Challenger 604 MLG Main Fitting Bushing Improvement

December 2012

Messier is aware that the current configuration and greasing procedure of the main landing gear (MLG) main fitting may not allow grease to be forced into the joint between the MLG main fitting and trailing link assembly. The lack of grease on these parts can lead to abnormal and excessive wear on the bushings. A supplemental greasing procedure and associated tooling has been developed by Messier to lubricate this joint. The procedure will allow grease to reach the affected areas, but is somewhat cumbersome to perform.

Messier and Bombardier are in the process of releasing Service Bulletins that improve the bushing design to eliminate the need for a supplemental greasing procedure. It is recommended that this improvement be installed during the next 96-month or 192-month inspection interval.

The improvement not only rectifies the problem of grease passage to the proper area but also implements a new installation procedure. The installation procedure, which uses wet sealant on all areas of the bushings, will help to alleviate the corrosion problem present on many of the main fittings under the bushings.

While the bulletins have not yet been released, the improvements can be implemented and approved through a Messier concession and subsequent Bombardier SRPSA approval. Consider these improvements and the next scheduled inspection to prevent further or future problems with the MLG that could lead to costly repairs or even more costly replacement.

Corrosion in the pintle pin bushing boss of the MLG casing.

Corrosion on the MLG casing.