Mid-air technical snag: Engine fire or not? One incident, two versions

AAIB in its letter to AviationMin said there was a fire due to rubbing and excessive friction, but the govt said there was “no fire as confirmed by GoAir”.

Written by Pranav Mukul | New Delhi | Updated: November 14, 2017 4:48 am
aviation safety, india aviation safety, aviation safety india, goa plane, plane crash india, india flight safety, flight safety, flight safety india, In response to a query by The Indian Express, Civil Aviation Secretary R N Choubey said: “Earlier AAIB ordered investigation citing engine fire. However, there was no engine fire as confirmed by GoAir as well as P&W.

On the evening of February 8 this year, a new Airbus A320neo aircraft with registration VT-WGB being operated by GoAir, took off from Delhi for Bengaluru, but returned minutes later. This was because of, according to one version, an engine fire while on the basis of another set of accounts, this was due to an alert of a component failure.

The aircraft did not operate commercially for the 16 days that followed, but the said event was not the only one faced by that aircraft on that day.

In the early hours of that winter Wednesday, the aircraft, equipped with Pratt & Whitney’s new and snag-ridden geared turbofan engines, made its first flight of the day from Mumbai to Delhi. An hour into flight, the pilots in the cockpit received a warning of low oil pressure in one of the engines, which was soon followed by another alert for the same engine in form of a chip warning. The flight continued on its routine course and landed safely at its destination.

After the warning was reported upon landing, GoAir, as per the procedures laid down by the manufacturer, scheduled a physical inspection to find out the reason for the warnings after 10 hours — a duration under minimum equipment list, which is the number of hours the aircraft could have flown after the fault was discovered and before a physical inspection was made. The aircraft, under the minimum equipment list hours, then flew to Leh from Delhi, but could not make an approach due to poor weather and thus returned to Delhi. After this, VT-WGB did a Delhi-Guwahati-Delhi trip. Next, it was scheduled to take-off for Bengaluru at 1840 IST with 187 passengers and six crew members on board.

“The flight took off in a very normal way. But within ten minutes of flight — I was sitting over the right wing of the plane on the middle seat — and suddenly I heard lot of people suddenly screaming ‘fire fire fire’.

I didn’t see it initially, but my attention was there because people on the left hand side of the plane shouted repeatedly.

When I turned towards the left, I saw flames. I could see the flames through the windows, but I believe within a minute the flames were put off,” Saurabh Tandon, one of the passengers on board the VT-WGB that night, told The Indian Express.

Two days after the incident on February 10, the Aircraft Accident Investigation Bureau (AAIB) wrote to the Ministry of Civil Aviation, seeking a probe into the incident. “As per the information received, aircraft returned back to Delhi immediately after liftoff due Eng#1 low pressure followed by Eng#1 auto shut down. Aircraft was dispatched from Delhi under MEL for Engine #1 oil chip warning and also for air bleed maintenance message. As per PIC (pilot in command), all ECAM (electronic centralised aircraft monitor) actions were taken and PAN PAN call was given to Delhi ATC. Aircraft had to carry out a heavy landing and landed safely on runway 28 at Delhi. As per preliminary information there was a fire in the engine due to rubbing and excessive friction of the rotating parts (bearing). Aircraft is grounded at Delhi for further investigation/rectification,” AAIB’s head B S Rai wrote in his letter.

ECAM is a system that monitors aircraft functions and relays them to the pilots along with producing messages about occurrences of any failures. In certain cases, ECAM also lists procedures needed to be undertaken for correcting a problem. ‘PAN PAN’ call is type of a standard distress call, which is used in situations that demand urgent attention but do not, for the time being, pose any immediate danger to life. Multiple attempts to reach Rai through e-mail, SMS and telephone, seeking comments for this story did not elicit any response.

The AAIB sought the permission from the ministry to investigate the incident citing Aircraft (Accident and Incident Investigation) Rules 2012, according to which occurrences classified as ‘Serious Incidents’ are investigated by AAIB. One of the examples of a serious incident under the said rules, as also cited by AAIB, is: “Fires or smoke in the cockpit in the passenger compartment, in cargo compartments or engine fires, even though such fires were extinguished by the use of extinguishing agents”.

The AAIB, as per norms, even sent an initial notification of the incident to the International Civil Aviation Organization (ICAO), a United Nations agency for laying down of principles and techniques for international air navigation. ICAO is currently conducting an audit of the Indian civil aviation sector. According to the rules, the AAIB was bound to notify as much information about the incident “as may be available with a minimum of delay and by the most suitable and quickest means available”, to ICAO and other parties, as the aircraft involved had a maximum mass of over 2,250 kg, or is a turbojet powered aeroplane.

However, despite AAIB’s request for investigation based on the rules, the civil aviation ministry later that month on February 28, wrote back saying that the investigation of the incident would be conducted by DGCA. The reason for the investigation being undertaken by the regulator, and not the accident investigator, according to the government, was that there had been no fire that night on VT-WGB.

In response to a query by The Indian Express, Civil Aviation Secretary R N Choubey said: “Earlier AAIB ordered investigation citing engine fire. However, there was no engine fire as confirmed by GoAir as well as P&W. Accordingly, MoCA took a conscious decision and DGCA was asked to conduct the investigation. The failed engine was sent to manufacturer’s facility for strip examination and to pin point cause of failure. NTSB (the US National Transportation Safety Board) has forwarded the report and concluded wrong fitment of gear in the main gear box which led to chip warning.”

A Pratt & Whitney spokesperson declined comments for this story. A GoAir spokesperson responded to the newspaper’s queries and said: “There was no engine fire reported. Engine was shut down due to low oil pressure. External inspection was carried out for engine in flight shut down. There was neither any fire reported by captain nor indicated in the PFR (post flight report). There was no evidence of fire seen on arrival inspection. As per P&W shop inspection report, in-flight shut down was due to an internal component failure”.

Even as the final report of DGCA, the incident’s investigator, is yet to be made public, based on the preliminary probe, the regulator had suspended the licence of GoAir’s aircraft maintenance engineer, alleging lapses in form of clearing the plane to fly after the engine warnings were received, leading to the incident. The airline, however, had denied any negligence on its part and had pointed out that it only followed the procedures prescribed by the manufacturer.

Apart from GoAir, Pratt & Whitney’s newly-launched PW1100G-Jm engines have been a cause of concern for India’s largest airline IndiGo as well, with both the airlines facing operational issues due to grounding of aircraft. The new engines, which are still in their entry-into-service period, where performance issues and glitches are expected to turn up, faced premature wear and tear of two particular components — the carbon seal in the third chamber of the engine and its combustion chamber.

Even as the manufacturer, now, has started providing spare engines to both these operators, ensuring that none of their aircraft are grounded due to the said problems, passengers on board VT-WGB on the night of February 8 remain distressed about the incident. “It was a very close call for me and my family, and it has had a very long lasting impact on my memory,” Tandon told The Indian Express last month.

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