Aer Lingus A319 EI-EPR operated EI30 Belfast City – London Heathrow this morning, however it was unable to operate the return EI31 due to a technical issue. Airbus A320 EI-DVM, which had arrived at London Heathrow as EI154 from Dublin was used to operate EI31 Dublin – Belfast City with EI155 London Heathrow – Dublin being cancelled.