Originally Posted by
tdracer
The problem with the PW4000/94" compressor was that the case didn't stay round as it got hot - which then rubbed the blade tips and increased clearances
Wasn't this exactly what afflicted the original JT9Ds on the first 747s, and which therefore seems to have taken them nearly 40 years to overcome ? I seem to remember the US used the word "Ovalise", which was not to be found in any UK dictionary !