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What Are The Honeywell TFE731 Inspection Intervals For New And Classic Engines?

November 2023

Duncan Aviation Engine Tech Reps and Sales Reps field many questions regarding engine inspection intervals. Most often, these pertain to the newer model engines: TFE731-20/-40/-60 and the -5BR. Intervals for the -20/-40/-50/-60 models can be found in Chapter 5 of the LMM 7 Ch 5-20-00, Temporary Revision 5-18. Some of the qualifications for the longer intervals can be done without any actual work on the engine. The intervals can actually go backward to a shorter interval at a shop visit if particular requirements are not met.

TFE-731-CZI.jpgEngine Intervals

  • -50 and -40BR-1B engines are 3000-hour MPI/6000-hour CZI or 3500-hour MPI/7000-hour CZI intervals depending on the SBs (Service Bulletins) that have been accomplished.
  • -20/-40/-60 engines are either 2500-hour MPI/5000-hour CZI, 3000-hour MPI/6000-hour CZI, or 3500-hour MPI/7000-hour CZI intervals, depending on the SBs that have been accomplished.
  • -40 and -60 engines will be on the 2500-hour MPI/5000-hour CZI intervals unless service bulletin 72-5194 has been completed. This SB had a limited release in December 2007 and a full release in April 2008. There are several other SBs that are part of the extension. If SB 72-5194 is not done, there is no need to look any further.
  • -20 engines engine serial number P-116487 and later will have all of the internal parts upgraded for the 3000-hour MPI/6000-hour CZI hour intervals. Some simple external bulletins may need to be complied with to make the interval extension official, such as checking the Fuel Control serial number and putting heat shrink on the N1 monopole. If you have any questions, please give us a call and we will help you clarify the intervals.

Classic Engines

In the case of classic engine models, the official answer is to reference the following Service Bulletins: 


SB 72-3105

TFE 731-2C

SB 72-3630

TFE 731-3 & 3A

SB 72-3106

TFE 731-3B

SB 72-3233

TFE 731-3C & 3D

SB 72-3527

TFE 731-4

SB 72-3466

TFE 731-5R, 5AR, 5BR

SB 72-3263

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The basic rules for these classic engines can be best explained as follows:

  • Almost all -2 and -3 engines that have not been upgraded to -2C/-3A/-3C/-3D are on 1400-hour MPI/4200-hour CZI intervals.
  • All -2C/-3C/-3D engines are on a 2100-hour MPI/4200-hour CZI schedule.
  • The -4/-5 engines are either 2100-hour MPI/4200-hour CZI or 2500-hour MPI/5000-hour CZI intervals. The TFE731-5BR-1H engines have had the 2500-hour MPI/5000-hour CZI intervals added as an option again depending on which SBs have been accomplished. If you have any questions, please call and we will clarify.
  • The MPI can be overrun by 100 hours and the CZI by 200 hours on all of these models of the TFE 731 engine.

Engine Component Life Limits

In addition to inspection intervals, TFE731 engines are impacted greatly by the life limits of the engine components within them. Read more about it here: How To Track Life Limits For Honeywell TFE731 Internal Components.