Taiwan's newest Apache helicopters could be flying next month after being grounded because of concerns over the transmission package.

Citing a defense source it did not identify, the Central News Agency reported the 12 AH-64E Apache attack aircraft could be flying again by mid-February if replacement transmissions start arriving soon.

Defense officials grounded the aircraft -- sometimes called the Guardian -- this month following a failure in the same model reported by the U.S. Army, CNA reported.

The U.S. Army has started replacing the main transmission boxes on its helicopters, the source said.

Taiwan took delivery in early November of six knocked-down Apache AH-64E helicopters from Boeing in the United States as part of a 30-aircraft order worth $2 billion.

Six more of the four-bladed twin engine Apaches arrived in Taiwan Jan. 2 for reassembly at Tainan air base.

All the main transmission boxes removed from Taiwan's 12 Apaches in-country will be sent back to the U.S. for inspection.

Main transmission boxes for the next three batches of helicopters -- set for delivery in March, May and July -- will be checked thoroughly before the aircraft are shipped from the United States, CNA reported.

Though the helicopters have been grounded, ground and simulation training have continued, the source said.

The Taiwanese army has sent 61 pilots to the United States for flight training on the heavily armed Guardians, which eventually will replace Taiwan's aging AH-1W Super Cobra attack helicopters.

The Apaches are powered by fuel-efficient T700-GE-701D engines and improved aircraft handling, performance and agility at higher altitudes.

The United States and Taiwan are the first countries to use the Apache.

South Korea announced in April it had chosen the Apache Guardian helicopter in a deal the South Korean Defense Acquisition Program Administration said was worth $1.6 billion.

The fleet of 36 new Apaches, to arrive between 2016 and 2018, will play a crucial role in countering North Korean amphibious infiltrations into western border islands should they occur, a report by The Korea Herald newspaper said.

DAPA chose Boeing's Apache over Bell's AH-1Z and the Turkish Aerospace Industries T-129 -- a joint development with AgustaWestland as the primary partner and based on Agusta's A129 Mangusta.

However, DAPA said sustainment costs for the Apaches are expected to be higher than for the helicopters already operated by South Korea, the 500MD, made by Hughes Helicopters and McDonnell Douglas Helicopter Systems, and Bell's Cobra AH-1S attack helicopters.

South Korea's Apaches will have fire control radars supplied by Longbow under a $51 million deal announced in September.

Longbow, a joint venture between Lockheed Martin and Northrop Grumman, sealed the deal as a foreign military sales contract, a statement from both companies said.

Under the contract, South Korea will get six FCR systems, spares and in-country support.