ACR MLG; UNABLE TO CLB TO ASSIGNED ALT; REQUESTS LOWER. ATC UNABLE; PIC DECLARED AN EMER AND IS ASSIGNED LOWER ALT AFTER HDG TRACK ALTDEV.

Narrative

ACFT PLANNED FOR DEP AT MAX GROSS WT 149500 POUNDS. DURING CARGO LOADING; A TEAR WAS FOUND IN THE FLOOR SEAM OF THE AFT CARGO COMPARTMENT AND COMPARTMENT PLACARDED UNUSABLE AND ALL AFT CARGO TRANSFERRED TO FRONT AND MID POSITIONS. DURING TKOF AT BDL FO STATED THAT THE ACFT WAS EXTREMELY NOSE HVY DURING ROTATION. INITIAL CLB OUT WAS SLOW AND PASSING 29000 FT MSL UNABLE TO MAINTAIN NORMAL RATE OF CLB AND ATC ADVISED. REQUESTED TEMPORARY LEVEL OFF AT 30000 FT MSL TO INCREASE SPD FOR CLB. ATC REQUEST DENIED; TOLD TO CLB TO 31000 FT MSL. CONTINUED CLB THROUGH 30500 FT WITH AIRSPD DECREASING. ACFT IN ICING CONDITIONS WITH SAT PLUS 15 ABOVE STD. ATC ADVISED THAT A RETURN TO A LOWER ALT WAS REQUIRED. ATC STATED UNABLE. ATC ADVISED THAT AN IMMEDIATE DSCNT WAS REQUIRED OR AN EMER WOULD BE DECLARED FOR DSCNT. ATC UNABLE. EMER DECLARED AND IMMEDIATE DSCNT INITIATED WITH ALT AND HDG STATED. ATC RESPONDED WITH CLRNC TO LOWER ALT AND HDG BUT DID NOT ACKNOWLEDGE EMER. CTL TRANSFERRED TO ANOTHER FREQ AND THAT CTLR NOTIFIED OF ICING ALT AND REASON FOR EMER. THROUGH OTHER SIDE OF FRONTAL SYS IN VFR CONDITIONS ACFT SLOWLY RETURNED TO 31000 FT AFTER BURNING OFF FUEL WT. DURING FINAL DSCNT TO DFW TO LAND; ACFT REQUIRED FULL NOSE UP TRIM FOR LNDG. SUSPECT ACFT LOADED OUTSIDE CARGO LIMITS AND UNABLE CLB/CRUISE AT 31000 FT WITH SAT PLUS 15 STD. THE ATC CTLR BEING USED TO ISSUING DIRECTIVES WAS NOT RESPONSIVE TO OUR REQUEST/REQUIREMENTS IN AN UNUSUAL SITUATION AND FORCED US TO DECLARE AN EMER TO PREVENT SIGNIFICANT/UNSAFE AIRSPD DECLINE. AFTER LNDG THE CTLR NEVER UNDERSTOOD THAT WE HAD DECLARED AN EMER BUT ISSUED THE CLRNCS TO LOWER ALT WHEN HE SAW US DSNDING ON HIS RADAR.