# NTSB WPR15LA218: Dafoe Gerald W Tcow Smith CUB, N810GL, Cascade, ID, July 14, 2015 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 14, 2015, 10:30 local (16:30 UTC) - Place: Cascade, ID - Coordinates: 44.491664, -116 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=44.4917&lon=-116.0000&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report April 4, 2016 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: FAA - NTSB case key (mKey): 91572 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR15LA218 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91572/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91572 - Page: https://openairdocs.org/ntsb/WPR15LA218 ## Probable cause A gouge in the right brake master cylinder piston O-ring, which resulted in a loss of brake pressure and reduced effectiveness after landing. Contributing to the accident was the pilot’s decision to operate the airplane with an ongoing brake issue. ## 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 · Malfunction (probable cause); cases with it: [Dafoe Gerald W TCOW SMITH CUB, 1 case](https://openairdocs.org/ntsb-findings/01023242/cases.md?model=05627VD), [All aircraft, 297 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md) - [Landing gear system: brake](https://openairdocs.org/ntsb-findings/01023242): Aircraft › Aircraft systems · Damaged/degraded (probable cause); cases with it: [Dafoe Gerald W TCOW SMITH CUB, 1 case](https://openairdocs.org/ntsb-findings/01023242/cases.md?model=05627VD), [All aircraft, 297 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Dafoe Gerald W TCOW SMITH CUB, 1 case](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=05627VD), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/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: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Dafoe Gerald W TCOW SMITH CUB, 1 case](https://openairdocs.org/ntsb-events/230/sequence.md?model=05627VD), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) ## Analysis The private pilot/owner of the ultralight airplane was conducting a personal flight. He stated that, after landing, he applied the brakes to slow the airplane. He did not feel any right brake resistance, and the airplane swerved left due to left brake application. He attempted to correct with rudder inputs, but the airplane ground looped to the left, which resulted in the right landing gear collapsing and damage to the right wing. The pilot stated that the he had recently been having ongoing difficulty with the airplane's right brake function. Examination and disassembly of the right brake master cylinder revealed that the master cylinder piston O-ring had a gouge in it. The gouge likely allowed brake fluid to bypass the seal, which resulted in a loss of brake pressure and, therefore, reduced effectiveness after landing. ## Factual narrative On July 14, 2015, at 1030 mountain daylight time, a Dafoe TCOW Smith Cub, N810GL, ground looped after landing, collapsing the right landing gear and substantially damaging the right wing. The private pilot was not injured. The airplane was registered to the pilot, and was operated as a personal flight under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the flight, and no flight plan had been filed. The pilot stated to the NTSB investigator that after landing he applied brakes to slow the airplane. He did not feel any right brake resistance, and the airplane swerved left due to left brake application. He attempted to correct with rudder but the airplane ground looped to the left, collapsing the right landing gear, and damaging the right wing. An FAA inspector examined the airplane and the brake system. He did not note any unusual wear on the pins or brake pads. He did note that the owner had installed an additional brake fluid reservoir to the right brake master cylinder. There was no indication of brake fluid leak. The pilot/owner did state to the inspector that he had been having on-going issues with the right brake. The NTSB investigator authorized the pilot to disassemble and examine the right brake system. The pilot reported back that he found a gouge in the master cylinder piston o-ring that would allow brake fluid to bypass the seal. ## Aircraft - Registration: [N810GL](https://openairdocs.org/aircraft/N810GL), registered now, S/N TC0609002, built 2009 (OpenAirDocs) - Reported make and model: DAFOE GERALD W TCOW SMITH CUB (NO SERIES) - Registry model: [Dafoe Gerald W TCOW SMITH CUB](https://openairdocs.org/model/dafoe-gerald-w-tcow-smith-cub) (registry code 05627VD) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: TC0609002 - Year built: 2009 - Airframe hours: 481 - Engines: AMA/EXPR ECI340 177 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental light sport (Special) - Last inspection: Condition, May 1, 2015 - Departed: KU70, Cascade, ID - Destination: KU70, Cascade, ID - Airport: KU70, Cascade, runway 12, 4,300 × 60 ft, asphalt - Equipment: Electronic flight bag or handheld device, Auto-pilot, Angle of attack indicator, Stall warning system, Satellite tracking device, Handheld GPS, Electronic primary flight display, Electronic multifunction display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 68; injuries: none; commercial; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: sport pilot; last flight review August 13, 2013; seat: front; restraint: 4-point; flight hours: 4,015 total, 481 in this make and model, 3,646 as pilot in command, 30 in the last 90 days, 20 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 61 °F, dew point 52 °F - Altimeter: 30.09 inHg - Observed at: KMYL, 24 nm away ## 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 20150714010309A](https://openairdocs.org/incident/20150714010309A), Jul 14, 2015: Dafoe Gerald W TCOW SMITH CUB, Cascade, ID, Substantial damage. During landing rollout, the PIC applied both brakes simultaneously. The left brake grabbed but the right brake did not produce any braking action. This caused… ## Docket (3 files) The files NTSB released with the investigation on February 11, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91572. 3.0 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40432530&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Records of Conversations - FAA Inspector and Pilot (item 2, .PDF, 63 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40432531&FileExtension=.PDF&FileName=Records%20of%20Conversations%20-%20FAA%20Inspector%20and%20Pilot-Master.PDF - Accident Photo - View of Airplane on the Side of the Runway (item 3, .PDF, 1 photo, 422 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40432532&FileExtension=.PDF&FileName=Accident%20Photo%20-%20View%20of%20Airplane%20on%20the%20Side%20of%20the%20Runway-Master.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.