China's civil aviation regulator has found no fault with two airlines' emergency procedures after recent mechanical problems during flights.

On Sunday, Shenzhen Airlines' Airbus A330-343 lost cabin pressure at 9,200 meters during a flight to Xian in Shaanxi province, Civil Aviation Administration of China said on Thursday.

The pilots followed procedure and descended to a safe height, before flying the airbus to the airport of origin in Shenzhen, Guangdong province.

No one was injured and the crew had operated "correctly and properly" during the whole process, said the CAAC's deputy director of aviation security, Wu Shijie.

The loss of pressure was caused by the failure of a seal on a cargo door, the CAAC found.

In another flight incident on Sunday, a China Eastern Airlines' Airbus 330-243 had a flight instrument display malfunction while flying from Chengdu, Sichuan province, to Beijing, Wu said.

Due to rainy weather in Beijing, the pilots landed the airbus at Xian, Shaanxi province, as a precautionary measure. A fault in the flight instrument display had given an incorrect reading on the status of one of the engines. The part was later replaced and the display returned to normal operations, Wu said.

He said the two mechanical failures have a "certain probability of occurring", but the pilots were able to handle the emergencies correctly to ensure flight safety as they receiving training every year, which covers such emergencies.