# NTSB WPR21LA362: Maule MX-7-235, N235X, Ontario, OR, March 28, 2021 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: March 28, 2021, 12:00 local (18:00 UTC) - Place: Ontario, OR · Airport Environment - Coordinates: 44.019361, -117.01302 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=44.0194&lon=-117.0130&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Dragged wing/rotor/float/other](https://openairdocs.org/ntsb-events/093) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Maule Air, Federal Aviation Administration - NTSB case key (mKey): 104075 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21LA362 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/104075/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=104075 - Page: https://openairdocs.org/ntsb/WPR21LA362 ## Probable cause A loss of hydraulic fluid and failure of the right brake for reasons that could not be determined due to a lack of available evidence. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: brake](https://openairdocs.org/ntsb-findings/01023242): Aircraft › Aircraft systems · Failure; cases with it: [Maule MX-7-235, 3 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md?model=5470207), [All aircraft, 297 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md) - [Fluids: hydraulic fluid](https://openairdocs.org/ntsb-findings/01071015): Aircraft › Fluids/misc hardware · Fluid level; cases with it: [Maule MX-7-235, 1 case](https://openairdocs.org/ntsb-findings/01071015/cases.md?model=5470207), [All aircraft, 33 cases](https://openairdocs.org/ntsb-findings/01071015/cases.md) - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Maule MX-7-235, 1 case](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=5470207), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-landing roll: Dragged wing/rotor/float/other](https://openairdocs.org/ntsb-events/093) (defining event); cases with it: [Maule MX-7-235, 2 cases](https://openairdocs.org/ntsb-events/093/sequence.md?model=5470207), [All aircraft, 319 cases](https://openairdocs.org/ntsb-events/093/sequence.md) - [Landing-landing roll: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330); cases with it: [Maule MX-7-235, 1 case](https://openairdocs.org/ntsb-events/330/sequence.md?model=5470207), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) ## Analysis The pilot reported that, when he applied brakes during the landing roll, there was no pressure on the right brake pedal. The airplane veered left and ground looped, resulting in substantial damage. The pilot reported that he observed hydraulic fluid on the right main landing gear after the accident. The accident was not reported until several months later. An examination of the parts retained by the pilot’s mechanic, including the brake, brake disc, and fittings did not reveal any preimpact mechanical anomalies or failures that would have precluded normal operation. The hydraulic fluid observed on the landing gear suggests the brake failure may have resulted from a leak at either the hydraulic line or the hydraulic inlet fitting to the brake; however, these items were discarded or replaced before the event was reported and could not be examined. The cause of the leak and right brake failure could not be determined due to a lack of available evidence. ## Factual narrative On March 28, 2021, about 1200 Pacific daylight time, a Maule MX-7-235, N235X, was substantially damaged when it was involved in an accident near Ontario, Oregon. The private pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. According to the pilot, he pressed the left and right toe brakes to decelerate the airplane during landing roll following an uneventful touchdown. The left brake pedal functioned normally, while the right brake pedal provided no resistance and depressed to the floor. The airplane immediately veered to the left, the right wing contacted the ground, and the airplane ground looped. After the pilot exited the airplane, he observed hydraulic fluid on the right main landing gear wheel. The ground loop was not reported to the NTSB until about 6 months after the accident. Photos provided by the accident pilot revealed substantial damage to the right aileron and elevator. The pilot reported that he was ferrying the airplane from Utah to his home after purchasing it when the accident occurred. One month before the accident, he told the owner that the right brake pedal on the pilot’s side didn’t work. He reported that the pedal movement was similar to what occurred during the accident. The owner informed the pilot that he would have his mechanic look at it; however, when the pilot arrived the day before the accident to take the airplane, he discovered that the brake issue had not been resolved. The owner’s mechanic then bled the brake, which seemed to resolve the issue at the time. The pilot then flew for 2 hours that day and did not experience any anomalies or failures with the brake system when he landed. He stated that he taxied the airplane the length of the runway twice and brought the airplane to a full stop to test the brakes before departing on the accident flight and noted that each pedal had equal pressure. The airplane’s brake system comprised both master and slave cylinders at the pilot and front seat passenger’s rudder pedal positions, connected to brake lines that feed into the brake through the hydraulic inlet port. The system is actuated by hydraulic pressure that extends the brake piston at the brake. This applies pressure to the brake disc on the wheel, which slows the airplane. The last annual inspection was completed 8 months before the accident. An examination of the brake system did not reveal any preimpact mechanical anomalies with the retained parts. The examination did not include the original inlet fitting from the accident airplane or hydraulic brake lines, as those parts had been discarded by the mechanic before the accident was reported. The original master and slave cylinders were not replaced but were successfully tested by the mechanic after new brake system components were installed. ## Aircraft - Registration: [N235X](https://openairdocs.org/aircraft/N235X), registered now, S/N 10054C, built 1987 (OpenAirDocs) - Reported make and model: MAULE MX-7-235 - Registry model: [Maule MX-7-235](https://openairdocs.org/model/maule-mx-7-235) (registry code 5470207) (OpenAirDocs) - Registry engine: [Lycoming IO-540 series](https://openairdocs.org/engine/lycoming-io-540-series) (registry code 41530, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 10054C - Year built: 1987 - Airframe hours: 3141 - Engines: Lycoming Engines IO-540 235 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 1, 2020 - Departed: BMC, Brigham City, UT - Destination: Same as departure - Airport: ONO, Ontario Muni, runway 15/33, 5,006 × 100 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 63; injuries: none; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review March 27, 2021; seat: left; restraint: 3-point; flight hours: 524 total, 75 in this make and model, 524 as pilot in command, 5.9 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 3 knots - Visibility: 4 statute miles - Lowest ceiling: none - Temperature: 63 °F, dew point 34 °F - Altimeter: 30.09 inHg - Observed at: KONO - METAR: METAR KONO 281853Z AUTO 17003KT 4SM HZ CLR 17/01 A3009 RMK AO2 SLP192 T01720011= ## 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 20210328015709A](https://openairdocs.org/incident/20210328015709A), Mar 28, 2021: Maule MX-7-235, Ontario, OR, Substantial damage. Late reported accident - this accident investigation began after a field approval request was made to this office on 09/29/2021. A mechanic was requesting an… ## Docket (8 files) The files NTSB released with the investigation on January 24, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=104075. 22.2 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 587 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13033659&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Record of conversation (item 2, PDF, 2 pages, 119 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14955545&FileExtension=pdf&FileName=Record%20of%20conversation-Rel.pdf - Brake system drawings (item 3, PDF, 4 pages, 12.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13045872&FileExtension=pdf&FileName=brake%20system%20drawings-Rel.pdf - Email correspondence with airplane manufacturer (item 4, PDF, 4 pages, 166 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13045638&FileExtension=pdf&FileName=email%20correspondence%20with%20airplane%20manufacturer_Redacted-Rel.pdf - Excerpt from aircraft logbook (item 5, PDF, 6 pages, 3.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13033362&FileExtension=pdf&FileName=Aircraft%20logbook_Redacted-Rel.pdf - Manufacturer's brake system examination report (item 6, PDF, 8 pages, 4.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13049007&FileExtension=pdf&FileName=Maule%20AWB%20Exam%20Field%20Notes%2011-18-2021-Rel.pdf - Statement of party representatives to NTSB investigation (item 7, PDF, 2 pages, 301 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14955743&FileExtension=pdf&FileName=party%20form_Redacted-Rel.pdf - Accident photograph (item 8, PDF, 1 page, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13033225&FileExtension=pdf&FileName=Accident%20Photographs-Rel.pdf 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.