60/40 Rear Seat Part 1

I have been meaning to tell the story behind the new rear seat that we have started installing at the beginning of the year. Adding a 3rd seat belt in the back has been a common request from sales for several years. We have done a couple of mock-ups over the years, but the project never advanced any further than that due to other priorities.

That changed in early 2010 when we built another mock-up and started to seriously scope out the project and define the features that it needed. We knew we could take some significant weight out of the rear seat with a redesign, and make it more comfortable at the same time. With an official go-ahead, Engineering started to design the new seat, structural changes, and interior pieces. It still took about 15 months from that point until we had new seats in production.

The initial scope included 60/40 seat back split, more comfortable seating, recline, 3 point safety belts and the associated changes to go with adding a 5th seating location like a 3rd headset jack for the back and an extra oxygen port. The scope changed some over the course of the project. We added LATCH anchor and tether locations, more recline that initially designed and a cargo net in the back.

Designing a seat for modern aircraft is not an easy task. The testing loads and occupant protection requirements are clearly spelled out in the regulations and guidance, but when trying to add fuctionality, reduce weight, keep R&D and production costs in check, all while maintaining a schedule, it becomes an incredibly challenging design problem. But as engineers, this is what we live for!

SR22T Cabin Air Coupler Rigging

It was discovered during a production flight test that the cabin heat seemed too hot, and that even turning the heat off (vent only), there still seemed to be some heat coming through. Coincidently, that same week we had a complaint that even with an OAT of 40F, the pilot had to turn on the air conditioning to keep the cabin comfortable.

Investigation revealed the same problem in both airplanes. On the firewall is a mixing box that mixes the heated and ambient air before it enters the cabin. There are a couple of electrically actuated valves that control the flow of heat into the system. In some cases, these were improperly rigged and the valve allowing heat into the system didn't close completely which means warmer than normal air enters the cabin.

This issue is less likely to be noticed in the winter when you want the higher heat, but it is more likely to be seen as inadequate cooling as with heated air consistently leaking into the vent air (or conditioning air), the perceived cooling performance would be anemic.

We recently released Service Bulletin SB2X-21-05 which inspects for this valve not properly closing, and provides rigging instructions to ensure it is properly closed.

FIKI

Flew myself and 2 coworkers to Chicago yesterday for a business meeting. Weather at 6am had icing forecast for 60 miles along our direct route of flight. We were flying a FIKI airplane and departed due south so that we could get out of the area of clouds in closer to 15-20 miles. Airliners that departed ahead of us had no pireps for ice and it turned out that the clouds were only 2,000 feet thick, clear sunny skies above and no ice.

For our flight home, we had to stop in the upper penninsula of Michigan to drop off one of the guys. Picked up a trace of ice, but it was mostly just light snow showers. Departed for Duluth and again just light snow showers and no ice enroute until we descended through about 2,000 feet of clouds in Duluth and we picked up some ice. Weather below was clear and made an uneventful landing.

It was my first icing experience in a FIKI airplane, and a trip I could not have made otherwise. Despite having been part of the FIKI certification program, I have not had much opportunity to fly one. It worked as expected, and I was happy to have it.

Amsafe Inflater Replacement Time

We recently released Service Advisory SA12-01 that clarifies the inflator assembly replacement interval for the Amsafe inflatable air bags. The replacement interval for the inflators has been increased from 7 years to 10 years. The electronic module assembly remained unchanged and must be refurbished at 7 years and replaced at 14 years.

Alt 2 Winter Update

Recently looking back, I noticed that I haven't updated the blog about our Alt 2's since this post in October.

As I mentioned in that post, In late 2010, the alternator vendor made several changes. Those were all implemented in the 'k' (2011) date code alternators. Those alternators hit our factory floor and field replacements in the march time frame.

About a month ago, we went through the data, and to date we have had 3 failures of these new 'k' alternators. The picture shown is a graph of serial number versus hours for the SR22 (SR22T is graphed separately). The vertical line on the graph shows where the new alternators were implemented into the line.

This is a VAST improvement over previous model years, and reason for continued optimism that we might be on to a solution.

As I also mentioned in that post, there are 2 additional improvements coming. The new rotor bonding process is now online and those parts are now being produced. The new diode is scheduled to be in place in a couple of months. We will continue to monitor the reliability of these parts, and keep you updated.

Tires and Tubes Cont.

Over the past few years we have received reports of tires going flat. The reports are sporatic with seemingly no common theme. I blogged about it back in this June 2010 post. We have been working with Goodyear to try to understand what might be causing this, and have tried some of their new tires.


More explanation has come from the FAA via a revision to a Special Airworthiness Information Bulletin (SAIB) published today. CE-11-47R1 explains how Goodyear has been working with different compounds to try and eliminate the various tube failures they have seen in cold and warm weather. Cirrus continues to be active in discussions with Goodyear and help in any way we can.

"Orbits" Part 2

In my previous post I described some of the technical hurdles we encountered during the development and certification of the Garmin GSR56 Iridium Transceiver. The story continues with the new Garmin GMA350 audio panel. We had been evaluating some prototypes of this new audio panel and wanted to put it into production, but we also wanted to be able to offer a GSR56 Iridium transciever retrofit kit for existing users to install in their airplanes that have the existing GMA347 audio panel. This meant we had to test the Iridium system with both the existing GMA347 audio panel and the new GMA350 audio panel.

What this means for us is that we had to install and test this in an airplane twice. The wiring for the two audio panels is completely different which complicates things. We had to take one of our experimental airplanes which has the GMA347 audio panel and  install the Iridium box and associated structural modifications, hardware and new antenna. We then did all the testing with that version of the installation. Then we took out the old audio panel, rewired the airplane for the new audio panel and repeated all the testing for that installation.

Software is another area where people tend to think it is an easy change, but we spend a lot of time doing enough testing, in many different conditions and scenarios, to ensure that there are no bugs in the software. This involves not only on-aircraft testing, but also installing it in a "bench" installation in our lab. We can simulate a lot of different warnings and other scenarios on the bench before actually doing the flight testing.

But real world results come from the extensive ground and flight testing we do. Every flight test program ends up with some interesting stories and this project is no different. One interesting bug we discovered was that a phone call would not terminate when you clicked hang-up on the aircraft but the guy on the other end of the phone didn't hang up (like when dialing into your voice mail.) This has since been fixed.

Another instance occurred when we were proofing out the voice service. From the ground we called the test aircraft and the guy talking from the plane then sat through a 45 minute teleconference. What we didn't know was that when we dialed the aircraft from our land line it was being considered an international call by our company phone service which racked up quite a charge. Oops.

So after all this testing we finally got a solution that we were happy with and began the process of creating all the various drawings (wire harnesses, installations, structural changes etc), and summarized all of our testing through plans and their test reports, along with a couple of certification reports and submitted that to the FAA.

While that was going on, we sent an airplane down the production line to act as a "pilot build" aircraft. We use this aircraft to proof out our drawings, any new processes, parts and installations. It also provides a chance to give the factory technicians training if necessary. We then feed back any information we learn to correct drawings or re-orient the line flow prior to the need to build these airplanes at rate.

With all of that complete, and final approval from the FAA we are able to confidently move forward with production knowing that there will be a few minor changes needed but overall production will proceed smoothly.