What was found
BOTH ENGINES STARTED FOR TAXI OUT, SHUT DOWN NR 2 ENG TO SAVE FUEL. WHEN NR 2 ENG SHUT DOWN WE IMMEDIATELY GOT, RUD HDOV PROT FAIL & E2 SHORT DISP ON EICAS RTG. R & R RT RELAYS KO774, K0112 & K0384 IAW EMB AMM 20-13-02 ENGINE RUN REQUIRED.