(Reuters) Russian plane maker Sukhoi will repair defects in its Superjet 100 aircraft by late January, the company said after problems detected by airlines including Russia’s Aeroflot and Mexico’s Interjet caused the grounding of 18 planes.

Having announced last week that the Russian aviation authority had discovered a defect in the tail section of its Superjet 100, Sukhoi said it has completed its fleet inspection and aircraft that passed its checks have resumed flying.

The replacement of the defective parts will be completed by late January, Sukhoi said in a statement late on Tuesday, adding that the problem is not of a critical nature and that the parts in question feature “a multi-level redundant structure” with “a safety margin that is more than twice the operational loads”.

Interjet said this week that it had detected “potential anomalies” in 11 Superjet 100s and industry sources said that Aeroflot grounded six planes. Another Superjet 100 operated by Russian carrier Iraero was also grounded.

Sukhoi, which is part of state-owned United Aircraft Corp, has been dogged by safety concerns over the Superjet line.

In 2012 45 people were killed when a Superjet crashed in Indonesia during a promotional flight, causing Aeroflot to ground four planes.

Reuters