4-Day Quickturn HTF7000 Bi-Modal Carbon Seal Service

August 2026

Duncan Aviation is fully equipped to perform the bi-modal carbon seal replacement (SB AS907-72-9094) for HTF7000/AS907 series engines with a 2-4 day turn time, subject to parts availability and input schedule. This turntime is available on engine-only events, not scheduled alongside airframe work.

Service Bulletin SB AS907-72-9094

Honeywell issued this SB (Service Bulletin) to introduce an improved #4 carbon seal (PN 70041289-2), addressing bi-modality and reducing the risk of aft sump failure. It applies to the following models:

SB AS907-72-9094 Compliance

• Eliminates the 150 to 250-hour SOAP required by SB 72-9084 and returns oil filter analysis and EEI downloads (25–35 days) to standard LMM intervals.
• Eliminates the need for SB 72-9090.

Note: Must be accompanied by SB 72-9080 (new #4 bearing, PN 3035647-7) and SB 72-9045 (improved tower shaft bearing, PN 3033024-2, -4, or -6).

For more information about this Service Bulletin or to schedule your engine event, don’t hesitate to contact me.