More than a dozen Airbus SE A320neo jets operated by IndiGo could be grounded if the Indian budget carrier doesn’t update some Pratt & Whitney engines within two weeks, the nation’s aviation safety regulator said.

IndiGo won’t be allowed to fly A320neo jets fitted with two 1100 production series engines that have been in operation more than 3,000 hours, the Directorate General of Civil Aviation said in a statement following three in-flight engine shutdowns on three IndiGo planes last week.

Failing that, as many as 16 jets could be grounded, the DGCA said. IndiGo, operated by InterGlobe Aviation Ltd., had 89 A320neos as of Sept. 30.

United Technologies Corp.’s Pratt & Whitney has seen delivery delays and groundings in India after spending $10 billion to develop fuel-efficient engines for single-aisle jets. IndiGo, the world’s biggest A320neo customer, decided in June to order $20 billion-worth of engines from a joint venture of General Electric Co. and France’s Safran SA, which competes with Pratt & Whitney.

Indian aviation officials held a meeting with IndiGo executives Monday after visiting the airline’s premises to review maintenance and safety data in the wake of the in-flight failures, the DGCA said. In August, the regulator ordered IndiGo and smaller rival Go Airlines India Ltd. to not accept engines without a modified version of the 1100-series turbines.

On the recent failures, pilots had to shut down engines mid-flight, the DGCA said, without detailing their routes. The glitches follow 15 in-flight shutdowns, turnarounds or rejected takeoffs Indian carriers experienced due to failure of the low-pressure turbines in the past three years through August, according to the DGCA.

A Pratt & Whitney representative declined to comment, while an IndiGo spokeswoman said the airline continues to work with authorities and will take required action. Airbus is supporting its customer in its daily operations along with the engine maker, a company spokesman said.