China's Civil Aviation Administration called for airlines to detect defects in their Boeing 737s and replace faulty parts Monday, after more than 400 operating aircrafts were reported to have serious problems with their elevator systems.

The findings affect only some lines of Boeing 737. They are 737-600, -700, -700C, -800, -900 and -900ER.

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???CAAC: Safety checks on Boeing 737s 'routine inspections'

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???China's Civil Aviation Administration orders checks on Boeing 737s