PLT OF VINTAGE F100 SUPER SABREJET EXPERIENCES PARTIAL EXTENDED THRUST LOSS. DIVERTS AND LANDS AT DEP ARPT.

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I PROCEEDED DIRECT TO ZZZ. I WAS CLRED IN UNRESTR AND MADE 2 PASSES AT APPROX 100 FT AGL AND 400 KIAS USING AFTERBURNER ON EACH DEP. FOLLOWING THE SECOND PASS; I TURNED ONTO A WIDE DOWNWIND AND REDUCED TO IDLE PWR. I LOWERED THE GEAR AND FLAPS AND TURNED A L BASE LEG ABOUT 1 MI FROM THE END OF RWY 25. IN THE TURN; I PUSHED THE THROTTLE FORWARD AND THE ENG BEAN TO 'CHOO CHOO;' AND WAS VERY SLOW TO ACCELERATE. ALTHOUGH 'CHOO CHOO' CAN BE NORMAL IN THE F100; THIS ACFT HAS NEVER DONE IT IN THE AIR DURING THE DOZEN OR SO TIMES THAT I HAVE FLOWN IT. THE AIRSPD DETERIORATED TO 170 KIAS AND THE ACFT DSNDED TO ABOUT 500 FT AGL. I WAS CONSIDERING EJECTING WHEN THE PWR FULLY CAUGHT. I CONTINUED THE APCH AND FLEW DOWN RWY 25 SIMULATING A TOUCH-AND-GO BUT NOT REDUCING THE PWR. I THEN DEPARTED FOR ZZZ1. AFTER QUICKLY THINKING THROUGH THE ENG 'CHOO CHOO' AND REFLECTING THAT I MIGHT HAVE SOME PNEUMATIC PROBS; I PLANNED TO DEVIATE FROM A NORMAL OVERHEAD PATTERN UPON ARR AT ZZZ1. I PLANNED AN OVERHEAD PATTERN BUT DID NOT WISH TO REDUCE THE PWR BELOW THE 80% ENG RPM RANGE UNTIL LNDG WAS ASSURED. I APCHED ON A LOW INITIAL FOR RWY 16 AFTER MAKING APPROPRIATE RADIO CALLS. I BELIEVE I WAS AT ABOUT 500 FT AGL AND 350 KIAS. AT THE APCH END OF RWY 16 I EXTENDED THE SPD BRAKES AND STARTED A CLBING R TURN TO REDUCE THE AIRSPD FOR NORMAL GEAR/FLAP EXTENSION WHILE MAINTAINING THE ENG PWR. AS I DID NOT REDUCE PWR SOON ENOUGH; I WAS HIGH AND FAST OVER THE END OF THE RWY. I ELECTED TO GO AROUND. I REPEATED THE SAME PROC; ONLY AS I ROLLED OUT ON DOWNWIND FOR RWY 1. I EXTENDED FLAPS TO INTERMEDIATE WHICH IS ALLOWED AT A HIGHER AIRSPD (350 KIAS) THAN THE NORMAL FULL FLAPS WHICH ARE LIMITED AT 220 KIAS. FOLLOWING GEAR/FULL FLAP EXTENSION; I LANDED WHILE AGAIN MAINTAINING ABOUT 90% ENG RPM UNTIL LNDG WAS ASSURED. WHILE WE WERE DEBRIEFING THE FLT; ONE OF OUR MECHS NOTICED THAT THE PANEL FORMING THE EXHAUST END OF THE ENG COMPRESSOR INTER-STAGE BLEED VALVE WAS MISSING. THIS PANEL IS APPROX 8 INCHES SQUARE AND CONTAINS A SPRING LOADED FLAPPER VALVE WHICH IS DUCTED OFF THE 8TH STAGE OF THE ENG. ITS FUNCTION IS TO SMOOTH THE ENG ACCELERATION. WE DISCUSSED THE PROB THOROUGHLY AND BELIEVE THAT THIS WAS THE CAUSE OF THE ABNORMAL AND EXTENDED 'CHOO CHOO' EFFECT INFLT. WE BELIEVE THE PANEL SEPARATED INFLT AT A TIME AND LOCATION THAT IS UNKNOWN. WE FURTHER BELIEVE THAT THE PANEL WAS NOT COMPLETELY FASTENED FOLLOWING MAINT. I UNDERSTAND THAT MY LOW APCH TO ZZZ1 STARTLED SOME OF A LCL SOCCER GROUP. I REGRET THAT I CAUSED THEM ALARM AND APOLOGIZE FOR DOING SO. I THOUGHT THAT I WAS BEING RESPONSIBLE IN MY PLANNING AND EXECUTION OF A SOMEWHAT ABNORMAL MECHANICAL SIT WHICH IS NOT COVERED IN THE EMER PROCS IN THE PLT'S HANDBOOK.