BLUE BIRD IS RECALLING CERTAIN MODEL YEAR 2013 ALL AMERICAN REAR ENGINE SCHOOL BUSES AND ONE AFTERMARKET BRAKE TREADLE VALVE. THE AFFECTED BUSES WERE MANUFACTURED FROM DECEMBER 9, 2011, THROUGH MARCH 9, 2012. THE BRAKE VALVE PLUNGER MAY FRACTURE DURING BRAKE APPLICATION, RESULTING IN REDUCED BRAKE PEDAL ANGLE AND TRAVEL. THIS CONDITION MAY LIMIT THE DRIVER?S ABILITY TO DELIVER FULL PRESSURE FROM THE FOOT BRAKE VALVE. THERE IS ALSO A POTENTIAL THAT THE BRAKE PLUNGER COULD BECOME LODGED AND NOT ALLOW RELEASE OF THE SERVICE BRAKES.