A decathlon pilot reports that fuel leaked into his wing and then out wing ventilation vents onto hi...

Attributes
ACN	341405
Time
Date	199606
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : lns
State Reference	PA
Altitude	agl bound lower : 0 agl bound upper : 0
Aircraft 1
Operator	general aviation : personal
Make Model Name	Decathlon
Operating Under FAR Part	Part 91
Flight Phase	ground : preflight other
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
ASRS Report	341405
Person 2
Affiliation	Other
Function	other personnel
Qualification	other other : other
Events
Anomaly	aircraft equipment problem : less severe non adherence : published procedure other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

During aerobatic flight, I noted the loss of 20 gals of fuel. Dissolved asphalt on the hangar floor indicated that leakage was coming from inside a wingtip through drainage holes on the under surface. Also, dope on horizontal stabilizer washed off same side of decathlon as loss of fuel. I suspected the problem was an internal tank problem. I had a mechanic remove the tank and no problems were found. I suspect what actually happened was that fuel flowed from improperly applied cap but did not touch the top of the wing and was sucked into the negative pressure under the wing and into the drainage holes, giving the appearance of some kind of internal problem. A better preflight check would probably have obviated the large expense and unnecessary procedure.

Original NASA ASRS Text

Title: A DECATHLON PLT RPTS THAT FUEL LEAKED INTO HIS WING AND THEN OUT WING VENTILATION VENTS ONTO HIS HANGAR FLOOR. ERROR ADMITTED, THE FUEL CAP PROBABLY WAS NOT PROPERLY INSTALLED.

Narrative: DURING AEROBATIC FLT, I NOTED THE LOSS OF 20 GALS OF FUEL. DISSOLVED ASPHALT ON THE HANGAR FLOOR INDICATED THAT LEAKAGE WAS COMING FROM INSIDE A WINGTIP THROUGH DRAINAGE HOLES ON THE UNDER SURFACE. ALSO, DOPE ON HORIZ STABILIZER WASHED OFF SAME SIDE OF DECATHLON AS LOSS OF FUEL. I SUSPECTED THE PROB WAS AN INTERNAL TANK PROB. I HAD A MECH REMOVE THE TANK AND NO PROBS WERE FOUND. I SUSPECT WHAT ACTUALLY HAPPENED WAS THAT FUEL FLOWED FROM IMPROPERLY APPLIED CAP BUT DID NOT TOUCH THE TOP OF THE WING AND WAS SUCKED INTO THE NEGATIVE PRESSURE UNDER THE WING AND INTO THE DRAINAGE HOLES, GIVING THE APPEARANCE OF SOME KIND OF INTERNAL PROB. A BETTER PREFLT CHK WOULD PROBABLY HAVE OBVIATED THE LARGE EXPENSE AND UNNECESSARY PROC.

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.

A decathlon pilot reports that fuel leaked into his wing and then out wing ventilation vents onto his hangar floor. Error admitted, the fuel cap probably was not properly installed.