What was found
AT THE BEGINNING OF THE TAKEOFF ROLL, THE NOSE OF THE ACFT SUDDENLY LOWERED AND THE PROPELLER MADE CONTACT WITH THE GROUND. MX ARRIVED AT THE ACFT AND DISCOVERED THE LT BRAKE LOCKED AND THE LT WHEEL UNABLE TO ROLL. THE RT WHEEL WAS FREE TO MOVE. THE LT BRAKE GRADUALLY FREED UP BUT NOT COMPLETELY WITH REPEATED APPLICATION AND RELEASE OF THE BRAKE. THE ACFT HAD BEEN STORED IN AN UNHEATED HANGER THE NIGHT BEFORE. TEMPERATURE APPARENTLY WAS AT OR BELOW FREEZING WHEN THE PROBLEM OCCURRED. ACFT WAS MOVED INTO A HEATED MX HANGER AND AFTER A WHILE, NORMAL BRAKE RELEASE WAS OBSERVED.