LNDG C560 JUST MISSES MD80 LNDG ON INTERSECTING PHL RWY.

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ON A FERRY LEG FROM PWK TO PHL. DURING A VISUAL APCH AND LNDG AT PHL; THE TWR KEPT US AT 1800 FT ON FINAL UNTIL CLRING US TO LAND. WE WERE AT 140 KTS AND WERE REQUESTED TO KEEP THIS SPD AS LONG AS PRACTICAL. MY FO WAS THE PF AND COMPLIED UNTIL SHORT FINAL WHERE HE SLOWED TO REF +10 KTS. I WAS CALLING OUT REF SPDS WHEN I NOTICED MOVEMENT FROM MY R. I TURNED AND SAW AN ACR MD80 WHO WAS IN THE FLARE FOR RWY 27R. RWY 35 AND RWY 27R ARE INTERSECTING RWYS. UPON SEEING THIS; I TOLD MY FO TO GET THROUGH THE INTXN. HE ADDED PWR AND WENT THROUGH THE INTXN TOUCHING DOWN JUST PAST IT. THE MD80 CREW ASKED TWR 'WHAT WAS THAT?' THE TWR REPLIED THAT THE LNDG CITATION 'SLOWED DOWN.' WE MADE NO COMMENT TO TWR. WE THEN TAXIED TO OUR FBO. NO FURTHER CONTACT FROM OR BY TWR WAS MADE. SUPPLEMENTAL INFO FROM ACN 562141: JUST AS WE CROSSED THE THRESHOLD OF RWY 35 THE CAPT TOLD ME TO STAY AIRBORNE UNTIL XING RWY 27R (THE INTERSECTING RWY). I ADDED PWR AND TOUCHED DOWN PAST RWY 27R. AFTER LNDG I WAS TOLD THAT WE ALMOST COLLIDED WITH AN MD80 WHICH WAS LNDG ON RWY 27R. I DID HEAR THE PLT QUESTION THE CTLR AND HIS RESPONSE THAT 'THE CITATION HAD SLOWED DOWN.' I HELD THE REQUESTED AIRSPD AS LONG AS PRACTICAL BUT HAD TO SLOW TO THE APPROPRIATE SPD FOR LNDG.