Date: 201904
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Weather elements / visibility: 10
Light: Night
Aircraft: DA20 Undifferentiated
Operator: FBO
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Takeoff / Launch
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Fuel Quantity-Pressure Indication
Component problem: Malfunctioning
Reporter organization: FBO
Reporter function: Instructor
Reporter qualification: Flight Crew Multiengine; Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument
Human factors: Troubleshooting; Training / Qualification; Confusion; Situational Awareness
Second reporter function: Trainee; Pilot Flying
Anomaly: Aircraft Equipment Problem Critical; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Rejected Takeoff
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: [In the evening]; my student went out to Aircraft X to perform his preflight check. Attached to the clip board was a sticky note stating that the fuel level was at least 3/4 full. Per the checklist; he dipped the fuel tank and read approx 3/4 full. A few minutes later I joined him at the plane and dipped the tank myself. I also read approx 3/4 full of full. Both of us agreed that the fuel load was enough for a 1.5 hour flight. Before takeoff; I noticed a discrepancy between the fuel gauge and the level that my student and I believed was on board. It read slightly lower; than what we believed was on board; but not so much so to cause me concern due to the unreliable nature of the fuel gauge during previous flights. We departed without incident; and flew to ZZZ1 and practiced pattern procedures there. After approx .5 of flying; we departed ZZZ1 to ZZZ2 to continue pattern work. While departing ZZZ1; we looked at the fuel gauge and noticed it indicated lower than 1/4 full. At this point we discussed the possibility that the fuel level was low and what to do. We both confirmed with each other that the fuel level had been 3/4 full before the flight. We had originally planned to do multiple landings at ZZZ2 but decided to return to ZZZ after one; fearing a possible leak; but believing we still had at least 1/2 tank. We entered the pattern at ZZZ and performed another two landings; still believing that the fuel gauge was faulty. After completion of the second landing at ZZZ; the fuel gauge had dropped to zero and the engine stopped during takeoff roll. We stopped the aircraft on the runway without incident. After reporting our situation to ZZZ tower; we secured the aircraft and dipped the fuel tank once more to find it empty after 1.2 hours of flight time.Either a mechanical defect caused fuel starvation or an error reading the fuel level by three separate people. In either situation; the fuel gauge was accurate. Having encountered previous instances with inaccurate fuel gauges; I did not trust the reading the gauge was giving me. I believed a visual reading was more accurate. In hindsight I should have aborted the flight and returned to ZZZ the moment I noticed the discrepancy.


Second narrative: Fuel starvation during takeoff; touch and go's in pattern. During pre-light; instructor and I both physically checked fuel. Was at 3/4 tank of 18 gallon. This is about 3 hours of flight. Flight was scheduled for 1.5 dual night flight in local practice area. We knew we would have enough fuel. During flight; periodically checked fuel via the gauge. Fuel was dropping at quicker intervals than normal. We have seen many faulty gauges and knew that since we physically checked the fuel that we had enough fuel. We were going to report the gauge when we finished the flight. Doing pattern work; and the engine died on us while take off roll after previous landing. We were not off the ground yet; called tower. Tower closed runway and instructed us to push the plane off the runway and waited for the airport services to come help us. Nobody was hurt; including the plane. Do not know what happened; we should have had enough fuel. Maintenance is going to look at the plane on the next business day.


Synopsis: DA-20 Flight Instructor and student reported engine failure due to fuel starvation during take-off roll.