China's civil aviation regulator said on Wednesday it had finished the inspection of the country's Boeing 737 jets affected by a recent emergency directive issued by the U.S. Federal Aviation Administration (FAA) concerning engine risks.

The FAA's emergency airworthiness directive, issued on July 23, ordered inspections of the engine bleed air 5th-stage check valves on Boeing 737NG (models 737-600, -700, -800, -900) and 737CL (models 737-300, -400, -500) aircraft.

Corrosion of these valves during airplane storage could result in a dual-engine power loss without the ability to restart, according to the FAA directive. The grounded Boeing 737 Max was not included in the ordered inspection, it said.

The Civil Aviation Administration of China (CAAC) said it issued its own emergency airworthiness directive on July 24, ordering domestic airlines to check the valves on Boeing 737NG and 737CL aircraft that have been parked for more than six days and operated no more than 10 flight cycles.

Of all the 1,397 737NG and 737CL Boeing airplanes in China, 73 were found to require inspections, the CAAC said. By 5 p.m. on Tuesday, 70 of them had been deemed safe and had resumed operations, it added.

The remaining three jets will have their check valves replaced before their next flight, the CAAC said.