In March 2018, the planes were grounded by the Directorate General of Civil Aviation (DGCA) for technical reasons, related to Pratt and Whitney turbofan engines. The concerned planes were subject to repetitive engine failures.
At least three A320neo owned by Indian companies have had emergency landing between February and March 2018. Overall, Times of India recorded 69 single engine failures on IndiGo planes in 18 months. The grounding forced both companies to cancel around 626 flights (488 for IndiGo, 138 for GoAir) in March 2018..
Pratt & Whitney initially announced that it would find a solution before June, 2018. The constructor offered a fix that would require to fly planes with one faulty engine for the next three months – something approved by the European Aviation Safety Agency (EASA). But India’s Directorate General of Civil Aviation (DGCA) refused this solution.PW then announced it would deliver replacement PW1100 engines within 40 days. The first delivery started on March 28, 2018.
Every faulty engines are now replaced, according to IndiGo and GoAir officials. Both companies operate normally and Airbus is delivering them the remaining A320neo orders.
Source – AeroTime