What happened
On July 9, 2009, at approximately 10:25 local time, a Grumman G-164 B biplane, registration CS-ASN, was performing agricultural work near Alcácer do Sal, Portugal. The aircraft, operated by AGROAR – Trabalhos Aéreos Lda, was returning to the Barrosinha landing strip to reload product.
During the flight, the pilot engaged the parking brake, inadvertently leaving it in the "on" position. As the aircraft touched down on the unpaved runway, the pilot noticed the main gear wheels were locked and the aircraft began to pitch forward. The pilot attempted to release the brake by pressing the pedals, but the maneuver was unsuccessful and likely exacerbated the situation. The increased resistance from the locked wheels caused the nose to drop toward the ground. The propeller blades struck the runway, losing much of their tractive capability, which caused the aircraft to pivot and eventually capsize into an inverted position. The aircraft came to rest approximately 90 meters from the initial touchdown point.
The investigation
The GPIAAF examined the wreckage and the flight sequence. The investigation established that the aircraft's main gear wheels were locked at the moment of touchdown. Physical evidence showed the right wheel made the first contact with the runway, followed by the left wheel. The propeller blades and hub struck the surface 32 meters after touchdown, leaving marks that extended for 36 meters. The investigation also reviewed the pilot's actions and the maintenance records of the operator, confirming the aircraft was maintained according to regulations.
Findings
- The pilot engaged the parking brake while in flight.
- The parking brake remained in the "on" position during the landing phase.
- The engagement of the brake caused increased resistance upon touchdown, leading to a loss of directional control and a forward pitch.
- The impact of the propeller with the ground acted as a pivot point, resulting in the aircraft overturning.
- The pilot escaped the accident without any injuries.