Challenger 604/605/650 passenger door motor best practices

Effectivity: Challenger 604/605/650 aircraft 

ATA: 52-11 

By: Victor Silva, Technical Services 

This article clarifies the role of the passenger door motor and best practices related to the passenger door motor assembly.

Contrary to common belief, the passenger door motor function is not to dampen or decelerate the door during the opening cycle, as may be the case with other aircraft models. The door deceleration and weight support is accomplished by both gas spring struts and the related counterbalance adjustments. The gas spring struts also assist the door motor during the door closing cycle, supporting most of the door weight.  

To extend the service life of the passenger door motor, it is advisable to note any change in the door weight or extension speed during the opening cycle. A passenger door that is observed to feel heavier or with little dampening when opening would indicate worn gas spring struts. If left unresolved, the heavier door will adversely affect the motor life by inducing greater stress to the motor during the closing cycle.  

As a recommendation, it is advisable to follow passenger door operational or functional tests found in the AMM ATA 52-11 most recent revision, which provide guidelines on how to identify weak door gas spring struts during the door opening cycle. It is more cost effective to replace worn gas struts than repairing the eventual failure of a passenger door motor.  

Lastly, the door motor assembly PN 604-31940-3, together with the latest cable guide pulley and bracket assembly (PN K604-31904-7), are the preferred installation configuration for reliability improvements.