What was found
RDR BST FAIL LIGHT FLASHED INTERMITTENTLY DURING TAKEOFF, THEN CAME ON STEADY 1 MIN AFTER TAKEOFF. 09-27-07 INTERROGATED AVIONICS STATUS ON THE MFD & FOUND NO CODES FOR RUDDER BOOST FAIL MESSAGE. PER THE RUDDER BOOST T/S CHART INTERROGATED THE LRU FAULT HISTORY & FOUND THE FOLLOWING LRU FAILURES. REMOVED & REPLACED THE SIGNAL INTERFACE ADAPTER W/ OVERHAULED UNIT. FUNCTION CHECK OF THE SIGNAL INTERFACE ADAPTER GOOD IAW COLLINS SYSTEM MM 52-0775811 TABLE 5-74 STA TEST PROCEDURES.