Originally Posted by
noooby
Different P/N for the FIPS Main and Tail blades compared to standard blades, with different constructon and different stresses. So the life limit is different too. As more of the blades approach retirement, the life may be increased.
The 70°C difference in operating temp will be the primary reasoning for the reduced limit.
The lives will have been determined and demonstrated by test, with articles heated to simulate the heater temps.
Unless those tests are still running, inservice items reaching retirement is a moot point.