The country's civil aviation regulator, Directorate General of Civil Aviation (DGCA), on Monday asked IndiGo not to use such A320 Neo planes which are fitted with PW engines already used for over 3,000 hours, or face grounding of aircraft, officials said.

A DGCA official said there are 16 aircraft in IndiGo's fleet in which both the Pratt and Whitney (PW) engines have been used for more than 2,900 hours.

All such 16 aircraft have to be fitted with at least one modified LPT engine within the next 15 days, said the official.

"Failing which, all these aircraft shall be grounded. This has been done after studying the pattern and evaluating the risk," the DGCA official said.

In October, there Indigo has reported three in-flight engine shutdowns on the A320 (Neo) fitted with PW engines.

These were commanded shutdowns, however, due to the fact that they occurred on consecutive days -- 24th, 25th and 26th October -- a DGCA team visited Indigo premises on October 28 to review the maintenance and safety data.

"A meeting was chaired by DGCA later in the day with senior Indigo team members including COO, safety and maintenance heads. Subsequent to the discussions, Indigo has been instructed to ensure that no such Neo aircraft should be operated which has two Pratt and Whitney 1100 series engine of more than 3000 hour's engine life each. Indigo has been given a fortnight to comply with the instructions," the official said.