Date: 201404
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: Haze / Smoke; Rain; 10
Light: Daylight
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Landing
Airspace: Class E ZZZ
Aircraft component: Engine
Component problem: Failed
Reporter organization: Personal
Reporter function: Single Pilot; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Human factors: Human-Machine Interface; Situational Awareness
Anomaly: Aircraft Equipment Problem Critical; Ground Excursion Runway; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: I had intended to take 7 gallons of fuel. Unfortunately; the FBO informed me just prior to my departure that the fuel delivery had not come in so they wouldn't be able to provide me with fuel. Based on my knowledge of the fuel level I believed I would have enough fuel to make it to my destination [about 85NM to the northeast]; plus have an additional 45 minutes worth of fuel. After startup I noticed some engine roughness up to 1300 RPM; but the engine smoothed out at higher RPM so I didn't assume it was anything to worry about. Due to extremely turbulent air I decided to climb above my flight planned altitude; from 4;000 to 6;000. Although the climb put me in mostly smoother air; it increased my headwind by approximately 10 and decreased my ground speed by about 9%. Almost the entire flight was conducted in rain; clouds; or high moisture environment. As I got closer to my destination I decided to make a visual approach to Runway 25; so I canceled my IFR flight plan while VMC. I navigated directly to the field; and set up for a 3 mile final approach for 25. At approximately 2 mile distance [from] the runway I reduced power for the approach. Immediately after the power reduction the engine sputtered very briefly then died. I attempted multiple throttle configurations and assured the mixture was full rich; but the engine never restarted. I was around 800 AGL at the time of the engine failure. Due to a 12 KT; gusting 19 KT; headwind; I decided to aim for the taxiway which comes to the departure end of [Runway] 34; and parallels Runway 25. The taxiway extends farther than the runway and I thought if I was going to make a paved surface I should aim for the closest one. I ended up landing in the grass; coming to rest approximately 100 FT from the edge of Runway 34. Absolutely no damage was incurred by myself; the airplane; or the airport property besides the nose wheel getting a little pushed into the mud. At first I was sure that I had run out of fuel; as the fuel gauges were known to be unreliable from time to time. However; in an attempt to get the plane unstuck from the mud 10 minutes later; I started the engine multiple times; running it at full power for up to 2 minutes without any observed problems. Eventually; we were able to push the plane out of the mud onto the pavement at which time I started it back up and taxied it to the FBO. Because the plane ran for at least 5 minutes after the off runway landing; I no longer believe my problem was fuel exhaustion; but possibly carb ice. This is the first carbonated airplane I have ever flown; and from time to time I forgot to turn on carb heat during landings. After landing I noticed the carb heat was pulled slightly; but I don't believe it was pulled enough to be engaged. The plane is being looked at for defects at this time before it is flown back to its home base. As I stated; I originally believed the engine failure was caused by fuel exhaustion; but after greater thought I believe it was caused by carburetor ice or some other defect. I especially think this because there was still some fuel present in the left tank; and the airplane ran for at least 5 minutes once on the ground near full power without adding additional fuel. Because I'm not 100% sure what caused the failure; I don't believe I can make a good recommendation of what can be done to remedy it. If the issue was carb ice or fuel exhaustion; these are things that I have been trained on and the fault lies with me for not engaging carb heat fully; or adding additional fuel even though I thought I would be fine. From now on I will always fly with extra fuel; and will never forget to fully engage carb heat prior to landing. If the issue was maintenance related then there's nothing that could be changed about the situation.




Synopsis: Unable to obtain additional fuel at his departure airport; the pilot of a C-172 took off for his destination some 85 NM away believing there was sufficient fuel remaining for the approximately one hour flight plus reserves for his IFR flight plan. For uncertain reasons the engine quit; almost close enough to allow a power off approach and landing. The undamaged airplane completed its journey only yards short of the hard surface. The cause is under investigation.