# NTSB DEN02LA081: Grumman G-164A, N5416, Two Buttes, CO, July 24, 2002 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 24, 2002, 07:45 local (13:45 UTC) - Place: Two Buttes, CO - Coordinates: 37.55389, -102.39167 - Nearby events: https://openairdocs.org/map.md?lat=37.5539&lon=-102.3917&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report April 1, 2003 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 55366 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN02LA081 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/55366/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=55366 - Page: https://openairdocs.org/ntsb/DEN02LA081 ## Probable cause the failure of the right main landing wheel master brake cylinder and the subsequent inadvertent ground loop during the landing roll by the pilot. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, landing - roll - landing gear,normal brake system - failure (cause) - Loss of control - on ground/water, landing - roll - ground loop/swerve - inadvertent, pilot in command (cause) ## Analysis The pilot said that he was landing with a load of herbicide. During the landing roll, the airplane started to veer to the left. The pilot said he applied right rudder and right brake, but the airplane did not respond. The airplane ground looped to the left, and the right main landing gear separated from the airplane. He said all four wings appeared wrinkled, but the lower right wing was bent up. Postaccident investigation of the right brake revealed that its master brake cylinder had failed. ## Factual narrative On July 24, 2002, at 0745 mountain daylight time, a Grumman G-164A, N5416, was substantially damaged when the airplane ground-looped while landing at Doyle's Airfield, Two Buttes, Colorado. The commercial pilot, the sole occupant in the airplane, was not injured. The airplane was being operated by the pilot under Title 14 CFR Part 137. Visual meteorological conditions prevailed for the local aerial application flight which originated approximately 30 minutes before the accident. The pilot had not filed a flight plan. The pilot said that he was landing with a load of herbicide. During the landing roll, the airplane started to veer to the left. The pilot said he applied right rudder and right brake, but the airplane did not respond. The airplane ground looped to the left, and the right main landing gear separated from the airplane. He said all four wings appeared wrinkled, but the lower right wing was bent up. Postaccident investigation of the right brake revealed that its master brake cylinder had failed. ## Aircraft - Registration: [N5416](https://openairdocs.org/aircraft/N5416), registered now, S/N 1030 (OpenAirDocs) - Reported make and model: Grumman G-164A - Registry model: [Grumman G-164A](https://openairdocs.org/model/grumman-g-164a) (registry code 3952704) (OpenAirDocs) - Category: Airplane - Serial number: 1030 - Airframe hours: 8152 - Engines: Pratt & Whitney R1340 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Vic L. Doyle - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, July 15, 2002, 5 hours before - Departed: NONE, Two Buttes, CO - Airport: NONE, Doyle's Airfield, runway 180, 2,640 × 60 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 36; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; last flight review July 15, 2002; seat: center; flight hours: 1,700 total, 300 in this make and model, 1,600 as pilot in command, 140 in the last 90 days, 40 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 57 °F - Altimeter: 30.20 inHg - Observed at: SPD, 11 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 20020724021399A](https://openairdocs.org/incident/20020724021399A), Jul 24, 2002: Scwzer G164A, Twobuttes, CO, No damage. (-23) During landing rollout, Grumman G-164A, N5416, was substantially damaged when the right hand brake failed, causing the aircraft into a ground loop. The… ## Other investigations on N5416 (2) 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 CEN25LA160](https://openairdocs.org/ntsb/CEN25LA160), Apr 18, 2025: Grumman G164 (N5416), Louise, TX, substantial damage. Probable cause: The reported loss of engine power for undetermined reasons. - [NTSB MIA90LA078](https://openairdocs.org/ntsb/MIA90LA078), Mar 5, 1990: Grumman G-164A (N5416), Mattson, MS, substantial damage. Probable cause: THE NO. 6 CYLINDER WHICH CRACKED ACROSS THE TOP FROM ONE SPARK PLUG HOLE TO THE OTHER, RESULTING IN THE LOSS OF ENGINE POWER. ## Docket (1 files) The files NTSB released with the investigation on December 10, 2002, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=55366. 281 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 281 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40463531&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-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.