CEN18LA032 · Cessna T207A

The public aircraft aerial survey flight with a commercial pilot and three survey crewmembers had a planned duration of 1 hour 45 minutes. The pilot stated that the airplane departed with full fuel in the left- and right-wing fuel tanks, which provided a usable fuel capacity of 36.5 gallons per tank. His fuel consumption calculations for the flight determined that a total of 27 gallons would be used for 1 hour 30 minutes of flight; he stated that he planned to use fuel from the left fuel tank for 1 hour 30 minutes and then switch to the right fuel tank. After 1 hour 30 minutes of flight time, when the airplane was 10 minutes from the destination, the pilot observed the left fuel gauge "rapidly shifting from full to 1/4." The pilot had observed similar indications before with the left gauge, as it was "often stuck at a full reading then flicked back and forth between full and the actual fuel level," on previous flights; he thought there was 1/4 tank of fuel remaining. He planned to switch to the right fuel tank when he entered the airport traffic pattern. When the airplane entered the base leg, the engine sputtered before the pilot switched fuel tanks. The pilot then selected the right fuel tank, pushed the throttle control full forward, and selected the auxiliary fuel pump to HI and then LOW; the engine continued to sputter. He did not follow the airplane manufacturer's emergency checklist for engine failure restart, which instructed to select the auxiliary fuel pump switch to ON, select the fuel tank containing fuel, position the throttle to half open, and then turn the auxiliary fuel pump switch off.

Unable to restart the engine, the pilot chose a road for a forced landing. During his approach, the stall warning horn sounded periodically and the airspeed indicated 65 knots, which was below the recommended engine-out glide airspeed of 80 knots. The pilot lowered the airplane's nose to increase airspeed, and the airplane descended "rapidly." He was still unable to restart the windmilling engine. When the airplane was over the road, he fully extended the flaps and then veered the airplane right to land in the dirt next to the road to soften the landing. The airplane sustained substantial damage to the nose landing gear and fuselage.

Postaccident examination of the airplane revealed that the left fuel tank contained no useable fuel, and the right tank contained full fuel. Further examination of the fuel system found that the left fuel quantity transmitter did not move smoothly from the upper stop to the lower stop and repeatedly stuck in place. There was no evidence of other preimpact engine or fuel system malfunctions or failures that would have precluded normal operation.

Two of the survey crewmembers reported that they had witnessed a similar discrepancy with the left fuel gauge during flights 7 months before the accident. However, no writeups of the discrepancy were made. The airplane had annual and 50-hour inspections less than 1 month before the accident; the airplane service manual called for troubleshooting of the fuel gauges at these inspections. However, maintenance personnel were not aware of the discrepancy with the left fuel gauge and, therefore, did not troubleshoot it and identify that the transmitter needed replacement. Regardless, the pilot did not manage the fuel properly by switching fuel tanks when he planned and instead continuing toward his destination for another 10 minutes, relying on a faulty fuel gauge, which led to the fuel tank he was using becoming devoid of fuel, which led to fuel starvation. Further, once the airplane lost engine power, he did not follow the emergency checklist procedures for restoring power.

Verbatim NTSB analysis and probable cause from the NTSB dataset