(Reuters) - Airbus faces a record $4 billion fine and lower 2019 profits after unveiling a preliminary deal with French, British and U.S. authorities following a crippling three-year probe into allegations of bribery and corruption over jetliner sales.

The deal, believed by anti-corruption experts to be the largest ever in a bribery case, ends an almost four-year crisis that led to a sweeping management overhaul and delayed plans to redeploy the plane giant’s cash surplus.

If approved by courts, the deal is expected to allow Airbus to avoid criminal charges that risked banning the company from public contracts in the United States and European Union - a massive setback for one of Europe’s top defense and space firms.

The European planemaker has been investigated by French and British authorities for suspected corruption over jet sales dating back over a decade. It has also faced U.S. investigations over suspected violations of export controls.

Announcing the tentative agreement, Airbus - which dominates the commercial jet market alongside U.S. rival Boeing - said it would take a provision of 3.6 billion euros ($3.96 billion) in its 2019 earnings if the deal won approval in court hearings in the United States, Britain and France on Jan 31.

“To my knowledge, an approximate $4 billion global settlement amount would be the largest global bribery settlement amount in history,” said bribery law expert Mike Koehler, a professor at Southern Illinois University School of Law.

That compares with analyst expectations of 3-5 billion euros and dwarfs an $809-million multinational settlement in 2017 over the use of middlemen by aero-engine maker Rolls-Royce, which included the biggest ever corruption fine in Britain.

Airbus said the charge would affect 2019 results due on Feb 13. Analysts had expected 2019 net profit of 4.638 billion euros against 4.405 billion in 2018, according to Refinitiv data.

Despite the hit, Airbus shares rose 1% on what appeared to end one of the most damaging chapters in its history.

FILE PHOTO: An Airbus A350 takes off at the aircraft builder's headquarters in Colomiers near Toulouse, France, September 27, 2019. REUTERS/Regis Duvignau

“Sorting out the fraud investigation is likely to remove a major overhang for the company,” said Vertical Research Partners analyst Rob Stallard. Others noted plans for a new share buyback had been postponed as Airbus faced uncertainty over the fines.

British and French investigations began after Airbus alerted regulators to misleading and incomplete declarations it had made to Britain’s export credit agency over payments to sales agents.

Britain’s Serious Fraud Office (SFO) launched its probe in August 2016, followed seven months later by France’s Parquet National Financier (PNF).

It was not immediately clear to what extent the U.S. part of any settlement would stick to the infringement of export control violations or include the broader corruption case.

The U.S. Department of Justice has signaled a close interest in the bribery affair while mainly allowing Britain’s SFO to take the lead, say people familiar with the matter.

It was also not clear whether a deal would lead to individual prosecutions, which are not covered by corporate plea bargains. Britain’s SFO abandoned individual prosecutions over the Rolls-Royce case last year.

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At the center of the Airbus case was a decades-old system of third-party sales agents run from a now-disbanded headquarters unit which at its height involved some 250 people in parts of the world and several hundreds of millions of euros of payments a year, sources familiar with the matter have said.

In 2014, then finance director Harald Wilhelm ordered a halt to all third-party payments, triggering a massive internal probe and claims from unpaid consultants.

The investigation, which racked up legal bills of around 100 million euros a year, led to a board-driven clearout of the company’s top management and plunged the company into years of self-examination, hampering its sales efforts.

Nobody has been accused of wrongdoing but Airbus acted to clear out its senior ranks to improve its chances of winning a U.S.-style deferred prosecution agreement (DPA), insiders said.

In a landmark 2017 ruling setting the bar for future settlements, a British judge had described Rolls-Royce as “dramatically changed” with a new leadership and culture.

Airbus has fired more than 100 people over ethics and compliance issues as a result of its own probe into the allegations, which widened to other divisions.

But the internal probe led to anger within the Franco-German firm and its jet sales teams who denied any influence over the tightly controlled agent system, which political sources have described as part of a wider French influence network abroad.

It also threatened to reopen Franco-German tensions over Airbus as French sources complained the row diverted attention from a separate probe into fighter jet dealings with Austria, partially overseen by German-born Tom Enders who later served as chief executive. Enders has denied any wrongdoing.

A further German probe into potential misuse of client documents is ongoing.