Bombardier’s proposal to build a three-row stretch follow-on of its 86-seat CRJ900 not only begs the question why, but perhaps more immediately, how. Bombardier v-p of marketing and sales Trung Ngo has built the business case for an airplane that would represent the third stretch of a tube originally meant for the Challenger business jet.

According to Bombardier, the CRJ900X shouldn’t prove too complex an undertaking, but the company hasn’t divulged design specifications. Sources close to the project say the airplane will require some relatively significant changes to the wing, including a 7.5 percent trailing edge extension, a 26-inch wing to tip extension, a change in the max flap setting from 45 to 40 degrees and some structural reinforcements.

Along with 62-inch forward and 54-inch aft extensions to the center barrel section, larger passenger windows and a new dual zone ECS system would account for the main changes to the cabin. Other interior changes would include an enhanced Pro Line 4 avionics suite, the introduction of Pro Line 21 navigation and communications LRUs and increased volume in both fore and aft baggage compartments.

Aside from the stretch, structural changes will involve main landing gear reinforcements, upgraded rolling stock and carbon brakes in place of steel for less weight. A new electro-thermal de-icing system would appear in the H-Stab.

Finally, the heavier, longer airplane will require 2 percent more thrust from the GE CF-34-8C5 engines common to the CRJ900. Bombardier would also offer an option for another 5 percent of thrust.