Aircraft and Flight Details
On April 8, 2024, at 13:15 UTC, a Boeing 737-401, registration YV3011, serial number 23989, operated by Avior Airlines, departed from Simón Bolívar International Airport (SVMI) in Maiquetía, Venezuela, bound for General Jacinto Lara International Airport (SVBM) in Barquisimeto. The aircraft carried 74 persons on board (67 passengers and 7 crew members) and had 2 hours 30 minutes of fuel endurance.
Sequence of Events
After completing the takeoff phase, the flight crew attempted to use the stabilizer trim (STAB TRIM). They heard a loud noise and the STAB TRIM did not respond. The crew then performed the Quick Reference Handbook (QRH) procedure for "STABILIZER TRIM INOPERATIVE 9.30" and declared an emergency to air traffic services. They decided to return to the departure airport (SVMI) and landed without further incident. The crew and passengers were uninjured, and the aircraft sustained the aforementioned failure.
Aircraft Information
The aircraft was a twin-engine turbofan-powered land plane, manufactured by Boeing Company. It was categorized as Commercial Aviation – Public Air Transport Service and held a standard classification issued by the Venezuelan Aeronautical Authority (INAC). Its type certificate (A16WE) was issued by the U.S. Federal Aviation Administration (FAA).
The last scheduled preventive maintenance was performed by OMAC-Nº440 Avior Airline, C.A., located at General de División José Antonio Anzoátegui International Airport in Barcelona, Anzoátegui State.
Flight Crew
The pilot (Captain), aged 43, held a valid Airline Transport Pilot License and Medical Certificate issued by INAC. His ratings included Instrument Rating (expiring 16 Oct 2024) and B732/734 Captain/PIC (expiring 16 Oct 2024). He had 8,000 hours as pilot-in-command, 12,000 total flight hours, and 4,000 hours on the accident aircraft type.
The copilot (First Officer), aged 44, also held a valid license and medical certificate. His ratings included Instrument Rating (expiring 14 Jun 2024), B734 Copilot/SIC (expiring 14 Jun 2024), C550/PIC (expiring 14 Jun 2024), and PAY2 (expiring 14 Jun 2024).
Weather
Meteorological conditions at the time were calm wind, unlimited visibility, and generally good weather throughout the day.
Investigation Findings
The investigation, conducted by the Junta Investigadora de Accidentes (JIA), included interviews, document reviews, and physical inspections. It was found that the chain (chain movement) actuating the pulley in the elevator control system had excessive inappropriate play. The chain was adjusted according to the Aircraft Maintenance Manual (AMM 27-41-41-00).
Additionally, during functional testing of the secondary trim actuator, an unusual sound was heard. The component was replaced and retested successfully.
Status
The investigation remains ongoing, with further review of maintenance records and work orders pending to verify the aircraft's airworthiness condition prior to the event.