Originally Posted by
Turbine D
tdracer,
I also suspect the alloy being used for the turbine blades may be more prone to corrosion than perhaps other alloys required by other engine manufacturers. In other words, if the coating deteriorates, the bare alloy needs to provide a margin for a period of time in terms of strength and corrosion resistance.
I understand the coatings are ceramic with the nickel alloy at the core having a melt point several hundred degrees short of the temps seen in that stage of the engine.
Originally Posted by
KelvinD
Doesn't this issue go back a couple of months to some issues with ANA aircraft? I seem to remember RR discovered an issue with premature wear or something and began a programme of engine inspections/replacements. I think a couple of the LHR based VS planes were taken out of circulation for a while recently because of this.
Yes, this happened summer, years past (2016). The initial findings suggested a vibration problem in the intermediate stage turbine rotor. Additionally, the same blades are subject to an abnormal amount of corrosion. RR said they would redesign the blades and refit them across the fleet, which was to begin in early 2017. The cost is reported to be in excess of £60M, without including compensation figures.
According to RR, the corrosion problem is more likely to appear on long haul flights due to the nature of the corrosion process. A separate issue, involving the IP compressor blades is currently under an EASA mandate review for early inspection to avoid a blade out event, of which three have been reported so far, while RR works on a solution.