2021 Antonov/PZL Mielec AN-28 incident at La Paragua (YV2773)

Incident Overview and Flight Details On July 8, 2021, at 20:30 UTC, an Antonov/PZL Mielec AN-28, registration YV2773, serial number 1AJ00703, departed Aeropuerto La Paragua (SVPU) in La Paragua, Estado Bolivar, Venezuela, bound for Aeropuerto Parque Nacional Canaima (SVCN). The aircraft was owned by Arenas Airlines C.A. and carried two crew members: a pilot and a co-pilot. The planned flight time was 15 minutes, with 2,204 pounds of fuel and 3 hours 30 minutes of endurance. ## In-Flight Engine Indications and Crew Actions After takeoff, during initial climb at 13 nautical miles from the departure aerodrome, the pilot in command observed a turbine temperature indication of 640°C on the left engine, along with low oil pressure in the same engine. The pilot reduced power on the left engine and decided to return to La Paragua. During approach, oil pressure continued to decrease, prompting the crew to shut down the engine and feather the propeller in accordance with the Quick Reference Handbook (QRH) emergency procedures. ## Landing and Damage The aircraft landed and performed a displaced braking run toward the left side of the runway, remaining within the runway boundaries. The leading edge of the left wing tip struck a bush in the safety area. The aircraft came to a stop with both crew members uninjured. The report describes the aircraft as having the previously mentioned failure, identified as SCF-PP. ## Aircraft Description and Maintenance The AN-28 is a transport-category aircraft used for general aviation/corporate operations, with type certificate TL0023. It was airworthy under a valid certificate of airworthiness (Control No. 013190) issued by the state of registry. The aircraft was manufactured in Ukraine and designed in Poland, with a payload capacity of 1,750 kg (3,860 lb). It is powered by two Omsk/Glushenkov TVD-10B turboprop engines, each with a maximum output of 993 hp, mounted below the wings. The wingspan is 22 m (72.2 ft), and the maximum takeoff weight is 6,500 kg (14,330.05 lb). The aircraft was used commercially for cargo transport. The last preventive and scheduled maintenance was performed by OMAC-N 514: Servicios Aeronauticos R.A, C.A, located at Aeropuerto “General José Tadeo Monagas,” Hangar Helitec, Zona Postal 6201, Maturin, Estado Monagas. ## Crew Qualifications The pilot in command was 25 years old and held a valid medical certificate and an airline transport pilot license for commercial aircraft, along with an instrument flight instructor qualification, issued by the Instituto Nacional de Aeronáutica Civil (INAC). The pilot held instrument flight and captain ratings for the AN-28, with 602 hours as pilot in command on the type and 1,050 total hours. The co-pilot was 38 years old and held a valid medical certificate and commercial pilot license for aircraft, issued by INAC. The co-pilot held instrument flight and co-pilot ratings for the AN-28. ## Weather and Investigation Activities Weather conditions at Aeropuerto La Paragua (SVGA) were reported as unlimited visibility and generally good weather throughout the day. The investigation included notification of the occurrence, crew interviews, and collection of documentation from the crew, operator, and maintenance organization. Documents obtained included identity cards, licenses, medical certificates, recurrent training records, logbook copies, initial training certificates, registration and airworthiness certificates, operator certificate, radio frequency license, acoustic homologation certificate, insurance policy, passenger list, flight plan, meteorological reports along the route, and fuel supply invoice. Maintenance records from OMAC-N 514 included airworthiness directive compliance, scheduled maintenance compliance, component control, maintenance orders, weight and balance certificate, malfunction reports with corrective actions, maintenance conformity certificate, and avionics equipment control certificates. ## Maintenance Inspection and Findings During a maintenance validation inspection addressing the reported high temperature and low oil pressure during climb, investigators conducted a visual and photographic inspection of the aircraft’s external structure, noting a bush impact on the leading edge of the left wing tip. A video and photographic record was made in the cockpit, where the pilot and co-pilot explained the procedures used to shut down the engine and feather the propeller, referencing the QRH checklist. A borescope inspection of the combustion chamber and compressor turbine found conditions within the limits permitted by the maintenance manual (10B.00.030 PE2 Rev 109, dated 12/12/2018, section 072.50.00, page 206). Following the maintenance manual, the fault was isolated and determined to be caused by obstruction of the propeller governor filter and lack of regulation in oil pressure. As a result, the fuel system, detecting a decrease in propeller revolutions, increased fuel flow, which raised turbine temperature. ## Root Cause Determination The Junta Investigadora De Accidentes E Incidentes De Aviación Civil (JIAAC), based on inspections performed with the company’s technical maintenance personnel, determined that the left turbine, serial number 181961035, had accumulated 2,920 flight hours against a life limit of 3,000 hours or 3,000 cycles. The turbine was close to its life limit, which could have caused accumulation of particles from engine wear in the lubrication system, leading to obstruction of the oil filter in the governor and reduced oil pressure. The report identifies this as the root cause of the incident. Low oil pressure accelerates wear of internal components requiring lubrication and can lead to catastrophic engine failures. The investigation was closed based on the findings presented in the report. All times in the report are given in Coordinated Universal Time (UTC); Venezuela’s UTC offset is -4:00 hours.