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Learjet 40 & Learjet 45 Coupe Rail 5,000 Hour Recurring Inspection Update

November 2014

In the 4800 Hour Inspection (5-15-00), IRN U5323168 calls out the following:

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 have been re-identified depending on the extent of material loss found during the NDT inspection part of the Service Bulletin (SB).

IRN Update

IRN U5323168 has been moved into “Special Inspections (5-19-00) by Temp Rev 5-102 for the Learjet 45. The Learjet 40 Airframe Maintenance Manual was integrated in the last revision.

At Duncan Aviation, we have also been hearing differing interpretations on how the interval is stated. It is written as:

“5,000 Hr. Initial, 5,000 Hrs. repeat.”

We have confirmed with Learjet Maintenance Engineering that the 5,000 Initial starts when the Coupe Rail was re-identified per the instructions in SB 40-56-3 or SB 45-56-3.

IRN L5600010—GKN Windshields

Now another bit of information to keep in mind is that GKN ONLY (not Sierriacin) windshields are removed for a bolt hole inspection per IRN L5600010, which calls out the following:

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

This IRN is also due at a 4,800 Hour Interval, but is a “Special Inspection” (5-19-00) and is NOT part of the 4,800 Hour Inspection (5-15-00).