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Honeywell AS907 Engine Service Bulletin: Reduced Intervals For Oil Filter Analysis & ECU

September 2019

Service Bulletin AS907-72-9084 Engine – Servicing – Reduce Time Intervals for Oil Filter Replacement and Engine Fault Diagnostic data (EEI) Download to Provide Enhanced Monitoring of Aft Sump Components.

Honeywell has issued SB (Service Bulletin) AS907-72-9084 to investigate and address unanticipated events concerning the aft sump non-bearing components affecting the AS907 fleet. The aft sump is located in the turbine section of the engine and houses the #4 and #5 carbon seals and bearings.

All model number and all serial number AS907 engines are affected by this SB. This includes:


AS907-1-1A  Bombardier Challenger 300


AS907-2-1A Bombardier Challenger 350


AS907-2-1G  Gulfstream G280


AS907-2-1S Cessna Citation Longitude


AS907-3-1E Embraer Legacy 450/500, Praetor 500/600


This SB temporarily overrides the Honeywell Maintenance Manual on the following inspections:

800-hour periodic inspection oil filter sample

AS907-1-1A, AS907-2-1A, & AS907-2-1S

750-hour periodic inspection oil filter sample


1,000 hour periodic inspection oil filter sample



SB AS907-72-9084 outlines more frequent intervals for the oil filter analysis and ECU (Electronic Control Unit) downloads. The recommended interval to perform this SB is 150-250 hours from receipt of the SB, recurring every 150-250 hours from time of initial compliance.

Duncan Aviation strongly encourages bi-weekly ECU downloads, not to exceed one month for optimum trend data analysis as a precautionary measure.

The oil filter should be sent to a Honeywell-approved laboratory for analysis. The ECU download files should be submitted to CAMP for trend monitoring. The increased monitoring has been proven effective on identifying at risk parameters. Service Information Letter AS907-3 has been released to inform operators of the process of communication between operators, Honeywell, and CAMP for trend monitoring.

Once the aft sump issue has been identified and a corrective action is developed, the hourly interval for the oil filter analysis and ECU download trend monitoring will revert back to the hourly interval outlined in the respective Honeywell Maintenance Manual.