Sept 9 (Reuters) - U.S. President Donald Trump on Wednesday boarded the Qatar-gifted Air Force One en route to Texas after saying that an emergency slide that had deployed on one side of the aircraft was being checked.

The slide appeared to have deployed shortly before Trump was due to board to travel to Dallas for thefirst-ever Republican midterm convention.

Trump remained on the Marine One helicopter for about 20 minutes after landing, before speaking to reporters on the tarmac.

Asked by a journalist whether he was sure that the plane was safe to fly, Trump said: "Yeah, I am, or I wouldn't be on it."

Several minutes later, the emergency slide was being taken away.

Trump started flying aboard the jumbo jet on July 1 after accepting the plane as a gift last year. There was an accelerated effort to renovate the Boeing 747 before Trump started using it.

(Reporting by Steve Holland, Costas Pitas and Katharine Jackson; Editing by Caitlin Webber and Michelle Nichols)