What happened
On April 18, 2018, a Boeing 737-500, registration N240AT, operated by LC Busre S.A.C., was performing flight LCB 2511 toward Cusco, Peru. The aircraft was cruising at FL370 when the flight crew completed the necessary procedures prior to the top of descent (TOD).
As the crew retarded both throttles to the idle position and reached a speed of 225 KIAS to begin the descent, the number 1 engine experienced an in-flight shutdown (IFSD). Following the shutdown, engine parameters decreased progressively. This event triggered several system alerts in the cockpit, including autothroable disconnection, loss of generator 1, and low oil pressure for engine number 1.
The flight crew declared an emergency and was transferred from Lima Sur Radar to Cusco Approach, receiving instructions for a priority approach to runway 28. To manage the electrical failure, the crew started the APU upon crossing FL250 to restore power to the aircraft's electrical system. To prioritize a timely landing, the crew elected not to attempt an in-flight engine restart. The aircraft completed a circling approach via the Descent Charlie VOR DME to runway 28 and landed safely at 22:07 local time. The aircraft subsequently taxied to stand number 2 at Cusco airport, where the number 2 engine was shut down. There were no injuries among the 71 passengers or 6 crew members.
The investigation
The CIAA dispatched investigators to Cusco to conduct field inquiries. The investigation focused on evaluating the number 1 engine and its related systems, as well as examining the fuel system and fuel supply as potential factors in the engine shutdown. The investigation also involved notifications to relevant international organizations and the aircraft manufacturer.