The Director General of Civil Aviation on Monday warned IndiGo that its Airbus A320neo jets could face a catastrophic situation if they continue to operate with unmodified Pratt & Whitney engines, NDTV reported.

“These conditions, if not addressed, could result in uncontained release of the LPT 3rd stage blades, failure of one or more engines, loss of thrust control, and loss of aircraft,’’ the DGCA said.

The aviation watchdog said deliveries of new planes taken by IndiGo must be used to replace the aircrafts that are fitted with turbine blades, PTI reported. Those planes should then be grounded until their engines are replaced with new ones, after which they can be allowed to fly again, it added.

“Simply put, the new aircraft will slip into the role of one existing aircraft with unmodified engines...The grounded aircraft can be allowed a fresh schedule once its PW engines are replaced,” a senior DGCA official said.

On November 1, the regulator had instructed the budget airline to replace all the Pratt & Whitney engines “at all costs” by January 31, 2020, or they would be grounded.

The DGCA said that the steps taken by IndiGo so far to replace all the engines “do not instil enough confidence with regard to the timely completion of the said task”. “If left unaddressed, we may find ourselves in a situation, in which, we remain saddled with large number of aircraft with unmodified engines ... and we are left with the only option i.e. to ground them,” the regulator said.

Indigo is the biggest customer of Airbus A320neo jets. It operates approximately 100 old A320neo aircrafts.

If the replacement is not complete, all planes that still have unmodified engines will be grounded and could cause “large scale disruptions” in operations. The latest directive is aimed at preventing such a situation, the DGCA said.

IndiGo, owned by InterGlobe Aviation, in a statement said the current schedule to replace the engine blades remains intact. “IndiGo is working with PW and Airbus to adjust inflow of LPT (low pressure turbine) 3rd stage modified engines to meet the DGCA guidelines,” the airline said.