Narrative:

I was piloting a diamond DA20-C1 on a cross country flight. I was direct VFR with flight following at a cruising altitude of 8;500 ft at 2600 RPM/5.3 gph (gallons per hour). I [previously flew a] two hour [flight]. I landed and shut down with 5/8 of a tank of fuel. Prior to departure for the return flight I had requested a few (3) additional gallons of fuel. This brought my total fuel on board to read 3/4 of a tank. I departed and had a cruising altitude of 9;500 ft at 2650 RPM/5.3 gph. Weather conditions were ideal from both VFR flights that day. Approach had just cleared me to begin my descent from 9;500 ft at approximately 45 NM from the airfield. Once I began my descent procedures I noticed some engine fluctuations; and during the flight the fuel consumption seemed higher than normal on the fuel tank indicator.at this point I notified approach of my situation and requested to divert from my current course and land at [a nearby airport]. While reading back ATC's instructions the situation became more serious and then the engine stopped while descending through 8;500 ft. I immediately notified approach of the development; [they] asked if I would still like to make [another airport]? I suggested that if possible I would prefer a closer airfield to avoid any further unnecessary risks. Approach agreed and cleared me to descend into [a closer airport]. During my slow and controlled descent I attempted an engine restart and was able to get some power to the engine but still continued [the divert]. Once I was safely on the ground; I contacted approach via cell phone to report that the aircraft was safely on the ground and that there were no injuries or damages incurred. I began to review the situation that had occurred to assess what went wrong. The first question I had to answer was the fuel total prior to departure versus what was burned in flight; to assess why I had an inadequate amount of fuel to reach [my original destination]. All indications said that I had 3/4 of a tank on board which would have indicated to me that I had approximately 18 gallons of fuel. At this time I was under the knowledge that per the manufactures/owners manual that I was operating an aircraft with a 24 gallon fuel tank; but what I was unaware of at the time was that this particular tail was a slightly different version and only had a 20 gallon fuel tank. This resulted in my fuel on board estimates to be inaccurate and in turn made my return flight math inaccurate. There was also the factor that on this flight I should have only required the 2 hours of fuel for en route plus a 30 minute reserve available; but what is still unknown is how the 3/4 of a tank did not make even a two hour flight. There are suspected possible issues with the fuel tank indication in the cockpit and also if one of the fuel sumps might have been slightly stuck open during flight from the pre-flight inspection. Either or both of these could have played a part in the events that lead up to this incident. Once the aircraft had been inspected by its home base mechanic; it was refueled; ground tested and cleared the short direct return flight. No further issues were found during the short flight home.

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Original NASA ASRS Text

Title: A Diamond DA20 pilot reported engine failure due to fuel exhaustion despite what he calculated should have been sufficient fuel on board. A safe landing ensued at a nearby airport.

Narrative: I was piloting a Diamond DA20-C1 on a cross country flight. I was direct VFR with flight following at a cruising altitude of 8;500 FT at 2600 RPM/5.3 gph (gallons per hour). I [previously flew a] two hour [flight]. I landed and shut down with 5/8 of a tank of fuel. Prior to departure for the return flight I had requested a few (3) additional gallons of fuel. This brought my total fuel on board to read 3/4 of a tank. I departed and had a cruising altitude of 9;500 FT at 2650 RPM/5.3 gph. Weather conditions were ideal from both VFR flights that day. Approach had just cleared me to begin my descent from 9;500 FT at approximately 45 NM from the airfield. Once I began my descent procedures I noticed some engine fluctuations; and during the flight the fuel consumption seemed higher than normal on the fuel tank indicator.At this point I notified Approach of my situation and requested to divert from my current course and land at [a nearby airport]. While reading back ATC's instructions the situation became more serious and then the engine stopped while descending through 8;500 FT. I immediately notified Approach of the development; [they] asked if I would still like to make [another airport]? I suggested that if possible I would prefer a closer airfield to avoid any further unnecessary risks. Approach agreed and cleared me to descend into [a closer airport]. During my slow and controlled descent I attempted an engine restart and was able to get some power to the engine but still continued [the divert]. Once I was safely on the ground; I contacted Approach via cell phone to report that the aircraft was safely on the ground and that there were no injuries or damages incurred. I began to review the situation that had occurred to assess what went wrong. The first question I had to answer was the fuel total prior to departure versus what was burned in flight; to assess why I had an inadequate amount of fuel to reach [my original destination]. All indications said that I had 3/4 of a tank on board which would have indicated to me that I had approximately 18 gallons of fuel. At this time I was under the knowledge that per the manufactures/owners manual that I was operating an aircraft with a 24 gallon fuel tank; but what I was unaware of at the time was that this particular tail was a slightly different version and only had a 20 gallon fuel tank. This resulted in my fuel on board estimates to be inaccurate and in turn made my return flight math inaccurate. There was also the factor that on this flight I should have only required the 2 hours of fuel for en route plus a 30 minute reserve available; but what is still unknown is how the 3/4 of a tank did not make even a two hour flight. There are suspected possible issues with the fuel tank indication in the cockpit and also if one of the fuel sumps might have been slightly stuck open during flight from the pre-flight inspection. Either or both of these could have played a part in the events that lead up to this incident. Once the aircraft had been inspected by its home base mechanic; it was refueled; ground tested and cleared the short direct return flight. No further issues were found during the short flight home.

Data retrieved from NASA's ASRS site as of July 2013 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.