Budget carrier IndiGo has grounded one more Airbus A320 neo plane after it was forced to return to Bhubaneswar following high engine vibrations experienced by the aircraft on the way to Bengaluru.Since their induction in March last year, the A320 neo planes in IndiGo fleet are going out of operations at a regular interval due to the frequent glitches in the Pratt & Whitney engines, which power these planes.The airline currently has 140 A320s, of which 23 are A320 Neos.Though the US engine maker has started supplying new engines to the country’s largest airline by market share which has helped it put some of the grounded planes back into flying, many of such planes remain out of operations, including the one which was grounded in Bhubaneshwar on September 20.Last week, a senior official at the Directorate General of Civil Aviation (DGCA) had said that as many as six A320 neo planes of IndiGo were on ground and awaiting engine replacement.“On September 20, IndiGo flight 6E-3869, which took-off at 8.50 pm for Bengaluru from Bhubaneswar, was diverted back to Bhubaneswar due to the high vibrations in one of the engines of the A320 neo plane. The flight later made an emergency landing,” an official source said.The aircraft is on ground since then, he said.Repeated calls and queries sent to IndiGo remained unanswered.“The vibrations were caused due to the sudden rise in the exhaust gas temperature of an internal combustion engine. As the increased temperature could have burnt other engine components, the pilot was forced to return the flight back to Bhubaneswar,” the official said.Promoted by Rahul Bhatia and Rakesh Gangwal, the airline had taken off nine A320 Neos from its fleet in the June quarter owing to engine issues.After the media reported the grounding of nine planes, the airline issued a statement saying, “We have faced some issues with the neo engine, causing operational disruptions. Both Pratt & Whitney and Airbus are working to address the issues.”However, during the analysts call on Q1 earnings on July 31, airline IndiGo’s president and whole-time director Aditya Ghosh admitted that nine of their planes were on ground.“There were days when we had had to ground as many as nine A320 Neos due to lack of spare engines. While we do receive certain compensation from Pratt & Whitney for these groundings, the operational disruptions are quite challenging and we are not happy with that situation,” Ghosh had said.The grounding of these planes had forced IndiGo to cancel over 600 flights between late June and early July.