A landing signal officer guides an Airbus A350-900 to be parked for the ILA Berlin Air Show in Selchow near Schoenefeld south of Berlin May 19, 2014. REUTERS/Tobias Schwarz

BERLIN (Reuters) - European aviation safety authorities have issued an emergency directive for operators of the Airbus AIR.PA A350-900 long-haul aircraft to upload a software fix to prevent potential overheating of the hydraulic system and a risk of explosion.

Airbus has delivered over 100 of the aircraft so far, which is flown by airlines including Lufthansa LHAG.DE, Singapore Airlines SIAL.SI, Cathay Pacific 0293.HK and Qatar Airways.

In the directive, the European Aviation Safety Agency (EASA) said that an overheat failure mode of the hydraulic engine driven pump had been found, which could cause the temperature of the hydraulic fluid to rise fast.

If that is not noticed and corrected, it could, if combined with an inoperative fuel tank inerting system, lead to the fluid overheating uncontrollably, which could then in turn lead to the fuel-air mixture in the affected fuel tank igniting, EASA said.

Airbus said it had informed operators of the short-term software fix and was investigating whether further action was needed.

A spokesman for Lufthansa said the German flagship carrier was complying with the directive and did not expect any impact on its A350 fleet or operations.