As Challenger 604 operators, you may be familiar with SB 604-32-031 Modification – Main Landing Gear (MLG) System – Introduction of Improved Dynamic Joint at LH/RH Main Landing Gear (MLG) Shock Strut to Trailing Arm (605-.32-008 (605), 650-32-005 (650).

However, are you familiar with the timing and planning issues related to this SB? If not, read on. This could save you some money!

The service bulletin (SB 604-32-031) is recommended within five (5) years of basic issuance, December 29, 2022, and effective for all 604s. With five (5) years from issuance given, with proper planning this should get any operator to the next 48-month inspection and will allow for ample downtime, and more than likely allow completion of the SB with a 96-month gear inspection or 192-month gear overhaul. 

The estimated man hours to complete this bulletin is nine (9), which doesn’t seem like a lot. However, this SB does require a kit, and the bulletin itself states the man-hour estimate is based on the performing the modification at the next scheduled maintenance task or inspection on the landing gear, not an airframe-only inspection. 

In reality, if this service bulletin is completed at any other airframe inspection interval where the gear is not being removed from the aircraft, operators can expect an additional 30 to 40 man hours would be required to complete the service bulletin!

Service bulletin kit 650-K32-005 is required for this modification. Currently, when West Star Aviation orders a kit for a customer, we are not given a lead time as to when the kit will arrive. This further complicates the timing and scheduling for the operator. 

Recently, we have seen operators ordering the kits themselves and bringing them into the facilities, which is perfectly fine, but remember the additional downtime and labor required when this SB is completed outside of a 48-, 96-, or 192-month airframe inspection where the gear is being removed. 

West Star Aviation highly recommends completing this service bulletin along with an airframe inspection no smaller than the 48-month, saving the operator additional cost in materials outside of the required kit. If this SB is scheduled with any other airframe inspection, an additional cost of an estimated $10,000 and five (5) business days of downtime would be required. To date, West Star Aviation has completed approximately 50+ of these AD modifications.