Late last month, Delta Air Lines gave Bombardier's (NASDAQOTH:BDRBF) troubled CSeries aircraft program a big lift by placing a firm order for 75 CS100 jets, with another 50 options. This order -- along with Air Canada's recent order for 45 CS300 jets -- will give other airlines more confidence in ordering the CSeries.

A longer production run will ensure that spare parts remain plentiful, keeping long-term maintenance costs down. It will also create a more-vibrant market for used CSeries jets.

Bombardier Cseries

Two big orders have gotten Bombardier's CSeries program off the ground. Image source: Bombardier.

As a result, Bombardier expects to be able to use the big Delta deal to bring in more orders. Just this week, Bloomberg reported that Bombardier was in talks with JetBlue Airways (NASDAQ:JBLU) about a potential CSeries order. However, while JetBlue may be talking to Bombardier, I'm very skeptical that it will purchase any CSeries jets.

JetBlue-Bombardier deal rumors resurface
The recent report that JetBlue is looking at the CSeries jets follows a similar story that came out in October. At that time, Bombardier was still searching for a marquee deal with an established North American airline.

However, JetBlue was never likely to become one of the first CSeries customers. A decade ago, JetBlue helped launch Embraer's (NYSE:ERJ) 100-seat E190 jet, and it proved to be a big mistake. Former JetBlue CEO Dave Barger has publicly stated that the company wasn't big enough to take on the risk of operating a brand-new aircraft type.

Now that Delta and Air Canada have both placed substantial orders, it's more plausible that JetBlue would be interested in one or both of the CSeries models. However, that would mean adding a third aircraft type to its fleet of Airbus (NASDAQOTH:EADSY) and Embraer planes.

How would the CSeries fit in?
JetBlue currently operates 159 Airbus A320-series aircraft -- outfitted with 150-200 seats each -- along with 60 100-seat Embraer E190s. Thus, while it has deviated from the single-aircraft-type strategy followed by many low-cost carriers, it still has a very simple fleet.

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JetBlue has two aircraft types in its fleet today. Image source: JetBlue Airways.

The CSeries jets would fit somewhere in between the E190s and the A320s. In JetBlue's single-class configuration, a CS100 might hold 110-115 seats, while the CS300 could fit 135 seats.

JetBlue plans to add two rows of seats to all of its A320s between 2017 and 2019, which would increase their seating capacity from 150 to 162. Thus, the gap in seating capacity between JetBlue's E190 and A320 fleets is set to widen in the next few years. That could increase the company's interest in buying planes in the CSeries size range.

Hard to justify the additional complexity
Even if JetBlue wants to buy a plane that is bigger than its E190s, but smaller than its A320s, it can do so without adding a third aircraft type to its fleet. Airbus and Embraer both have new products arriving in the next few years that will be more competitive with Bombardier's CSeries jets than their current offerings.

Airbus has the A319neo, which is part of the A320neo family that JetBlue has already ordered in large numbers. It's roughly similar in size to the CS300. While the A319neo won't be as fuel-efficient as the CS300, Airbus' huge manufacturing scale could allow it to offer much lower pricing to seal the deal.

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Embraer's E2-series jets will share a type rating with JetBlue's existing E190 fleet. Image source: Embraer.

Embraer's E195-E2 is potentially an even more-compelling option. It's somewhere between the CS100 and CS300 in size. Thanks to its lighter weight, the E195-E2 will be very close to the CSeries jets in fuel efficiency and unit costs, according to an analysis by Airways News.

Additionally, the E195-E2 will share a common type rating with JetBlue's existing E190 fleet. As a result, with just three extra days of training, pilots would be able to operate either one of those models. The E195-E2 also has a lower list price than the CSeries jets or the A319neo.

Does JetBlue even want more planes?
A final consideration is that JetBlue's order book is already quite full. As of the end of March, it had firm orders for 112 aircraft scheduled for delivery between now and early 2023. Most of these are growth aircraft, as none of JetBlue's planes need to be replaced soon -- although it could opt to return some of its leased airplanes.

With this fleet plan, JetBlue already has all the orders it needs to maintain its high single-digit growth rate through 2022 -- even if it returns some leased aircraft during that period. It's very doubtful that JetBlue would want to grow any faster than that.

Thus, to score a big coup with JetBlue, Bombardier will have to offer extremely low pricing or offer to buy back JetBlue's Embraer fleet. Even then, Airbus and Embraer would fight hard to keep Bombardier out by offering huge discounts on their next-generation planes. Thus, the chances of a JetBlue CSeries order remain very slim.

Adam Levine-Weinberg owns shares of Embraer-Empresa Brasileira and JetBlue Airways and is long July 2016 $25 calls on Embraer-Empresa Brasileira, long January 2017 $17 calls on JetBlue Airways, and long January 2017 $40 calls on Delta Air Lines, The Motley Fool recommends Embraer-Empresa Brasileira. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.