydraulic fluid

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NTSB finding · Aircraft › Fluids/misc hardware › Fluids

All 33 cases28 in the probable cause
Cases
33
In the probable cause
28 (85%)
Fatal cases
1
NTSB code
01071015

NTSB has coded findings and defining events since 2008. Earlier cases used its older occurrence and cause codes, so they aren’t counted here.

When and where

In green, cases where NTSB made it part of the probable cause; in gray, a factor or other finding. Findings are coded with the final report, often a year or more after the event, so the latest years are incomplete.

Cases per year

2008In the probable causeFactor only2026

Where

Open the map
Query with SQL
duckdb -csv -c "SELECT year(c.\"eventDate\") AS year, count(DISTINCT f.case_mkey) AS cases,
    count(DISTINCT f.case_mkey) FILTER (WHERE f.\"inProbableCause\") AS in_probable_cause
  FROM 'https://openairdocs.org/data/latest/ntsb_findings.parquet' f JOIN 'https://openairdocs.org/data/latest/ntsb_case_detail.parquet' c ON c.\"mKey\" = f.case_mkey
  WHERE starts_with(f.\"findingCode\", '01071015') AND c.\"eventDate\" >= DATE '2000-01-01'
  GROUP BY 1
  ORDER BY 1"

Prints the counts as CSV. It reads the release’s Parquet files over HTTPS, so there’s nothing to download first. Install DuckDB to run it.

In the same cases

Defining events
Aircraft models

Aircraft matched to the registry by N-number and date.

Other findings
Query with SQL
duckdb -csv -c "WITH matched AS (SELECT DISTINCT case_mkey, aircrafts_position FROM 'https://openairdocs.org/data/latest/ntsb_findings.parquet' WHERE starts_with(\"findingCode\", '01071015'))
  SELECT * FROM (
  SELECT 'Defining event' AS kind, e.\"tier2Number\" AS code, max(e.\"eventTier2Name\") AS name, count(DISTINCT f.case_mkey) AS cases
  FROM matched f JOIN 'https://openairdocs.org/data/latest/ntsb_events.parquet' e ON e.case_mkey = f.case_mkey AND e.aircrafts_position = f.aircrafts_position AND e.\"isDefiningEvent\"
  WHERE e.\"tier2Number\" <> ''
  GROUP BY ALL
  UNION ALL
  SELECT 'Aircraft model', a.aircraft_model_code, any_value(concat_ws(' ', m.manufacturer, m.model)), count(DISTINCT f.case_mkey)
  FROM matched f JOIN 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' a ON a.case_mkey = f.case_mkey AND a.position = f.aircrafts_position
  LEFT JOIN 'https://openairdocs.org/data/latest/faa_aircraft_model.parquet' m ON m.code = a.aircraft_model_code
  WHERE a.aircraft_model_code IS NOT NULL
  GROUP BY ALL
  UNION ALL
  SELECT 'Other finding', left(g.\"findingCode\", 8), max(g.\"tier4Name\"), count(DISTINCT g.case_mkey)
  FROM 'https://openairdocs.org/data/latest/ntsb_findings.parquet' g
  WHERE g.case_mkey IN (SELECT case_mkey FROM matched) AND NOT starts_with(g.\"findingCode\", '01071015') AND g.\"findingCode\" GLOB '[0-9][0-9]*'
  GROUP BY ALL
  )
  QUALIFY row_number() OVER (PARTITION BY kind ORDER BY cases DESC) <= 10
  ORDER BY kind, cases DESC"

Prints the counts as CSV. It reads the release’s Parquet files over HTTPS, so there’s nothing to download first. Install DuckDB to run it.

