What was found
98-0110 - STA-DFW - AFTER ROTATION AND DURING CLIMB, EXPERIENCED A SEVERE VIBRATION FROM NR 1 ENG. WHEN POWER PULLED BACK BELOW 1.2 EPR, VIBRATION WOULD STOP, NO ABNORMAL READING NOTED ON VIBRATION METER. NOTICED NEED FOR RUDDER TRIM DURING CLIMB. REMOVED NR 1 ENG NOSE COWL, FAN BLADES, FRONT CASE PER M/M 71-11-00, 72,23-00, 72-10-00 SEE LOG 01039388 FOR NOSE COWL INSTALLATION. INSTALLED FRONT FAN CASE PER JTPD-7R4 SEC 72-33-00 RUB WEAR CHECKED OK AFTER RUN PW INSPECT XC374 EVM ON ENG RUN 0.4 RAN ENG PER JRH INSTALLED FAN BLADES PER PW SEC 72-31-00.