Budget carrier Ryanair is adding orders for five more Boeing 737-800s to the deal for 175 of the type reached last year.
The carrier says four of the jets will be delivered in early summer 2015 and the fifth in February 2016.
All 737-800s are powered by CFM International CFM56 engines.
The agreement means Ryanair will acquire 21 aircraft between September 2014 and July 2015 which, it says, will enable it to enhance its summer 2015 network.
"These new Boeing aircraft enable Ryanair to keep the fleet average age below five years," says chief executive Michael O'Leary.
Ryanair has also expressed interest in the re-engined 737 Max.