Newest cases · 33

NTSB ERA25LA314Accident · No injuriesClass 4 · LimitedFinal reportPiper PA32R · Miami, FLAn inflight loss of hydraulic fluid from the landing gear system through a cracked fitting, which resulted in a landing gear collapse upon touchdown.Aug 20, 2025 · N990DM · Substantial damageNTSB WPR25LA178Accident · No injuriesClass 4 · LimitedFinal reportPiper PA-28R-200 · Vancouver, WAA failure of the brake system during landing due to a hydraulic fluid leak, which resulted in a runway excursion.Apr 4, 2025 · N9404N · Substantial damageNTSB ERA24LA051Accident · No injuriesClass 3 · LimitedFinal reportLancair 235 · Stuart, FLA landing gear collapse due to a hydraulic fluid leak in the landing gear system.Nov 28, 2023 · N235N · Substantial damageNTSB WPR23LA076Accident · No injuriesClass 3 · LimitedFinal reportCessna 210N · Morgan, UTFailure of the brake system O-rings on the left landing gear trunnion, which allowed the hydraulic fluid to drain from the left brake system, resulting in a runway excursion and impact with a fence.Dec 26, 2022 · N210CU · Substantial damageNTSB WPR22LA341Accident · No injuriesClass 3 · LimitedFinal reportCessna 750 · Mesa, AZThe 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 approach, which resulted in a loss of control during the…Sep 7, 2022 · N15TZ · Substantial damageNTSB WPR21LA362Accident · No injuriesClass 3 · LimitedFinal reportMaule MX-7-235 · Ontario, ORA loss of hydraulic fluid and failure of the right brake for reasons that could not be determined due to a lack of available evidence.Mar 28, 2021 · N235X · Substantial damageNTSB WPR20LA172Accident · No injuriesClass 3 · LimitedFinal reportAyres S2R · Imperial, CAThe pilot's loss of control during a landing roll due to a failure of the main O-ring in the right brake assembly, which resulted in a loss of brake pressure and subsequent brake failure.May 9, 2020 · N2245S · Substantial damageNTSB WPR20LA104Accident · No injuriesClass 3 · LimitedFinal reportPiper PA46 · San Jose, CAThe failure to properly service the hydraulic power pack prevented a normal landing gear extension. Contributing to the accident was the failure of the landing gear emergency release valve to function properly for reasons that could not be determined based on…Feb 28, 2020 · N304LA · Substantial damageNTSB ANC20LA013Accident · No injuriesClass 3 · LimitedFinal reportPiper PA31 · Fairbanks, AKThe improper installation of a hydraulic line at the right main landing gear (MLG) unlock actuator, which resulted in a total loss of system hydraulic pressure and failure of the landing gear to extend. Contributing to the accident was the failure of the…Jan 12, 2020 · N4112K · Substantial damageNTSB ERA19LA239Accident · No injuriesClass 3 · LimitedFinal reportCessna 210 · Chattanooga, TNThe improper maintenance of the airplane’s landing gear system, which resulted in a hydraulic fluid leak and insufficient pressure to extend and lock the landing gear during the accident flight.Jul 30, 2019 · N2362F · Substantial damage
See all 33 cases
Query with SQL
duckdb -csv -c "SELECT c.\"ntsbNumber\", c.\"eventDate\", c.\"eventType\", c.\"eventCity\", c.\"eventStateOrRegion\", a.n_number, a.\"aircraftMake\", a.\"aircraftModel\", c.\"highestInjuryLevel\", c.\"totalFatal\", c.\"completionStatus\", c.report_url
  FROM 'https://openairdocs.org/data/latest/ntsb_case_detail.parquet' c LEFT JOIN 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' a ON a.case_mkey = c.\"mKey\" AND a.position = 1
  WHERE c.\"mKey\" IN (SELECT f.case_mkey FROM 'https://openairdocs.org/data/latest/ntsb_findings.parquet' f WHERE starts_with(f.\"findingCode\", '01071015'))
  ORDER BY c.\"eventDate\" DESC, c.\"ntsbNumber\" DESC"

Prints the whole list as CSV. It reads the release’s Parquet files over HTTPS, so there’s nothing to download first. Install DuckDB to run it.