FTW98LA298

NTSB accident investigation · North American AT-6G · Longmont, CO · July 5, 1998

Accident · No injuriesLimited investigationFinal report
Date
July 5, 1998, 10:50 local (16:50 UTC)
Place
Longmont, CO
Injuries
2 uninjured
Damage
Substantial damage
Phase of flight
Landing
Aircraft
N8399HNorth American AT-6G
Weather
Visual (VMC) · Day
Status
Completed · report January 28, 2000
Report
Approved by Office Director
FAA report
19980705023879A
Case key
20670

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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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

NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.

Loss of control - on ground/waterLanding - roll
Landing gear,steering system - failure,partialCause
Ground loop/swerve - inadvertentPilot in commandCause
Maintenance,adjustment - improperCause
On ground/water collision with objectLanding - roll
Object - signFactor
Landing gear,main gear - failure,partialFactor
Nose downLanding - 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
Reported as
North American AT-6G
Category
Airplane
Serial number
49-3190
Airframe hours
4,950
Engine
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.

Role
Pilot
Age
45
Certificates
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.