CF34 Engine: Moisture Build-Up in Power Drive Unit on Challenger* Aircraft

May 2015

Moisture has been found to build up in the 14 stage bleed air supply ducting when operating in hot / humid temperatures; this then condenses in-flight. When there is no usage of the anti-ice system, this moisture build up has no place to go except when forced through the ducting to operate the thrust reverser power drive unit, allowing the ingestion of moisture.

The simple fix is to drill a .0625 inch hole in the thrust reverser ground supply cap. This new hole will allow the continuous purging of air and prevent moisture from accumulating in the duct work.

This will aid in preventing moisture-laden air getting into the power drive unit. It may also prevent having to prematurely replace the power drive unit. Refer to CF34-NAC-30-005 for reference data.

*Trademarks of Bombardier Inc. or its subsidiaries