G159 CREW DSNDED BEFORE THEY HAD ATC CLRNC.

Narrative

I WAS THE PIC FLYING A G159 FOR A NEW ENG CERTIFICATION TEST FLT. I FILED AN IFR FLT PLAN WITH ANNISTON FSS DEPARTING HSV TO MSL VOR AND RETURN TO HSV AT 10000 FT. I TOLD FSS TO NOTE IN THE REMARKS SECTION THAT WE WERE ON AN ENG TEST FLT FOR THE PURPOSE OF THE FLT. WE DEPARTED HSV AND CLBED TO 10000 FT AND ACCELERATED TO CRUISE SPD TO OBSERVE THE PROP OP. THEN WE SLOWED THE AIRSPD TO SHUT DOWN THE L ENG AND FEATHERED THE PROP; PER THE EMER CHKLIST; FOLLOWED WITH AN ATTEMPTED ENG AIR START. WHEN WE BROUGHT THE PROP OUT OF FEATHER THE ENG FAILED TO LIGHT AND THE PROP WAS WINDMILLING. I WAS DISTR FOR A MOMENT TO OBSERVE THE SET UP FOR START; THEN I NOTICED THE ALT WAS DOWN 200 FT AND ASKED THE COPLT TO CALL ZME AND REQUEST A LOWER ALT. I BELIEVE WE RECEIVED A CLRNC TO DSND TO 8000 FT. I THEN REQUESTED THE COPLT TO RE-FEATHER THE PROP AND TO SET UP AGAIN PER THE CHKLIST FOR AN ENG AIR START. THIS TIME THE START WAS NORMAL. WE WERE THEN RECLRED TO DSND TO 8000 FT BY ZME; WITH NO REMARKS ABOUT ANY CONFLICTS. WE REQUESTED A CLRNC TO RETURN TO HSV. AFTER LNDG AT HSV; GND CTL TOLD US ZME HAD A PROB WITH US DSNDING BEFORE WE WERE CLRED AND CREATED A CONFLICT WITH A CITATION JET AT 9000 FT. GND CTL REQUESTED I CALL THE ZME SUPVR. I CALLED AND TALKED WITH MR X AND HE SAID WE HAD DSNDED TOO SOON AND HAD CAUSED THE CONFLICT WITH THE CITATION. I HAVE LEARNED FROM THIS THAT EXPERIENCED PLTS WITH OVER 30000 HRS AND 11000 HRS IN TYPE WERE COMPLACENT. WE HAVE SHUT DOWN AND RESTARTED ENGS MANY TIMES WITH NO PROBS IN THE PAST. IF WE CAUSED THE CONFLICT; IT WOULD BE THE FIRST VIOLATION IN OUR FLYING CAREERS. WE SHOULD HAVE REQUESTED A BLOCK ALT; AND I WILL IN THE FUTURE; TO PERFORM ANY MAINT TEST FLT. THIS HAS BEEN A WAKE-UP CALL TO US; T NOT BE COMPLACENT.