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Honeywell HTF7250 Engine Inspection Intervals for Gulfstream G280

April 2020

The Honeywell HTF7250 (AS907-2-1G) propulsion engines are used on the Gulfstream G280 aircraft. It does not have mandatory scheduled overhauls or HSI (Hot Section) teardown inspections. Instead, it follows an on-condition maintenance program where the engine stays 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 AS907-2-1G engine are listed in Chapter 5 of the applicable Airframe Maintenance Manual, Maintenance Review Board (MRB) Report and Engine Maintenance Manuals (MM).

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.

1A and 500 Hour
The Engine MM 500 Hour (table 8004) and the Airframe MM 1A engine-related items have the same information.

Note The Difference:
The Engine MM has a two-year inspection interval for the Engine Fuel Filter Mechanical Differential Pressure Indicator.

2A and 1000 Hour
Both the Airframe and Engine MMs state an oil change.

Note The Difference:
The Engine MM (table 8005) specifically states the oil filter.
Airframe MRB Manual lists the filter as a 2A item.
This requirement has been superseded by SB AS907-72-9084 that puts the interval for the oil filter change and analysis at the 150-250 hour interval.

4A and 2000 Hour
Airframe MM

  • The 4A requirement state Turbine Stage 1 rotor blade and Aft Flow Discourager—Accomplish at 4A since new.
  • Aircraft over 1500 flight hours, accomplish within 500 flight hours from date of Revision 8 (see Table 29) and every 4A thereafter.

Engine MM
Required during the 2000 hour (table 8007) inspection:

  • Special Detailed Inspection of the HPT1 blade aft flow discourager
  • Replacement of the start fuel nozzles (included in the Airframe MRB)
  • Replacement of the engine fuel filter (included in the Airframe MRB)

Note The Difference:
The Airframe MM specifically states blades and the blade discourager. The Engine MM only states the blade discourager.

8A and 4,000/4,800 Hour
In both the Engine and Airframe MMs the requirement to move from the 8A/4000-Hour to the 4800-Hour (table 8008) interval with the following SBs are required:

  • SB AS907-72-9001 Rev2—The best time to complete this is at the 2000 hour since most of the access will already be completed. The Airframe MM does reference this bulletin but only for the Compressor Variable Geometry Actuator (CVGA) System.
  • SB AS907-76-9021 Rev1—99% of the engines are already in compliance. The Airframe MM does reference this bulletin but only for the Electronic Control Unit - Detailed Inspection. G-280 engines SN P-130337 and subsequent had this incorporated at engine production.

Several of the tasks for the 8A and 4,800 Hour (Table 8009) between the Airframe and Engine MMs are the same.

Note The Difference:
The Engine MM states restoration of the Main Fuel Nozzles.
The Airframe MRB Manual lists these along with most of the other Engine MM requirements.
Honeywell does have a special program for replacement of the #4 bearing for SBs AS907-72-9045 and AS907-72-9080 at the 4200- or 4800-hour inspection, as applicable. MSP does cover this cost, but at a discounted amount for engines not on the program.

7,000 Hour

The Engine MM (table 8010) requires the HMU (Hydro Mechanical Unit) be removed, disassembled, cleaned, assembled, and tested at 7000 hours of operation. This is also listed under 14A in the Airframe MRB manual.

Note The Difference:
This is not referenced in the Airframe MM.

16A and 9600 Hour
According to the Airframe MM & MRB, SB 72-9055 is required to move the Compressor Zone Borescope from the 16A to the 9,600 Hour interval. Engine serial numbers P-130168 and subsequent had this bulletin incorporated at engine build.

Note The Difference:
The Engine MM does not list SB 72-9055 as a requirement for the 9600 hour interval.