Slower replacement of turbines force IndiGo, GoAir to ground planes

Lingering issues with Pratt and Whitney engines are leading to grounding of planes for IndiGo and GoAir. The issue has become complicated as manufacturer Pratt and Whitney has not kept up with delivery of sufficient spare engines. IndiGo, India's biggest airline by market share is the largest customer for the A320neo model with 430 jets on order.

According to an analysis done by Business Standard using data from aircraft tracking website Flightradar24, currently six jets of A320 Neo variant of IndiGo and GoAir are grounded waiting for replacement. Earlier, news agency Bloomberg had reported that Toulouse-based airframe manufacturer Airbus expects to deliver 30 to 40 fewer A320 Neos than previously planned 210 jets. IndiGo has also over the last two months occasionally grounded many of its A320 Neo jets for replacement of engines.

"A few A320 neos have been taken out of service pro-actively and await spare engines from Pratt & Whitney. The release of additional spare engines has been initiated by P&W so that all aircraft are expected to be back in service in the second half of August,” an IndiGo spokesperson said.

A senior DGCA official explained the reason for replacement due to more stringent norms of boroscopic (visual) inspection of the combustion chamber. “DGCA has recommended inspection of combustion chamber at 1,000 hours instead of 1,500 hours recommended by the engine manufacturer. The airlines have been asked to do an engine replacement if any sign of stress is found. Hence, it is leading to higher rate of removal,” said a senior DGCA official.

The Pratt and Whitney engine since being pressed into service have faced operational issues. In 2016, initially it started reporting oil metal detector warnings. The third engine bearing compartment had a seal which didn’t work correctly at high Flight Levels. The thin air caused the air riding seal members to sometimes oscillate and touch. This left metal particles in the engine oil, which caused warnings pointing to a potential engine problem. The manufacturer gave a fix which was a change to a more classical carbon seal.

The third problem was combustion chamber linings which had unforeseen hot spots, reducing the linings operational life. The fix provided was a combustion chamber with more porosity.

Early this year, however, a more serious problem surfaced. A modified knife edge seal introduced by Pratt and Whitney in late 2017 started showing signs of wear ina very early cycle of their life. The broken seal started damaging the compressor and turbine causing in flight shut downs leading to Airbus stopping of any new jets.

Analysts indicated that the current grounding will not have any material impact on IndiGo’s market share  as the airline continues to add capacity from both Airbus and secondary lease markets.” The capcity addition momentum is intact. This is reflected in the recent quarterly figures where Indigo continued to deliver growth of 20 percent ahead of the market to regain  lost market share in first half of 2018,” brokerage firm SBI Caps noted in a research report.

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