Narrative:

My cessna 172M recently was modified. A factory new lycoming 0-360-A4M with a sensenich propeller was installed. I have been the only owner of this 1974 skyhawk. At the time of the engine change there was 1950 tach hours on the original 0-320-E2D engine and mccauley propeller. Detailed records of the aircraft performance have been kept, including fuel consumption in gpth (gallons per tach hour) from every fill-up. The consumption varied somewhat, but averaged around 8.7 gpth. This produced about 5.5 tach hours of flying time (without reserve) on the 48 gallon usable long range fuel supply. As the engine aged, this fuel burn changed to an endurance (without reserve) of about 5.3 hours at 9.1 gpth. The new engine, with its greater displacement and horsepwr, burns more fuel per hour. Having had no experience with this engine, I raised the estimated fuel consumption rate to 10 gpth. This was based on the fuel flow graph from the 0-360-a series graph in the new engine manual as well as what I had been told. It shows a fuel burn rate that slopes from about 9.7 at 75 percent through 12 at 82 percent power (see the reconstructed graph that follows). Even though the lycoming chart showed this rapid increase in consumption for a relatively small increase in horsepwr, I used 10 gpth in my calculations. This is how the problem arose. A VFR flight plan was filed for my first flight. The total time available was 4.8 hours, based upon 48 usable gallons and 10 gpth. Most of the flight was at 6500 ft MSL. For proper break-in I was advised to operate with at least 75 percent power. This translated into full throttle. I leaned the engine according to the lycoming manual by moving the mixture from full rich until engine roughness was noted. I then enriched the mixture until the engine was smooth. It was so very cold and dry that I wanted to be sure that there was no chance this new engine would be too lean on any cylinder, so the mixture was further moved to a richer position. The first flight was uneventful. The new engine operated superbly. The trip only took 2.7 tach hours with moderate headwind. The aircraft was not refueled before the next flight. Near tri-city airport (mbs) the engine quit. Shortly into the emergency checklist when the fuel selector was switched to the left tank the engine operated normally. Saginaw approach was advised of my intention to climb to higher altitude. I climbed to 8500 ft MSL. Not long thereafter, about 3 miles northwest F tri-city airport, the engine quit again. The aircraft was out of gas. Saginaw approach was informed of the situation and asked if I wanted to declare an emergency. I replied yes. Plenty of altitude was available to glide to tri-city. I had planned it that way for the worst case scenario. There was a brisk northwest wind that would push me towards the airport. With the climb to 8500 ft MSL and the elevation of tri-city airport at 668 ft MSL, I was a mi above the airport when I began the spiral descent. I have taught this procedure to many commercial and CFI students, but never before did I need to use it. Tri-city tower was requested to advise the wind direction at each turn of the spiral. Runway 32 was the favored runway. With the fuel selector now on both tanks and the pitch attitude changed for the descent, power was available. The engine was kept warm and cleared and the tower was advised that some power was available. The spiral approach was made, however, as if there would be no power. When on the base leg at pattern altitude in the 'key' position, I turned on final and landed on runway 32. The engine functioned normally for taxiing and I was able to get to the FBO fuel ramp under my own power. The lineman was asked to 'squeeze' in as much fuel as possible, and managed to get 46.4 gallons into the 48 gallon fuel tanks. The actual fuel burn rate turned out to be 11.6 gallons per tach hour. It was also 11.6 gallons per hobbs hour. Clearly, had I refueled at detroit city airport after my first flight I would have determined the true fuel consumption and avoided what happened. My future students and other pilots will certainly gain from this knowledge. This experience will be used to help others avoid what has been describedhere. I will not only be a better pilot, my students in high school and other pilots I service in my role as an accident prevention counselor certainly will benefit.

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Original NASA ASRS Text

Title: FLT INSTRUCTOR WHO WAS A DESIGNATED PLT EXAMINER RAN OUT OF FUEL AND MADE AN EMER FORCED LNDG ON ARPT.

