Four other Turkish engineers aboard the helicopter were freed yesterday, three weeks after the crash in Logar province, a Taliban stronghold south of the capital Kabul.
The Taliban said in an emailed statement that the four had been released as a "goodwill, humanitarian gesture and as a sign of respect to the Muslim people of Turkey".
"The other four will be released in the near future," it added.
The Islamist militants made no reference to a Russian, a Kyrgyz national and an Afghan also taken hostage after the crash-landing.
The men were freed in a remote area of Nangarhar province, which borders Pakistan, local officials told AFP, adding that tribal elders had acted as mediators with the Taliban.
The seizure was the largest abduction of foreigners in almost six years and highlighted Afghanistan's continuing insecurity as NATO combat troops prepare to pull out next year.