New NetJets Chief Executive Adam Johnson just might be the most effective letter writer in the country.

The 44-year-old executive has twice in six years written letters to Warren Buffett, the owner of the fractional jet-ownership company, suggesting that he can the CEO — and twice gotten the billionaire investor to act, The Post has learned.

Johnson was instrumental in not only toppling Jordan Hansell in recent weeks, but also took a lead role in pressuring Buffett’s Berkshire Hathaway in 2009 to replace NetJets founder Richard Santulli, a source with direct knowledge of the situation told The Post.

“This is coup No. 2,” the source noted.

Johnson’s latest “Dear Warren” letter came earlier this year as he resigned as NetJets president effective on May 1.

“He sent a letter to Buffett saying he was dissatisfied with the direction of the company,” a source at NetJets said.

The letter must have found a receptive ear in Omaha.

In recent weeks, Berkshire Hathaway’s Tracy Britt Cool, who helps Buffett manage Berkshire’s troubled companies, was spotted around NetJets offices, two sources said.

As The Post reported last month, tension between the union representing NetJets pilots, who have been working under an expired contact, and the company has been rising — and hurting the company — at a time the corporate jet sector is booming and there’s a national pilot shortage.

Johnson, who left NetJets without a disclosed job offer elsewhere, was rehired, but for the top spot, just this week. Bill Noe, who resigned as COO in April, rejoined as president and COO.

The move may already be paying dividends.

Johnson and Noe met Wednesday with Pedro Leroux, president of the pilots union, The Post has learned.

Hansell, Johnson’s predecessor, had not met with Leroux since the contract expired two years ago.

“For us, it’s a welcome change,” Leroux told The Post, confirming the meeting.

Johnson, reached on his cellphone, declined comment.

In the letter to Buffett about Santulli, Johnson and two other NetJets executives stressed alleged improprieties in the corner office, the source with direct knowledge of the situation said.

In response, Buffett sent David Sokol, his manager of troubled companies at the time, to investigate.

Santulli resigned.

Sokol and Santulli up until that time were both considered possible successors to Buffett at the top of Berkshire Hathaway.

Soon after Santulli’s exit, Sokol promoted Johnson, then the head of catering, to the company’s executive committee.

“[Johnson] is the best politicker I’ve ever seen,” a former NetJets executive said.

NetJets, unlike other Berkshire companies, has no board of directors. There is an executive committee, and the CEO reports directly to Buffett.

Johnson has most recently been NetJets president dealing mostly with customers.

Berkshire Hathaway did not return calls.