Accident to Airbus A319-131, G-EUOE London Heathrow Airport 24 May 2013

Both engine fan cowl doors detached during takeoff. This led to damage the airframe and a number of aircraft systems. The flight crew elected to return to Heathrow , leaking fuel from a damaged fuel pipe on the right engine which ignited and an external fire developed.

The fan cowl doors detached from the aircraft during takeoff because they remained unlatched following overnight maintenance and the unlatched condition of the fan cowls   was not detected prior to the flight.

The technicians  servicing the aircraft decided to defer a task later in their shift, but left the aircraft with the cowls closed but not latched. When they later returned to complete the task, they went to the wrong aircraft and finished servicing that instead.

The unlatched fan cowl doors were not detected by the tug driver during his inspection of the aircraft prior to pushback - but his training and instructions for the  inspection of the aircraft did not contain the necessary detail. The unlatched fan cowl doors were also not detected during the co-pilot’s external walk-around.

the full detail are here https://assets.digital.cabinet-office.gov.uk/media/55a4bdb940f0b61562000001/AAR_1-2015_G-EUOE.pdf