Narrative:

During takeoff roll at approximately XA14, and at approximately 75-80 KTS, a significant yaw to the left occurred with no change in control input. At this time an abort decision was made and I reduced both engines to idle immediately. Right after reducing the power to idle, the aircraft became extremely unstable and near uncontrollable. I used rudder and brake application to attempt to control the yaw, remain on the runway, and stop the aircraft. During the abort, the nose yawed right while skidding to the left side of the runway. No amount or change of control pressure seemed to overcome the force occurring to the aircraft causing it to continue on a course off the left side of the runway. The aircraft came to a complete stop approximately 15 ft off the left most edge of runway 21. The right wingtip was directly over the left edge of the runway as the aircraft sat at rest. Both tires were observed to be flat, no fire noted. The engines were shut down, the tower was called to request assistance, and all 3 on board deplaned. Both main wheels were found damaged. No other damage was found during inspection of the aircraft after the incident. Of note: the passenger informed me after the incident that he felt a vibration that continued to increase as the aircraft progressed down the runway. The vibration was not felt in the cockpit. The aircraft seemed to accelerate normally during the takeoff roll. The aircraft became extremely unstable with limited control once the engines were reduced to idle. The tower later informed me that he initially observed the right tire smoking followed by the left tire. After assessing the facts of the event, I feel the abort was necessitated because of some type of braking abnormality not commanded. Had the takeoff continued, I feel that one or both tires would have still blown and/or caused a fire, leaving us in a more difficult situation for a return landing. For some reason, it appears there was braking friction during the takeoff roll causing the vibration the passenger felt and eventually what led to a tire blowout and ensuing departure from the runway. Whether the brakes were locked or the parking brake was partially engaged, I cannot be positive. Possible ideas to prevent a recurrence: look at the feasibility and/or necessity of changing or modifying the brake system in the CE525A. Provide an indication in the cockpit as to what condition the parking brake is in, whether it be engaged partially or fully. Callback conversation with reporter revealed the following information: the reporter stated maintenance checked the airplane and found nothing at fault with the braking system but did replace the parking brake control valve as precautionary. The reporter said the right wheel and brake displayed indications of being locked up but operated normally when tested.

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Original NASA ASRS Text

Title: A C525 REJECTED TKOF AT 75-80 KTS DUE TO L YAW FOLLOWED BY A R YAW AND SKIDDING L INCURRING A RWY EXCURSION.

Narrative: DURING TKOF ROLL AT APPROX XA14, AND AT APPROX 75-80 KTS, A SIGNIFICANT YAW TO THE L OCCURRED WITH NO CHANGE IN CTL INPUT. AT THIS TIME AN ABORT DECISION WAS MADE AND I REDUCED BOTH ENGS TO IDLE IMMEDIATELY. RIGHT AFTER REDUCING THE PWR TO IDLE, THE ACFT BECAME EXTREMELY UNSTABLE AND NEAR UNCTLABLE. I USED RUDDER AND BRAKE APPLICATION TO ATTEMPT TO CTL THE YAW, REMAIN ON THE RWY, AND STOP THE ACFT. DURING THE ABORT, THE NOSE YAWED R WHILE SKIDDING TO THE L SIDE OF THE RWY. NO AMOUNT OR CHANGE OF CTL PRESSURE SEEMED TO OVERCOME THE FORCE OCCURRING TO THE ACFT CAUSING IT TO CONTINUE ON A COURSE OFF THE L SIDE OF THE RWY. THE ACFT CAME TO A COMPLETE STOP APPROX 15 FT OFF THE L MOST EDGE OF RWY 21. THE R WINGTIP WAS DIRECTLY OVER THE L EDGE OF THE RWY AS THE ACFT SAT AT REST. BOTH TIRES WERE OBSERVED TO BE FLAT, NO FIRE NOTED. THE ENGS WERE SHUT DOWN, THE TWR WAS CALLED TO REQUEST ASSISTANCE, AND ALL 3 ON BOARD DEPLANED. BOTH MAIN WHEELS WERE FOUND DAMAGED. NO OTHER DAMAGE WAS FOUND DURING INSPECTION OF THE ACFT AFTER THE INCIDENT. OF NOTE: THE PAX INFORMED ME AFTER THE INCIDENT THAT HE FELT A VIBRATION THAT CONTINUED TO INCREASE AS THE ACFT PROGRESSED DOWN THE RWY. THE VIBRATION WAS NOT FELT IN THE COCKPIT. THE ACFT SEEMED TO ACCELERATE NORMALLY DURING THE TKOF ROLL. THE ACFT BECAME EXTREMELY UNSTABLE WITH LIMITED CTL ONCE THE ENGS WERE REDUCED TO IDLE. THE TWR LATER INFORMED ME THAT HE INITIALLY OBSERVED THE R TIRE SMOKING FOLLOWED BY THE L TIRE. AFTER ASSESSING THE FACTS OF THE EVENT, I FEEL THE ABORT WAS NECESSITATED BECAUSE OF SOME TYPE OF BRAKING ABNORMALITY NOT COMMANDED. HAD THE TKOF CONTINUED, I FEEL THAT ONE OR BOTH TIRES WOULD HAVE STILL BLOWN AND/OR CAUSED A FIRE, LEAVING US IN A MORE DIFFICULT SIT FOR A RETURN LNDG. FOR SOME REASON, IT APPEARS THERE WAS BRAKING FRICTION DURING THE TKOF ROLL CAUSING THE VIBRATION THE PAX FELT AND EVENTUALLY WHAT LED TO A TIRE BLOWOUT AND ENSUING DEP FROM THE RWY. WHETHER THE BRAKES WERE LOCKED OR THE PARKING BRAKE WAS PARTIALLY ENGAGED, I CANNOT BE POSITIVE. POSSIBLE IDEAS TO PREVENT A RECURRENCE: LOOK AT THE FEASIBILITY AND/OR NECESSITY OF CHANGING OR MODIFYING THE BRAKE SYS IN THE CE525A. PROVIDE AN INDICATION IN THE COCKPIT AS TO WHAT CONDITION THE PARKING BRAKE IS IN, WHETHER IT BE ENGAGED PARTIALLY OR FULLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED MAINT CHKED THE AIRPLANE AND FOUND NOTHING AT FAULT WITH THE BRAKING SYS BUT DID REPLACE THE PARKING BRAKE CTL VALVE AS PRECAUTIONARY. THE RPTR SAID THE R WHEEL AND BRAKE DISPLAYED INDICATIONS OF BEING LOCKED UP BUT OPERATED NORMALLY WHEN TESTED.

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.