Skyhawk 172/Cutlass 172
Flight Crew Commercial
Flight Crew Last 90 Days 71; Flight Crew Total 1350; Flight Crew Type 65
Troubleshooting; Time Pressure; Workload
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification
Aircraft; Human Factors
Departed ZZZ VFR to ZZZ1. Landed at ZZZ1. Hobbs showed exactly 3.0 hours. Checked fuel on landing (19 useable gallon 'straw' showing about 4.5 gallons each tank). We received 22.9 Gal fuel. Prior to departing ZZZ1 re dipped the tanks showing just shy of 16.5 gal each side. Departed ZZZ1 on an IFR clearance filed 10;000 ft. We started encountering moderate turbulence at 12;000 ft. so we requested lower and eventually canceled IFR to descend to about 7;500 ft. to get out of the very occasional severe turbulence. About 40 miles north of ZZZ2 the air smoothed out and we started incremental climbs back to 9;500 ft. 5 miles south of ZZZ2 we contacted approach to file IFR. ZZZ approach cleared us for the visual approach and gave us vectors to the downwind then handed us off to Tower. They told us to descend from 10;000 t. to 8;000 ft. and then told us we would be number 2 behind traffic approaching from the north.There was another heavy on about a 3 mile final to Runway XX. While descending at 500 fpm (about 1800 RPM) the engine went to 1000 rpm on its own. We pulled Carb heat with no change; mixture full rich. We changed fuel selector from both first to left then back to right with about 10 seconds in between. I [advised ATC] and they gave me right base to Runway XX. We pitched for 65 kts. and turned NE direct toward the approach end of the runway. The engine would occasionally rev back up to 1400ish RPM then back to 1000.Tower told me they also had Runway XY available. I said I was going to try for Runway XY. We (my Safety Pilot) passenger at the time since I was not under the hood discussed that we would not make Runway XX or XY and turned toward Runway XZ as it was closest to us. Tower said it looked like we were headed toward Runway XZ and I told them we were going down. They told me the runway was closed and I told them I was going down and had no other option. The runway lights were out but the blue taxi lights were on for Taxiway XX. We touched down about 10 ft. prior to plastic water barricades (about 6 in. tall) center on the taxiway and came to a rest between X3 and X4. We let Tower know we were OK. Some ZZZ2 ground employees came out and checked on us and the aircraft was eventually tugged back to [the FBO]. No damage or injuries were present.Fuel was found to be near empty in both tanks. Hobbs showed 3.2 additional hours. The engines are 180 HP so I calculate W&B with the 172N POH and W&B form. I use a 172S POH for calculating performance since it has the same 180 hp engine. The average fuel burn should be approx. 8.3 gph conservatively with climb and level off to 12;000 ft. Temp at level off was 9 to 11 degrees C. Calculated fuel was 8.3 X 3.0 = 25 gallons. IFR reserve about 6.1 gallons for a total of 31 gallons. These numbers also matched what we had going to ZZZ1 based on actual fuel usage. Other than claiming at about 2500 to 2600 RPM; we maintained about 2400 RPM. We feel that this was somehow mechanical in nature. However would also like to note that older C-172 aircraft seem to have very unreliable analog fuel gauges. This almost requires that you must have a fuel probe for accurate calculations. Also not sure if the turbulence we encountered could have caused fuel to vent out.
Flew to ZZZ2 from ZZZ1. When landed Hobbs was 3.0 more than take off. Added 22.9 gallons of fuel. Before takeoff the other pilot who was PIC (Pilot In Command) on the flight back dipped the tank and it was slightly more than 16 on each side and I checked visually. On the flight back when we were cleared for a visual landing Runway XX. Soon after; our engine went to idle. Immediately we added Carb heat; mixture rich; check that the fuel selector was on both; when we saw it was on both we checked the left tank for 10 seconds than the right tank for 10 seconds. When this had no effect PIC pitched for best glide (65 knots) and [advised ATC]. ATC cleared us for Runway XX. We realized soon after that we could not land on Runway XX; so we notified ATC that we were going to land Runway XY. Soon after that we realized we would not make Runway XY; but we saw the blue taxiway lights and saw we could make the taxiway. We touched down on Taxiway XX center line near some barriers. We came to a full stop at X4.
C-172 flight crew reported an engine failure due to fuel starvation that resulted in a landing on taxiway.