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Thread: SA0009 progress

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    Senior Member randylervold's Avatar
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    Default SA0009 progress

    CC11 airframe family owners,

    This is the companion thread to the announcement thread on SA0009 where we will provide periodic updates as available. As hopefully was communicated with the mailing to all owners this is our top priority until finished.
    Randy Lervold

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    Senior Member randylervold's Avatar
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    Default Re: SA0009 deployment progress

    Update: 12/2/2013

    One of our outside DERs will be back on site tomorrow for the final round of flight testing. This testing will be to hopefully validate our preferred retrofit design. If the data from all the flight modes comes back positive we will immediately begin manufacturing parts in quantity. It might be possible to provide a shipping estimate at that time. If there are any stress issues remaining unfortunately we'll need to adjust the design and re-test.

    We should have a decision on whether we'll be moving on to manufacturing by Thursday or Friday, I'll post an update at that time.
    Randy Lervold

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    Junior Member BarryP's Avatar
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    Default Re: SA0009 deployment progress

    Quote Originally Posted by randylervold View Post
    Update: 12/2/2013

    One of our outside DERs will be back on site tomorrow for the final round of flight testing. This testing will be to hopefully validate our preferred retrofit design. If the data from all the flight modes comes back positive we will immediately begin manufacturing parts in quantity. It might be possible to provide a shipping estimate at that time. If there are any stress issues remaining unfortunately we'll need to adjust the design and re-test.

    We should have a decision on whether we'll be moving on to manufacturing by Thursday or Friday, I'll post an update at that time.
    Once the final design is selected do you plan to release the details before starting parts production? I know you have a lot of smart folks looking at this, but it might be worth letting the customers review the design with a fresh set of eyes (or 400 sets) before cutting metal.
    Just a thought.
    Thanks, Barry

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    Senior Member randylervold's Avatar
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    Default Re: SA0009 deployment progress

    Quote Originally Posted by BarryP View Post
    Once the final design is selected do you plan to release the details before starting parts production?
    I'm sure we an post some drawings of the design once locked.
    Randy Lervold

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    Member davidmorris's Avatar
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    Default Re: SA0009 deployment progress

    Quote Originally Posted by randylervold View Post
    I'm sure we an post some drawings of the design once locked.
    I think Cubcrafters is doing an excellent job so far. I would much rather be in the hangar waiting for a fix than in the air wondering what just happened.

    David Morris
    N63PG
    #275

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    Junior Member BarryP's Avatar
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    Default Re: SA0009 deployment progress

    Quote Originally Posted by randylervold View Post
    I'm sure we an post some drawings of the design once locked.
    Sounds good. Thanks to everyone there for the tremendous effort! I look forward to flying the new parts.
    Barry

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    Default Re: SA0009 deployment progress

    Quote Originally Posted by BarryP View Post
    Sounds good. Thanks to everyone there for the tremendous effort! I look forward to flying the new parts.
    Barry
    As Randy Lervold mentioned in another post, we intend to provide updates here periodically, and this post will provide all owners with an update on our progress regarding SA0009. Please understand that this will be an overview, it is simply not possible to relay all the details of the process here.

    Over the Thanksgiving holiday weekend our engineering team was working to get our demo/test aircraft ready for flight tests which began today. There has been much discussion of wire tension and trim changes. When the first case happened, we immediately thought it could be caused by improperly set wire tensions. One of the first things we did was to check the inspection records of the affected aircraft to ensure that the tension was set correctly. The records were all in order. Then, we checked the tension on all the aircraft we could get our hands on at Cub Crafters and found they were all within specifications.

    Next, like so many of you, we wondered if the position of the trim affected the tension of the wire. We did tests and found that the changes in tension as the trim was moved were so small that were not able to measure any difference in the tension of the wires. We checked this mathematically and found that the change in length in the wire, and hence the tension, because of the movement of the trim is in fact, very small. Because we knew that the question would come up in the future, we decided to amend the specification for tensioning the wires in the maintenance manual to include the position of the trim, even though we knew it made little difference. During the tests with the strain gauged wires that we have been doing for the past few weeks, we have been able to physically observe that there no change in tension with trim.

    During the flight tests with instrumented wires we have conducted trim sweeps to ascertain the effects of changing the angle of the stabilizer on the wires. The tail is in a very dynamic environment. There are the aerodynamic forces that are required to keep the aircraft balanced in trim, forces required to change pitch angles and the effects of propeller wash. On top of that, the powerplant itself introduces vibrations into the whole structure of the aircraft which vary with power. The testing has focused on understanding these effects and ensuring that the design of the tail bracing is such that the wires experience a limited amount of bending throughout the whole flight envelope.

    We are very reluctant to speculate as to when the design solution will be finalized, and following that, when parts might be manufactured and available so as to get you back flying. The reason is that if any part of the design does not meet acceptable specifications then we’ll need to iterate the design. Estimating the time that process might take simply isn’t possible. We know our owners are anxious but we are conscious that whatever solution we come up with must be safe. Once the testing is finalized, I can only estimate that it would be a matter of a few weeks before parts could be made, inspected, packaged, and shipped.

    The pace of work here on this issue has been hectic which has not left much time for the engineering staff to participate in the forums. As has been mentioned previously, the team of engineers working on this includes experienced FAA DERs. We want the best talent working on this issue so we can all have confidence in a proper root cause analysis and solution.

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    Senior Member carlconti's Avatar
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    Default Re: SA0009 deployment progress

    Eric,

    Thank you for the excellent update.

    Since it may be several weeks before parts are shipped, is there any chance that an operating work around could be developed. It would be nice if we could fly our airplanes with some limitations while we wait for parts.

    regards, Carl

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    Senior Member randylervold's Avatar
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    Default Re: SA0009 deployment progress

    To supplement Eric's update below are some pics I quickly snapped yesterday. They show some of the strain gauges we've installed, the possible new bracket and wire fitting solution, and tensioning the wires. Again, this is the second round of flight testing...
    Attached Images Attached Images
    Randy Lervold

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    Senior Member carlconti's Avatar
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    Default Re: SA0009 deployment progress

    Outstanding! Simple and effective.

    Carl

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