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Airworthiness Directive AD 2012-17-05: Logbook Errors & Due Dates

September 2020

AD (Airworthiness Directive) 2012-17-05 impacts the Honeywell TFE731-4,-4R,-5R & -5BR engines on the following aircraft:

  • Hawker 800A, 750XP, 800XP, 850XP
  • Falcon 20 (with TFE731-5BR)
  • Falcon 50 (with TFE731-4)
  • Falcon 900/B/C
  • Citation VII

Logbook Errors
In the eight years since this AD was released, we have come across many logbook entries stating that AD 2012-17-05 is ‘Not Applicable Per Part Number.’ Upon further investigation, we have discovered many of these entries to be wrong.

The AD calls out the First Stage LPT (Low Pressure Turbine) assembly part number. If the assembly part number begins with 307XXXX-X or sub part, then this AD applies. The LPT assembly includes the disc and blade.

The root cause of the error mentioned above happens when the operator looks up the disc part number, instead of the assembly part number. They, of course, do not see it listed in the AD and declare it Not Applicable. 

The only way this AD is Not Applicable Per Part Number is if the part number (disc or assembly) begins with 7008XXXX-X. 

AD Due Date
The due date for AD 2012-17-05 is October 2, 2020.

Alternative Method Of Compliance
Honeywell has released and revised three SBs (Service Bulletins) that list an AMOC (Alternative Method Of Compliance) to AD 2012-17-05. The revisions extend the due date.

Honeywell Service Bulletins

Service Bulletin

Applicable engines/airframe

AMOC Due Date

SB 72-3768:

All relevant engines and airframes
Does NOT include the Falcon 20

October 2, 2028

SB 72-3769:

TFE731-5BR on the Falcon 20 aircraft ONLY

October 2, 2024

SB 72-3737:

All relevant engines and airframe

Not applicable * 

Honeywell has also issued Service Information Letter D201801000043 with more information on this subject.

*Most operators will be required to update to the 7008XXXX-X assembly at the next MPI due to the blades being timed out and the old part numbers no longer available. The new part number blades cannot be installed in the older part number discs.