Complex sentence: Robert Cumming, a general manager at Republic Steel, had owned a Mooney M20F Executive for years and flew it frequently, and wished to put the Mooney M20 back into production, which began in January 1974 with the reintroduction of the M20F Executive.
Split into simpler sentences: Robert Cumming, a general manager at Republic Steel, had owned a Mooney M20F Executive for years and flew it frequently, and wished to put the Mooney M20 back into production. This began in January 1974 with the reintroduction of the M20F Executive.