Created Friday, Feb 10th 2023 17:43Z, last updated Tuesday, Jan 20th 2026 17:36Z
An Indigo Airbus A320-200N, registration VT-ISE performing flight 6E-5926 from Amritsar to Kolkata (India) with 122 passengers and 6 crew, was climbing out of Amritsar's runway 34 when the crew stopped the climb at 4000 feet due to the failure of the left hand engine (PW1127G). The crew shut the engine down and returned to Amritsar for a safe landing on runway 34 about 15 minutes after departure.
A replacement A320-200N registration VT-IVI reached Kolkata with a delay of about 2.5 hours.
The occurrence aircraft remained on the ground in Amritsar for 4 days before positioning to Delhi (India) and resuming service.
On Apr 20th 2023 India's AAIB reported the aircraft was climbing through 3000 feet when a loud bang occurred and an engine #1 failure indication occurred on the ECAM. The engine was shut down and the aircraft returned to Amritsar. The occurrence was rated a serious incident and is being investigated by India's AAIB.
On Jan 20th 2026 the AAIB released their final report concluding the probable causes of the serious incident were:
The probable cause of this serious incident could be attributed to the fracture of the HPT 2nd stage Air seal caused due to axial rubbing between the HPT 2nd stage air seal and the TIC inner case. The axial rubbing was caused due to the reduced gap between the HPT 2nd stage air seal and TIC.
Contributory Factors
a) The HPT 2nd stage air seal wire seal was likely mis-assembled causing a bulge at the rear of the HPT 2nd stage Air Seal, reducing the cold assembly gap between the HPT 2nd stage air seal and TIC.
b) The hardware design process did not capture accurately the maximum gap closure between the HPT 2nd stage Air Seal and TIC Inner Case.
The AAIB analysed:
As per last shop visit records, the HPT 2nd stage air seal wire seal (Part No.50L294) was installed according to step 14 of the “HPT 2nd stage rotor assembly (final)” special procedure of the EM (SP1100G-B-72-5140-00B-710A-B, “Version B”).
Post wire seal installation, the visual check as mentioned in the Step 16.B of the “HPT 2nd Stage Rotor Assembly (Final)” special procedure of the EM (SP1100G-B-72-5140-00B-710A-B, “Version B”) to make sure that the wire seal remained in position on the air seal was carried out.
On completion of task as per work scope, the engine was assembled, and all necessary tests were carried out as per OEM maintenance data (Engine Manual-5316992 rev. 30.00 dated 15 June 2022). On successful completion of all checks the PW1127GA-JM engine (serial no. P770369) was finally released to service at 8212:32 total engine hours (TSN) and 5174 cycles (Total) on an Authorized Release Certificate (FAA Form 8130-3, dated 24th May 2022) by the OEM.
However, the engine was re-inducted in the same engine shop to undergo the maintenance tasks as per the workorder no. 9A 120-02 rev. A, dated 08.12.2022. The reason for the original induction was HPT 1st stage blade distress beyond AMM. After completion of maintenance tasks on 29th August 2022, again an Authorized Release Certificate (ARC) was issued by the engine shop at 8212:32 engine hours (TSN) with 5174 cycles.
The engine (serial no. P770369) was installed on the aircraft VT-ISE on 13th September 2022 and had accumulated 1,646 hours TSLSV (Time since Last Shop Visit) and 1002 cycles till the incident flight.
Post incident involved engine was thoroughly examined at the OEM’s facility. The laboratory examination and witness marks of HPT 2nd stage air seal wire indicate that the HPT 2nd stage air seal wire seal (Part No.50L294) was out of the air seal groove and was likely mis-assembled during the last shop visit.
The engine examination confirmed that the clashing contact between the HPT 2nd stage Air Seal and the TIC Inner case was an unprecedented event and was likely due to a combination of local air seal deflection and greater than predicted gap closure. In view of the above discussions, it is concluded that the serviceability of the engine was the main contributory factor to this serious incident.
