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Thread: Datum Ski Field Approval

  1. #1

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    Datum Ski Field Approval

    Does anyone know of or heard about a pair of Datum Skis being field approved?
    Thanks,
    DT

  2. #2
    Charlie Longley's Avatar
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    Quote Originally Posted by DCT View Post
    Does anyone know of or heard about a pair of Datum Skis being field approved?
    Thanks,
    DT
    Yeah it’s not that big of a deal to put skis on an airplane. Talk to any reasonably experienced IA.

    Interesting looking ski! I’ll do a little research.

  3. #3
    Charlie Longley's Avatar
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    Did a little research. Yep you’ll have to involve the FAA on those skis.

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    Quote Originally Posted by Charlie Longley View Post
    Did a little research. Yep you’ll have to involve the FAA on those skis.
    Does a FA typically involve the FAA?

  5. #5
    Charlie Longley's Avatar
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    Quote Originally Posted by DCT View Post
    Does a FA typically involve the FAA?
    Unfortunately typically it does.

  6. #6
    wireweinie's Avatar
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    Hate to tell ya, but since all pilots and mechanics are licensed by the FAA and the airplane is registered and declared airworthy by the FAA, we're kind of stuck with dealing with them, lol.

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    BC12D-4-85's Avatar
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    Another option is to source a Designated Engineering Representative (DER) and pursue their approval. You might eventually discover whether or not that pursuit is worth the expense and wait. Some do and go fly the approved mod...others just do it, or simply walk away from the alteration.

    Gary

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    One of the big problems with trying to do an installation on non TSO skis is that the aircraft certification regulations (CAR 4, CAR 3 and Part 23) all require TSO skis. Unless Datum is able to show the skis at least meet the TSO requirement a DER can’t really do an approval since we need to show compliance to the regulation. I had this issue with an applicant that wanted an approval for Summit skis. We tried to get the data from Summit and they told us they don’t have any data (more likely they just didn’t want to share it). As a DAR doing Field Approvals, my hands are tied by the same requirement. All that said, if you can get an ASI to give a field approval you are golden, they don’t have to play by the same rules that designees do.


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  9. #9
    EdH's Avatar
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    What is the TSO requirement for skis? CAR 3 says they have to be an “approved type.” What did “approved type” mean in 1949?


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    BC12D-4-85's Avatar
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    Look at TSO-C28 that references another document of ski specs

    Gary

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    In 1949, "approved Type" meant Type Certificated under CAR 15. All those CAR 15 Type Certificates were chang4ed to the current TSO system (not sure when, but I suspect shortly after the FAA Act of 195. Under the TSO system, for skis to meet TSO C28 they have to meet the strength and performance requirements of NAS 808. Since I don't subscribe to the NAS standards, I don't have any idea what is included in NAS 808. If you really want to know AIA sells the NAS808 in digital form for $63.

  12. #12
    RaisedByWolves's Avatar
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    I have a letter from summit on the load rating, that was field approved by the fsdo. Not sure if that helps. The FSDO did make me change the wording of my 337 to incorporate the previously approved skis. They have sense stopped field approvals at my fsdo





    The SS2300 skis, are carbon fiber skis designed for installation on several conventional (tail wheel) fixed-gear experimental airplanes.

    Using the math in AC 4313.2b, the Maximum Limit Load Rating for the SS2300 series skis have been determined to be 9729 pounds. This is based on the aircrafts gross weight limit of 2300 pounds.

    The SS2300 skis are recommended for aircraft with a 2300 pound gross weight or lighter.


    Summit Aircraft, LLC
    63004 Powell Butte Hwy.
    Bend, OR. 97701
    541-678-5775

  13. #13
    BC12D-4-85's Avatar
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    Look up "Civil Air Regulations Part 15 Aircraft Equipment Airworthiness". I had a PDF bookmarked for my use but posting a .pdf here results in vague images. There's quite a section on Skis under Section 15.12. For example: 15.120 Skis, including ski pedestals, will be certificated for a maximum static load which will be determined from the strength of the ski. And so on with lots of math and testing requirements.

    Gary

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    wireweinie's Avatar
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    Quote Originally Posted by dgapilot View Post
    In 1949, "approved Type" meant Type Certificated under CAR 15. All those CAR 15 Type Certificates were chang4ed to the current TSO system (not sure when, but I suspect shortly after the FAA Act of 195. Under the TSO system, for skis to meet TSO C28 they have to meet the strength and performance requirements of NAS 808. Since I don't subscribe to the NAS standards, I don't have any idea what is included in NAS 808. If you really want to know AIA sells the NAS808 in digital form for $63.
    Hey dga

    What's your view on the last part of pragraph 3.365? While 3.364 specifically states that skis need to be approved, the last part of 3.365 calls out procedures to deal with non approved skis.

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  15. #15
    EdH's Avatar
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    Datum Ski Field Approval

    IMO, “approved type” is different from “type certificated,” as both of those terms are used separately and would counteract is they were the same. If they were the same meaning, the first paragraph would say you MUsT have TC’d skis and the second says you can have non-TC’d skis. That doesn’t make sense.

    Ҥ 3.364 Skis. Skis shall be of an approved typed. The approved rating of the skis shall not be less than the maximum weight of the airplane on which they are installed.

