Quoted from aer lingus web site
Aer Lingus - Need Help - Baggage Information- Economy - 2nd and subsequent bag weighing up to 23kg (50lbs) will be charged.
- Flexifare - 3rd and subsequent bag weighing up to 23kgs will be charged as below.
- Business Class - 3 bags up to a total of 69kgs (150lbs) carried free of charge.
2nd and subsequent bags weighing up to 23kgs (50lbs) - £36
Excess for all bags over 23kg-32kgs (50lbs-70lbs) - £36