Cessna 402/402C/B379 Businessliner/Utiliner
Flight Crew Air Transport Pilot (ATP)
Confusion; Distraction; Time Pressure; Troubleshooting
Aircraft Equipment Problem Less Severe
Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
First Officer (FO) was climbing through approximately 7800 ft for 10;000 ft during our instrument scan we both noticed a drop in fuel flow from 120 to ~50 on the LEFT engine. This was accompanied by a loss in engine RPM; fluctuation in Manifold Pressure and roughness. The engine felt like it was shutting down but then the fuel flow rose back to 120; then fluctuated around 100. It then stabilized and we made the decision to return to ZZZ; no emergency was declared and the flight landed without further incident. The event happened over 5-10 seconds.
A Cessna 402 Captain reported fluctuating fuel flow and engine roughness during climbout. Though the engine recovered somewhat he elected to make a precautionary landing at the departure airport.