India’s aviation regulator, DGCA, has asked IndiGo to ground an A320neo with unmodified engines for each new A320neo that it inducts. IndiGo has over such 20 A320neo planes whereby both engines are unmodified.

“This process may remain in force till all engines in its fleet are replaced,” DGCA has ordered.

Earlier, IndiGo and GoAir were asked to complete engine replacement exercise for one of the two engines of their 36 A320neo aircraft by November 24 to fix issues in LPT. However, this was limited to those aircraft which had two Pratt and Whitney 1100 series engine of more than 3000 hour's engine life each.

“Now, we have included all those which, simply put, have unmodified engines. Earlier this was limited to those with engine life of over 2,900-3,000 hours. 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 engines are replaced,” DGCA DG Arun Kumar said.

The regulator has also asked the airline to ensure that all imported leased engines must come with the unmodified low-pressure turbine.

The move from the regulator comes after IndiGo on Monday presented an unsatisfactory action plan for engine replacement of all its neo fleet.

“During the review meeting on the issue, it was noted that efforts undertaken (till time) by the operator to replace all unmodified engine son their neo fleet by January 31 do not instill enough confidence with regard to the timely completion of the said task,” the regulator said.

The situation, if left unaddressed, may result in a large number of aircraft with unmodified engines operating on a schedule approved by the DGCA and hence any groundings may cause widespread disruption, the regulator has noted, adding that this sub-optimal solution will be avoided to the extent possible.

The review meeting was taken after the US aviation regulator FAA issued a notice on November 22 stating that Airbus has determined to replace any affected low-pressure turbine (LPT) 3RD stage blade with an LPT blade of a different material that is less susceptible to impact damage.

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

On November 1, DGCA had asked IndiGo to replace both the engines of its entire A320neo fleet of 97 aircraft by Jan 31 "at all costs" or face grounding. The issue was about low-pressure turbines which result in the breakage of LPT blades, engine vibration and then the aircraft has to return back to the ground.

The decision was taken after four consecutive incidents of air "turn back" or "inflight shutdown" over the last week of October in the Pratt & Whitney-run A320neos.

Pratt & Whitney has been in the spotlight in the Indian aviation space since 2016 when India's largest airline IndiGo started facing delivery delays in A320neo aircraft amid issues related to cooling down and a start-up time of the engine, reliability, combustion chamber lining, oil seal and fan blades.

In fact, last year India's aviation regulator DGCA grounded as many as 14 Airbus A320neos following warning of a potential in-flight shutdown in a sub-category of its Pratt & Whitney engines.

While the substitution of an aircraft with unmodified engines with modified one, will not cause any disruption, this process can be suitably altered if IndiGo manages to procure sufficient engines from Pratt & Whitney for replacement, DGCA added.