Serbian investigators have disclosed that an Airbus A319 shed a large engine panel while climbing out of Belgrade three weeks ago.

Operated by Air Serbia, the aircraft (YU-APD) is fitted with International Aero Engines V2500 powerplants.

Serbian traffic accident research centre CINS states that the aircraft had been conducting a flight from Belgrade to Budapest on 26 December.

It had previously arrived from Copenhagen “without any problems”, the centre states, and the crew did not find any issues during a pre-flight inspection.

Engine start was normal and the take-off proceeded without any indication of defects.

A319 YU-APD-c-TJDarmstadt Creative Commons

Source: TJDarmstadt/Creative Commons

Inspection of the twinjet, picture here in an earlier photograph, revealed damage to its left-hand V2500 engine

But about 3min 30s after departure, at an altitude of 9,460ft, the crew “heard a loud and unusual sound” from the left-hand engine, says the centre, accompanied by cockpit indications of a problem with the powerplant.

It adds that the crew ran a relevant checklist and opted to return to Belgrade, where the twinjet landed without further incident.

Inspection of the aircraft found the left engine to have sustained damage to the inner structure of its thrust-reverser.

The centre states that the reverser was “missing” a casing section, at least 2m by 1m (6ft by 3ft) in size, which “fell off during the climb phase of flight”, at around 14:15 local time, in the vicinity of Stara Pazova which lies about 12nm northwest of Belgrade airport.

Thrust-reversers on the V2500 feature a translating sleeve, rather than the pivoting doors of the CFM International CFM56.

None of the 67 passengers and five crew members was injured. The inquiry says it has yet to establish conclusions over the circumstances and cause of the incident.