Narrative:

Engaged in flight instructor training; my 2 instructor 'students' had completed the preflight inspection by the time I joined them and advised me that the FBO had been contacted by 'right/T' with a fuel request. Although we had sufficient fuel for at least the first planned mission; we deemed that we were able to fuel for both planned activities that day without the requirement to refuel at base or down route later; thus saving time. We waited by the aircraft for some time and eventually; mindful of our block time remaining; I visually inspected both fuel tanks. I elected to delay departure and continue to wait for the fueler to arrive. Subconsciously; in an effort to save time; I believe I left the fuel caps partially open; in the expectation that the fuel truck would shortly arrive. I was then distraction by a company mechanic who had a brief discussion with me regarding an unrelated issue. Following this; still without additional fuel; I decided to start the flight and return either to base later for fuel or else land elsewhere as we had already waited nearly 30 mins. The crew boarded and we taxied; completed pre takeoff checks then departed; climbing on runway heading. Shortly after takeoff; the rear instructor 'student' declared that the port fuel cap was not secure which immediately prompted us to check the starboard cap. This was also not secured. We continued climbing and initiated a turn to a close-in downwind; reduced speed and advised ATC of a return to the airport. The port fuel cap shortly followed by the starboard then departed the aircraft. An uneventful landing was made at the airport. My immediate concerns on landing were what may have been beneath us when the caps fell as they would have developed significant energy by the time they reached the surface. The airport is located in a densely populated area.

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Original NASA ASRS Text

Title: PIPER PA28 FLT INSTRUCTOR AND STUDENTS DEPART SDL WITH THE FUEL CAPS NOT SECURED. RETURN FOR LNDG AFTER BOTH CAPS LOST INFLT.

Narrative: ENGAGED IN FLT INSTRUCTOR TRAINING; MY 2 INSTRUCTOR 'STUDENTS' HAD COMPLETED THE PREFLT INSPECTION BY THE TIME I JOINED THEM AND ADVISED ME THAT THE FBO HAD BEEN CONTACTED BY 'R/T' WITH A FUEL REQUEST. ALTHOUGH WE HAD SUFFICIENT FUEL FOR AT LEAST THE FIRST PLANNED MISSION; WE DEEMED THAT WE WERE ABLE TO FUEL FOR BOTH PLANNED ACTIVITIES THAT DAY WITHOUT THE REQUIREMENT TO REFUEL AT BASE OR DOWN RTE LATER; THUS SAVING TIME. WE WAITED BY THE ACFT FOR SOME TIME AND EVENTUALLY; MINDFUL OF OUR BLOCK TIME REMAINING; I VISUALLY INSPECTED BOTH FUEL TANKS. I ELECTED TO DELAY DEP AND CONTINUE TO WAIT FOR THE FUELER TO ARRIVE. SUBCONSCIOUSLY; IN AN EFFORT TO SAVE TIME; I BELIEVE I LEFT THE FUEL CAPS PARTIALLY OPEN; IN THE EXPECTATION THAT THE FUEL TRUCK WOULD SHORTLY ARRIVE. I WAS THEN DISTR BY A COMPANY MECH WHO HAD A BRIEF DISCUSSION WITH ME REGARDING AN UNRELATED ISSUE. FOLLOWING THIS; STILL WITHOUT ADDITIONAL FUEL; I DECIDED TO START THE FLT AND RETURN EITHER TO BASE LATER FOR FUEL OR ELSE LAND ELSEWHERE AS WE HAD ALREADY WAITED NEARLY 30 MINS. THE CREW BOARDED AND WE TAXIED; COMPLETED PRE TKOF CHKS THEN DEPARTED; CLBING ON RWY HDG. SHORTLY AFTER TKOF; THE REAR INSTRUCTOR 'STUDENT' DECLARED THAT THE PORT FUEL CAP WAS NOT SECURE WHICH IMMEDIATELY PROMPTED US TO CHK THE STARBOARD CAP. THIS WAS ALSO NOT SECURED. WE CONTINUED CLBING AND INITIATED A TURN TO A CLOSE-IN DOWNWIND; REDUCED SPD AND ADVISED ATC OF A RETURN TO THE ARPT. THE PORT FUEL CAP SHORTLY FOLLOWED BY THE STARBOARD THEN DEPARTED THE ACFT. AN UNEVENTFUL LNDG WAS MADE AT THE ARPT. MY IMMEDIATE CONCERNS ON LNDG WERE WHAT MAY HAVE BEEN BENEATH US WHEN THE CAPS FELL AS THEY WOULD HAVE DEVELOPED SIGNIFICANT ENERGY BY THE TIME THEY REACHED THE SURFACE. THE ARPT IS LOCATED IN A DENSELY POPULATED AREA.

Data retrieved from NASA's ASRS site as of January 2009 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.