Narrative:

IFR flight from fwa to arb. Fwa 2 mi 9 overcast, arb 11 broken, 10 mi. Dtw taf just amended from 40 overcast to 14 overcast. Departed fwa 30 mins before sunset. Estimated time en route 60 mins. Had aircraft topped prior to departure. I dipped tanks to check level before departure (high wing C182). Trip was uneventful until last 20 mins -- became very right wing heavy. I then noticed both fuel gauges showed empty. I then suspected loss of fuel cap. I was IMC and it was now dark! I switched to left tank so I would not exhaust both at once. I also delayed my descent to MDA until the last min. I found about 20 gallons in my left tank and 0 gallons in the right tank. The right gas cap was gone. I must not have tightened it securely when I checked it. I also found an accumulation of ice on the top of the wing aft of the fuel cap, which may explain the right wing being heavy even though it was the left tank that had fuel. Also the flap motor is in the right wing aft of the fuel tank. I supposed that could have started a fire. The moral of the story is always get a ladder when you check the tanks on a high wing airplane! Even though I walked around and looked at it from behind. I did not notice it being loose.

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Original NASA ASRS Text

Title: C182 ENRTE FWA-ARB NOTICED L AND R FUEL GAUGE INDICATING ZERO. SUSPECTED HAD LOST FUEL CAP. CONTINUED TO DEST OK. FOUND 20 GALLONS FUEL IN L TANK, ZERO IN THE R AND R FUEL CAP MISSING.

Narrative: IFR FLT FROM FWA TO ARB. FWA 2 MI 9 OVCST, ARB 11 BROKEN, 10 MI. DTW TAF JUST AMENDED FROM 40 OVCST TO 14 OVCST. DEPARTED FWA 30 MINS BEFORE SUNSET. ESTIMATED TIME ENRTE 60 MINS. HAD ACFT TOPPED PRIOR TO DEP. I DIPPED TANKS TO CHK LEVEL BEFORE DEP (HIGH WING C182). TRIP WAS UNEVENTFUL UNTIL LAST 20 MINS -- BECAME VERY R WING HVY. I THEN NOTICED BOTH FUEL GAUGES SHOWED EMPTY. I THEN SUSPECTED LOSS OF FUEL CAP. I WAS IMC AND IT WAS NOW DARK! I SWITCHED TO L TANK SO I WOULD NOT EXHAUST BOTH AT ONCE. I ALSO DELAYED MY DSCNT TO MDA UNTIL THE LAST MIN. I FOUND ABOUT 20 GALLONS IN MY L TANK AND 0 GALLONS IN THE R TANK. THE R GAS CAP WAS GONE. I MUST NOT HAVE TIGHTENED IT SECURELY WHEN I CHKED IT. I ALSO FOUND AN ACCUMULATION OF ICE ON THE TOP OF THE WING AFT OF THE FUEL CAP, WHICH MAY EXPLAIN THE R WING BEING HVY EVEN THOUGH IT WAS THE L TANK THAT HAD FUEL. ALSO THE FLAP MOTOR IS IN THE R WING AFT OF THE FUEL TANK. I SUPPOSED THAT COULD HAVE STARTED A FIRE. THE MORAL OF THE STORY IS ALWAYS GET A LADDER WHEN YOU CHK THE TANKS ON A HIGH WING AIRPLANE! EVEN THOUGH I WALKED AROUND AND LOOKED AT IT FROM BEHIND. I DID NOT NOTICE IT BEING LOOSE.

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