B737 CREW WAS PUSHED INTO A CARGO LOADER ON PUSHBACK AT IAD.

Narrative

ON PUSHBACK; WE HEARD A NOISE LOOKING BACK; A LOADER FOR A B747 WAS IN VIEW. THE TUG DRIVER SAID HE THOUGHT WE MIGHT HAVE CONTACTED IT. WE HAD; AND WE RETURNED TO THE GATE. NEW WING WALKER; AND THE TUG DRIVER'S MOMENTARY LOSS OF SIGHT OF THE WALKER; COMBINED WITH RELATIVELY CLOSE PROX OF GND EQUIP TO THE ACFT TO CAUSE THIS EVENT. HOWEVER; THE EQUIP WAS CLR ENOUGH TO BE EASILY AVOIDED WITH SOME CARE. SUPPLEMENTAL INFO FROM ACN 464046: PUSHBACK CLRNC WAS GIVEN WITH AN 'E TAXI' POS GIVEN FOR PUSHBACK TERMINATION. FLT WAS ACR #ABC; SVC FROM IAD TO FLL. DURING PUSHBACK PROC ACFT SHUDDERED AND CAME TO A STOP. TUG DRIVER STATED THE ACFT MAY HAVE MADE INADVERTENT CONTACT AND HE WANTED TO RETURN TO THE GATE AND PULLED BACK TO THE JETWAY. UPON VISUAL INSPECTION FOUND L AILERON HAD SUSTAINED DAMAGE DUE TO CONTACT WITH ACR CARGO BIN LOADER. DURING MY EXTERIOR PREFLT LOADER LOCATION WAS NOTED IN ITS USUAL POS. WING WALKER WAS PRESENT ON L WING. CAPT AND I WERE ALONG FOR THE RIDE AND DID NOT SEE OR KNOW OF COLLISION COURSE UNTIL AFTER CONTACT. NO INJURIES EXCEPT TO PRIDE OF COMPANY. SUBSTANTIAL FLT CTL DAMAGE.