On January 13, the Directorate General of Civil Aviation (DGCA) had said the unmodified PW engines do contain an unsafe condition, which is prone to undesirable outcomes and therefore, needs to be dispensed with.
On Monday, the regulator said: "We took a call a couple of days back and instructed both the airlines. Both taken together about 60 engines are yet to be replaced and the obvious reason was Covid-19 impact and the resultant lockdowns."
Supply chains and production lines got impacted due to the Covid-19 pandemic and in turn, disturbed the process, it added.
"Keeping all this in view, we have extended the deadline by three months; up to 31st of August 2020. Also, we instructed that for current times, aircraft with both engines modified should be flown and this should not be difficult as the curtailed operations are likely to last for some more time," the regulator said.
Four Air Turn Back (ATB)/Inflight Shut Down (IFSD) events were witnessed on Airbus A320Neo aircraft operated by Indigo in a week during October 2019 due to the failure of third stage LPT (low pressure turbine) blades.