Date: 201406
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: Citationjet (C525/C526) - CJ I / II / III / IV
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
Airspace: Class A ZZZ; Class E ZZZ1
ATC / advisory: CTAF ZZZ1; Center ZZZ
Aircraft component: Fuel
Reporter organization: Personal
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Second reporter function: Pilot Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Fuel Issue
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Diverted; Flight Crew Landed As Precaution; General Maintenance Action; General Declared Emergency
Contributing factors: Equipment / Tooling
Primary problem: Equipment / Tooling

Narrative: During cruise flight at FL330; RH Fuel Filter Bypass Caution segment light illuminated. While reaching for the Emergency Checklist; the LH Fuel Filter Bypass caution segment illuminated. Immediately requested a descent to FL240 and direct to ZZZ. Center cleared as requested and we declared an emergency due to the possibility of a dual engine flameout. Emergency procedure depicts; 'LAND AS SOON AS POSSIBLE'. We were cleared down to lower altitudes and issued a visual approach to ZZZ1. Called the CTAF/UNICOM frequency to determine landing runway. Entered a modified high; left downwind to base leg. Landed under power and taxied to general aviation parking area. Fuel Filter Bypass Caution segments stayed illuminated until engines shut down. After one hour on ground; temp +40C; started the engines and ran at idle power for 10 minutes. Shutdown and sumped both tanks and found very minute amount of water in one sump. Continued process until fuel was clear and correct. Refueled with 60 gallons each side and allowed to sit overnight for at least 12 hours. Previous fueling was 312 gallons with PRIST [anti icing fuel additive]. Advised previous fueler to check their fuel truck PRIST injector and filters. Next morning; again sumped both tanks; started and performed an extensive runup. Takeoff was normal and climbed over airport to 15;500 MSL to pick up IFR clearance. All systems operated normally at FL230 with no issues. Landed with no further issues. Maintenance at home base will sump the tanks several more times and inspect/replace the fuel filters.


Second narrative: Dual fuel bypass lights at 33;000. Notified Center. Performed emergency checklist; 'land as soon as practical'. Declared emergency. Given vectors to ZZZ1; 54 NM north of current position. Landing uneventful; engines continued to run normally. Continued to destination the next day after adding fuel with PRIST and sumping tanks to confirm no water. Normal flight.


Synopsis: CE-525 flight crew experiences a dual fuel filter bypass caution lights at FL330 and diverts to the nearest suitable airport. Fuel icing is suspected and the last fuel supplier is contacted to check their fuel truck for proper PRIST injection.