According to a recent report by Russian media outlet Vedomosti, approximately 20% of Sukhoi SuperJet (SSJ100) planes are not in flying condition due to serious tail stabilizer defects.
According to a ruling by the Federal Air Transport Agency (Rosaviatsiya) dated December 22, 2016, Russian operators of the jetliner were mandated to perform checks of upper and lower stiffeners of the tail stabilizer, after a defect had been found by Russian airline IrAero. As a result, defects were discovered in six more jets belonging to IrAero, which led to the grounding of said planes.
According to Vedomosti, 14 instances of such defects have been discovered in Russia. A representative of Sukhoi Civil Aircraft Company (SCAC) said that this number is “close to reality”. On the other side of the Atlantic, Mexican Interjet had discovered faults in eleven out of 22 SSJ100 it operates.
On the 9th of January, Interjet announced that six of the problematic SSJ100s had been re-introduced to service after the flaws were fixed.
With only 87 Sukhoi SuperJet 100 planes operated around the world, right now 20% are grounded due to tail stabilizer defects discovered in December 2016. The replacement of nodes on the aircraft with the defect identified will be completed by late January 2017, according to a press release by SCAC.