What happened
On June 11, 2008, a BE-55 Baron, registration PT-LTY, was operating a flight from Rondonópolis to Barra do Garças, Brazil. Approximately 20 minutes after takeoff, the right forward cabin door unexpectedly unlatched and opened. This event caused significant airframe vibration and a sudden loss of 500 feet in altitude.
Following the incident, the pilot initially attempted to land in Guiratinga, but low cloud cover prevented an approach to that airfield. The pilot then diverted to an unpaved, non-certified landing strip at Fazenda Caiser in Tesouro, Mato Grosso. This strip was extremely narrow, measuring only 12 meters wide, which was nearly equal to the aircraft's 11.5-meter wingspan. The surface was also noted for being highly irregular and riddled with potholes.
During the landing roll, the aircraft drifted toward the left side of the runway. In an attempt to avoid entering a nearby cornfield, the pilot initiated a go-around. However, the left wing struck the tall corn stalks, leading to a loss of directional control. The aircraft veered into the field, traveling approximately 60 meters before coming to a stop. The nose gear and right main gear collapsed, and both propellers struck the ground. The two occupants survived the accident uninjured.
The investigation
CENIPA investigators examined the mechanical state of the door latching mechanism and the maintenance history of the aircraft. The investigation focused on why the door unlatched and why the pilot selected such a restricted landing site. Technical inspections of the wreckage revealed that the right door's locking support axis was bent. Furthermore, investigators found that an extra washer had been installed on the axis, exceeding the quantity specified in the Illustrated Parts Catalog (IPC).
Findings
- Maintenance error: The installation of an unauthorized third washer and a bent support axis made the locking mechanism inefficient, allowing vibrations to trigger the door opening.
- Poor pilot judgment: The commander chose to perform an immediate landing on an unsuitable, highly restricted strip rather than continuing to a more appropriate airfield, despite the manufacturer stating that the door opening did not require an immediate landing.
- Inadequate cockpit coordination: The crew decided to proceed with the landing at the narrow strip despite the high operational risk.
Safety action
Following the investigation, safety recommendations were issued to the operator, Oliveira Silva Táxi Aéreo Ltda., to ensure all aircraft markings and warnings are present and in good condition, and to instruct pilots to strictly adhere to aircraft checklists.