MADRID, May 13 (Reuters) - Spanish engineering firm Tecnicas Reunidas on Thursday fell to a first-quarter net loss as slowed spending in the oil sector cut revenue by 35%. The net loss of 61 million euros ($73.75 million) compared with a profit of 8.7 million euros a year earlier while revenue fell to 763 million euros. It blamed the revenue decline on requests from customers to slow investment due to the pandemic though it added the commercial environment has improved. The company expects to sign contracts worth 4 billion euros this year and maintained its targets of revenue of 3.5 billion this year, the same as in 2020, with a margin of earnings before interest and taxes of 3%. $1 = 0.8271 euros Reporting by Inti Landauro; editing by Jason Neely Our Standards: The Thomson Reuters Trust Principles.