Budget carrier IndiGo today grounded five A320 neo aircraft due to issues with Pratt & Whitney engines, according to sources. Without specifying the number of planes, an IndiGo spokesperson confirmed that "a few A320 neos have been taken out of service pro-actively and await spare engines from Pratt & Whitney". Since the induction of A320 neo planes powered by P&W engines in March 2016, IndiGo has intermittently been facing engine issues and has grounded some of these aircraft on earlier occasions also. The problems varied from mid-air engine shutdowns to oil chip detection. "IndiGo has grounded five of its A320neo aircraft \u00a0due to P&W issues. These aircraft are currently grounded at New Delhi's Indira Gandhi International Airport," a source said. Another source said the five aircraft were grounded today. "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," the spokesperson said in a statement. However, the spokesperson did not mention whether flight services have been disrupted due to the grounding of five planes.