What happened
On February 4, 2017, at approximately 09:30 UTC, an Embraer EMB-810D, registration PT-VSM, was performing a takeoff roll at the Redenção Aerodrome (SNDC) in Pará, Brazil. The aircraft, operated by Agropecuária S. Barbara Xinguara S.A., was scheduled to transport a pilot and one passenger to Palmas, Tocantins.
After traveling approximately 150 meters along the runway, both the nose gear and the right main landing gear retracted unexpectedly. This sudden retraction caused the propeller blades to strike the ground, forcing the aircraft off the right side of the runway. The incident resulted in substantial damage to the aircraft, specifically affecting the propeller blades, the lower fuselage, and the right wing tip. Both occupants of the aircraft escaped without injury.
The investigation
CENIPA investigators examined the aircraft's maintenance history and mechanical systems. The investigation revealed that this was the second landing gear-related incident involving PT-VSM within a two-month period; a similar event had occurred in December 2016, involving the retraction of the left main gear.
Technical inspections focused on the landing gear assembly and the hydraulic system. Investigators performed functional tests on the aircraft using jacks and inspected the nose gear locking mechanism. While the hydraulic system was found to be a single, closed circuit where movement in one cylinder affects pressure in others, the investigation identified specific mechanical discrepancies in the nose gear assembly. Furthermore, the investigation noted that maintenance records provided by the operator were incomplete.
Findings
- The investigation identified a "spring effect" in the nose gear drag link central articulation, which prevented the gear from remaining securely locked.
- A discrepancy was found in the nose gear down-lock gap, which exceeded the limits established in the service manual.
- The improper adjustment of the nose gear drag link was the primary cause of the nose gear retraction.
- The retraction of the nose gear, combined with the impact of the propeller strike, likely caused a pressure fluctuation in the unified hydraulic system, leading to the subsequent retraction of the right main gear.
- Maintenance and managerial supervision were identified as contributing factors to the occurrence.