Engineering and testing-services firm National Technical Systems Inc. is being acquired for $267 million in cash by Los Angeles private equity firm Aurora Capital Group, the companies announced Friday.

Aurora is offering $23 a share for all outstanding shares in National Technical, a publicly traded company in Calabasas. The offer represents about a 39 percent premium over the company’s closing share price on Thursday.

A special shareholders meeting to approve the sale will be held before the end of October. The deal is expected to close before the end of the year.

National Technical provides testing and engineering services for the aerospace, defense and transportation industries at facilities throughout the United States, including the Santa Clarita Valley. Existing staff and management are expected to remain.

“(The transaction) will allow NTS and our employees to continue to grow and excel as the preeminent independent testing and engineering services organization in North America,” said company founder and Vice Chairman Aaron Cohen, in a prepared statement.

Aurora Capital has invested more than $2 billon into more than 100 companies since its founding in 1991. Its current portfolio of companies has combined revenue of more than $1.5 billion.

Shares gained $6.31, or 38 percent, to close at $22.89 on the Nasdaq.