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.

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"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.

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Child Safety and the NTSB

We are quite honored that Debbie Hersman, the Chairwoman of the NTSB took note of our new LATCH system installation in the 2012 model rear seats by writing about it in her official blog called the NTSB Safety Compass.

We pride ourselves, and work very hard to make our airplanes as safe as possible, this new rear seat is just another step in our always ongoing process of continous improvement.

http://safetycompass.wordpress.com/2012/01/20/improving-child-safety-on-airplanes-one-seat-at-a-time/

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Perspective Global Connect Retrofit

We have received a lot of inquiries about whether the GSR56 Iridium transceiver will be retrofittable for existing Perspective airplanes and the answer is yes. The engineering team is working on the retrofit kit that would go out to the field. It is not a simple installation as there are structural modifications to the CAPS bulkhead and wiring harness changes, and installations of racks and antennas. These changes are quite different than the changes we make for production.

For example there are things we can do to the bulkhead during the initial lay up of the part like add hard points that cant be as easily done in the field or at least not in the same way. So it requires developing special instructions, and parts to complete the retrofit properly.

My intention is to have that kit available for the field in the first half of 2012.

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"Orbits" Parts 1

One of the biggest requests from our European and other foreign customers is the ability to download satellite weather. We here in the US have been blessed with XM weather but that does not extend beyond our boundaries. Orbits was our internal code name for the project that installs the Garmin GSR56 satellite transceiver that uses the Iridium satellite network and integrates it into the Perspective system. This option is called the Perspective Global Connect by the sales and marketing group. We use code names to make it easier to describe internally, to give some security to the project and it is just fun coming up with names as a project kick-off exercise.

This project took about 9 months to complete, and although on the surface it may seem to be easy (it's just box and some wires right?) or that FAA certification causes a big delay, the truth is, to find a place to put the product, run the wires and test it enough to insure it meets Cirrus standards takes some time.

So the first step for us was to find a place to put the antenna. Anyone who has looked at our airplane lately realizes that there isn't room for any more antennas on the airplane. The antennas need to be spaced apart from one another to ensure they work properly. In this case we identified a combo antenna (with GPS 2) to use, and put it in the same spot as the existing GPS 2 antenna.

Of course we now have to verify the performance of GPS 2 in a bunch of different conditions to ensure there wasn't any interference or performance degradations due to the new antenna. Also since this is transmit/receive based system we have to ensure performance during both modes.

Then we had to find a place to put the actual GSR56 box. The console is full, all the under floor space has long been used up and the shelves in the aft equipment bay are also full. We ended up creating mounting locations on the back side of the CAPS bulkhead. It is accessible through the access hole on the side of the airplane. This required structural changes to the bulkhead and we used a mock-up to ensure we could actually install the bracket and box during production and in the field, and assessing the weight and balance impact.

Having this box in the back of the airplane also meant a long harness connecting it to the Perspective system in the cockpit. So once again, we had to ensure that the long harness didn't create any RF noise issues.

That summarizes the high level design considerations we had to go through. Stay tuned for Part 2 which will describe some of the test articles, the affects of the audio panel, and some funny stories that happened along the way.

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New Features

Last week we announced some new features in the 2012 models. We added an Iridium based satellite transciever which allows our customers outside of the US to download weather to the cockpit and everyone to make phone calls and text messages.

We also updated our rear seat. Making it more comfortable, adding a 3rd seat belt for those who have young kids, and adding LATCH (lower anchors and tethers for children) hardware to allow those with car seats to attach them to the airplane just like their car.

Over the next couple of weeks I will be writing a few blog posts describing the ups and downs of designing and certifying these new features. Until then check out CirrusAircraft.com for more details.

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Flap Relay Winter Update

I just realized that it has been 6 months since I last updated everyone on the flap relay redesign progress. Unfortunately things slowed down quite a bit in the fall. We put together a drawing and requirements package and sent that out to several potential manufacturers. We chose a vendor to build some pre-production parts but then further discussions with them led us to choose a different vendor.

This latest vendor has given us some great suggestions for packaging and design changes to lower the production costs yet make it more robust. So we expect to get 4 pre-production samples in early February for evaluation and to prove out their production methods.

The prototype unit continues to be used in one of the experimental airplanes with no issues. We are now hoping for a late Q1 release of the new flap relays.

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SR22T Oil Separator

I mentioned in an October blog post that one of the biggest reliability issues we were having that was specific to the SR22T was with the oil cooler flange cracking. This is due to the existing oil separator being attached to this flange and applying excessive fatigue loads.

We had identified this area as a good place for a potential redesign at the start of production because it was difficult to access, and had potential chafing issues. With other priorites in Engineering we didn't focus on it for about a year. As fate would have it, it took a year or so before the fatigue cracks grew to the point they were noticable on the flange and we began to get reports from the field. We then put a production fix in place replacing the existing oil separator with an Andair separator which mounts completely differently and also provides more access.

All the parts are now in place to fix the airplanes in the field. SB2X-71-19 provides the necessary instructions to replace the separator and prevent future oil cooler cracking.

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