Background
A newly certificated private pilot embarked on a short cross-country flight to accumulate flight time toward a commercial pilot certificate. The airplane was in cruise flight when the right outboard wing separated at the wing strut attachment point, at both the front and rear wing spars. The separation occurred as a result of preexisting compressive damage. Following the wing separation, the airplane descended out of control and impacted the ground in a near-vertical nose-down attitude.
Maintenance and Inspection
Review of the airplane's maintenance logbook records revealed that an annual inspection had been completed approximately 10 days and 4.2 flight hours before the accident. The inspection write-up stated that on the day of the annual inspection, the airframe and powerplant mechanic with an inspection authorization (IA) complied with airworthiness directive (AD) 2000-25-02 R1 by inspecting the wood wing spars in accordance with American Champion Aircraft Corporation (ACAC) Service Letter 406. The logbook entry noted that no cracks were detected.
Further examination of the right wing disclosed several inspection holes, including one located at the wing strut attachment point on the underside of the wing, and additional inspection holes on the upper surface. However, the location and number of these inspection holes were inadequate to allow total compliance with AD 2000-25-02, ACAC Service Letter 406, or ACAC Service Letter 417.
Given the size of the area of preexisting damage, had the IA inspected the wing spars at the wing strut attach point—where an inspection hole was present—in an attempt to comply with the AD and service letters, he would have seen the preexisting damage.
Findings
The preexisting compressive damage to the wing spars led to the in-flight wing separation, and the maintenance inspection performed days earlier did not detect the damage due to inadequate inspection hole placement and coverage.