Country's largest airline IndiGo is again battling Pratt & Whitney engine problems, with at least four of its planes experiencing glitches in one week, according to industry sources.



The P&W engine problems had led to grounding of around 25 Airbus A320 neo aircraft of IndiGo and GoAir during the period from April 2017 to March this year.



On June 3, an IndiGo flight carrying 183 passengers from Delhi to Ranchi was forced to return to the airport in the national capital due to mid-air engine shut-down.



The incident came just a day after another IndiGo plane, which was bound for Port Blair from Kolkata, had to abort take-off at the last minute due to an engine glitch, sources said.



Prior to that on May 30, IndiGo's flight to Delhi from Udaipur was canceled and the aircraft was grounded due to engine failure, they added.



All these planes were A320 neos powered by P&W engines.



On May 29, another flight had faced engine issues. This was a Bengaluru-bound flight from Pune, sources said. This flight was operated by A320 ceo having P&W engines.



However, an IndiGo spokesperson said that except for the Ranchi flight wherein the aircraft had mid-air engine issues, the rest of the incidents were due to "standard issues" which occur in the day-to-day operations of a plane.



Queries sent to US engine maker P&W remained unanswered.



"Airbus A320 neo plane (VT-ITE) operating airline's flight 6E-509 to Ranchi from New Delhi had an air turn back to Delhi. The crew carried out an engine in flight shut down following the standard industry procedure," the airline said in a statement about the June 3 incident.



"Leaving aside Ranchi flight (engine) shut down, the reason of which still needs to be determined, none of the other incidents had to do with the known PW engine issues, which occur in the day-to-day operations of an aircraft," IndiGo said.



However, the airline did not provide a response to queries on whether it was mulling grounding of its A320 neo fleet in view of the safety concerns.



In the 2017 June quarter, IndiGo had grounded nine A320 neo planes due to engine issues. The grounding had also resulted in IndiGo cancelling 84 flights on a particular day last year.



Then again between February and March this year, 14 of these planes -- 11 of IndiGo and three of Go Air -- were taken out of operations due to the same engine issues on the directions of the aviation regulator after a series of mid air shut downs were reported by the two carriers.