Rear Seat Development Part 3

Previous blog posts about the new rear seat discussed the requirements and then the prototype design and testing, now we head towards certification and production. With the data from the sled testing, and feedback from the mock up we went through another round design iteration.

One of the surprisingly more complicated design aspects was the recline mechanism. There were a lot of design requirements that were in conflict with process capability, and it took several iterations to get a design that worked as expected, and fit within our build and assembly tolerances.

Recline mechanism installed on seat

In parallel to the more obvious structural changes, we had to update the oxygen manifold STC so that it could support 5 masks, and we also had to find a place to put a 5th headset jack. We ended up moving all the headset jacks to the inside of the center console with the thinking that putting 3 kids in the back puts little kicking feet way too close to the headset jacks.

There were a lot of structural design changes to the fuselage to accommodate the new seat. We had to add support and layup changes to the floor and aft bulkhead. This includes several new aluminum fittings. There were a few new composite layup tools including the carbon fiber seat back, and the recline fitting, better known as "the ears." All of these significant changes to the structure of the airplane is why the new seats cannot be retrofitted to earlier airplanes.

Clockwise: Inertial reel and tether attachments on the bulkhead, the under floor support beam, the "ear"

Layup tools had to be designed, fabricated and inspected, and with each layup tool is a trim and drill fixture. The "ears" are bonded to the fuselage so a bonding tool had to be designed and fabricated. Fitting all these new parts, and assemblies into the build process is another very important step. We need to ensure that there is balance of time/work in each station so that the parts flow evenly from one station to the next. Subassembly stations for putting hardware on the seats had to be created since they didn't exist before. There is a lot of manufacturing and industrial engineering that has to happen in parallel with the design team to ensure a smooth transition to production.

So with the final design, and tooling in place, we once again install all the pieces in a mock up to verify fit and comfort and begin the conformity testing. Conformity testing sounds onerous but really it is just common sense. It is verifying that the parts you are testing were built to the drawing you intend to use for the type design product. Bottom line it is just a documented quality inspection.

Left to Right: Seat base, LH seat back, RH seat back

Testing included another trip to the sled test facility (all dummy legs stayed attached this time) and also a series of static load tests on the seat belt attachments and the LATCH attachments. With all the testing complete with no surprises, it was time to write the final reports and submit everything to the ACO for approval.

But the project isn't done until it is successfully in production. To help ensure a smooth transition, we typically have at least one "pilot" airplane go through the assembly line to ensure that all the tooling and production planning work as expected. We also use this opportunity to provide training to the technicians and it also gives us a good finished example for marketing materials when the airplane is complete.

We ran into an unexpected issue when we did the pilot airplane.The seat backs didn't fit! How could that possibly be? We installed several versions of these seats with no issues in our mock-up fuselage. Well it turns out that when you hang an engine and a wing on an empty fuselage, the fuselage changes shape every so slightly. It narrows just enough at the seat backs that the interface between the recline mechanism and the "ears" didn't work. After measuring about a dozen airplanes, we found the width change was very consistent and we modified the ears slightly by trimming them, and now the seats fit perfectly. With a successful pilot airplane, and project approval from the FAA, we begin sending airplanes down the production line for 2012 deliveries.

An interesting followup, I flew down to Chicago for a business meeting back in March in one of the new airplanes. Our Chief Engineer sat in the back and absolutely LOVED the recline of the new seats as he did work on his laptop. Although my daughter has outgrown the LATCH type car seats and I personally wont be able to use it, we are all particularly proud to be the first airplane manufacturer to have it available.

It takes a lot of hard work by many people to do a project like this. We have very high expectations for the product we sell, but in the end to get compliments from the Chief Engineer, see customers using all 5 seats, seeing kids in car seats buckled to our LATCH system, and to get some recognition from the Chairwoman of the NTSB makes us all proud and all the work worthwhile.