# NTSB GAA19CA572: Piper PA18, N4785F, Boulder, CO, September 23, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: September 23, 2019, 14:20 local (20:20 UTC) - Place: Boulder, CO - Coordinates: 40.039443, -105.226112 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.0394&lon=-105.2261&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report March 17, 2020 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA - NTSB case key (mKey): 100336 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA19CA572 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/100336/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=100336 - Page: https://openairdocs.org/ntsb/GAA19CA572 ## Probable cause The pilot's failure to maintain directional control during the landing roll, which resulted in a ground loop. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Piper PA-18-150, 160 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=7101828), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Piper PA-18-150, 98 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=7101828), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Piper PA-18-150, 109 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=7101828), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) ## Analysis The pilot reported that he conducted a normal three-point landing. During the landing roll, the airplane ground looped to the left, and the left wing struck the ground. The airplane sustained substantial damage to the left wing spar and the rudder. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. ## Factual narrative The pilot in the tailwheel-equipped airplane reported that, he made a normal three-point landing. During the landing roll, the airplane ground-looped to the left, and the left wing struck the ground. The airplane sustained substantial damage to the left wing spar and the rudder. The airport's METAR reported that about the time of the accident, the wind was calm. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. ## Aircraft - Registration: [N4785F](https://openairdocs.org/aircraft/N4785F), registered now, S/N 18-7906, built 1962 (OpenAirDocs) - Reported make and model: Piper PA18 (150) - Registry model: [Piper PA-18-150](https://openairdocs.org/model/piper-pa-18-150) (registry code 7101828) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18-7906 - Year built: 1962 - Airframe hours: 15624.7 - Engines: Lycoming O-360-A3A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Soaring Society Of Boulder Inc - Registered owner: Soaring Society Of Boulder Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 7, 2019 - Departed: BDU, Boulder, CO - Destination: BDU, Boulder, CO - Airport: BDU, Boulder Muni, runway 08, 4,100 × 75 ft, asphalt - Equipment: ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 57; injuries: none; flight instructor, airline transport, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review August 16, 2019; seat: front; restraint: 5-point; flight hours: 20,403 total, 24 in this make and model, 6,169 as pilot in command, 58 in the last 90 days, 5 in the last 30 days, 0.5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 77 °F, dew point 28 °F - Altimeter: 30.07 inHg - Observed at: KBDU, 1 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 20190923013579A](https://openairdocs.org/incident/20190923013579A), Sep 23, 2019: Piper PA-18-150, Boulder, CO, Substantial damage. The PIC stated that on September 23, 2019 at approximately 1400 local, he had a stabilized approach to runway 08 at kbdu in Boulder, CO. The pilot stated and… ## Other investigations on N4785F (3) 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. - [NTSB GAA15CA011](https://openairdocs.org/ntsb/GAA15CA011), Mar 16, 2015: Piper PA18 - 150 (N4785F), Boulder, CO, substantial damage. Probable cause: The pilot's loss of directional control during a bounced landing, which resulted in a runway excursion. - [NTSB DEN00LA126](https://openairdocs.org/ntsb/DEN00LA126), Jul 8, 2000: Piper PA-18-150 (N4785F), Erie, CO, substantial damage. Probable cause: Aircraft control was not possible by the flight instructor due to the inadequate maintenance adjustment of the tail wheel steering system by maintenance personnel. Factors were the inadequate… - [NTSB DEN99LA111](https://openairdocs.org/ntsb/DEN99LA111), Jul 1, 1999: Piper PA-18-150 (N4785F), Boulder, CO, substantial damage. Probable cause: The pilot's failure to maintain control of the aircraft during landing roll. ## Docket (2 files) The files NTSB released with the investigation on January 3, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=100336. 3.7 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40479612&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Photo (item 2, .PDF, 153 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40479613&FileExtension=.PDF&FileName=Photo-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.