Narrative: MY CESSNA 172M RECENTLY WAS MODIFIED. A FACTORY NEW LYCOMING 0-360-A4M WITH A SENSENICH PROP WAS INSTALLED. I HAVE BEEN THE ONLY OWNER OF THIS 1974 SKYHAWK. AT THE TIME OF THE ENG CHANGE THERE WAS 1950 TACH HRS ON THE ORIGINAL 0-320-E2D ENG AND MCCAULEY PROP. DETAILED RECORDS OF THE ACFT PERFORMANCE HAVE BEEN KEPT, INCLUDING FUEL CONSUMPTION IN GPTH (GALLONS PER TACH HR) FROM EVERY FILL-UP. THE CONSUMPTION VARIED SOMEWHAT, BUT AVERAGED AROUND 8.7 GPTH. THIS PRODUCED ABOUT 5.5 TACH HRS OF FLYING TIME (WITHOUT RESERVE) ON THE 48 GALLON USABLE LONG RANGE FUEL SUPPLY. AS THE ENG AGED, THIS FUEL BURN CHANGED TO AN ENDURANCE (WITHOUT RESERVE) OF ABOUT 5.3 HRS AT 9.1 GPTH. THE NEW ENG, WITH ITS GREATER DISPLACEMENT AND HORSEPWR, BURNS MORE FUEL PER HR. HAVING HAD NO EXPERIENCE WITH THIS ENG, I RAISED THE ESTIMATED FUEL CONSUMPTION RATE TO 10 GPTH. THIS WAS BASED ON THE FUEL FLOW GRAPH FROM THE 0-360-A SERIES GRAPH IN THE NEW ENG MANUAL AS WELL AS WHAT I HAD BEEN TOLD. IT SHOWS A FUEL BURN RATE THAT SLOPES FROM ABOUT 9.7 AT 75 PERCENT THROUGH 12 AT 82 PERCENT PWR (SEE THE RECONSTRUCTED GRAPH THAT FOLLOWS). EVEN THOUGH THE LYCOMING CHART SHOWED THIS RAPID INCREASE IN CONSUMPTION FOR A RELATIVELY SMALL INCREASE IN HORSEPWR, I USED 10 GPTH IN MY CALCULATIONS. THIS IS HOW THE PROB AROSE. A VFR FLT PLAN WAS FILED FOR MY FIRST FLIGHT. THE TOTAL TIME AVAILABLE WAS 4.8 HRS, BASED UPON 48 USABLE GALLONS AND 10 GPTH. MOST OF THE FLT WAS AT 6500 FT MSL. FOR PROPER BREAK-IN I WAS ADVISED TO OPERATE WITH AT LEAST 75 PERCENT PWR. THIS TRANSLATED INTO FULL THROTTLE. I LEANED THE ENG ACCORDING TO THE LYCOMING MANUAL BY MOVING THE MIXTURE FROM FULL RICH UNTIL ENG ROUGHNESS WAS NOTED. I THEN ENRICHED THE MIXTURE UNTIL THE ENG WAS SMOOTH. IT WAS SO VERY COLD AND DRY THAT I WANTED TO BE SURE THAT THERE WAS NO CHANCE THIS NEW ENG WOULD BE TOO LEAN ON ANY CYLINDER, SO THE MIXTURE WAS FURTHER MOVED TO A RICHER POS. THE FIRST FLT WAS UNEVENTFUL. THE NEW ENG OPERATED SUPERBLY. THE TRIP ONLY TOOK 2.7 TACH HRS WITH MODERATE HEADWIND. THE ACFT WAS NOT REFUELED BEFORE THE NEXT FLT. NEAR TRI-CITY ARPT (MBS) THE ENG QUIT. SHORTLY INTO THE EMER CHKLIST WHEN THE FUEL SELECTOR WAS SWITCHED TO THE L TANK THE ENG OPERATED NORMALLY. SAGINAW APCH WAS ADVISED OF MY INTENTION TO CLB TO HIGHER ALT. I CLBED TO 8500 FT MSL. NOT LONG THEREAFTER, ABOUT 3 MILES NW F TRI-CITY ARPT, THE ENG QUIT AGAIN. THE ACFT WAS OUT OF GAS. SAGINAW APCH WAS INFORMED OF THE SIT AND ASKED IF I WANTED TO DECLARE AN EMER. I REPLIED YES. PLENTY OF ALT WAS AVAILABLE TO GLIDE TO TRI-CITY. I HAD PLANNED IT THAT WAY FOR THE WORST CASE SCENARIO. THERE WAS A BRISK NW WIND THAT WOULD PUSH ME TOWARDS THE ARPT. WITH THE CLB TO 8500 FT MSL AND THE ELEVATION OF TRI-CITY ARPT AT 668 FT MSL, I WAS A MI ABOVE THE ARPT WHEN I BEGAN THE SPIRAL DSCNT. I HAVE TAUGHT THIS PROC TO MANY COMMERCIAL AND CFI STUDENTS, BUT NEVER BEFORE DID I NEED TO USE IT. TRI-CITY TWR WAS REQUESTED TO ADVISE THE WIND DIRECTION AT EACH TURN OF THE SPIRAL. RWY 32 WAS THE FAVORED RWY. WITH THE FUEL SELECTOR NOW ON BOTH TANKS AND THE PITCH ATTITUDE CHANGED FOR THE DSCNT, PWR WAS AVAILABLE. THE ENG WAS KEPT WARM AND CLRED AND THE TWR WAS ADVISED THAT SOME PWR WAS AVAILABLE. THE SPIRAL APCH WAS MADE, HOWEVER, AS IF THERE WOULD BE NO PWR. WHEN ON THE BASE LEG AT PATTERN ALT IN THE 'KEY' POS, I TURNED ON FINAL AND LANDED ON RWY 32. THE ENGINE FUNCTIONED NORMALLY FOR TAXIING AND I WAS ABLE TO GET TO THE FBO FUEL RAMP UNDER MY OWN PWR. THE LINEMAN WAS ASKED TO 'SQUEEZE' IN AS MUCH FUEL AS POSSIBLE, AND MANAGED TO GET 46.4 GALLONS INTO THE 48 GALLON FUEL TANKS. THE ACTUAL FUEL BURN RATE TURNED OUT TO BE 11.6 GALLONS PER TACH HR. IT WAS ALSO 11.6 GALLONS PER HOBBS HR. CLRLY, HAD I REFUELED AT DETROIT CITY ARPT AFTER MY FIRST FLT I WOULD HAVE DETERMINED THE TRUE FUEL CONSUMPTION AND AVOIDED WHAT HAPPENED. MY FUTURE STUDENTS AND OTHER PLTS WILL CERTAINLY GAIN FROM THIS KNOWLEDGE. THIS EXPERIENCE WILL BE USED TO HELP OTHERS AVOID WHAT HAS BEEN DESCRIBEDHERE. I WILL NOT ONLY BE A BETTER PLT, MY STUDENTS IN HIGH SCHOOL AND OTHER PLTS I SVC IN MY ROLE AS AN ACCIDENT PREVENTION COUNSELOR CERTAINLY WILL BENEFIT.

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.