What happened
On August 27, 2017, an Airbus A320-233, registration N-491TA, operated by Trans American Air Lines (TACA), was performing a scheduled flight from Lima to Piura when it encountered a series of technical failures. The aircraft had departed with one engine bleed pack deferred due to an overheat condition.
While cruising at FL 340 near the IRSEN position in Ancash, the crew received an ECAM alert indicating an AIR ENG BLEED 1 FAULT. Following this failure, the cabin began to depressurize slowly. The flight crew initiated the Quick Reference Handbook (QRH) checklists and requested instructions from Air Traffic Control to descend and return to Lima.
During the subsequent left turn for descent, a cabin pressure excess altitude alert triggered, prompting the crew to declare an emergency and initiate an emergency descent at 17:32:31 local time. During the descent, which reached a rate of 6,000 feet per minute, oxygen masks were deployed for the 128 passengers and 6 crew members. During the rapid descent, additional ECAM alerts were triggered, including warnings for cabin pressure differential, a left aft cabin door, and the cabin pressure safety valve opening.
The investigation
The CIAA investigation involved field inquiries, interviews with the flight and cabin crew, and an analysis of the Flight Data Recorder (FDR). The investigation also included coordination with the French Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA) to obtain technical information. Investigators reviewed the operator's Safety Management System (SMS) reports and airworthiness maintenance records, and conducted simulator tests to evaluate the application of operational procedures.