Date: 202201
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Night
Aircraft: Cessna 152
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Climb; Cruise
Airspace: Class B ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Fuel Storage System
Component problem: Improperly Operated
Reporter organization: Personal
Reporter function: Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Commercial; Flight Crew Flight Instructor
Human factors: Situational Awareness; Human-Machine Interface; Communication Breakdown
Second reporter function: Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Overcame Equipment Problem; Flight Crew Landed As Precaution; General Flight Cancelled / Delayed
Contributing factors: Aircraft; Procedure; Human Factors
Primary problem: Procedure

Narrative: The flight was from ZZZ to ZZZ1 back to ZZZ. we departed around XApm; landed ZZZ1 around XC:15pm. on the return flight back to ZZZ near by ZZZ2; the engine was rough and partially lost power and we [requested priority handling] right away with ZZZ3 Approach. We did our best to land aircraft safely at ZZZ2 and no one was injured. Before the flight; we did the flight plan; based on the POH (Pilot Owner's Handbook); we calculated the fuel burn. Total route is 298 NM; which will cost 3.5 hours. So we should have had remaining 1 hour fuel. I believe low fuel caused the problem. In the future I will pay more attention to the fuel; do not trust fuel indicator; give myself a bigger fuel margin.


Second narrative: On a 298 NM flight from ZZZ to ZZZ1 and back to ZZZ in a Cessna 152; the PIC calculated fuel burn over the flight based on the POH and fell within the expected reserve requirement.  The plane took off at XA:00 with verified completely full fuel tanks.  When we landed at ZZZ1 at XC:15 and the fuel gauge appeared to show a fuel level in line with calculations to make the return flight.  On the return trip; approximately 20 NM from ZZZ at around XD:45; the engine was rough and lost partial power.  I immediately radioed in and [requested priority handling] with ZZZ3 Approach and the tower requested that I remain on frequency and cleared our aircraft for immediate landing at ZZZ2.  The PIC landed the plane safely without power; there was no damage; and no one was injured.   Between the timing of the failure and calculated fuel burn; the numbers did not align. We followed every altitude assigned by ATC along the flight; leaned the fuel mixture and kept appropriate power as calculated but margin was insufficient.  In the future I will take an even more conservative approach to my own fuel calculations after this impactful experience.


Synopsis: Flight crew reported partial engine power loss during cruise. The flight crew elected to divert and make a precautionary landing.