What happened
On April 4, 2016, a Thrush S2R-T34, registration PR-FIM, was performing an agricultural spraying mission at the private Aeródromo da Fazenda Irmãos Munaretto in Lucas do Rio Verde, Mato Grosso. During the initial takeoff roll on runway 19, the pilot noticed the aircraft yawing to the right, causing the wing to strike an adjacent cornfield while at low speed.
The pilot aborted the takeoff and realigned the aircraft to attempt a second departure. However, the same directional tendency recurred during the second roll. Upon liftoff, the yaw intensified, leading the aircraft to strike the vegetation flanking the runway again. This resulted in a loss of control and a subsequent collision with the ground. The aircraft sustained substantial damage, but the pilot escaped uninjured.
The investigation
CENIPA investigators examined the aircraft's flight controls and braking system, finding no mechanical failures or obstructions. The engine, a Pratt & Whitney turboprop, was functioning normally. Investigators noted that the high torque produced by the engine during takeoff power creates a natural tendency for the aircraft to yaw, requiring significant right rudder input to maintain centerline.
Analysis of the runway surface revealed tire marks that suggested the pilot may have inadvertently applied the brakes while attempting to correct the yaw with the rudder. Furthermore, the investigation considered the narrow margin for error provided by the 20-meter wide gravel runway relative to the aircraft's 13.54-meter wingspan.
Findings
- Inadequate risk assessment: The decision to proceed with a second takeoff attempt after experiencing unexpected aircraft behavior on the first attempt contributed to the accident.
- Flight control application: It is possible that improper use of flight controls, such as inadvertent braking during rudder application, contributed to the directional instability.
- Airport infrastructure: The limited width of the runway relative to the aircraft's wingspan reduced the available time for the pilot to recover from the deviation before striking the adjacent crops.