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Bombardier Learjet Nacelle Heat Tube Inspections Planning

May 2018

I would like to remind you of the four ASBs (Alert Service Bulletins) Bombardier released on April 25, 2016, that apply to the Bombardier Learjet 40, 45, 70, and 75 model aircraft. They require the inspection of the nacelle anti-ice tube and have a time of compliance of 25 Hours.

Hopefully you have already complied with the initial applicable ASB, as the Aircraft Maintenance Manuals have been revised (Temp Revs & E-Inspector revised-June 2016 and Non E-Inspector Manuals Ch. 4 & 5-Nov 17) to include this inspection as an IRN (Inspection Reference Number). You can reread my article here: Bombardier Learjet Aircraft Nacelle Heat Tube Inspection Alert SBs

Once the above ASB has been complied with, the Nacelle Heat Anti-Ice Tube 250 Hour recurring Inspection IRN 3020005 is applicable until the Nacelle Heat Tubes are modified per the applicable SB listed below. At that time, the recurring inspection will increase from 250 Hours to 1,200 Hours. At this point IRN 3020005 (250 Hour) is no longer applicable and IRN 3020006 (1,200 Hour) becomes active.

Bombardier Learjet* Model              Service Bulletin to Improve Nacelle Heat Tubes

Learjet 40*

SB 40-72-02

Learjet 45*

SB 45-72-03

Learjet 70*

SB 70-72-01

Learjet 75*

SB 75-72-01

 As you begin to plan for the above Inspection, there are a few items to be aware of. 

If during the course of this inspection a crack is found, the inlet is no longer airworthy. You can realistically expect a minimum of three weeks downtime for the removal, repair, and re-installation of the inlet. Inlets are shipped to Learjet in Wichita, Kansas, for repair. Unfortunately, rental inlets are not always available. The probability of acquiring an extension or Ferry Permit is unlikely, since finding a crack will be considered an undetected failure. I recommend you check on the availability of a rental inlet prior to doing the inspection if there is any time remaining until the inspection is due.

You can expect additional downtime for the required paint work after installation. This time will vary depending on the number and color of the aircraft stripes.

In closing, I would highly recommend that you schedule the SB for the improved Nacelle Heat Tubes at your next scheduled inspection to avoid any unplanned downtime in the future.

Additional Service Bulletin

If not already complied with, I recommend you schedule SB 40-54-01, 45-54-6, 70-54-01, Modification of the Pylon Leading Edge Seal Installation, at that time as the above. You will want to measure the pylon skin to inlet skin before removing the inlet.

*Trademarks of Bombardier Inc. or its subsidiaries.