On Tuesday, the US Department of Commerce is expected to announce its first ruling on the Boeing's complaints against Bombardier's sale of its new C Series airliner to Delta. It's a ruling that could set off a trade war between the US and Canada.

For years, the story around the Bombardier C Series program has been blighted cost overruns, developmental delays, and slow sales.

In 2015, Bombardier was forced to write down $4.4 billion. At the same time, the company took a $1 billion bailout from the Quebec government. In return, the provincial taxpayers took a 49.5% stake in the C Series. Even as it struggled to close a sale, Bombardier was credited with building an aircraft that's one of the most capable on the market today — besting rivals Boeing and Airbus in terms of efficiency and ability.

At the heart of Boeing's complaint is a deal that was widely seen as the order that saved the Bombardier C Series program from its demise.

Looking for a blockbuster sale to help build traction for the plane in the US, Bombardier went all in on a pitch to United Airlines. Sensing the new competition, Boeing bit the bullet and gave United a whopping 70% discount on the 40 737-700s. While large airlines like United never pay list price, 70% off is the aviation equivalent of a Black Friday sale price.

In January 2016, United announced the sale of 40 737-700s followed by an order of another 25 of the same planes in March. (Oddly enough, United realized several months later they actually didn't want any of these planes and converted them to four of the larger 737-800s and 61 737MAX jets.)



Finally, in April 2016, Bombardier struck pay dirt. Delta Air Lines ordered 75 C Series 100 airliners in a deal worth up to $5.6 billion. In addition, Bombardier and Delta agreed to an option for 50 additional jets.

With the Delta order, Bombardier has not only found a US launch customer for the C Series, but it had the blockbuster deal it needed to validate the attractiveness of aircraft to other prospective buyers.

With the C-Series, Delta has a long-range ultra-fuel-efficient, 100-seat jet capable of making money in markets where competition has depressed profits. In addition, the new Bombardier jet will allow Delta to operate mainline service in markets that traditionally were serviced by smaller regional jets.

From Boeing's perspective, how Bombardier netted the deal has it seeing red.

According to its complaint, Boeing claims Bombardier sold the CS100 for just $19.6 million. That's far less than the $33.2 million the Chicago-based aviation giant alleges it cost Bombardier to make the plane and a mere fraction of the CS100's $79.5 million sticker price. As a result, Boeing claims the Montreal-based company is dumping its product on the US market to the detriment of the US aviation workers.

Thus, it wants to slap a 160% tariff on every one of the C Series jet ordered by Delta. It's a move that is seen as one that could effectively kill off the C Series program.

In response, Delta and Bombardier posit that Boeing complaint is baseless because neither it nor any other US airplane maker currently offers a product comparable to the CS100's size and performance. In fact, Boeing hasn't included the pint-sized 737-600 in its annual price list for more than half a decade. As a result, they say Boeing didn't lose a sale because they don't have a product in the running.

In addition, Bombardier argues protectionist action against the C Series would harm US aviation industry as more than 50% of the plane's components come from US suppliers.

The dispute how now entered the realm of politics with Canadian Prime Minister threatening to scuttle the country's plans to buy $5 billion worth of F/A-18 Super Hornet fighter jets from Boeing. British Minister Theresa May expressed her concerns regarding the dispute due to the fact that the C Series' wings are made in Northern Ireland.

On Monday, the Commerce Department is expected to rule on whether Bombardier benefitted from improper government subsidies, CTV reported. However, the contents of the ruling aren't likely to be made public until Tuesday. On October 4, the Commerce Department will also rule on whether Bombardier dumped the C Series on the US market.

As we await the rulings, let's take a closer look at the plane behind all of this controversy.

Shortly after the deal's announcement, Bombardier flew one of its CS100 demonstrators down to Delta's Atlanta headquarters for journalists and the airline's staff to get a closer look.