Narrative:

Upon occurrence of rough engine and suspected fuel problem, I declared an emergency situation with phx approach controllers requesting vector to nearest airport. They responded quickly and professionally, pointout gyr, alerting tower controller of the situation and taking care of traffic. I carried power to the ground and shut down the engine due to rough idle, fearing fuel contamination. The gyr tower controllers sent a tow truck to remove the aircraft from the runway. Upon refueling (50.5 gal) I visually inspected the tank drains and found one with a slow leak. There was a streak on the wing underside starting at that drain. Movement of the drain stopped the dripping. Engine start and idle was normal and fuel pressure ok, so I continued the flight. Usable fuel is 52 gals, so I landed with 1.5 gals on board. 1 tank indicated 1/4 tank (8 gals) and the other 3/8, with both needles active at that time. Upon fuel inspection prior to takeoff, both tanks were visually inspected; 1 full (3 hours), and the other 1/3 remaining (approximately 1 hour). I checked both tank drains and the sump drain, but did not rechk drains for leakage. On this airplane there was a history of leakage; a bar of soap was kept on board to plug leaking drains to return for repair. Prior to takeoff, there was 4 hours fuel on board. Outside buckeye VORTAC the fullest tank (3 hours) indicating 1/4 tank remaining gave indications or exhaustion with only 2.4 hours off it. (This is the tank with the drain later found leaking.) I switched to the remaining tank which later also indicated exhaustion as described previously with only another .3 hours use. Fuel consumption at 75% power at 7500' was 8 gph, as planned. Henceforth, with this aircraft, I intend to a) check all drains for leakage, and B) always fly with full fuel with at least a 2 hour or more reserve. The in-cockpit fuel indicators were never trusted, nor will they ever be.

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Original NASA ASRS Text

Title: SMA HAD ROUCH ENGINE AND DECLARED EMERGENCY, WAS VECTORED TO NEAREST ARPT AND LANDED OKAY.

Narrative: UPON OCCURRENCE OF ROUGH ENG AND SUSPECTED FUEL PROB, I DECLARED AN EMER SITUATION WITH PHX APCH CTLRS REQUESTING VECTOR TO NEAREST ARPT. THEY RESPONDED QUICKLY AND PROFESSIONALLY, POINTOUT GYR, ALERTING TWR CTLR OF THE SITUATION AND TAKING CARE OF TFC. I CARRIED PWR TO THE GND AND SHUT DOWN THE ENG DUE TO ROUGH IDLE, FEARING FUEL CONTAMINATION. THE GYR TWR CTLRS SENT A TOW TRUCK TO REMOVE THE ACFT FROM THE RWY. UPON REFUELING (50.5 GAL) I VISUALLY INSPECTED THE TANK DRAINS AND FOUND ONE WITH A SLOW LEAK. THERE WAS A STREAK ON THE WING UNDERSIDE STARTING AT THAT DRAIN. MOVEMENT OF THE DRAIN STOPPED THE DRIPPING. ENG START AND IDLE WAS NORMAL AND FUEL PRESSURE OK, SO I CONTINUED THE FLT. USABLE FUEL IS 52 GALS, SO I LANDED WITH 1.5 GALS ON BOARD. 1 TANK INDICATED 1/4 TANK (8 GALS) AND THE OTHER 3/8, WITH BOTH NEEDLES ACTIVE AT THAT TIME. UPON FUEL INSPECTION PRIOR TO TKOF, BOTH TANKS WERE VISUALLY INSPECTED; 1 FULL (3 HRS), AND THE OTHER 1/3 REMAINING (APPROX 1 HR). I CHKED BOTH TANK DRAINS AND THE SUMP DRAIN, BUT DID NOT RECHK DRAINS FOR LEAKAGE. ON THIS AIRPLANE THERE WAS A HISTORY OF LEAKAGE; A BAR OF SOAP WAS KEPT ON BOARD TO PLUG LEAKING DRAINS TO RETURN FOR REPAIR. PRIOR TO TKOF, THERE WAS 4 HRS FUEL ON BOARD. OUTSIDE BUCKEYE VORTAC THE FULLEST TANK (3 HRS) INDICATING 1/4 TANK REMAINING GAVE INDICATIONS OR EXHAUSTION WITH ONLY 2.4 HRS OFF IT. (THIS IS THE TANK WITH THE DRAIN LATER FOUND LEAKING.) I SWITCHED TO THE REMAINING TANK WHICH LATER ALSO INDICATED EXHAUSTION AS DESCRIBED PREVIOUSLY WITH ONLY ANOTHER .3 HRS USE. FUEL CONSUMPTION AT 75% PWR AT 7500' WAS 8 GPH, AS PLANNED. HENCEFORTH, WITH THIS ACFT, I INTEND TO A) CHK ALL DRAINS FOR LEAKAGE, AND B) ALWAYS FLY WITH FULL FUEL WITH AT LEAST A 2 HR OR MORE RESERVE. THE IN-COCKPIT FUEL INDICATORS WERE NEVER TRUSTED, NOR WILL THEY EVER BE.

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.