india

Updated: Oct 30, 2019 03:52 IST

The aviation regulator told GoAir on Tuesday to replace the Pratt & Whitney (PW) engines in 13 Airbus A320 Neo planes that have flown more than 3,000 hours, or face grounding of the aircraft, one day after instructing IndiGo not to operate such planes.

“If they fail to carry out the changes that we have asked for in the coming fortnight, we will be compelled to ground the aircraft,’’ said Arun Kumar, chief of the Directorate General of Civil Aviation (DGCA).

On Monday, DGCA, asked IndiGo, India’s largest airline by market share, not to use A320 Neo planes which are fitted with PW engines already used for over 3,000 hours. A DGCA official said there are 16 aircraft in IndiGo’s fleet in which both PW engines have been used for more than 2,900 hours, adding that 16 aircraft have to be fitted with at least one modified LPT (low pressure turbine) engine within next 15 days, said the official.

Aircraft fitted with the engines have run into technical and operational glitches, and DGCA has detected a pattern of an increasing number of incidents involving Airbus 320 Neo planes. Those that have flown more than 2,900 hours and didn’t have a new modified engine that were supplied after June this year were found to be most prone to developing glitches.]

IndiGo has ordered 430 jets in the A320 Neo family on top of an initial contract for 100 older A320 models, making it one of the biggest buyers of Airbus’s best-selling plane.

As DGCA sent out the warning to GoAir, its officials were preparing to meet with the top bosses of IndiGo, run by InterGlobe Aviation Ltd.The airline’s president and chief operating officer, Wolfgang Prock Shauer, was meeting with the DGCA chief to figure out how to change the Neo engines of 16 of the airline’s planes in the next fortnight.

DGCA officials were in the Gurgaon office of the airline since Tuesday morning. Indigo has the largest fleet -- 92 planes -- fitted with the problematic engines.

Until now, the aviation regulator has stopped short of grounding the aircraft fitted with the engines that cater to 40% of the domestic flights, but three consecutive incidents on IndoGo flights on October 24, 25 and 26 have raised concern at the aviation regulator.

The first incident was on a Kolkata-Chennai flight, which developed a snag while climbing to 27,000 feet. On inspection, it was found that the engine shut down during the flight and the low pressure turbine was damaged.

The next day, a similar incident took place on a Delhi-Goa flight when the aircraft experienced high vibrations. A preliminary inspection found that he blades of the LPT of the second engine in the plane were damaged, and the plane was sent back to Delhi.

On October 26, a Mumbai-Coimbatore flight was made to turn around and go back to Mumbai after it experienced high vibrations. When the airline checked the plane after its return, it found that yet again the LPT blades were damaged.

The engine used in the plane on the October 24 had a flying history of 4,253 hours, the one on 25 October had done 3,641 hours, and the third 2,372 hours.

“While the last day’s engine was newer than the rest, we studied all 11 instances in the recent past and found that nine out of 11 had a problem in engines older than 2,900 hours and they didn’t have the new Neo engine,’’ said a DGCA official, requesting anonymity.

In the new and modified Neo engines, fitted after June, the design problems of the gear box or the LPT have been remedied. The solution being suggested by DGCA to IndiGo and GoAir is to replace the engines on the older aircraft with one of the two modified engines fitted on newer planes.

A study of the incidents that have taken place on Airbus Neo planes (Neo entered the Indian market in 2016) shows that the incidents of LPT or the blades of the engines braking have been more frequent in India than elsewhere . While globally, 12 instances of LPT problems have been reported, IndiGo itself has reported 14 such incidents since 2017 and GoAir has reported one.

Vibrations that lead to breaking of the turbine were reported in 15 IndiGo engines while globally, there were 30 instances. GoAir reported six such instances .

“They cite the climate and dust in India to explain why the instances of engine trouble are much more common here,’’ said the DGCA official cited above.

While IndiGo and GoAir declined to comment, Pratt and Whitney responded to queries from HT with a statement that said: “Pratt & Whitney is working in coordination with our airline customers to incorporate upgrades improving the durability of the low pressure turbine in the PW1100G-JM fleet to address a known issue.’’

It did not say by when the entire fleet of the planes would be fitted with the new and modified engines. Each engine replacement costs $10 million.

DGCA said that as the airlines slowly changes all their outdated engines, the regulator expect problems with the engines to end in the next four months.