The crash involved a Textron Aviation Citation Latitude (Model 680A), registration N523QS, operating under Part 91 Subpart K fractional ownership rules. The NTSB said the accident happened at about 10:00 p.m. CDT as the flight traveled from Los Cabos, Mexico, to Austin, Texas. The aircraft sustained substantial damage.
The NTSB reported one passenger was killed. The captain was seriously injured, while the first officer and three passengers suffered minor injuries. One person on the ground — an occupant of a vehicle — also had minor injuries.
Early in the flight, the crew reported an unusual vibration they had not experienced before during a phone call with NetJets Flight Operations and Maintenance Control. The crew described a low-frequency vibration and a humming sound resembling a fan running, with vibration felt through the instrument panel. The vibration was initially steady during climb, then became intermittent and eventually disappeared.
During that discussion, the aircraft generated a “BOTH ON ADC 1” Crew Alerting System message involving the Air Data Computer. Maintenance personnel believed the symptoms could be caused by an avionics cooling fan behind the instrument panel, and the NTSB said that explanation appeared consistent with the ADC warning. The crew completed the Quick Reference Handbook checklist, the warning cleared, and after consulting with maintenance and flight operations, they elected to continue to Austin and document the vibration after landing. At that point, the NTSB said no other abnormal aircraft indications were reported.
As the aircraft approached the U.S.-Mexico border, the NTSB said additional failures developed rapidly. The crew first received a “FUEL BST PUMP ON R” alert indicating low fuel pressure on the right side, followed seconds later by “FUEL PRESS LOW R.” About three minutes later, the aircraft generated “ELEC TRU FAIL R” and “WSHLD HEAT INOP R.” About 11 minutes after that, the crew received “FUEL LEVEL LOW R.” The NTSB said the alerts indicated a progression from fuel system problems into electrical system failures affecting the aircraft’s right side.
The crew declared an emergency with Monterrey Area Control Center before being transferred to Houston Air Route Traffic Control Center, the report said. The pilots reported generator failure, multiple additional system failures and low fuel indications, and requested an immediate diversion to Laredo International Airport.
Because the aircraft was high above the airport, Houston Center issued radar vectors, including a large 270-degree turn, to position the aircraft for a 14-mile final to Runway 36L, according to the NTSB. When asked if they needed additional time to complete emergency checklists, the crew said they were ready to continue the approach.
While established on final approach, the NTSB said the right engine flamed out, and seconds later the left engine also failed. The first officer asked Laredo Tower whether there was an open field to the aircraft’s right suitable for an emergency landing. Controllers advised there were no fields available, only the nearby highway.
The Citation touched down on the northbound lanes of Bob Bullock Loop, about one mile southeast of Laredo International Airport, the NTSB said. Video from security and residential cameras captured the aircraft during its descent and showed two separate bursts of fire while still airborne.
During touchdown, the aircraft struck several light poles, collided with a moving vehicle, came to rest partially on an overpass and rolled onto its right side, the report said. With the aircraft on its side, the main cabin door faced upward and the rear emergency exit was pinned against the ground. The NTSB said five occupants escaped through the main cabin door after it was opened.
Investigators moved the airplane to a secure hangar in Laredo for a preliminary inspection. The NTSB said the examination found flight control continuity for the ailerons, elevator and rudder, suggesting no pre-impact flight control failure.
However, investigators found significant damage within the right engine fuel system. The NTSB said the right engine fuel pressure switch had separated from its fuel tube assembly, and the fuel tube assembly had fractured adjacent to the welded fitting where the pressure switch attached. Investigators also found multiple P-clamps — which secure the fuel tube assembly against vibration — were fractured.
The investigation also identified abnormalities involving the right engine starter generator, manufactured by Safran. The NTSB said multiple exterior housing screws were missing. The unit had 57.2 operating hours remaining since its most recent overhaul, far below its 1,200-hour overhaul interval, indicating it had not reached overhaul limits.
After removal of the starter generator, investigators found a bent generator shaft, a fractured cooling fan, broken cooling fan blades, loose ball bearings and circular scoring marks inside the cooling fan shroud, the report said.
The starter generator, damaged fuel tube assembly and additional components were sent to the NTSB Materials Laboratory in Washington, D.C., for detailed examination. The aircraft’s flight data recorder and cockpit voice recorder were recovered and transported to the NTSB laboratory in Washington for download and analysis, and the wreckage was relocated for additional examination.
Weather was not considered a significant factor, according to the NTSB. The report cited visual meteorological conditions at night with clear skies, 10 miles visibility, light winds at 2 knots, and a temperature of 28C with a 24C dew point. The aircraft was operating under an IFR flight plan.
The NTSB emphasized the report is preliminary and subject to change, and that it has not determined a probable cause. The agency said the investigation is continuing, including laboratory analysis of the damaged components and review of cockpit voice and flight data recorder information to determine how the failures developed and whether they were connected.
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