At Duncan Aviation, we have been asked many questions about the AD (Airworthiness Directive) 2018-19-04. This AD requires the replacement of the structural components in the flaps on the following Bombardier Learjet models: 28, 29, 31(A), 35(A), 36(A), 55(B, C), & 60 by complying with their applicable SBs (Service Bulletins).
The AD 2018-19-04 effective date for all models is Oct 23, 2018.
The terminating action for Learjet 60 aircraft is due by October 22, 2019, or 200 landings after October 23, 2018, whichever comes first.
Terminating actions for all other affected models are due by October 22, 2020, or 400 landings after October 23, 2018, whichever comes first.
How Can I Tell If My Flaps Have Been Previously Modified?
This is the question we get asked most often.
The old style flap roller rib is a thin piece of formed sheet metal (See figure 1). It, as well as the support ribs, is Life Limited by Chapter 5 or EMP, as applicable.
The new flap roller rib is a machined part that requires the flap leading edge skin to be notched. (See figure 2). The new style is not Life Limited.
Figure 1
Figure 2
The nose roller support ribs are a component that we find commonly cracked. They should have been replaced at the same time as the flap roller ribs.
Figure 3
Figure 4
The flap track roller fittings are easily identified. The old style has a reduced thickness between the bolt hole lugs and the body of the fitting (See figure 3). The new flap track roller fitting has a constant thickness between the bolt hole lugs & the body of the fitting (See figure 4).
These flap track roller fittings are the least likely to have been changed previously. The old and new style roller fittings are NOT Life Limited by Chapter 5 or EMP, as applicable.
Duncan Aviation has the experience & equipment to comply with all applicable SBs associated with the AD.