Gulfstream IV / G350 / G450
Maintenance Airframe; Maintenance Powerplant
Communication Breakdown
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft; Human Factors
At approximately XA14; I walked to my desk and noticed that the Gulfstream MEL (Minimum Equipment List) box had an open item. At the time; I was working the large cabin desk. 2 hours from finishing my 12 hour shift.I asked the other two controllers if they had spoken to the flight crew and they said no. I read the MEL. 'Potable water system drains out whenever pressure is put on the system.' I looked at the MEL references which was inop the whole system. Fault Name? Potable Water System - System DrainedAnd my first thought was this aircraft is just like the Global - when there is a problem with the EIB (ELECTRONIC INTERFACE BOX) - the potable water system will dump the system. I hit the button to defer it at XA16. The next thing I did was I read the whole sentence. Potable water system drains out whenever pressure is put on the system. Water drains into the belly of the aircraft and drains out weep holes. At which time I called and emailed the flight crew at XA20 XA22 XA25. I also called the FO (First Officer) at XA29 and called the flight at XA29. I called the front desk at the FBO (Fixed Base Operator) and asked if Aircraft X had departed and they told me yes. I wanted to talk to the flight crew to understand why they feel they could MEL the water system but they had left.  I then reported this to the Manager on Duty.  I understand flight crew get fed up by being on hold to [Maintenance Control]. However this Captain has been with [the company for a while]. He should know we don't fly with water leaking from the belly of the aircraft. The only thing I wish I could have done is call Dispatch and ask them to stop them.
Maintenance Controller reported that the potable water system on a G450 aircraft was improperly deferred.