"FASCINATIN' RAMPAL: JEAN-PIERRE RAMPAL PLAYS GERSHWIN." Rampal, flute and alto flute. Michel Colombier conducting members of the Los Angeles Philharmonic. John Steele Ritter, piano, flute. Randy Kerber, synthesizer. CBS Masterworks Compact Disc. MK 39700. This is one of the merriest CDs yet produced, with only the most devoted purist railing against an eight-minute-plus arrangement of "An American in Paris." Rampal's flute rolls over such Gershwin songs as "Liza," "A Foggy Day," "Nice Work If You Can Get It," "Fascinating Rhythm," "I Got Rhythm" and "Someone to Watch Over Me," three excerpts from "Porgy and Bess," and the album's highlight, the three preludes for piano arranged for flute.