Narrative:

We were flying into ord on a VFR day. The approach and landing on runway 9R was normal. I slowed the airplane with reverse thrust and brakes. At about 80 KTS a vibration occurred which rapidly became severe. The aircraft began to veer to the right and became uncontrollable with the rudder pedals. Maximum braking and rudder inputs were used but we could not stop the airplane until after it departed the right side of the runway. The engines were immediately shut down and no evacuate/evacuation was ordered because the airplane appeared to be ok. A pin in the nose gear scissor spring assembly appeared to have broken where it connects to the top of the nose gear strut. The nose gear and tires rested at a 90 degree angle to the nose of the airplane. There were skid marks from all 6 tires leading off the runway. None of the landing gears collapsed. Callback conversation with reporter revealed the following information: reporter stated that the aircraft was a B-737- 300. He has not heard back from maintenance regarding the reason for the failure of the bolt but is going to call them and attempt to get further information. The bolt is about 5 centimeters thick by about 6 inches long. It is a torque link bolt at the top of the scissor spring that secures the torque link to the top of the nose gear strut. He is not aware of any other type failures such as this one. Supplemental information from acn 276587: the shaking got worse and the first officer was unable to keep it on centerline. We started drifting off to the right. I took over about 80 KTS and attempted to use the steering tiller to no effect.

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Original NASA ASRS Text

Title: RWY EXCURSION.

Narrative: WE WERE FLYING INTO ORD ON A VFR DAY. THE APCH AND LNDG ON RWY 9R WAS NORMAL. I SLOWED THE AIRPLANE WITH REVERSE THRUST AND BRAKES. AT ABOUT 80 KTS A VIBRATION OCCURRED WHICH RAPIDLY BECAME SEVERE. THE ACFT BEGAN TO VEER TO THE R AND BECAME UNCTLABLE WITH THE RUDDER PEDALS. MAX BRAKING AND RUDDER INPUTS WERE USED BUT WE COULD NOT STOP THE AIRPLANE UNTIL AFTER IT DEPARTED THE R SIDE OF THE RWY. THE ENGS WERE IMMEDIATELY SHUT DOWN AND NO EVAC WAS ORDERED BECAUSE THE AIRPLANE APPEARED TO BE OK. A PIN IN THE NOSE GEAR SCISSOR SPRING ASSEMBLY APPEARED TO HAVE BROKEN WHERE IT CONNECTS TO THE TOP OF THE NOSE GEAR STRUT. THE NOSE GEAR AND TIRES RESTED AT A 90 DEG ANGLE TO THE NOSE OF THE AIRPLANE. THERE WERE SKID MARKS FROM ALL 6 TIRES LEADING OFF THE RWY. NONE OF THE LNDG GEARS COLLAPSED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE ACFT WAS A B-737- 300. HE HAS NOT HEARD BACK FROM MAINT REGARDING THE REASON FOR THE FAILURE OF THE BOLT BUT IS GOING TO CALL THEM AND ATTEMPT TO GET FURTHER INFO. THE BOLT IS ABOUT 5 CENTIMETERS THICK BY ABOUT 6 INCHES LONG. IT IS A TORQUE LINK BOLT AT THE TOP OF THE SCISSOR SPRING THAT SECURES THE TORQUE LINK TO THE TOP OF THE NOSE GEAR STRUT. HE IS NOT AWARE OF ANY OTHER TYPE FAILURES SUCH AS THIS ONE. SUPPLEMENTAL INFO FROM ACN 276587: THE SHAKING GOT WORSE AND THE FO WAS UNABLE TO KEEP IT ON CTRLINE. WE STARTED DRIFTING OFF TO THE R. I TOOK OVER ABOUT 80 KTS AND ATTEMPTED TO USE THE STEERING TILLER TO NO EFFECT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.