In addition to the inspection intervals, TFE731 engines are impacted greatly by the life limits of the engine components within them. Most of the rotating components installed in the TFE731 engines have a life limit. These items are generally addressed at the MPI or CZI event.
There are two types of life limits: 1) Cycle Life Limits that apply to turbine and compressor discs, and 2) Hourly Life Limits that apply to turbine blades.
Turbine and compressor discs can last between 3,000 and 20,000 cycles and can cost $60,000-$200,000 each. Maintenance tracking programs typically track the life limits of these discs, however you can calculate it yourself by using simple math—take how many cycles have been used on the disc minus its life limit. No overruns or exceedances are allowed.
Calculating hourly life limit is a bit more complicated. The hourly life limit on turbine blades can range between 1,400 and 12,000 hours. The official hourly limit is based on marks. These marks are based off of the number of hours since the last MPI, in most cases. Some of these limits can be overrun and others cannot. Maintenance tracking programs generally do not track the hourly life limits of turbine blades. Blades can cost up to $180,000 per set.
For TFE731-2, -2C, -3, -3A, -3B, -3C, -3D, -4, -5R, -5AR and -5BR
For TFE731-20,-40,-50,-60 engines
Accessories such as fuel controls, fuel pumps, and oil pumps do not have a life limit.
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Honeywell TFE731 Engine Inspection Intervals