The request for the U.S. government to intervene comes as Airbus (AIR.PA) has been talking about the development of a new plane as early as 2030, potentially kickstarting a new wave of competition in the global jet market.
Both sides won partial victories in a 17-year battle at the World Trade Organization over mutual claims of aircraft subsidies that led to a wave of Transatlantic tariffs hitting other industries, before agreeing a five-year truce in 2021.
The truce, which was set to expire on July 6, has been extended indefinitely as both sides draw back from a renewed trade war in aerospace.
In a letter to U.S. Trade Representative Jamieson Greer, seen by Reuters, Boeing said it had been surprised by a June 29 announcement from the European Investment Bank, the EU lending arm, committing to its largest-ever corporate loan for Airbus.
It asked the USTR to request a "full accounting of the terms of this loan" from the EU and to explain why it was compatible with the 2021 truce agreement, which called for an "open and transparent process".
Boeing noted that the announcement, which included an initial tranche of €1 billion, came just four days after the EU adopted the decision to extend the standstill agreement.
"At a minimum, the timing of this loan is surprising," Boeing said in its letter.
The EIB said it finances thousands of companies every year and denied offering Airbus any unusual support.
"This is a normal loan, carrying interest, part of the EIB's overall financing activity," a spokesperson said.
Airbus and Boeing declined comment.
The USTR and European Commission did not immediately respond to requests for comment.
AIRPLANE DEVELOPMENTS
In its loan announcement, the EIB said the package of loans would support Airbus' long-term investments through 2030.
Boeing noted that this is the same year in which Airbus CEO Guillaume Faury has said Airbus plans to begin the development of an A320neo successor.
In an interview with Aviation Week ahead of the Farnborough Airshow, Faury spoke of a new plane in 2030 and disclosed the internal code word for the project, "eAction".
"The timing of this significant loan also coincides with Airbus leadership remarks publicly committing to a launch date of a new airplane, which further raises questions about both the size and the intent of this historic economic assistance package," Boeing's letter to the USTR said.
Boeing has said market conditions are not yet right for a new generation of planes, although analysts say both companies are expected to start the next developments by mid-decade.
Boeing's letter underscores wariness over funding on both sides, though tensions have eased considerably since the WTO subsidy battle.
The Trump administration last year agreed to exempt airplanes and parts from tariffs after briefly imposing duties on aviation last year.
Washington has not officially said it is extending the separate truce on tariffs tied to the Airbus-Boeing dispute, but four people familiar with the matter said both sides had effectively buried the marathon WTO dispute for the time being.
Trump called this month for talks with trading partners to address the impact of foreign jet imports.
Boeing's concerns about the EU loan to Airbus could also be raised in those talks, a U.S. official told Reuters. European sources say similar loans were cleared in the WTO dispute.
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