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Honeywell HTF7500E Engine Inspection Intervals for Embraer Legacy 450/500 and Praetor 500/600

June 2020

The Honeywell HTF7500E (AS907-3-1E) propulsion engines are used on the Embraer Legacy 450/500 and Praetor 500/600 aircraft. The engines do not have mandatory scheduled overhaul or HSI (Hot Section) teardown inspection. Instead, they follow an on-condition maintenance program where they remain on wing until an issue arises during a scheduled inspection, an unscheduled event occurs, or an engine component reaches its life limitation. This makes budgeting engine maintenance costs more challenging unless the engines are covered under a maintenance service program such as Honeywell’s MSP program.

Inspection requirements for the AS907-3-1E engine are listed in Chapter 5 of the applicable Airframe and Engine MMs (Maintenance Manuals).

Below is a summary of the more significant inspection requirements and applicable SBs (Service Bulletins). Please note that Chapter 5 of the applicable Airframe and Engine MMs should be consulted when determining engine maintenance requirements, and the below information should be considered reference only.

750 Hour

All of the 750-Hour Engine MM (Maintenance Manual) items on Table 8004 are included in the Airframe MM.

Please Note

SB AS907-72-9084 supersedes the 750-Hour inspection by moving the oil filter change and analysis to the 150-250 Hour interval.

Airframe and Engine 1500 Hour

Both airframe and engine MMs state that the oil replacement is due at 1,500 hours. 

Airframe and Engine 2250 Hour

Airframe and Engine Manuals have been updated to extend the Start Fuel Nozzle replacements at the 2250 Hour interval.

Airframe and Engine 4000/4500 Hour

The 4,000-Hour inspections and can be extended to the 4,500-Hour interval if in the engine is in compliance with the following engine SBs:

  • SB AS907-72-9001 Rev 2—The best time to complete this is at the 2250 Hour since most of the access will be already completed. 
  • SB AS907-76-9021 Rev1—most AS907-3-1E engines should already be in compliance with this SB. AS907-3-1E engines SN P-131224 and subsequent had this SB incorporated at engine production. 

Note the difference

The Engine MM does have several other visual inspection tasks due at this interval that are not listed in the Airframe MM. 

Please note:

Honeywell has a special program for the replacement of the #4 bearing for SB AS907-72-9045 and SB AS907-72-9080 at the 4000 or 4500 Hour inspection as applicable. MSP will cover this cost. There is a discounted amount for engines not on the program. 

7,000 Hour

The Engine MM, Table 8009, requires the HMU (Hydro Mechanical Unit) be removed, disassembled, cleaned, assembled, and tested at 7,000 hours of operation. An additional 750 flight hours or flight cycles are permitted to provide operator schedule flexibility. There is no reference to this in the Airframe MM. 

Airframe 9000 Hour and Engine 8000/9000 Hour

Both the Airframe and Engine MMs require the Compressor Section Borescope be completed at 8,000 Hour and can be extended to the 9000 Hour interval with compliance of the same service bulletins listed in the 4500 Hour requirements