UPDATE 2-Ametek Q3 results beat Street, shares up

* Q3 adj EPS $0.42 vs est $0.40

* Net sales falls 23 pct

* Says 2009 continues to be very challenging

* Shares up 4 pct in pre-mkt trade (Recasts; Adds details)

Oct 27 (Reuters) - Electronic instruments maker Ametek Inc (AME.N) posted better-than-expected quarterly results, helped by lower expenses, and narrowed its 2009 earnings outlook range.

Ametek, whose key customers are Boeing Co (BA.N) and Airbus (EAD.PA), said 2009 continues to be a very challenging.

For the full year, the company now expects earnings of $1.87 to $1.92 per share. Excluding restructuring costs in the third quarter, it sees earnings of $1.89 to $1.94 per share.

It earlier forecast full-year earnings of $1.85 to $2.00 per share.

"For the full year, we expect revenue to decline approximately high-teens on a percentage basis," Chief Executive Frank Hermance said in a statement.

Analysts on average were expecting full-year earnings of $1.92, on revenue of $2.09 billion, according to Thomson Reuters I/B/E/S.

Ametek -- which operates in the United Kingdom, Germany, Denmark, Italy and France apart from the United States -- had said in July that it expected a few end markets to improve in the fourth quarter.

For the third quarter, Ametek reported net income of $43.0 million, or 40 cents a share, compared with $70.9 million, or 66 cents a share, a year ago.

Excluding restructuring costs, it earned 42 cents a share, beating analysts' average expectation of 40 cents a share.

Net sales for the company, which also makes electric motors, fell 23 percent to $497.1 million. Analysts were expecting $496.5 million.

Sales at the company's electronic instruments group -- which builds monitoring, testing and display devices for the aerospace and industrial markets -- fell 24 percent.

Revenue at the segment fell on weakness in the aerospace aftermarket, process and industrial businesses.

Sales at the electromechanical group fell 22 percent.

However, selling, general and administrative expenses for the quarter fell 18 percent to $63.9 million.

Shares of the company were up at $37.25 in trading before the bell. They closed at $35.70 Monday on the New York Stock Exchange. (Reporting by Bhaswati Mukhopadhyay in Bangalore; Editing by Himani Sarkar)