Narrative:

Climbing out in excellent VFR conditions; through 7500 ft; we heard 2 loud booms; in succession; come from the #1 engine. First officer saw momentary flicker of the engine instruments but all parameters remained normal. I reduced thrust to idle and asked for ECAM action. There was nothing on ECAM. (Later the postflt ECAM showed #1 fadec; but we never saw it.) we assumed we had a compressor stall and I decided to return to the departure airport. Since all parameters were normal; I decided to keep the #1 engine running; for hydraulics and to have it if I needed it. I did check the response to moving the thrust lever 1/2 way up to the climb detent and the engine did respond normally. We made an approach using flaps 3 degrees; treating it as if the #1 engine was shut down; but kept it at idle until after we landed. Approach; landing; and taxi in were all normal. Both pilots heard a loud 'boom; boom.' the first officer noticed a momentary flicker of the #1 engine instruments. Flight attendants and passenger also heard the same thing. Passenger located on the left side at row 22 observed flames coming out of the tailpipe. Operated engine at idle since all parameters were normal and no ECAM warnings were present. Landed safely utilizing single engine (flaps 3 degrees) procedures; even though #1 was at idle. Called company operations and maintenance. Taxied in to the gate normally. Engines and their components do fail. I am sure we are working to ensure the highest degree of reliability.

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Original NASA ASRS Text

Title: A320 FLT CREW EXPERIENCES LOUD BOOMS DURING CLIMB AT 7500 FEET AND ELECTS TO RETURN.

Narrative: CLBING OUT IN EXCELLENT VFR CONDITIONS; THROUGH 7500 FT; WE HEARD 2 LOUD BOOMS; IN SUCCESSION; COME FROM THE #1 ENG. FO SAW MOMENTARY FLICKER OF THE ENG INSTS BUT ALL PARAMETERS REMAINED NORMAL. I REDUCED THRUST TO IDLE AND ASKED FOR ECAM ACTION. THERE WAS NOTHING ON ECAM. (LATER THE POSTFLT ECAM SHOWED #1 FADEC; BUT WE NEVER SAW IT.) WE ASSUMED WE HAD A COMPRESSOR STALL AND I DECIDED TO RETURN TO THE DEP ARPT. SINCE ALL PARAMETERS WERE NORMAL; I DECIDED TO KEEP THE #1 ENG RUNNING; FOR HYDS AND TO HAVE IT IF I NEEDED IT. I DID CHK THE RESPONSE TO MOVING THE THRUST LEVER 1/2 WAY UP TO THE CLB DETENT AND THE ENG DID RESPOND NORMALLY. WE MADE AN APCH USING FLAPS 3 DEGS; TREATING IT AS IF THE #1 ENG WAS SHUT DOWN; BUT KEPT IT AT IDLE UNTIL AFTER WE LANDED. APCH; LNDG; AND TAXI IN WERE ALL NORMAL. BOTH PLTS HEARD A LOUD 'BOOM; BOOM.' THE FO NOTICED A MOMENTARY FLICKER OF THE #1 ENG INSTS. FLT ATTENDANTS AND PAX ALSO HEARD THE SAME THING. PAX LOCATED ON THE L SIDE AT ROW 22 OBSERVED FLAMES COMING OUT OF THE TAILPIPE. OPERATED ENG AT IDLE SINCE ALL PARAMETERS WERE NORMAL AND NO ECAM WARNINGS WERE PRESENT. LANDED SAFELY UTILIZING SINGLE ENG (FLAPS 3 DEGS) PROCS; EVEN THOUGH #1 WAS AT IDLE. CALLED COMPANY OPS AND MAINT. TAXIED IN TO THE GATE NORMALLY. ENGS AND THEIR COMPONENTS DO FAIL. I AM SURE WE ARE WORKING TO ENSURE THE HIGHEST DEGREE OF RELIABILITY.

Data retrieved from NASA's ASRS site as of May 2009 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.