NetJets Chief Executive Adam Johnson appears to be the most effective letter writer in the country.

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

Johnson has been instrumental in not only bringing down Jordan Hansell in recent weeks, but has also taken 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.

Two sources familiar with the issue said Johnson's latest 'Dear Warren' letter came earlier this year when he resigned as NetJets' president effective on May 1. The sources said Johnson sent a letter to Buffet saying he was dissatisfied with the direction of the company.

The sources said that in some past few weeks, Berkshire Hathaway's Tracy Britt Cool, who helps Buffett manage Berkshire's troubled companies, was spotted around NetJets offices.

The Post last month reported about the tension between the union representing NetJets pilots, who have been working under an expired contact.

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

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

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