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Gulfstream Heated Drain Masts Failing

September 2009

Several recent Gulfstream inspections have revealed failed heated drain masts on GII through GV models. Some of these failures were noted during operational checks and others during arrival after an extended flight. There maybe several early tell-tale signs of a failed drain mast.


  • The crew may report slow or no draining of the sinks or ice drawers at cruise altitude.
  • If your operations are in a colder climate, ice may still be present on the drain mast after landing. This would be noticed during the post-flight walk-around.
  • If your operations are in a warmer climate and your aircraft is a forward fuselage drain mast configuration, you may notice small missing paint chips on the wing to fuselage forward fairing assembly. Several recent failed forward drain masts have caused ice impact damage to the wing to fuselage forward fairing assembly. This has ranged from minor paint damage to major damage requiring extensive composite repair to the forward fairing assembly.


Routine operational checks and early detection of a failed drain system may help reduce the need for these types of repairs. If your drain mast requires replacement and your aircraft is compliant with the Inspection-Water System Heating and Plumbing (Customer Bulletin) and /or Water Line Ribbon Heater Upgrade (Aircraft Service Change), then additional parts/labor may be required.

The Customer Bulletin/Aircraft Service Change removed the rubber or plastic hoses at the drain masts and installed braided shield type flex hoses and Swagelok fittings. These Swagelok fittings will also have to be replaced with the drain mast since the fitting nuts and ferrules cannot be removed from the drain mast stand pipe. Additional labor may be required depending on the Fuselage/Panel cut-out size and fitting configuration. This condition typically will not apply to the drain mast installations that use the Threadless Couplings.

If you have questions about this or other technical issues about the operation of your Gulfstream, contact your Duncan Aviation Gulfstream Tech Rep.