Since the PW1500G mount generates less strain on the turbine rotor assembly than the A320neo's PW1100G, it does not suffer from start-up and bearing problems but still from premature combustor degradation. After 28,000 engine hours in 14 in-service aircraft with a powerplant dispatch reliability of 99.9%, Swiss replaced an engine pair in May 2017 after 2,400 h, while AirBaltic replaced another one in June. An updated combustor liner with a 6,000–8,000 hour limit has been developed and a third generation for 2018 will raise it to 20,000 hours in benign environments.