Deep US refinery maintenance seen easing in second quarter-IIR

* Around 676,000 bpd offline in Q2-IIR Energy * Significant drop from 1.13 million bpd in Q1 * Turnarounds centered in Midwest, with 408,000 bpd offline By Sabina Zawadzki NEW YORK, March 4 (Reuters) - The amount of U.S. oil refinery capacity in maintenance should decline by almost 50 percent in the second quarter compared with the first three months of this year, according to data from consultancy IIR Energy, boosting output of diesel and gasoline after an intense work schedule