TFE731 Spring 2009

• Recent TFE731 Improvements
  • Carbon Seals
  • LPT Blade Retainers
  • Fuel / Oil Leak Operating Limits
  • Composite Fan Bypass Stator Vanes

Recent TFE731 Improvements

— Mike Bernholtz

Carbon Seals

There are improved designs of the #1, 3, 4 and 5 carbon seals introduced in service bulletins 72-3739, 72-3741 (-2/-3/-4/-5), 72-5202 and 72-5203 (-20/-40/-50/-60). These new seals operate at a cooler temperature than previous designs through a feature called hydrodynamic technology, which decreases the heat generated by friction, reducing oil coking on the carbon seal rotor.

During the next MPI, the new style #1 carbon seal will be installed on all models. TFE731-2/-3/-4/- 5 engines will also have the #3 seal updated. All seals will be updated at the next CZI event on all models of TFE731 engines with the exception of the #3 seal on the -20/-40/-50/-60 engines; the design of that seal has not changed.

LPT Blade Retainers

Updated LPT blade retainers have been introduced in service bulletins 72-3737, (-4/-5 engines) and 72-5204 (-20/-40/-50/-60 engines). Honeywell recommends that these improved blade retainers be installed at the next MPI on the LPT1 and LPT2 discs. MSP will pay for this update. This update will reduce the possibility of collateral damage from broken blade retainers going through the engine.

Fuel / Oil Leak Operating Limits

The limits specific to your engine model can be found in the Engine Light Maintenance Manual (LMM).

For classic engines 2/3/4/5, go to:

• Chapter 72 Engine
• 72-00-00 Engine
• Adjustment/Test
• Corrective Action When Operating Limits are Exceeded
• Table 501

For -20/-40/-50/-60 engines, go to:

• Chapter 72 Engine
• 72-00-00 Engine
• Testing
• Corrective Action When Operating Limits are Exceeded
• Table 1301 (20/40 engines) or Table 1302 (50/60 engines)

Other information found in this section are allowable oil usage rates, oil pressure and temperature limits as well as engine roll down rates and ITT temperature limits.

Composite Fan Bypass Stator Vanes

The limits on the composite fan bypass stator vanes have been increased. These vanes are installed on all models of the -20/-40/-50/-60 engines. These limits can be found in the LMM in chapter 72-70-04.

Nicks, dents or pits in airfoil leading edge can be deferred for 25 engine operating hours. In addition, Temporary Revision 72-193 has been released to include the 25 hour replacement grace period for vane leading edge screen separation.

For more information about these and other technical engine issues, contact Shane Heier (LNK) at 402.479.8166 or Ken Kuchenreuther (BTL) at 269.969.8486.

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