India's aviation regulator on Monday said it has extended deadline for IndiGo to replace all 135 unmodified Pratt and Whitney(PW) engines from Jan 31 to May 31, news agency PTI reported. The DGCA had earlier directed the budget carrier to carry out replacements on 97 Airbus A320neo aircraft having turbine blades built with titanium by January 31, 2020 following a series of engine incidents.