A mechanical engineer checks a plane at the Kunming Changshui International Airport in Guandu district to the northeast of Kunming, Jan. 15, 2020. Staff members of HNA Technic have enhanced maintenance to secure the safety and smooth operation during the Spring Festival travel rush season. (Photo: China News Service/ Liu Ranyang)

A mechanical engineer checks a plane at the Kunming Changshui International Airport in Guandu district to the northeast of Kunming, Jan. 15, 2020. Staff members of HNA Technic have enhanced maintenance to secure the safety and smooth operation during the Spring Festival travel rush season. (Photo: China News Service/ Liu Ranyang)

A mechanical engineer checks a plane at the Kunming Changshui International Airport in Guandu district to the northeast of Kunming, Jan. 15, 2020. Staff members of HNA Technic have enhanced maintenance to secure the safety and smooth operation during the Spring Festival travel rush season. (Photo: China News Service/ Liu Ranyang)

A mechanical engineer checks a plane at the Kunming Changshui International Airport in Guandu district to the northeast of Kunming, Jan. 15, 2020. Staff members of HNA Technic have enhanced maintenance to secure the safety and smooth operation during the Spring Festival travel rush season. (Photo: China News Service/ Liu Ranyang)

A mechanical engineer checks a plane at the Kunming Changshui International Airport in Guandu district to the northeast of Kunming, Jan. 15, 2020. Staff members of HNA Technic have enhanced maintenance to secure the safety and smooth operation during the Spring Festival travel rush season. (Photo: China News Service/ Liu Ranyang)

A mechanical engineer checks a plane at the Kunming Changshui International Airport in Guandu district to the northeast of Kunming, Jan. 15, 2020. Staff members of HNA Technic have enhanced maintenance to secure the safety and smooth operation during the Spring Festival travel rush season. (Photo: China News Service/ Liu Ranyang)

A mechanical engineer checks a plane at the Kunming Changshui International Airport in Guandu district to the northeast of Kunming, Jan. 15, 2020. Staff members of HNA Technic have enhanced maintenance to secure the safety and smooth operation during the Spring Festival travel rush season. (Photo: China News Service/ Liu Ranyang)

A mechanical engineer checks a plane at the Kunming Changshui International Airport in Guandu district to the northeast of Kunming, Jan. 15, 2020. Staff members of HNA Technic have enhanced maintenance to secure the safety and smooth operation during the Spring Festival travel rush season. (Photo: China News Service/ Liu Ranyang)