Comments

Sounds a little over-zealous to me. An airworthiness directive is supposed to be a procedure reserved for addressing highly probable/imminent faults or failures which will result in severe or catastrophic consequences. For the type of inspections being described, a mandatory service bulletin ought to be sufficient because all these old airplanes are still inspected every year as part of their annual airworthiness check anyway, and a good mechanic will be checking all of the items described without needing to be prompted by an airworthiness directive. What an AD says, is that Cessna and the FAA have deemed all of the affected aircraft NOT airworthy, until the one-time mandatory inspection is carried out, which if the aircraft passes it suddenly becomes airworthy again in the eyes of the FAA and the airframer, even if no work has been done. What it ultimately boils down to is liability, for an old aircraft out of warranty an AD is desirable as it holds the customer hostage until the mechanic waives Cessna of any liability for a failure, and ensures that the suspect areas are given a thumbs up, or replaced, which gets Cessna off the hook before wings start falling off, which keeps the lawyers happy, and yes it's obviously going to generate business for the mechanic and after-market spares sales too. But for comparison, on a new airplane still under warranty, Cessna would have to foot the bill for an airworthiness directive, which means for a new model airplane with stacks of infant mortality problems (sustaining engineering teams are actually busiest with the new airplanes, not the old ones) they'll be pushing for discretionary service bulletins instead of mandatory ADs, because that way the customer is made to pay for the repair instead of the airframer. So, the 'fatally flawed' logic behind the suspicion of this AD is somewhat justified, based on how the new vs old aircraft business models seem to be implemented.

I see some other problems with this concept; the unducted contra rotating fan powerplants in the centre are going to produce a lot of noise both in the cabin and on the ground, this can be dampened like the active suppression system used in the Q400s, but judging by the scale of these aircraft and the intended use of high-speed UDFs they could really stand to benefit from using ducts - the airplane is going to be pounded with shockwaves! Imagine listening to that drone for hours on end... The double-fuselage design is also going to result in a lot of duplication of system components for service air(pressurization), air conditioning, potable water, sewage, electronics, emergency slides, oxygen systems etc which will all add weight. By taking two airliner fuselages and gluing them together, you end up with double the weight not less, yes you probably achieve some bending relief on the wings which results in some structural weight savings, but I don't think it will result in a NET weight saving. Moreover, by splitting a single volume into two tubes, you actually increase the total fuselage surface area by 30% over what it would be if it were a single cylinder. This results in an increase in parasite drag! Finally - forward swept wings? Why? They are inherently unstable in roll and increase the risk of a wing-drop stall in a slideslip/crab. And they apparently made absolutely zero effort in area-ruling which will results in high transonic wave drag, so to me, this screams 'SLOW'. There are smarter ways to become more efficient than just going slower! Not quite sure what the point was in patenting this.