Nacelle anti-ice tube improvement 

Effectivity: Learjet 40/45/70/75 aircraft 

ATA:  ​71 - Power Plant​ 

By TJ Will – Technical Services  

Bombardier would like to remind operators of service bulletins that modify the engine inlet with an improved anti-ice tube (spray ring). Service bulletins 40-72-02, 45-72-3, 70-72-01, and 75-72-01 were released on June 19, 2017.   

IRN Z3020005 in 5-19-00 Special Inspections requires a borescope inspection of the anti-ice tube every 250 hours. Any cracks found during inspection will require incorporation of the service bulletin, as repairs to the older-style spray ring are not allowed. Incorporation of these service bulletins will increase the inspection interval to 1200 flight hours (IRN Z3020006).   

These service bulletins instruct operators to remove the inlet and send it for modification by the Bombardier Component Repair and Overhaul (CR&O) department in the Wichita Service Center. The modification includes an increase in material thickness at the transition between the bleed air supply tube and the circular spray ring inside the nacelle. Other improvements include a new gasket, improved spray ring attach brackets, and an additional doubler at the penetration location of the forward nacelle frame.   

Coordination with CR&O is essential to minimize aircraft downtime. Inlets can be modified independently; they do not have to be upgraded at the same time, although the increased inspection interval is only applicable to modified inlets. 

Modified inlets are reidentified with a new part number noted in the service bulletin after work is completed by CR&O.   

The above service bulletins and IPCs for Learjet 40/45/70/75 aircraft are being revised to clarify part numbers of modified inlets and spares replacements. After rework, the inlets are reidentified to 4572290001-801/-802, indicating the upgrade has been accomplished. These are not inlet part numbers carried in stock.

For spares, the part numbers to be ordered are 4571600005-001/-003, which are new inlets with the upgrade already incorporated at initial build.   

For additional information or questions, please contact your regional Field Service Representative.    

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