What happened
On June 17, 2015, an American Champion 8KCAB, registration PP-TZV, was performing a transport flight from Bauru to Piracicaba, Brazil. The aircraft was operated by the Associação Brasileira de Acrobacia Aérea and carried a pilot and one passenger.
Upon landing at Piracicaba Airport, the aircraft began to vibrate significantly during the landing roll. The pilot experienced difficulty maintaining a straight path as the aircraft began oscillating left and right. Despite attempts to use differential braking and rudder input, the aircraft drifted off the right side of the runway and came to rest in a roadside ditch. The impact resulted in substantial damage to the aircraft, though both occupants were unharmed.
The investigation
CENIPA investigators examined the tailwheel assembly and discovered several critical maintenance irregularities. The investigation revealed that the left side of the tailwheel assembly had been modified with a bolt and chain setup that did not comply with the manufacturer's manual. Furthermore, the external springs on the left and right sides were of different dimensions, destroying the necessary symmetry for stable operation.
Investigators also found that an internal locking spring had been improperly manufactured, likely through artisanal or non-standard methods, featuring irregular drilling and asymmetrical flanges. During the landing roll, a spring from the assembly detached and was found on the runway surface.
Beyond the immediate cause, the investigation uncovered a broader pattern of maintenance non-compliance. The aircraft's logs showed that a 50-hour inspection had been skipped, and several other issues were noted, including corrosion on elevator attachment bolts, adhesive tape used on the airframe, and rudder cables causing wear to the fabric covering. The investigation also noted discrepancies in the pilot's initial statements regarding the number of people on board.
Findings
- The loss of a tailwheel spring during the landing roll caused a loss of directional control.
- The tailwheel assembly contained non-standard, artisanal components and asymmetrical parts that did not meet manufacturer specifications.
- Maintenance practices were found to be deficient, characterized by a lack of proper supervision and the use of improper materials.
- There was a failure to adhere to required inspection intervals, with the aircraft flying over 123 hours without the required intermediate inspection.
- The pilot's attitude and the organizational processes regarding maintenance oversight contributed to the unsafe condition.