E. C. Ernst, a Washington electrical construction firm in Chapter XI bankruptcy, recorded profits of $5.2 million ($1.45 a share) for its fiscal year ended March 31 compared with a loss of $12.9 million a year earlier.

But Ernst lost $7.5 million before a one-time extraordinary gain of $12.7 million, that included $11.8 million from the divestment of its L. K. Comstock & Co. subsidiary.

Revenues for the year were $42.9 million compared with $72.2 million last year.

A spokesman for Ernst declined to release fourth-quarter earnings. But in a statement, the company said its loss before the extraordinary item occurred principally in the fourth quarter and reflected several events before it petitioned for bankruptcy.

The company said it lost about $2 million because of problems with estimating costs for the five unprofitable contracts remaining before it filed for bankruptcy.It also said it set aside $4 million for estimated losses on construction and other contracts ended during the bankruptcy and that it suffered costs related to the bankruptcy filing.

Hotel Investors said earnings for the third fiscal quarter ended May 31 rose to $1.57 million (75 cents a share) from $1.22 million (70 cents) a year earlier, with revenues up to $6.26 million from $2.76 million. Earnings for the nine months ended May 31 were $4.27 million ($2.16) compared with $3.68 million ($2.15).

In another development, the suburban Maryland real estate trust called for redemption on Aug. 1, all 7 3/4 percent convertible subordinated debentures that are due to mature in 1990. The redemption is set at 103.02 percent of the principal amount, Hotel Investors Trust announced.