Narrative:

The incident occurred during a student lesson. A student weighing about 220 pounds and an instructor (person filing the report and pilot in command of the airplane) weighing about 200 pounds were the only occupants. To keep gross weight under approved C150M gross weight limits; it was necessary to use partial fuel. Cessna C150M published payload is 340 pounds with full fuel which necessitated reduction of weight by partial fueling. The first flight of the day started with 3/4 fuel by visual inspection and by fuel gauge indication. No other fuel measurement method was available. The amount of fuel according to the fuel gauges and visual inspection was 3/4 of 22.5 gallons usable; or 17 gallons. The first flight after the initial inspection lasted 1.5 hours during which active leaning procedures were used. 10 more gallons were added after the first flight. A second flight of 1.2 hours was then flown during which active leaning procedures were used. 5 gallons were added and a third flight of 2.1 hours during which active leaning procedures were used; resulted in an off-airport landing. Engine surging was experienced during the takeoff portion of the flight at about 500 AGL. Partial power was available during the event flight. An off-airport landing was chosen to insure safe outcome due to surging and a plowed field was chosen for landing. No property damage or personal injury took place. The airplane was refueled and repositioned to the airport shortly after the event. A factor was a defective fuel gauge which indicated half-full during the flight. The faulty indicator was observed and verified by two independent observers. A replacement sending unit for the defective fuel gauge was to be installed according to the owner.

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Original NASA ASRS Text

Title: A C150 was flown on several flights with partial fuel loads because of the aircraft's occupant plus fuel max weight constraint. During the third flight of the day the crew landed off airport when the engine began running rough because of low fuel. Later a faulty fuel gauge was identified.

Narrative: The incident occurred during a student lesson. A student weighing about 220 LBS and an Instructor (person filing the report and pilot in command of the airplane) weighing about 200 LBS were the only occupants. To keep gross weight under approved C150M gross weight limits; it was necessary to use partial fuel. Cessna C150M published payload is 340 LBS with full fuel which necessitated reduction of weight by partial fueling. The first flight of the day started with 3/4 fuel by visual inspection and by fuel gauge indication. No other fuel measurement method was available. The amount of fuel according to the fuel gauges and visual inspection was 3/4 of 22.5 gallons usable; or 17 gallons. The first flight after the initial inspection lasted 1.5 hours during which active leaning procedures were used. 10 more gallons were added after the first flight. A second flight of 1.2 hours was then flown during which active leaning procedures were used. 5 gallons were added and a third flight of 2.1 hours during which active leaning procedures were used; resulted in an off-airport landing. Engine surging was experienced during the takeoff portion of the flight at about 500 AGL. Partial power was available during the event flight. An off-airport landing was chosen to insure safe outcome due to surging and a plowed field was chosen for landing. No property damage or personal injury took place. The airplane was refueled and repositioned to the airport shortly after the event. A factor was a defective fuel gauge which indicated half-full during the flight. The faulty indicator was observed and verified by two independent observers. A replacement sending unit for the defective fuel gauge was to be installed according to the owner.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.