What was found
DURING TAKEOFF ROLL, AIRCRAFT EXPERIENCED A SHORT LATERAL PULL AND SHUTTER SIMILAR TO A COMPRESSOR STALL BUT NEITHER PILOT SAW ANY INDICATION OF ANY FLUCTUATION ON EITHER ENGINE INDICATION. AFTER TAKEOFF, FLT ATTS CALLED REPORTING STRONG FUMES AND RUBBER BURNING ODOR. PASSENGERS REPORTED SPARKS FROM LEFT ENGINE, PAX REPORTED SPARKS FROM RIGHT ENG TO FLIGHT CREW AFTER LANDING, SHUTTER WENT AWAY RIGHT AFTER TAKEOFF. ENGINE INDICATION ROCK SOLID ENTIRE FLIGHT. DUE TO REPORTS OF FUMES AND BURNING ODORS, DECLARED AN EMERGENCY AND RETURNED TO DEPARTURE. LANDED WITHOUT INCIDENT. MTC ACCOMPLISHED CARD 05-95-70. REMOVED AND REPLACED THE A/C PACK FAN DUE TO GRINDING NOISE CAUSING POTENTIAL SPARKING AND SMOKING.