As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THIS OPERATOR HAS A FLEET OF CESSNA 172R AIRCRAFT (15). THERE IS A TREND DEVELOPING WHERE THE PILOTS WRITE UP THE FUEL SYSTEM FOR UNEVEN BURN FROM LT AND RT TANKS WHEN THE FUEL SELECTOR IS ON 'BOTH'. THERE IS NO DEFINITIVE REPAIR YET, BUT THE PROBLEM IS BECOMING MORE REPETITIVE. THE INVESTIGATION IS ONGOING.