# NTSB FTW98LA298: North American AT-6G, N8399H, Longmont, CO, July 5, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 5, 1998, 10:50 local (16:50 UTC) - Place: Longmont, CO - Location: 40.1682° N, 105.1005° W: Placed by OpenAirDocs: center of Longmont, CO, within about 6 miles (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=40.1682&lon=-105.1005&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report January 28, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 20670 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW98LA298 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/20670/pdf - Page: https://openairdocs.org/ntsb/FTW98LA298 ## Probable cause The partial failure of the tail wheel steering system due to improper maintenance and the subsequent inadvertent ground loop during the landing sequence. Factors were the airport taxiway sign and the subsequent failure of the left main landing gear. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, landing - roll - landing gear,steering system - failure,partial (cause) - ground loop/swerve - inadvertent, pilot in command (cause) - maintenance,adjustment - improper (cause) - On ground/water collision with object, landing - roll - object - sign (contributing factor) - landing gear,main gear - failure,partial (contributing factor) - Nose down, landing - roll ## Analysis The pilot was given airport advisories on unicom. He was told that the active runway was 29 and that the wind was 'light and variable.' He said that the 'windsock's movement was hardly perceptible and the velocity of the indicator indicated less than 5 knots.' The pilot reported that after touchdown, 'the aircraft's rollout path took multiple, short, quick inputs from the rudder to keep properly aligned with the runway centerline as the aircraft proceeded down the runway.' He further reported the rudder inputs became ineffective after approximately 400 to 500 feet of landing roll and the aircraft exited the right side of the runway. The aircraft subsequently impacted an airport taxiway sign, damaging the left main landing gear and the left wing. The aircraft came to rest with its nose down. The pilot said that the tail wheel steering cables had recently been replaced. Postaccident evaluation of the tail wheel steering cables by maintenance personnel found a tension of 5 pounds on these cables; 20 pounds is considered normal. ## Factual narrative On July 5, 1998, approximately 1050 mountain daylight time, a North American AT-6G, N8399H, was substantially damaged when it departed the side of the runway while on landing roll at Vance Brand Municipal Airport, Longmont, Colorado. The airline transport rated pilot and his passenger were not injured. The airplane was being operated by the pilot under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the cross-country flight which originated from Centennial Airport, Englewood, Colorado, approximately 50 minutes before the accident. No flight plan had been filed. The pilot said he requested airport advisories on unicom and was told that the active runway was 29, and that the wind was "light and variable." The pilot stated that he flew over the field to position himself for traffic pattern entry, and observed that the "windsock's movement was hardly perceptible and the velocity of the indicator indicated less than 5 knots." The pilot reported that after touchdown, "the aircraft's rollout path took multiple, short, quick inputs from the rudder to keep properly aligned with the runway centerline as the aircraft proceeded down the runway." He further reported the rudder inputs became ineffective after approximately 400 to 500 feet of landing roll and the aircraft departed the right side of the runway. The aircraft subsequently impacted an airport taxiway sign, damaging the left main landing gear and the left wing. The aircraft came to rest on its nose. The pilot reported to the Investigator-In-Charge that tail wheel steering cables had recently been replaced. Postaccident evaluation of the tail wheel steering cables by maintenance personnel found a tension of 5 pounds on these cables; 20 pounds is considered normal (see attached letter). ## Aircraft - Registration: N8399H (not matched to a registry record) - Reported make and model: North American AT-6G - Category: Airplane - Serial number: 49-3190 - Airframe hours: 4950 - Engines: P&W R1340-AN1 600 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Steven R. Cowell - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, June 19, 1998, 7 hours before - Departed: APA, DENVER, CO - Destination: 2V2 - Airport: 2V2, Vance Brand Airport, runway 29, 4,800 × 75 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; airline transport, flight engineer, commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: front; flight hours: 11,600 total, 60 in this make and model, 3,200 as pilot in command, 250 in the last 90 days, 80 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 350° at 7 knots - Visibility: 80 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 50 °F - Altimeter: 30.00 inHg - Observed at: BJC, 20 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 19980705023879A](https://openairdocs.org/incident/19980705023879A), Jul 5, 1998: Namer AT6G, Longmont, CO, Substantial damage. Lost directional control on 3 point landing. Skidded off rwy. Bent left wing and folded left main gear. (.4)the pilot was given airport advisories on UNICOM.… 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.