What happened
On April 8, 2024, at 13:15 UTC, a Boeing 737-401, registration YV3011, operated by Avior Airlines C.A., departed from Maiquetía International Airport (SVMI) bound for Barquisimeto (SVBM). The flight was carrying 74 people (67 passengers and 7 crew members).
Following the takeoff phase, while the crew was utilizing the stabilizer trim, a loud noise was heard and the system failed to respond. The crew immediately implemented the Quick Reference Handbook (QRH) procedures for an inoperative stabilizer trim and declared an emergency with air traffic services. The flight crew decided to return to the departure airport, successfully landing at Maiquetía without further incident. There were no injuries reported among the passengers or crew.
The investigation
The investigation involved interviewing the flight crew and reviewing flight logs, licenses, and medical certificates. Authorities also examined maintenance records from the operator's maintenance organization (OMAC) and requested documentation regarding the aircraft's airworthiness and insurance.
Technical inspections of the aircraft focused on the elevator control system. Investigators performed a functional test of the secondary trim actuator, during which an unusual noise was detected. The component was subsequently replaced to ensure proper operation.
Findings
- The investigation established that the chain movement mechanism, which operates the pulley anchored to the elevator control system, possessed excessive and inappropriate slack.
- Maintenance adjustments were performed on the chain movement in accordance with the Aircraft Maintenance Manual (AMM 27-41-41-00).