Troubleshooting tips for Under-Wing Fairing Drain Mast leaks

Effectivity: Challenger 300/350 aircraft

ATA: 28/53

By: Yvan Tremblay – Technical Services   

Here are some helpful tips on what to look for when troubleshooting leaks from Under-Wing Fairing Drain Masts. 

During a post-flight walk-around, when a leak is observed coming from the Under-Wing Fairing Drain Mast, the leaking fluid is often reported as fuel. 

The maintenance crew therefore focuses troubleshooting operations on the fuel system. In several cases, the leak cannot be found or reproduced during the investigation.  

This indicates that it may not have been a fuel leak, but rather a water leak (created by condensation or rain), or a Skydrol leak coming from the Under-Wing Fairing or AFT Fuselage Drains. 

Fluid coming out of the Under-Wing Fairing Drain Mast can come from: 

• FEED Lines 

• AFT Fuselage Drains 

• MOTIVE FLOW Lines 

• Under-Wing Fairing 

The fluid type that can come from Under-Wing Fairing Drain Mast:

When there is a leak coming from the Under-Wing Fairing Drain Mast, we recommend identifying which drain hole of the Under-Wing Fairing Drain mast the fluid is coming from and, if possible, what type of fluid it is (fuel, Skydrol or water). 

This will improve the troubleshooting process and save time for technicians.