FILE PHOTO: The logo of Brazilian aviation company Embraer is seen during the Latin American Business Aviation Conference & Exhibition fair (LABACE) at Congonhas Airport in Sao Paulo, Brazil August 14, 2018. REUTERS/Paulo Whitaker

SAO PAULO (Reuters) - Brazil planemaker Embraer EMBR3.SA delivered 26 commercial planes in the second quarter of 2019, down from 28 planes in the same period of 2018 and 35 in 2017, the company said in a securities filing on Tuesday.

Embraer has been struggling to turn a profit in recent months, as demand for its executive jets remains weak and its new generation commercial planes have not met certain requirements to be flown by the larger carriers in the United States.

The company said its firm order backlog, a gauge of future revenue, increased to $16.9 billion from $16 billion in the previous quarter. A year earlier, the backlog stood at $17.4 billion.

Deliveries of executive jets rose slightly to 22 planes from 20 planes a year earlier.

Embraer is in the process of finalizing the sale of 80% of its commercial jets division, its most profitable, to Boeing BA.N for $4.2 billion. The sale has been approved by Brazil's government and Embraer's shareholders but still needs regulatory approval from several countries.