Narrative:

On oct/xa/95 at approximately XA00, I taxied a PA31P on a part 135 ambulance flight at the blythe airport in california. There were 5 souls on board -- 2 flight nurses, a patient and his mother and myself (the captain). Upon completion of a normal start sequence of both engines and the pre-taxi checklist, I taxied the aircraft towards the hold short area at the approach end of runway 26 at blythe. After approximately 1/2 mi of taxiing, heading approximately 080 degrees, the PA31P suddenly suffered a directional control problem. The aircraft suddenly changed heading of about 10 degrees to the left. I countered the motion with right rudder and right brake. The aircraft responded and began turning to the right. Upon returning to the taxi centerline, I applied left rudder and left brake to return the aircraft to taxiway centerline tracking. The aircraft surprisingly continued to turn to the right, and I then attempted to stop the aircraft by applying both brakes with full left rudder. At this point, the aircraft turned very sharply to the right and the aircraft stopped on the southern edge of the taxiway facing approximately perpendicular to the runway. The airplane was directed back down the taxiway towards the hold short. A thorough directional control and brake check was completed during the remaining taxi with no apparent malfunctions. All engine run-up and pre-takeoff checks were normal and completed. A normal takeoff and flight was conducted to san diego at lindbergh field. Corrective action: malfunctioning brakes were the cause of the incident. An inspection and proper adjustment to the brakes would keep the problem from recurring. Additionally, the throttle rigging appeared to be out of adjustment which I think could have caused the initial jink to the left. Proper throttle rigging to create a more uniform engine RPM would also, in my belief, create greater directional control stability.

Related reports:

Google
 

Original NASA ASRS Text

Title: PLT EXPERIENCED DIRECTIONAL CTL PROBS WHILE TAXIING -- AIR AMBULANCE ACFT.

Narrative: ON OCT/XA/95 AT APPROX XA00, I TAXIED A PA31P ON A PART 135 AMBULANCE FLT AT THE BLYTHE ARPT IN CALIFORNIA. THERE WERE 5 SOULS ON BOARD -- 2 FLT NURSES, A PATIENT AND HIS MOTHER AND MYSELF (THE CAPT). UPON COMPLETION OF A NORMAL START SEQUENCE OF BOTH ENGS AND THE PRE-TAXI CHKLIST, I TAXIED THE ACFT TOWARDS THE HOLD SHORT AREA AT THE APCH END OF RWY 26 AT BLYTHE. AFTER APPROX 1/2 MI OF TAXIING, HDG APPROX 080 DEGS, THE PA31P SUDDENLY SUFFERED A DIRECTIONAL CTL PROB. THE ACFT SUDDENLY CHANGED HDG OF ABOUT 10 DEGS TO THE L. I COUNTERED THE MOTION WITH R RUDDER AND R BRAKE. THE ACFT RESPONDED AND BEGAN TURNING TO THE R. UPON RETURNING TO THE TAXI CTRLINE, I APPLIED L RUDDER AND L BRAKE TO RETURN THE ACFT TO TXWY CTRLINE TRACKING. THE ACFT SURPRISINGLY CONTINUED TO TURN TO THE R, AND I THEN ATTEMPTED TO STOP THE ACFT BY APPLYING BOTH BRAKES WITH FULL L RUDDER. AT THIS POINT, THE ACFT TURNED VERY SHARPLY TO THE R AND THE ACFT STOPPED ON THE SOUTHERN EDGE OF THE TXWY FACING APPROX PERPENDICULAR TO THE RWY. THE AIRPLANE WAS DIRECTED BACK DOWN THE TXWY TOWARDS THE HOLD SHORT. A THOROUGH DIRECTIONAL CTL AND BRAKE CHK WAS COMPLETED DURING THE REMAINING TAXI WITH NO APPARENT MALFUNCTIONS. ALL ENG RUN-UP AND PRE-TKOF CHKS WERE NORMAL AND COMPLETED. A NORMAL TKOF AND FLT WAS CONDUCTED TO SAN DIEGO AT LINDBERGH FIELD. CORRECTIVE ACTION: MALFUNCTIONING BRAKES WERE THE CAUSE OF THE INCIDENT. AN INSPECTION AND PROPER ADJUSTMENT TO THE BRAKES WOULD KEEP THE PROB FROM RECURRING. ADDITIONALLY, THE THROTTLE RIGGING APPEARED TO BE OUT OF ADJUSTMENT WHICH I THINK COULD HAVE CAUSED THE INITIAL JINK TO THE L. PROPER THROTTLE RIGGING TO CREATE A MORE UNIFORM ENG RPM WOULD ALSO, IN MY BELIEF, CREATE GREATER DIRECTIONAL CTL STABILITY.

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.