What happened
On September 18, 2013, an Aero Boero AB-115, registration PP-GJZ, was performing a flight instructor training mission at the Estância Santa Rita Aerodrome in Cuiabá, Mato Grosso. The flight, operated by Aeroclube de Várzea Grande, involved various flight exercises, including touch-and-go maneuvers, under visual flight rules (VFR) in favorable weather conditions.
After an initial period of flight, the instructor disembarked, leaving the student pilot to continue solo training. During a final landing attempt, the pilot noticed the aircraft drifting toward the right side of the runway. In an attempt to prevent the aircraft from exiting the runway, the pilot applied the brakes abruptly. This sudden braking action created a nose-down moment that caused the aircraft to lose control and overturn, coming to rest on its back approximately 30 meters from the runway centerline. The pilot was uninjured, but the aircraft sustained substantial damage to its engine, propeller, wings, struts, and vertical stabilizer.
The investigation
CENIPA investigators examined the aircraft's systems and found no evidence of failure in the flight controls or the braking system. The investigation noted that the meteorological conditions were favorable, with calm winds and good visibility.
Upon inspecting the landing gear, investigators discovered a discrepancy in tire pressures: the left tire was at 33 psi, while the right tire was at 27 psi. Given that the manufacturer's recommended inflation pressure for this tire type is 35 psi, the 6 psi differential was considered a factor that may have influenced the directional swerve (yaw) during the landing roll.
Findings
- Abrupt application of brakes
- Limited pilot experience
- Differential tire pressure (6 psi difference between left and right tires)
- The aircraft was within weight and balance limits and maintained valid airworthiness and maintenance documentation