Duncan Aviation logo

Learjet 40/45 Coupe Rail 5000 Hour Recurring Inspection Corrosion

January 2013

For the Learjet 40/45 model aircraft, there is an item in the 4800 hour inspection (5-15-00) that I would like you to be aware of regarding Inspection Reference Number (IRN) U5323168.

IRN U5323168

LH & RH Lower Coupe Rail Radius/Windscreen Retainer Attach (P/Ns 4553130001-802 thru 4553130001-809) – Perform Eddy Current Inspection. (Refer to the NDI Manual [NDI-104], Part 6, 53-30-23 & 53-30-24.) (Effective on aircraft that have complied with SB 45-56-3, “Windows – Windshield Coupe Rail Inspections.”)

As you are probably aware, the Windshield Coupe Rails may get re-identified depending on the extent of material loss found during the NDT inspection part of the Service Bulletin.

The issue that Duncan Aviation has come across is that we have seen this 5000 hour recurring inspection coming due within a matter of months from the completion of SB 40-56-3 or 45-56-3. This can happen since the recurring inspection is packaged as part of the 4800 hour inspection (5-15-00). Another thing to keep in mind: if your aircraft has GKN windshields installed, then both of the windshields will be removed for a bolt-hole inspection per IRN L5600010. This is for GKN windshields ONLY.

IRN L5600010

* Windshield – Perform bolt-hole inspection. (Refer to 56-10-01.) (Effective on Aircraft with GKN windshields installed.)

This IRN is also due at a 4800 hour interval, but is a “Special Inspection” (5-19-00) inspection and is NOT part of the 4800 Hour Inspection (5-15-00).