What happened
On January 18, 2021, at approximately 21:20 UTC, an Embraer EMB-810D, registration PT-VGQ, was conducting a private flight from Santa Rita, PB, to Maceió, AL. The aircraft was carrying a pilot and two passengers. Approximately 40 minutes into the flight, while descending at FL065, the aircraft experienced a loss of thrust in the left engine, followed by a significant yaw.
The pilot attempted to adjust the propeller lever but discovered the control had become disconnected. Realizing the destination could not be reached on a single engine, the pilot reduced the left engine to minimum power and prepared for an emergency landing. Due to the presence of power lines and oncoming traffic on a nearby highway, the pilot opted to land in a field of low vegetation near the PE 096 highway. During the landing, the aircraft struck a drainage ditch, causing the main landing gear to rupture and resulting in substantial damage to the aircraft. All three occupants survived the incident without injuries.
The investigation
CENIPA investigators examined the left TSIO-360-KB10 engine and found no evidence of internal engine malfunction. However, the investigation revealed that the control rod connecting the propeller lever to the propeller governor had become disconnected. The components required to secure this rod—specifically a bolt, washers, a nut, and a cotter pin—were missing from the aircraft.
Technical analysis determined that the rod was either improperly installed or installed without the necessary cotter pin during a previous maintenance session. Furthermore, the investigation found that the propeller governor's speeder spring had lost tension, likely due to improper cleaning or maintenance. This loss of tension prevented the propeller from returning to a minimum pitch setting when the rod disconnected, allowing aerodynamic forces to drive the propeller toward a high pitch, which caused the loss of thrust.
Additionally, the investigation noted significant documentation issues. The aircraft's engine and airframe logbooks had been lost, and the flight log was not presented for inspection. While the propeller logs were up to date, the lack of traceability for recent engine maintenance hindered the ability to verify the full maintenance history.
Findings
- Improper maintenance assembly: The failure to install the cotter pin on the propeller governor assembly was the primary cause of the control rod disconnection.
- Maintenance non-compliance: The missing hardware and the loss of tension in the speeder spring indicated a failure in maintenance execution and technical supervision.
- Loss of traceability: The loss of engine and airframe logbooks compromised the ability to track the aircraft's maintenance compliance.