On 21st June 2017, A GoAir Airbus A320-200, flight G8-338 to Mumbai (India) with 158 passengers and 6 crew, was in the takeoff roll at 05:33:20 hrs on runway 09 at Delhi Airport, when a bird struck the right hand engine (CFM56) causing vibrations and abnormal sounds.
Being unsure of the reason for vibrations, the crew continued takeoff, stopped the climb at 3300 feet, shut the left hand engine down and decided to return to Delhi.
The crew subsequently recognized they had shut the wrong engine down, restarted the left hand engine and reduced the right hand engine to idle. The aircraft landed safely on runway 10 about 20 minutes after departure.
During take-off roll, crew experienced abnormal sound & vibrations. Being unsure of the reason for vibrations, First Officer enquired PIC for rejecting take-off but PIC decided to continue for take-off as he was not sure that the aircraft would stop within the available runway, if executed rejected take-off, and probably wanting to investigate the problem after getting airborne.
ECAM advisory for high N1 vibration of Engine # 2 came at 05:40:32 hrs as value of N1 vibration of Engine # 2 reached above specified limit, i.e. ≥ 6. The vibration advisory was not called out by First Officer. Aircraft IAS was 129 knots at this stage. Values of V1, VR & V2 were calculated to be 146 knots, 146 knots and 147 knots respectively.
After getting airborne, cockpit crew noticed the problem of high engine vibration but assessed the situation incorrectly. As a result, they shut down the Engine # 1 (unaffected engine) by putting its MASTER- OFF at 05:41:48 hrs and increased power to TO/GA on the Engine # 2 (affected engine).
Crew declared emergency due to engine problem to ATC, Delhi at 05:41:50 hrs and requested immediate turn back to Delhi for landing, which was granted by ATC.
During subsequent conversations while climbing, wherein PIC inquired about the engine vibrations, First Officer repeatedly prompted PIC about Engine # 1 vibration out of limits.
The aircraft was climbing on affected engine’s power varying from TO/GA to CLIMB while the unaffected engine was shutdown. On directions from ATC, aircraft stopped climbing at 05:43:13 hrs at around 3330 ft altitude. Subsequently, PIC recognized that the Engine # 2 is affected with high vibrations. Crew realized their mistake at 05:43:42 hrs about shutting down the wrong engine and decided to switch on the unaffected engine.
Crew put MASTER-ON of the unaffected engine at 05:43:49 hrs and attempted to start the engine. While attempting the start of Engine # 1, the Engine # 2 power was put on IDLE at 05:44:15 hrs. At this stage, aircraft was flying at an altitude of around 3332 ft with only affected engine running on IDLE. The attempt to start Engine # 1 resulted in ‘Start Valve Fault’ at 05:44:57 hrs. Crew took appropriate action to rectify the same. Engine # 2 power was put on CLIMB again from 05:45:42 hrs up to 05:45:59 hrs.
First Officer confirmed at 05:45:58 hrs that Engine # 1 is available. Engine # 2 was put to IDLE at 05:46:00 hrs and Engine # 1 put to CLIMB on 05:46:01 hrs. Aircraft was at 3024 ft altitude at this stage.
As per the occurrence report, the weather, after take-off, was very turbulent and the autopilot was not holding. Autopilot was disengaged at 05:41:50 hrs and several times from 05:45:43 hrs to 05:46:44 hrs.
In the process of starting Engine # 1, aircraft lost considerable amount of energy which probably combined with manual handling of aircraft, immediately resulted in activation of protective ALPHA FLOOR at 05:46:01 hrs which lasted for 28 seconds. Crew carried out appropriate action and ALPHA FLOOR got deactivated at 05:46:29 hrs at 2600 ft altitude. ECAM advisory for high N1 vibration of Engine # 2 went off at 05:46:37 hrs.
Value of N1 vibration of Engine # 2 was above the specified limits (≥ 6) for approximately six minutes. The maximum value of N1 vibration of Engine # 2 recorded was 9.9.
While in approach for the landing at 05:50:57 hrs, crew requested ATC for Go-around as they were too high on a glide. The same was granted by ATC immediately. Crew initiated Go-around at approximately 05:51:07 hrs with Engine # 1 on FLX-MCT and Engine # 2 on IDLE.
In the second approach, aircraft landed uneventfully on Runway 10 at Delhi at 05:58:36 hrs with Engine # 2 on IDLE. No injury to any person was reported in the incident.
While taxiing to the allocated stand for parking, not realizing their position with respect to parking stand, crew took wrong turn. Crew of Follow Me # 8 realized the same and communicated to Surface Movement Control (Ground) to ask aircraft to hold the position and switch off the engines. Aircraft held its position and switched off both the engines at 06:01:40 hrs. Subsequently, aircraft was towed to reposition it correctly on the allotted parking stand.
On arrival, during physical inspection, the blood stains were observed spread on the acoustic panel of Engine # 2 & damage was observed on the tips of the leading edge of two fan blades i.e. blade # 21 & # 22.
As crew were unaware about the Bird Strike, no information was given to ATC, Delhi for the same during the incident flight. Identification of species of struck bird could not be carried out as only blood stains were observed on acoustic panel of Engine # 2.
Aircraft’s take-off weight was 65,700 kg and landing weight was 64,770 kg, which was above Maximum Landing Weight, i.e. 64,500 kg.
After the incident, both crew operated Airbus A 320 aircraft VT-WAF for the same flight G8 – 338 (Delhi – Mumbai).