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Probe launched after rash of 777-300ER shut-downs(Flight International Via Thomson Dialog NewsEdge) An unusual rash of engine shutdowns since early December has temporarily stranded three General Electric GE90-powered Boeing 777-300ERs. Although each incident involved a shutdown of the GE90-115B, GE's investigation so far indicates the causes of the power loss appear to have three different sources, says the engine maker. The incidents have forced two Air France twinjets to make emergency landings at alternate airports since 12 December. And on 1 February, a Singapore Airlines 777-300ER was forced to land at Frankfurt in Germany. In the first incident, the Air France pilot crew noticed "excess vibrations" and powered down the engine, making an emergency landing in Rome. A visual inspection revealed excessive wear on a stage six low-pressure turbine blade that "reduced contact pressure between blades on that disk," says GE. On 25 January, a second Air France 777 diverted to Milan Malpensa after an in-flight engine shutdown. The engine's transfer gearbox broke out of its housing, causing the power loss. Finally, the SIA flight was disrupted by an undisclosed problem with the engine's accessories gearbox. GE is not yet certain whether the pilot commanded the engine to power down, or the engine failed in flight. GE continues to investigate the incident to discover the root cause of the gearbox problem. Both the transfer gearbox and the accessories gearbox are produced by the same supplier, Italy's Avio and have been installed on older-model 777 aircraft equipped with lower thrust GE90-94B engines, achieving an 11-year in-service record with no previous incidents. Air France was the launch operator for the GE90-115B-powered 777-300ERs, receiving its first aircraft in May 2004, so has the fleet's oldest airframes and engines in service. Air France was 777-300ER launch operator, so has the oldest engines Copyright ? 2008 Reed Business Information - UK. All Rights Reserved. |