Challenger 604 SB 604-57-003

Service Bulletin (SB) 604-57-003 was just released earlier this year about a special check of inboard flaps forward lugs. While performing this SB, we made a couple of observations that will make this inspection easier.

If at all possible, perform this SB during a maintenance event that requires the canoe panels be removed. It provides easier access to the necessary area. If there are no such events scheduled, we suggest the following:

1. Instead of lowering the flaps in step A (3), leave the flaps at zero and remove the aft canoe fairings.
2. Only then, lower the flaps to 45 as stated.

By doing this, you alleviate removing the forward canoe panels. There is additional support for this thought process when you reference Figure 3 on page 10 of 10 in the SB. The illustration shows the area to be inspected is located under the aft canoe panel.