India's largest airline IndiGo, which flies four out of every 10 Indians, has had to replace Pratt & Whitney engines on its 32 A320 Neo aircraft at least 69 times in the period May 2016-November 2017. This is an astonishingly high number that raises a question mark over passenger safety in Indian skies. On an average, a fleet of 100 aircraft requires about 40 such engine changes/replacements in a 3-year period.
IndiGo says these are related to non-detection of chip, carbon seal lining or combustor chamber lining in Pratt & Whitney 1100 series engines. The airline calls these engine 'glitches' and 'non-safety' issues. Indigo's boroscopic tests (which are used to test defects or imperfections through visual inspection by a boroscope of aircraft engines and gas turbines, etc) detected these anomalies in 69 instances. As per practice, the defective engines were replaced with other engines. Such engine replacement is typically done overnight. After the replacement, the defective engine is sent to the manufacturer to fix the problem. The planes continue to operate with the replaced engines.
However, that's the least of IndiGo's problems as it has had graver issues to deal with. Over the past 18 months, IndiGo has had three instances of one of the two engines of the aircraft shutting down. The aircraft landed safely powered by the second engine. Those engines have been replaced and the aircraft are back in the air.
Over the past 2 days, however, its Pratt & Whitney PW4500 series engines have reported issues related to vibration. However, the manufacturer advised all airlines around the world to ground such planes which have both PW4500 series engines. Indigo had 3 such planes out of the 11 such planes worldwide. These planes are grounded and one of the PW4500 engines is being replaced in each of these aircraft.
IndiGo has been struggling with the Pratt & Whitney engines in the newest A320 Neo aircraft ever since they were first inducted in February, 2016. Greg Hayes, chairman of Pratt & Whitney's parent UTC, responded to the issue in the post-earnings call in September, saying the company remains, "on track to certify a combustor upgrade to incorporate into new engines."
Yet, it is the continuing problems with the engines that raise concerns regarding passenger safety in Indian skies. Especially, when it comes to India's biggest airline.