In all, 17 Trent 1000s are affected by the problem, which has been traced to a manufacturing flaw in the Hamilton Sundstrand-made transfer gearbox. “Hamilton Sundstrand changed the manufacturing process for some of the gears, and we identified that, through running of an endurance engine, [and] this caused unexpected corrosion. We started to examine it and saw it was to do with a modification in the manufacturing process,” the spokesman says.
The particular issue affected the crown gear assembly and was caused by a change in the chemical etching process used to make the part. The endurance engine, one of several units running alongside a “fleet leader” program engine to detect issues ahead of in-service discoveries, revealed the change could lead to pitting in the part and a reduced service life.