The European Aviation Safety Authority (EASA) has issued a "warning" of the highest level of urgency for the new Airbus A350-941, introduced into service in 2014. Complaint no. 2017-0154-E, was filed for a problem with the hydraulic fluid cooling system, which, if not fixed, could potentially lead to an engine explosion.
According to EASA, it all stemmed from the signal of a recent hydraulic pump overheating error. If the pump fails, the temperature of the hydraulic fluid may rise rapidly. If the error is not detected in time, there is a risk of ignition of the explosive mixture.
“In the A350 design, the hydraulic fluid cooling system is located in the fuel tanks,” the EASA document states. "Recently, a hydraulic pump overheating error was found at the A350 engine - EDP and that EDP error can cause a rapid rise in the temperature of the hydraulic fluid."
To address this potentially dangerous situation, Airbus has launched the A350's Major Event Revision procedure, the Master Minimum Equipment List (MMEL) which incorporates restrictions to avoid uncontrolled overheating of the hydraulic system.
Airbus claims that with a software update the identified risk can be disabled in the short term. Operators of approximately 100 A350 delivered have been briefed in detail.
Lufthansa, which currently operates four A350s, is already implementing the measures requested by EASA. This will have no impact on the flight plan, according to a Lufthansa spokesperson.
In both civilian and military aircraft, fixes are made to prevent injection of the fuel-air mixture into the tank. The introduction of the current tank safety systems began after the crash of Trans World Airlines' TWW1996 in 800 killed all 230 people on board. The plane crashed twelve minutes after take off. The investigation showed that the accident was caused by the explosion of a flammable mixture of fuel and air vapors in the fuel tank, possibly triggered by a short circuit.
Aerotime Source