What happened
On September 8, 2010, an Aero Boero AB-115, registration PP-GLH, was performing a flight instruction mission at the Veranópolis Aerodrome (SSVN) in Rio Grande do Sul, Brazil. The flight involved an instructor and a student pilot who was beginning their practical training phase.
During the takeoff roll, the aircraft began to deviate toward the right side of the runway. In an attempt to correct this deviation, the instructor applied control inputs that caused the aircraft to swing abruptly to the left. This resulted in the aircraft leaving the runway and colliding with several bushes. Both occupants of the aircraft were uninjured, though the aircraft sustained significant damage to the engine, propeller, and the tip of the right wing.
The investigation
CENIPA's investigation focused on the operational sequence and the inherent design characteristics of the aircraft type. Investigators found that the meteorological conditions were favorable for VFR operations and that the aircraft was within its weight and center of gravity limits. Maintenance records were up to date, and the crew was properly qualified.
The investigation highlighted several critical design aspects of the AB-115 and AB-180 models that contribute to directional instability. These include a high left-turning torque during acceleration, a narrow landing gear track, and a conventional gear configuration where the rudder becomes less effective once the tail lifts. Additionally, the investigation noted ergonomic challenges, such as the brake pedals being operated by the heels rather than the toes, and a flap control lever positioned in a way that was difficult for the instructor in the rear seat to manipulate.
Findings
- Inappropriate control inputs: The instructor may have applied excessive corrective rudder, which caused the aircraft to overcorrect and lose directional control.
- Failure to abort: The takeoff could have been safely aborted as soon as the initial rightward deviation was detected.
- Design-related instability: The inherent characteristics of the Aero Boero AB-115/AB-180 series, specifically the high torque and narrow track, make these aircraft highly critical during takeoff and landing operations.