Air Driven Generator partial deployment in flight

Effectivity: Challenger 600, 601, 604, 605 and 650 aircraft  

ATA 24-23 

By: Ron Simpson – Technical Services

Some cases of Air Driven Generators (ADG) partial deployments have been reported to Bombardier in the past few years. In most cases, it is suspected the ADG rotor lock pin was not engaged when the ADG was last stowed, causing the ADG rotor blades to move out of position and contact the ADG upper compartment structure during the release sequence. Operators are reminded that the ADG can be inadvertently stowed without the rotor lock pin engaged. This condition can remain undetected and result in an in-flight ADG deployment failure. 

Bombardier would like to remind operators to strictly adhere to the Aircraft Maintenance manual (AMM) procedures instructions when stowing the ADG. Special attention should be given to ensure the ADG rotor lock pin is engaged during the stow process.  

To prevent this condition, the dry ADG incorporates visual aids (see below) to confirm when the rotor lock pin is engaged (See views below). In case of doubt, the ADG should be manually released on ground and restowed as per AMM instructions to ensure the ADG lock pin is engaged. The ADG rotor status can also be manually verified through the nose landing gear access panel 123AZ.