NEW DELHI: The snag-prone Pratt & Whitney (PW) engine of yet another IndiGo Airbus A320 Neo stalled with a “big bang” and high vibration during take off from Kolkata to Pune on Wednesday (Oct 30). Since twin-engine aircraft can land safely on one engine, this Neo (VT-ITM) returned to do so at Kolkata and is now grounded there. This is the fourth case of PW engine on an IndiGo Neo stalling during take off within a week.

Hours after this fourth engine stall, Director General of Civil Aviation ( DGCA ) Arun Kumar on Thursday afternoon met PW’s top brass, who had flown in from the US following the spate of incidents.

Kumar “told PW in no uncertain terms to comply with the orders (for replacing an engine each on 29 A320 Neos of IndiGo and GoAir that have more snag-prone engines under both wings within 15 days or else be grounded) by providing sufficient modified engines. After this meeting, the PW team and Kumar met aviation secretary P S Kharola who also reiterated the same to the PW,” said a person who attended the meetings.

“PW was told India is a very important market for them (IndiGo is the world’s largest A320 Neo customer) and that they should somehow expedite modified engine deliveries to the country and help avoid grounding of some or any of the 29 planes of IndiGo and GoAir. PW team will return to the US and inform Indian authorities of their replacement engine delivery schedule early next week,” said sources.

Meanwhile, the latest engine stall of Wednesday saw IndiGo’s A320 Neo operating as 6E-862 saw one of its engines stall with a big bang sound and experience high vibration while climbing through 10,000 feet. Crew reduced thrust of this engine to idle and to reduce vibration. Ground inspection on landing revealed that engine one’s third stage low pressure turbine had been damaged.

An IndiGo spokesperson said: “IndiGo A320 Neo operating from Kolkata-Pune as 6E-862… During flight pilot observed engine 1 caution message. Pilot carried out the necessary checklist and returned the aircraft to Kolkata. The aircraft is currently withdrawn from operations and is under maintenance inspections. Alternate arrangements for all the passengers have been made.”

There has been a spurt in cases of PW engines staling with high vibration on IndiGo Neos during climb phase and then the flight returning to where it took off from in last one week. Last Thursday (Oct 24) 6E-563 Kolkata-Chennai returned to Kolkata; a day later 6E 375 Mumbai-Coimbatore returned to Mumbai and then on Saturday (Oct 26) 6E 329 Delhi-Goa landed back in Delhi.

The DGCA found unmodified or older engines of PW that had flown for over 2,900 hours on the Neos were facing this issue. Accordingly, the regulator directed IndiGo and GoAir to change one engine on 16 and 13 of their Neos respectively which had both unmodified engines that had done over 2,900 hours within 15 days. These 29 A320 Neos — that have the old PW engines which have flown for over 2,900 hours under both their wings — will be allowed to fly after 15 days only if one of their engines are replaced. This decision was taken after studying the pattern and evaluating the risk.

“The engine on Kolkata-Pune flight which suffered stall on Wednesday was also one of the old engines that needs to be replaced,” said sources.

