CSX Corp., the Richmond-based transportation company, yesterday reported a 28 percent drop in its second-quarter earnings, but the results were skewed by the fact that the year-ago quarter included a large gain from the sale of a subsidiary.

CSX earned $109 million ($1.08 a share) in the second quarter, compared with $151 million ($1.45) during the same period of 1989. Revenue rose 3.7 percent, to $2.04 billion from $1.97 billion.

In the first half, CSX reported a profit of $186 million ($1.30), down 20 percent from 1989 first half earnings of $233 million ($1.93). Revenue rose 3.6 percent, to $3.95 billion from $3.8 billion.

The 1989 results included a $52 million gain from the sale of CSX's Texas Gas Transmission Corp. unit to Enron Corp.

The company's earnings from continuing operations were $109 million ($1.08) in the second quarter, compared with $130 million ($1.24) a year before, when results included a one-time after-tax gain of $39 million from the sale of the company's Lightnet fiber-optics subsidiary. Excluding that transaction, CSX's earnings from continuing operations rose 20 percent over the 1989 second quarter.