B767 CAPT ALLOWED ACFT TO OVERROTATE ON TKOF.

Narrative

TAILSKID TOUCH/OVERWT LNDG. WE WERE CLRED FOR TKOF ON RWY 14L. THE WINDS WERE APPROX 200 DEGS AT 18 KTS GUSTING TO 28 KTS. I HAD AILERON AND RUDDER XCTL TO KEEP THE ACFT ALIGNED WITH THE CTRLINE. I LEFT THE NOSE ON THE RWY SLIGHTLY LONGER BECAUSE I DIDN'T WANT TO WXVANE. JUST AFTER V1; I PULLED THE NOSE UP SMOOTHLY AND AT THE SAME INSTANT THE AIRSPD JUMPED ABOUT +20 KTS. THE RESULT WAS THE NOSE CAME UP VERY FAST AND WE WERE AIRBORNE. EVERYTHING ELSE WAS NORMAL. AFTER DEPARTING AND ON CLBOUT; THE #1 FLT ATTENDANT ADVISED ME THAT #2 FLT ATTENDANT HAD HEARD A NOISE ON TKOF. I CALLED HER UP AND SHE SAID SHE AND #3 FLT ATTENDANT HAD HEARD A NOISE THAT LASTED LESS THAN 1 SECOND AND FELT NO BUMP OR MOTION IN THE AIRFRAME. THESE ARE EXCELLENT AND EXPERIENCED FLT ATTENDANTS. WE CHKED THE BOOK AND I CALLED DISPATCH AND TECHNICIAN. WE ELECTED TO RETURN TO ORD. I DSNDED TO 10000 FT AND LEFT THE SPD BRAKE OUT TO BURN FUEL. WE LANDED AT 326000 LBS. THE SINK RATE WAS 100 FPM. I USED LITTLE BRAKES WITH MORE REVERSE THAN NORMAL AND A LONGER LNDG ROLL. AT THE GATE; WE FOUND TAILSKID COMPRESSED. WE RECHARGED TAILSKID WITH N2 RESET DISCHARGE BUTTON; INSPECTED ACFT; AND DEPARTED FOR ZRH. SUPPLEMENTAL INFO FROM ACN 455967: I WAS THE FO ON THE DEP FROM RWY 14L AT ORD. WINDS WERE APPROX 200 DEGS AT 18 KTS GUSTING TO 25 KTS. THE RWY WAS DRY. THE CAPT APPLIED NORMAL XWIND CTLS AND FORWARD PRESSURE ON THE YOKE. THE CAPT BEGAN RELEASING FORWARD PRESSURE SLIGHTLY BEFORE V1. THE ACFT ROTATED RATHER ABRUPTLY AND RAPIDLY GAINED 15 KTS AS THE AIRSPD PASSED V1; VR; V2. THE #2 FLT ATTENDANT RPTED HEARING A SCRAPING SOUND ON TKOF. I WAS SURPRISED AS THE TKOF WAS NOT THAT FAR OUT OF NORMAL PARAMETERS AND I WOULD NOT HAVE SUSPECTED A TAILSKID STRIKE. AFTER REFERRING TO THE OPERATING MANUAL AND CONFERRING WITH DISPATCH; WE ELECTED TO RETURN TO ORD FOR AN OVERWT LNDG.