Pilot Debrief

HALL Kitfox near Nampa, ID — 2019-08-30

Final reportWPR19TA248
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Date
2019-08-30
Location
Nampa, ID, USA
Airport
MAN
Aircraft
HALL Kitfox
Registration
N87TJ
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Landing

Probable cause

The owner's improper installation of the tailwheel, which resulted in the pilot's inability to maintain directional control during landing as a result of severe tailwheel vibrations.

NTSB narrative

The pilot reported that, during takeoff in the experimental, amateur-built, tailwheel-equipped airplane, he experienced a hard shimmy before liftoff. Following an uneventful flight, the pilot landed the airplane onto the main landing gear. When the tailwheel touched down, the airplane immediately became uncontrollable and unresponsive. The airplane was rolling toward the right side of the runway and the pilot applied the brakes in an attempt to slow the airplane. The propeller contacted the runway surface before the airplane exited the runway, nosed over, and came to rest inverted. The pilot reported that, about 6 to 8 weeks before the accident, the owner installed a larger tailwheel on the airplane. The original tailwheel was about 3 or 4 inches in diameter. The new tailwheel was about 6 inches in diameter. A postaccident examination of the airplane revealed that the airplane was equipped with a 1 1/4-inch tailwheel leaf spring. The new tailwheel was designed for a 1 1/2-inch tailwheel leaf spring; therefore, a shim would have been required to ensure proper installation. In addition, a longer bolt would be needed to ensure that the bolt would properly secure within the locking nut. The examination revealed that the bolt was still present in the leaf spring, but the locking nut was not present and was not located along the runway. The washer was found underneath the tail, and there were no indications that a shim was installed. The bolt was removed from the leaf spring and measured; it was not long enough to reach the locking portion of the locking nut. Since the bolt was not long enough to reach the locking portion of the locking nut, it is likely that the nut vibrated loose during normal operations, which caused excessive play in the tailwheel during landing.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Proper installation of the new tailwheel could have prevented the loss of control.

NTSB coding

Evidence available

  • 3 docket documents
View NTSB final reportView NTSB docket

Docket documents3

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