The pilot reported that, after fueling the Pipistrel Alpha, he did not realize that he did not replace the fuel cap. During takeoff, the fuel gauge showed that the airplane had 74% of fuel (fuel gauge indicates in percent).
About 5 nm from the destination airport in Salida, Colorado, the fuel gauge showed that the airplane had 10% of fuel left. He flew the airplane in a straight line to the end of the runway and reduced the engine throttle setting to idle, which set up a lower glide path than normal.
When the airplane reached the field west of the runway, it “ran out of fuel,” the pilot told investigators. The airplane touched down on the field and hit a barb wire fence during the landing roll. The airplane sustained substantial damage to the forward fuselage.
An FAA inspector examined the wreckage and reported that less than half a gallon of fuel was recovered from the fuel tank.
The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.
Probable Cause: The pilot’s failure to replace the fuel cap after fueling, which resulted in a loss of engine power due to fuel exhaustion and a subsequent forced landing to a field and subsequent collision with a fence.
Interesting that low fuel status was not detected until 5nm from destination on a longer flight? Almost more alarming is reported 1600ft ceiling for X-C in this flight in mountainous terrain? Landing and checking fuel status at an intermediate airport would have been prudent.
This May 2019 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
One simple procedure before departure will prevent this mistake. Just before entering the cabin for engine start, make a 360 around the airplane looking for any overlooked item (tow bar, pitot tube cover, chocks, unsecured baggage door, tie-down rope, personal item on ground, etc.). For high wing models, it’s easy to check the fuel caps from behind the airplane.
I was shocked at home much fuel can get sucked out without the cap on.
I watched a bonanza take off, it looked like it was on smoking so much fuel was streaming out.
On a high wing there’s no way to see this.!
Looking at the specs for the fuel capacity, usable fuel is 12.7 gallons. At cruise power, the Rotax burns 3.6 gph, for an endurance of 3.5 hours.
https://www.pipistrel-usa.com/alpha-trainer/#technical_data.
If the displayed fuel of 74% at takeoff was accurate, it had 9.7 gallons, and at 3.6 gph it would fly for 2.7 hours, vs the .2.5 that he flew, before using all the fuel.
So, I think that he just ran the tank[s] dry, and little fuel was siphoned out.
Also the POH is severely lacking in cruise performance specs., with one data point, ‘ 5300 rpm, 100 kts, 3.6 gph, with a mention that htis is at 6,000 ft. vs the typical multiple altitudes vs airspeed and gph.
With 166 hours in the aircraft, he should have known the fuel burn rate for how he normally flew it.