Honeywell AS907 Series Engines Variable Guide Vane Bearing Loss

During regular Honeywell AS907 (HTF7000) series engine inspections, significant bearing loss in the variable guide vane arms in both the lower and upper portions of the engine have been observed and reported.

This loss is a result of normal wear that increases the clearance between the bearing and the variable guide vane arm allowing the bearings to become loose and slide down the unison ring pin and harmlessly fall away. While this is not out of the ordinary, a small number of engine surges have been reported due to excessive bearing loss.

To prevent this, Honeywell issued the recommended SB AS907-72-9001 Rev 2, dated August 2018, for the installation of o-rings on the unison ring pins the next time the bypass duct panels are removed for cause.

This SB is applicable to the following Honeywell AS907 series engines: