Recommended inspection of main entry door vent door bellcrank

Effectivity: Learjet 40/45/70/75 aircraft 

ATA Code: 52 - Doors 

By: TJ Will – Learjet Field Support Engineering 

The upper main entry door on Learjet 40/45/70/75 aircraft features a vent system that relieves cabin pressure prior to the main door opening. A vent door in the upper cabin door will open, venting excess pressure and allowing safe and proper opening of the cabin door.   

This vent door is controlled by linkage inside the upper door, which is connected directly to the door handle. At extreme angles, the vent door bellcrank can cause interference with the linkage, which in turn could impede vent door operation.   

Recommended Service Bulletins (SB) 40-52-13, SB45-52-22, SB70-52-04, SB75-52-04 were released on Sept. 19, 2022. The SB instructs operators to inspect the bellcrank with a borescope to look for indication of interference with the vent door linkage.  

If no damage is noted, no further action is required. If damage is discovered, the bellcrank is to be removed and modified by increasing the radius in the area of interference.    

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