Detailed analysis of the engines on the British Airways Boeing 747 used in a test flight through the European volcanic cloud has indicated no deterioration in performance.
Engine manufacturer Rolls-Royce monitored the RB211 powerplants in real time, from the ground, during yesterday's 2hr 46min flight between London Heathrow and Cardiff.
Technicians conducted a borescope inspection of the engines after the flight. "All these checks showed no deterioration from that previously recorded at London Heathrow," says BA.
Rolls-Royce is to analyse the engine oil and fuel filters from the aircraft.
BA says that information from the flight recorders indicates that all four RB211s performed "without fault for the duration of the flight" and without any degradation of performance.
Chief executive Willie Walsh is citing the technical analysis to support an argument that the blanket restrictions on European airspace are unnecessary.
"Since airspace was closed on [15 April] our assessment is that the risk has been minimal and can be managed by alternative procedures to maintain the highest safety standards," he says.
"We believe airlines are best-positioned to assess all available information and determine what, if any, risk exists to aircraft, crew and passengers."
The 747 operated up to an altitude of 40,000ft in a series of staged climbs to expose the jet to various layers of the atmosphere, in a bid to assess whether the volcanic ash from Iceland is liable to affect flight safety.
BA says the 747 underwent a full structural survey at Heathrow, including compilation of a photographic record, covering critical areas such as the wing and stabiliser leading edges, sensors, engine inlets and radome. Engineers also checked lights, the windshield and passenger windows.
All four powerplants underwent borescope checks and examination of the compressor, combustor, turbine and vanes. The carrier also replaced some of the equipment - including oil and fuel filters, recirculation fan and cooling filters - to simplify the post-flight detection of debris.
At specific intervals during the test flight specialists on board monitored not only the performance of the aircraft but also the cabin air to check possible build-up of acrid compounds that might signal concentrated volcanic gas.
"We use our expertise in risk assessment across a wide range of safety issues to make decisions on the safe operation of flights every day," says Walsh. "We believe that we should be allowed to take the same responsibility over safety issues over the recent volcanic eruptions in Iceland."