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CF34 5 & 6 Turbine Disk Airworthiness Directive Update

November 2009

December 31, 2009, is the deadline to comply with AD 2006-04-12; Inspection or replacement of the #5 & #6 Turbine Disk. Although General Electric is working diligently trying to contact operators with information on completing this AD prior to the deadline, they estimate there will be about 20 aircraft that will not be in compliance.

For the past several months, CF34 overhaul shops have been operating on a slot system that has filled up fast. This has kept all the CF34 shops, including the Duncan Aviation facilities in Lincoln and Battle Creek, busy working hard to accommodate everyone and has also made it more difficult for operators to wait for a scheduled event to get this work done in conjunction with additional airframe inspections.


Here are some additional items to consider and comply with if you haven’t accomplished the LPT Disk Airworthiness Directive.

SB 72-0093

  • Installs an improved #5 Bearing Rotating Air Seal
  • Complying with this SB will terminate AD 2001-12-06, recurrent chip detector check

SB 72-0176

  • Introduces a new #5 Bearing
  • The Air Balance Piston Stationary Seal is removed to gain access to the #5 bearing, saving labor charges to comply with SB 72-0217

SB 72-0217

  • Modifying the Air Balance Piston Stationary Seal from a 4-step honeycomb seal to an 8-step honeycomb seal and is terminating action for AD2009-07-12.

Removing the LPT Module alone doesn’t qualify for the mandatory compliance of the two ADs or GE’s recommended compliance of the three SBs. The cost benefits of doing these in conjunction with the LPT AD, in the end, will save a substantial amount of money.

Complying with the additional SBs provides operators of CF34-3A1 & -3B engines that are on-condition, an opportunity to get any repairs or preventive maintenance accomplished that might otherwise be for cause. We strongly urge operators who haven’t scheduled this work yet to contact Duncan Aviation Turbine Engine Service Sales. To discuss this topic or another issue with your CF34 engine, call your Duncan Aviation CF34 Engine Tech Rep.