What happened
During a local pleasure flight near a farm strip, the pilot of a Taylorcraft BC1sD-85 performed several low passes over a neighboring property. As the pilot initiated a climb following these passes, the aircraft suddenly rolled to the right and entered a vertical descent into an alfalfa field. The impact was severe, resulting in one fatality. The aircraft was destroyed in the crash.
The investigation
Investigators examined the wreckage and identified a vertical break in the right rear wooden wing spar, located inboard of the rear lift strut attachment. Laboratory analysis determined that the fracture was caused by compression damage to the wood. This type of damage, characterized by buckling wood fibers, likely occurred during a previous incident involving damage to the right wing.
Technical logs revealed that in 1985, the aircraft had undergone repairs to the right wing tip and landing gear following an unreported occurrence. Additionally, the aircraft had previously been blown over on its back, an event that likely subjected the spar to unusual bending loads. The investigation also noted that the aircraft was using mogas fuel without the required regulatory approval and was not equipped with an emergency locator transmitter.
Findings
- The right rear wooden wing spar failed due to pre-existing compression damage.
- This structural failure was likely caused by a previous undocumented or inadequately inspected incident involving the right wing.
- The existing wing inspection panels were insufficient to allow for a thorough examination of the spar's condition.
- Maintenance inspections failed to detect the internal damage because the applicable Airworthiness Manual Advisory lacked specific guidance for detecting compression failures in wooden spars.
- The pilot's recent low pass and subsequent climb provided the final stress necessary to trigger the structural failure.