SHANGHAI -- China Eastern Airlines has resumed commercial services with Boeing 737-800 passenger aircraft, while the jetliners with registration numbers close to the one that crashed on March 21 are still undergoing maintenance checks and evaluations.

The airline previously grounded a total of 223 Boeing 737-800 aircraft, and carried out individual system tests, structural inspections and continuous airworthiness data verifications, as an emergency safety measure following the plane crash.

The Boeing 737 aircraft flying from Kunming, Yunnan province, to Guangzhou, Guangdong province, crashed into a mountainous area in Tengxian county, Guangxi Zhuang autonomous region, killing all 132 people on board.

A preliminary investigation report on the plane crash is expected to be completed within 30 days of the incident.