...
On 7th December 2021, the PW1127GA-JM engine with ESN P770369, installed at position 01 on an Airbus A320 series aircraft operated by M/s IndiGo, was removed for an MRO’s engine shop visit at 8212:32 engine hours (TSN) and 5174 cycles (Total).
On 8th February 2022, the engine was inducted in the MRO’s engine shop to undergo the maintenance tasks as per the workorder no. 9A 120-01 rev. C, dated 05.02.2022. On 24th May 2022, upon completion of the tasks an Authorized Release Certificate (ARC) was issued by the engine shop. However, the engine was re-inducted in the same engine shop to undergo the maintenance tasks as per the workorder no. 9A 120-02 rev. A, dated 08.12.2022. The reason for the original induction was HPT 1st stage blade distress beyond AMM. After completion of maintenance tasks on 29th August 2022, again an Authorized Release Certificate (ARC) was issued by the engine shop at 8212:32 engine hours (TSN) with 5174 cycles.
During the above mentioned last shop visit, the HPT 2nd stage air seal wire seal (P/N 50L294) was installed in accordance with the maintenance procedures given in the HPT 2nd stage rotor assembly (final) special procedure of the EM (SP1100G-B-72-5140-00B-710A-B, “Version B” and subsequently the HPT 2nd stage air seal wire seal was visually checked to ensure that the wire seal remains in its position as per the same special procedure of the engine manual.
Later, the engine was installed on the aircraft (VT-ISE) at position 01 (LH-side) on 13th September 2022 at 8212:32 engine hours (TSN) and 5174 cycles (Total). Post installation on the aircraft VTISE, the engine had accumulated 1646 hours and 1002 cycles till the incident flight.
As per the OEM, “Once properly installed, the wire seal is unable to egress the seal slot during operation.” However, the traces observed during the investigation confirm that the wire seal had dislodged from the groove. Therefore, it infers that the wire seal was mis-assembled during the engine’s last shop visit.
During the engine examination & engineering analysis the OEM has also established that the misassembled wire seal produces a local axial bulge at the rear of the HPT 2nd stage air seal. Which pushes the HPT 2nd stage air seal towards the TIC i.e., a local axial deflection of HPT air seal OD surface. The delta displacement between the HPT 2nd stage air seal due to an out of position wire seal for one blade lug length and the air seal at nominal assembly condition is 0.034 inches.
This delta displacement reduces to 0.016 inches at ETO (End of Takeoff) running condition as the wire seal becomes softer at high temperatures. Test results also showed that the gap can have as much as +/- 30% variation in thermos-mechanical closure relative to initial calculations. Furthermore, at the upper end of this closure variation, in combination with a mis-assembled wire seal, Air Seal to TIC contact is predicted.
On February 5, 2023, M/s IndiGo’s A320 (NEO) aircraft with registration VT-ISE, equipped with a PW1127GA-JM engine (ESN P770369, fitted at position 01) was scheduled to operate flight 6E5926 from Amritsar to Kolkata. No abnormalities were observed by the maintenance personnel during the transit inspection carried out prior to the departure from Amritsar airport. After takeoff, when the aircraft was climbing around 3000 ft, a portion of the engine No. 1 HPT 2nd stage air seal, which had a local deflection likely due to a mis-assembled wire seal, fractured due to a clash between the TIC Inner Case and the air seal. This IOD (Internal Object Damage) had caused a high rotor imbalance. This high rotor imbalance led to an engine stall condition and surge of the HPC stage. Consequently, the LPT stage suffered damage. Subsequently, “ENG 1 STALL, ENG 1 HIGH VIBRATION, ENG 1 FAIL, ENG 1 START FAULT ENG 1 OIL CHIP DETECTED” ECAM messages triggered on the ECAM.
The pilot followed the company’s emergency handling procedure (QRH) and shut down the affected engine. Subsequently, the aircraft landed safely with one engine at departure Airport.
