Narrative:

Student and I flew to mry on an instrument training flight. Our flight routing was gnoss field, novato, ca, to point reyes VOR, V27 to eugen intersection, then via radar vectors to the final approach course for the NDB runway 10R approach, mry. The flight conditions from the point reyes VOR to the final approach fix (munso NDB) consisted of clear skies and visibilities of 20+ mi en route and at least 10 mi visibility at mry. The only clouds observed were the typical marine layer which extended from the golden gate bridge to south of the monterey peninsula. The flight was conducted entirely in VFR conditions on an IFR flight plan. While southbound on V27, abeam of sfo, I noticed the concave metal gas cap cover on the left wing tip fuel tank had become unlatched. There appeared to be no harm done to the airplane, so we continued to mry. The NDB approach, straight in landing to runway 10R and landing seemed routine. The only unanticipated occurrence was approximately 1 mi from the end of runway 1R, when we encountered moderate turbulence. Upon landing the ground control asked us if we had lost a gas cap. We advised them that we would investigate and soon discovered we had indeed lost our left tip tank gas cap. We then taxied the airplane to FBO ramp and parked. By phone the ground controller advised us the gas cap had ben observed falling from the airplane. The cap fell into the monterey county fairgrounds and struck a workman. Student and I went to eh fairgrounds and discussed the incident with the fairground official who advised us that neither he nor his workman cared to pursue the matter. Corrective actions: the student's preflight of his airplane's fuel tanks and fuel tank caps was superficial at best. He knew he had been the latitude pilot O have flown the airplane and he assumed that if the caps and covers looked secure, they must be secure. Lack of attention to detail was a contributing factor. A disciplined and complete preflight inspection must be accomplished by the pilot prior to each flight. Whether or not the pilot had ben the latitude to fly the airplane and regardless of the time between flts. Secondly, if the flight is a training flight, the flight instrument should always do his own secondary and abbreviated preflight inspection to verify the student's inspection.

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Original NASA ASRS Text

Title: SMA TWIN LOST IMPROPERLY SECURED GAS CAP DURING MODERATE TURBULENCE ENCOUNTER WHILE ON SHORT FINAL.

Narrative: STUDENT AND I FLEW TO MRY ON AN INSTRUMENT TRNING FLT. OUR FLT ROUTING WAS GNOSS FIELD, NOVATO, CA, TO POINT REYES VOR, V27 TO EUGEN INTXN, THEN VIA RADAR VECTORS TO THE FINAL APCH COURSE FOR THE NDB RWY 10R APCH, MRY. THE FLT CONDITIONS FROM THE POINT REYES VOR TO THE FINAL APCH FIX (MUNSO NDB) CONSISTED OF CLEAR SKIES AND VISIBILITIES OF 20+ MI ENRTE AND AT LEAST 10 MI VISIBILITY AT MRY. THE ONLY CLOUDS OBSERVED WERE THE TYPICAL MARINE LAYER WHICH EXTENDED FROM THE GOLDEN GATE BRIDGE TO S OF THE MONTEREY PENINSULA. THE FLT WAS CONDUCTED ENTIRELY IN VFR CONDITIONS ON AN IFR FLT PLAN. WHILE SBND ON V27, ABEAM OF SFO, I NOTICED THE CONCAVE METAL GAS CAP COVER ON THE LEFT WING TIP FUEL TANK HAD BECOME UNLATCHED. THERE APPEARED TO BE NO HARM DONE TO THE AIRPLANE, SO WE CONTINUED TO MRY. THE NDB APCH, STRAIGHT IN LNDG TO RWY 10R AND LNDG SEEMED ROUTINE. THE ONLY UNANTICIPATED OCCURRENCE WAS APPROX 1 MI FROM THE END OF RWY 1R, WHEN WE ENCOUNTERED MODERATE TURB. UPON LNDG THE GND CTL ASKED US IF WE HAD LOST A GAS CAP. WE ADVISED THEM THAT WE WOULD INVESTIGATE AND SOON DISCOVERED WE HAD INDEED LOST OUR LEFT TIP TANK GAS CAP. WE THEN TAXIED THE AIRPLANE TO FBO RAMP AND PARKED. BY PHONE THE GND CTLR ADVISED US THE GAS CAP HAD BEN OBSERVED FALLING FROM THE AIRPLANE. THE CAP FELL INTO THE MONTEREY COUNTY FAIRGROUNDS AND STRUCK A WORKMAN. STUDENT AND I WENT TO EH FAIRGROUNDS AND DISCUSSED THE INCIDENT WITH THE FAIRGROUND OFFICIAL WHO ADVISED US THAT NEITHER HE NOR HIS WORKMAN CARED TO PURSUE THE MATTER. CORRECTIVE ACTIONS: THE STUDENT'S PREFLT OF HIS AIRPLANE'S FUEL TANKS AND FUEL TANK CAPS WAS SUPERFICIAL AT BEST. HE KNEW HE HAD BEEN THE LAT PLT O HAVE FLOWN THE AIRPLANE AND HE ASSUMED THAT IF THE CAPS AND COVERS LOOKED SECURE, THEY MUST BE SECURE. LACK OF ATTN TO DETAIL WAS A CONTRIBUTING FACTOR. A DISCIPLINED AND COMPLETE PREFLT INSPECTION MUST BE ACCOMPLISHED BY THE PLT PRIOR TO EACH FLT. WHETHER OR NOT THE PLT HAD BEN THE LAT TO FLY THE AIRPLANE AND REGARDLESS OF THE TIME BTWN FLTS. SECONDLY, IF THE FLT IS A TRNING FLT, THE FLT INSTR SHOULD ALWAYS DO HIS OWN SECONDARY AND ABBREVIATED PREFLT INSPECTION TO VERIFY THE STUDENT'S INSPECTION.

Data retrieved from NASA's ASRS site as of August 2007 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.