Pilot Debrief

ELLEFSON T-BIRD II near Richfield, UT — 2012-09-05

Final reportWPR12LA413
Sign in to save
Date
2012-09-05
Location
Richfield, UT, USA
Airport
RIF
Aircraft
ELLEFSON T-BIRD II
Registration
N8106C
Category
Ultralight
Highest injury
Serious
Fatalities
0
Phase of flight
Landing

Probable cause

A loss of control during landing due to a pitch control malfunction. Contributing to the accident was the pilot’s decision to continue flight with a known mechanical problem.

NTSB narrative

The pilot reported that the new owner of the ultralight had reassembled it and found that it oscillated during level flight and that the owner then contacted him for assistance in diagnosing the issue. He reported that he conducted a preflight inspection and noted no anomalies. Immediately after takeoff, the ultralight began to oscillate up and down with no elevator input. The pilot stayed in the traffic pattern, and the oscillations continued at different altitudes and airspeeds. During landing, the ultralight touched down about 45 knots with upward oscillations. The pilot decided to take off again and experiment with different trim settings. Upon liftoff, the ultralight again began to oscillate with no throttle or elevator inputs. The pilot decided to depart the traffic pattern to further experiment with the trim and power settings; however, different trim and power settings had no effect on the oscillations. The pilot indicated that the oscillations were random, so he could only react to the direction with flight control corrections and could not anticipate which flight control corrections would be needed. The pilot reentered the traffic pattern for landing and, during the landing, when the ultralight was about 5 feet above the ground and at 40 knots, the oscillations began again. The pilot pushed the yoke forward, which stopped the oscillations; however, the rear main landing gear touched down on the runway, which forced the ultralight back into the air. The pilot recalled that the ultralight's nose then pointed downward and that he pushed full left rudder before the ultralight impacted the ground. After the accident, the pilot learned that the owner had reassembled the ultralight without assistance from a mechanic. While inspecting the ultralight after the accident, the pilot noted that, if the pitch control cable was loose, it would randomly move. The ultralight was not made available by the owner for examination; therefore, the reason for the oscillations could not be determined; however, it is likely that the pitch control cable was loose, causing the random oscillations.

Analysis

Primary failure mode
Loss of control
First missed decision gate
Owner reassembled ultralight without mechanic assistance, risking safety.

NTSB coding

Evidence available

  • 3 docket documents
View NTSB final reportView NTSB docket

Docket documents3

Related mishaps