Danish lessor Nordic Aviation Capital (NAC) has signed a firm purchase agreement for four Bombardier Q400 NextGens to be placed with Latvian carrier airBaltic.

The $134.8 million deal, announced Thursday, will take NAC’s Q400 portfolio to 43 aircraft, and firms up airBaltic’s Q400 fleet expansion plans reported by ATW in September.

“The four aircraft will be operated by airBaltic of Riga, Latvia and will join eight Q400 NextGen airliners ordered directly from Bombardier as the airline transitions to an all-Bombardier fleet,” NAC said in a statement.

At the 2012 Farnborough Air Show airBaltic committed to 10 CS300 aircraft, with purchase rights on a further 10, which will be used for its fleet renewal. It firmed the deal in December.

Billund-based NAC has also recently sealed a sale and leaseback with Marfin Investment Group covering 10 Q400s to be operated by Olympic Air. It has also agreed to the sale and leaseback of eight Q400 NextGens with Eurolot of Poland and the purchase of 12 CRJ1000 NextGens with Garuda Indonesia.