Narrative:

During the takeoff phase of flight at an altitude of approximately 150-200 ft, while the gear was retracting, a continuous loud banging noise occurred. Initially I believed that there was a serious problem with the engine, maybe a connecting rod or stuck valve. In the interest of safety of the flight, I called the tower and declared an in-flight emergency and asked for immediate clearance to land. The tower cleared me immediately and I started a left turn downwind. My thought process was I wanted to land back into the wind due to its direction and speed. As I was very close laterally to the runway I would have landed downwind if necessary. After a few more seconds, I had enough altitude to turn back into the wind midfield should the engine quit. During the turn I scanned the engine instruments and all were still in the green. I informed the tower on downwind that the engine was still running and I would make a landing on runway 9L. As the engine was still running at this time I thought that maybe something had come loose on the gear/undercarriage, so I extended it and got a positive 3 down and locked indication, but the banging continued. I checked the flaps and ailerons on both wings and all seemed normal. I also made a quick scan of the left rear tail surfaces and all seemed normal from my left seat position. My focus then turned back to the engine compartment where I thought maybe I had thrown a belt or an exhaust stack had come loose and was causing the continuous banging noise. I made an uneventful landing on runway 9L, the banging stopped. I taxied off the runway, stopped the engine and exited the airplane for inspection. Upon exiting the airplane, I determined that the right front seat lap belt was the cause of the noise as it was outside the cockpit about 4-6 inches and had banged into the cabin door hard enough to scar the paint. The short length of the belt outside cabin explained why it banged on a continuous basis into the cabin door and not intermittently. I inspected the complete airplane for any other damage or cause of the noise but could not find anything but the lap belt as the reason for the banging. I called the tower and informed them what caused the continuous banging noise in-flight. I gave my name and address to the fire rescue people and departed IFR for tampa for an uneventful flight. The lesson learned from this experience is that from the pilot's seat you cannot easily see if the right seat lap belt is inside the cabin when the cabin is shut if the lap belt is not buckled. For all future flts, I will ensure that if the left front seat is not occupied the lap belt will be fastened on the seat so it is visible to the pilot and there is no way the cabin door can be closed with the belt outside.

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Original NASA ASRS Text

Title: A COMMERCIAL INST RATED PLT FLYING A PA28R FROM MLB MADE AN EMER LNDG BACK AT MLG AFTER HEARING A BANGING NOISE COMING FROM OUTSIDE THE AIRPLANE AFTER THE TKOF AND CLB.

Narrative: DURING THE TKOF PHASE OF FLT AT AN ALT OF APPROX 150-200 FT, WHILE THE GEAR WAS RETRACTING, A CONTINUOUS LOUD BANGING NOISE OCCURRED. INITIALLY I BELIEVED THAT THERE WAS A SERIOUS PROB WITH THE ENG, MAYBE A CONNECTING ROD OR STUCK VALVE. IN THE INTEREST OF SAFETY OF THE FLT, I CALLED THE TWR AND DECLARED AN INFLT EMER AND ASKED FOR IMMEDIATE CLRNC TO LAND. THE TWR CLRED ME IMMEDIATELY AND I STARTED A L TURN DOWNWIND. MY THOUGHT PROCESS WAS I WANTED TO LAND BACK INTO THE WIND DUE TO ITS DIRECTION AND SPD. AS I WAS VERY CLOSE LATERALLY TO THE RWY I WOULD HAVE LANDED DOWNWIND IF NECESSARY. AFTER A FEW MORE SECONDS, I HAD ENOUGH ALT TO TURN BACK INTO THE WIND MIDFIELD SHOULD THE ENG QUIT. DURING THE TURN I SCANNED THE ENG INSTS AND ALL WERE STILL IN THE GREEN. I INFORMED THE TWR ON DOWNWIND THAT THE ENG WAS STILL RUNNING AND I WOULD MAKE A LNDG ON RWY 9L. AS THE ENG WAS STILL RUNNING AT THIS TIME I THOUGHT THAT MAYBE SOMETHING HAD COME LOOSE ON THE GEAR/UNDERCARRIAGE, SO I EXTENDED IT AND GOT A POSITIVE 3 DOWN AND LOCKED INDICATION, BUT THE BANGING CONTINUED. I CHKED THE FLAPS AND AILERONS ON BOTH WINGS AND ALL SEEMED NORMAL. I ALSO MADE A QUICK SCAN OF THE L REAR TAIL SURFACES AND ALL SEEMED NORMAL FROM MY L SEAT POS. MY FOCUS THEN TURNED BACK TO THE ENG COMPARTMENT WHERE I THOUGHT MAYBE I HAD THROWN A BELT OR AN EXHAUST STACK HAD COME LOOSE AND WAS CAUSING THE CONTINUOUS BANGING NOISE. I MADE AN UNEVENTFUL LNDG ON RWY 9L, THE BANGING STOPPED. I TAXIED OFF THE RWY, STOPPED THE ENG AND EXITED THE AIRPLANE FOR INSPECTION. UPON EXITING THE AIRPLANE, I DETERMINED THAT THE R FRONT SEAT LAP BELT WAS THE CAUSE OF THE NOISE AS IT WAS OUTSIDE THE COCKPIT ABOUT 4-6 INCHES AND HAD BANGED INTO THE CABIN DOOR HARD ENOUGH TO SCAR THE PAINT. THE SHORT LENGTH OF THE BELT OUTSIDE CABIN EXPLAINED WHY IT BANGED ON A CONTINUOUS BASIS INTO THE CABIN DOOR AND NOT INTERMITTENTLY. I INSPECTED THE COMPLETE AIRPLANE FOR ANY OTHER DAMAGE OR CAUSE OF THE NOISE BUT COULD NOT FIND ANYTHING BUT THE LAP BELT AS THE REASON FOR THE BANGING. I CALLED THE TWR AND INFORMED THEM WHAT CAUSED THE CONTINUOUS BANGING NOISE INFLT. I GAVE MY NAME AND ADDRESS TO THE FIRE RESCUE PEOPLE AND DEPARTED IFR FOR TAMPA FOR AN UNEVENTFUL FLT. THE LESSON LEARNED FROM THIS EXPERIENCE IS THAT FROM THE PLT'S SEAT YOU CANNOT EASILY SEE IF THE R SEAT LAP BELT IS INSIDE THE CABIN WHEN THE CABIN IS SHUT IF THE LAP BELT IS NOT BUCKLED. FOR ALL FUTURE FLTS, I WILL ENSURE THAT IF THE L FRONT SEAT IS NOT OCCUPIED THE LAP BELT WILL BE FASTENED ON THE SEAT SO IT IS VISIBLE TO THE PLT AND THERE IS NO WAY THE CABIN DOOR CAN BE CLOSED WITH THE BELT OUTSIDE.

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.