NHTSA Preliminary Evaluation PE08022

THE OFFICE OF DEFECTS INVESTIGATION HAS RECEIVED ONE FLEET COMPLAINT IDENTIFYING 33 ALLEGED FAILURES ON THE SUBJECT WHEELCHAIR LIFTS. THE ALLEGED FAILURES HAVE OCCURRED ON SCHOOL BUSES IN TWO ALASKAN SCHOOL DISTRICTS.THESE ALLEGATIONS DESCRIBE CRACKS DEVELOPING ON THE LIFTS' VERTICAL SUPPORT ARMS AT A PINNED JOINT WHERE A HORIZONTAL ARM INTERFACES WITH THE VERTICAL ARM.THE LIFTS ARE USED TO RAISE WHEELCHAIRS FROM THE STREET LEVEL TO ALLOW ENTRY INTO THE SCHOOL BUS.THESE BENT ARMS MAY CAUSE THREE POSSIBLE SAFETY CONCERNS.FIRST, THE BENT ARMS MAY PREVENT AN INBOARD BRIDGE FROM LAYING FLAT AND THUS PREVENT A WHEEL CHAIR FROM LOADING THE LIFT IN AN EMERGENCY.SECOND, BENT ARMS MAY CAUSE THE ANTI-STOW INTERLOCK SWITCH TO BECOME OUT OF ADJUSTMENT POSSIBLY ALLOWING THE LIFT TO START MOVING TO THE STOWED POSITION WHILE A CHAIR IS STILL ON THE PLATFORM.THIRD, THE BENT ARMS MAY ALSO CREATE A SITUATION WHERE THE REQUIREMENTS OF FMVSS 403 - S6.10.2.3 ARE NO LONGER MET.RICON FEELS THAT THE BENT ARMS ARE NOT A SAFETY CONCERN BECAUSE THE OPERATOR WILL SEE THAT THE LIFT IS DAMAGED BEFORE A PASSENGER IS LOADED ONTO THE BUS.IF THE DRIVER SEES THAT THE LIFT IS DAMAGED, THEY SHOULD NOT LOAD A PASSENGER THAT WOULD THEN NEED TO BE UNLOADED IN AN EMERGENCY.THIS PE HAS BEEN UPGRADED TO AN ENGINEERING ANALYSIS (EA) TO DETERMINE WHAT CAUSES THE ARMS TO FAIL, IF THE ARMS CAN FAIL WHILE THE LIFT IS IN A STOWED POSITION, AND IF A PASSENGER CAN BE LOADED WHILE THE LIFT IS IN A FAILED CONDITION.