The Chile DGCA concluded their investigation into an incident involving the loss of both engine cowlings on the engine of an Airbus A319.
On October 20, 2015 an Airbus A319 of Sky Airline departed Santiago-Arturo Merino Benitez Airport in Chile on a domestic flight to Copiapó-Chamonate Airport. During takeoff from from runway 35R at 07:39 hours local time both cowlings on the no.1 CFMI CFM56-5B5/P engine broke away. The aircraft circled back and landed safely on runway 35L at 08:04 hours.
The investigation showed that prior to departure, the No.1 engine cowlings were opened by maintenance crew to check the oil levels of the Integral Drive Generator (IDG) and the filter differential pressure indicator. After this was completed, the cowlings were closed but not locked. The captain performed the walk around check but did not notice this.
Aerodynamic forces during takeoff caused the cowlings to separate from the engine.
The report did not detail the reasons why the cowlings were not locked or the reasons why the aircraft was released for service this way.
This incident is (at least) the 39th event of the loss of an engine cowl door on an Airbus A320-family aircraft. The U.K. AAIB issued several safety recommendations in their July 2015 report of an accident involving Airbus A319 G-EUOE that lost the cowling doors on both engine on departure from London-Heathrow.
Official accident investigation report