Original quote by CM: I think this could be classed as a serious design flaw.
It is. It is not a matter of cutting seals deeper, wider or breaking the engine seals in at the expense of minimizing the flight envelope. It is a basic architectural problem with the engine and one that is not easily solved as I have said before. The problem is known as
out of round instability. If a seal is subjected to a rub over an arc, the resulting heating will have a tendency to make the seal member go out of round. So the basic support structure of the seal must be stiff enough in circumferential bending to restrict the out of roundness to a very small value. If it is not capable of doing this, then the rub will get worse to the point where the seals become unstable and usually result in a thermal runaway failure. Sound familiar? Corrections involve adding weight at one or more locations to increase stiffness, something I am sure the customer will resist or not like. What to do, what to do…
Right now I think we'll eventually end up with a platform that does stuff, but I think we're in danger of not having a great one.
The whole idea of the F110 engine was to give the customer (the pilot) an engine which he/she could then fly the aircraft to the limits and not the engine to some constraining limits. I think there was success in this endeavor.