(Adds comment from executives, analysts)
By Brad Haynes
SAO PAULO, April 27 (Reuters) - Brazilian planemaker Embraer SA on Friday posted a net loss due to weaker aircraft deliveries and write-downs on used airliners as major sales activity stayed quiet amid tie-up talks with Boeing Co.
The world's third-largest commercial planemaker reported a first-quarter net loss of $12.3 million, compared to a net profit of $53.2 million a year earlier, according to a securities filing.
Embraer shares fell 3.5 percent in Sao Paulo trading.
Boeing and Embraer announced in December that they were negotiating a "potential combination" and confirmed this month it could involve a new company making commercial jets, excluding Embraer's defense operations and perhaps its business jet unit.
Embraer shares are up about 40 percent since news of the talks broke, but there have been no big orders as airlines wait to see whether Boeing will integrate Embraer's regional E-Jets into its lineup.
Chief Executive Paulo Cesar Silva said the Boeing talks have not been affecting sales campaigns, adding that he expected "a very good year" for E-Jet sales.
Embraer's transition to a new generation of commercial jets, known as E2, has also pushed up costs and hurt demand for the prior E1 family of aircraft.
"Results confirmed our view that Embraer had a small E1 backlog for the transition period to the E2," wrote Bradesco BBI analysts led by Victor Mizusaki.
Embraer's firm order backlog excluding most service contracts continued to slip in the quarter to $18.1 billion at the end of March from $18.3 billion in December and a peak of $22.9 billion in June 2015. Under a new accounting method including all service and support contracts, the backlog – a gauge of future revenue – totaled $19.5 billion in March.
Net revenue slipped 5 percent from a year earlier due to fewer deliveries of airliners and business jets, partially offset by a 63 percent increase in defense revenue.
With less overall revenue to dilute fixed costs, earnings before interest, taxes, depreciation and amortization (EBITDA) fell 26 percent to $89.5 million.
Embraer also reported "other" operating expenses of $29.7 million, driven in part by expectations of a larger write-down on its portfolio of used commercial jets.
Executives said the impairments were related to old ERJ-145 planes and not likely to be repeated in coming quarters, adding that "other" operating expenses should return to around $20 million to $25 million per quarter for the year. (Reporting by Brad Haynes, additional reporting by Paula Laier; editing by Nick Zieminski and Phil Berlowitz)