Citation Excel (C560XL)
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor; Ground Event / Encounter Other / Unknown
General Evacuated; General Maintenance Action
Aircraft
On arrival and passenger disembarkement I started the APU to prepare for the next flight. With a reported temperature of -17C; I decided to utilize the heating capabilities of the APU and turned the bleed air on in accordance with the normal checklist. Fairly quickly; Jet Fuel fume smells developed throughout the cabin. The APU bleed air switch was turned off shortly thereafter. Upon APU and aircraft shutdown; I heard a streaming faucet sound from the rear of the aircraft -- it was after dark and the aircraft was 'dark'. Upon further inspection; I found Jet Fuel streaming out of a fuselage drain mast -- centerline immediately aft of the 'hell hole' door.I immediately informed and showed the PIC the fuel leak. We informed FBO personal as soon as possible of the leak. We queried them whether advising the fire department or the airport authority was necessary; we were informed that no report was necessary. The PIC promptly called maintenance control to report and document the discrepancy; and I called the chief pilot on duty [who] did not indicate any other actions were needed from us.In the future; I will immediately shutdown the aircraft upon Jet Fuel fume smell being present in the cabin; and let maintenance determine what led to said fumes.
After blocking their CE560XL in on a bitterly cold through flight the SIC started the APU to heat the aircraft in preparation for the subsequent trip.  He quickly sensed fuel fumes and; after shutting down the aircraft; heard a running faucet sound that led him to inspect the fuel drain from which he discovered jet fuel rapidly exhausting. They called Maintenance and a company Chief Pilot.