Investigators in India have identified that a high-pressure turbine blade giving way - due to “enormous stress” - was likely the cause of an engine failure on an IndiGo Airbus A321neo.
According to the final investigation report from the Directorate-General of Civil Aviation (DGCA), the incident on 10 June 2023 has also prompted CFM to redesign the Stage 1 high-pressure turbine blade on the Leap-1A, which “demonstrated improved durability during production testing”, and will be retrofitted globally.
The IndiGo jet (VT-ILN) was operating flight 6E2789 from Delhi to Chennai when the incident occurred just after take off. Six minutes after take-off and as the aircraft was climbing, the flight crew heard a loud bang, then were notified that the No.1 engine had stalled before it failed.
The crew transmitted a ‘pan pan’ urgency message and shut down the No. 1 engine. They subsequently performed a single-engine landing at Delhi airport, 30min after departure.
There was no evidence of external fire or smoke from the aircraft, nor were any injuries sustained among the 233 passengers and seven crew members.
Post-flight engine inspections found “metal particles” in the exhaust of the Leap-1A engine. Boroscope inspections also showed that the high-pressure turbine stage 1 and 2 blades, as well as the low-pressure turbine blades, were badly damaged.
A deeper analysis of the blades revealed that the engine was “exposed to structural overstress, sudden rotor stoppage, as well as excessive G-loads”.
The DGCA also notes that the incident is the first in a string of CFM International Leap-1A engine failures that hit the Indian low-cost carrier over the span of a year.
In October 2023, another A321neo flying from Udaipur to Mumbai had its no. 1 engine fail while taking off, forcing the aircraft to be diverted to Ahmedabad.
Similar engine failures happened in January and May this year, on an A320neo and A321neo respectively.
The DGCA has requested IndiGo to carry out borescope inspections of existing blades on its Leap-1A engines until the new turbine blades have been installed across its fleet.
According to Cirium fleets data, the aircraft (MSN10151) was delivered to the airline in 2021. IndiGo has 90 A321neos in service, 79 of which are powered CFM engines.
