Go First has stopped taking bookings for flights on May 3 and May 4, sources said on Tuesday, adding that the airline is facing a cash crunch as more than half of its 57-strong aircraft fleet is grounded due to a delay in engine supply by US-based Pratt and Whitney (PW).The airline has been making losses since FY20. The Wadia group, which is Go First’s promoter, has infused about Rs 3,000 crore in the airline in the last 21 months, sources said. The Group has also taken a debt of about Rs 1,300 crore in the same time period.Go First did not immediately respond to queries sent by ‘Business Standard’.About 90 per cent of the airline’s aircraft fleet uses PW engines. More than 50 per cent of the airline’s 57 planes are grounded due to delays in engine supply by PW. Therefore, Go First operated about 50 per cent fewer flights last month compared to a year before, as per aviation analytics firm Cirium.As per Cirium’s data, the airline operated about 2,771 flights weekly in April last year. However, due to more planes being grounded in the last year, flight operations have been reduced. Last month, the airline operated about 1,362 flights per week.PW’s contract with Go First has three main conditions: PW has to provide a spare engine within 48 hours of an aircraft getting grounded due to its faulty engine; faulty engines have to be repaired free of charge as they are under warranty; and compensation has to be provided to the airline for “productivity loss” due to grounded planes.”Till March 2020, PW did provide spare engines on time, did repair without cost, and did provide some compensation. However, the airline has not received anything after that time,” said a source privy to the development.Go First received its first PW engine-powered A320 plane in 2016. “PW engines started facing issues 6-8 months after the first delivery,” the source said.Go First is experiencing engine issues (and suffering from grounded planes) at a time when other Indian carriers are expanding their flights due to increased demand.Go First’s performance over the yearsYearNet profit/loss (in Rs crore)FY15 27.73FY16150.24FY17205.25FY18152.08FY19123.34FY20-1270.92FY21-870.48FY22-1807.91    Source: Go First