    § 3.365 Installation. (a) When type certificated skis are installed, the installation shall be made in accordance with the ski or airplane manufacturer’s recommendations which shall have been approved by the Administrator.
    When other than type certificated skis are installed, data shall be submitted to the Administrator showing a dimensional drawing of the proposed method of attaching the skis, the sizes and material of the restraining members and attachment fittings.”

    Key word might be “of.” Skis shall be OF an approved type. Would straight, penetration, etc be an approved “type” of ski? Or is it referring to them having an approved weight rating as the next sentence might imply?


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    Last edited by EdH; 12-01-2022 at 05:09 PM.

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    Quote Originally Posted by wireweinie View Post
    Hey dga

    What's your view on the last part of paragraph 3.365? While 3.364 specifically states that skis need to be approved, the last part of 3.365 calls out procedures to deal with non approved skis.

    Web
    I hadn't read the ski requirements for the earlier CAR 3 version. Interesting that 3.365'non-type certified skis. the CAR 3 reissue from 1956 does not have 3.365! That is why establishing Certification Basis is so important. My approach would be to show that the skis meet the requirements of CAR 15. When I was working with a guy a couple years ago to try and certify Summit skis, Summit would not provide any data that could be used to show they met the CAR 15 requirements. Without the data, you are pretty much stuck in the water. Maybe they have changed their tune since I contacted them. the 1937 version of CAR 4 only states items that are required to be certified shall be certified under CAR 15. It is interesting that CAR4 and CAR4a both don't specifically address skis.

  17. #17
    wireweinie's Avatar
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    How are 'approved' and 'type certificated' different? Where are they defined as individual terms?

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    Seems the CAA interchanged terms quite often. There are some places where they state "approved" in one sentence, and then point to CAR 15 as the method of approval in the next. Guess they didn't have as many lawyers working for the federal government back then!

  19. #19
    EdH's Avatar
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    I’d sure agree with that DGA, it makes interpreting these difficult, as there isn’t really any standard definitions for terms.


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  20. #20
    wireweinie's Avatar
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    Quote Originally Posted by dgapilot View Post
    I hadn't read the ski requirements for the earlier CAR 3 version. Interesting that 3.365'non-type certified skis. the CAR 3 reissue from 1956 does not have 3.365! That is why establishing Certification Basis is so important. My approach would be to show that the skis meet the requirements of CAR 15. When I was working with a guy a couple years ago to try and certify Summit skis, Summit would not provide any data that could be used to show they met the CAR 15 requirements. Without the data, you are pretty much stuck in the water. Maybe they have changed their tune since I contacted them. the 1937 version of CAR 4 only states items that are required to be certified shall be certified under CAR 15. It is interesting that CAR4 and CAR4a both don't specifically address skis.
    Would they accept you performing the tests required by CAM/CAR 15? The testing seems pretty straight forward.

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  21. #21
    wireweinie's Avatar
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    And where would I find a copy of the 1956 CAR3? I have a couple of copies but they are older.

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  22. #22
    BC12D-4-85's Avatar
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    CAR3 1956

    Search: dot_51990_DS1.pdf

    Gary
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  23. #23
    wireweinie's Avatar
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    Just downloaded it. I'm a repeat victim of the 'Dynamic Regulatory System'.

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  24. #24
    wireweinie's Avatar
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    Quote Originally Posted by dgapilot View Post
    Seems the CAA interchanged terms quite often. There are some places where they state "approved" in one sentence, and then point to CAR 15 as the method of approval in the next. Guess they didn't have as many lawyers working for the federal government back then!
    Other than certificating an accessory like a ski, what other 'approval' did they use back then?

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    Quote Originally Posted by wireweinie View Post
    Would they accept you performing the tests required by CAM/CAR 15? The testing seems pretty straight forward.

    Web
    I wouldn’t be doing the test, that’s the responsibility of the applicant. That said, I would need to see if observing the test would be required. Most certification tests are done at labs today.

    DRS is really a pain to navigate. There are some of the earlier regulations there. Another source I’ve found is the DOT Special Collections site. I don’t have the link on my phone though.


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  26. #26
    BC12D-4-85's Avatar
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    Here's more enlightenment re: Item 208. Skis approved as Equipment under TCDS 1A2 PA-18:

    "Approval for the installation of all items of equipment listed herein has been obtained by the aircraft manufacturer except those items preceded by an asterisk (*). The asterisk denotes that approval has been obtained by someone other than the aircraft manufacturer. An item marked with an asterisk may not have been manufactured under a FAA monitored or approved quality control system, and therefore conformity must be determined if the item is not identified by a Form ACA-186, PMA or other evidence of FAA production approval."

    Not sure what that all means but it's there. Obviously an STC would allow installation among other methods of approval.

    Gary

  27. #27
    TurboBeaver's Avatar
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    Something to consider about running a non FAA approved set of skis........... Alot of folks that run them with out a field approval do two things: Simply get inspections on wheels, and the second thing is, it is apparently not common knowledge the insurance company s are happy to insure the certified airplane with NON certified skis! They simply add a rider and it is less than 200 bucks to cover yourself on a $100 k investment. You are still out in the "dark grey area with big brother" if you wreck on non certified skis. But you are going to get paid by the insurance company. The rider will list Only the actual skis and their respective serial numbers, you can't put different ones on, and still be covered. The insurance company considers Summits and Datums ' experimental ' as far as quotes are considered. If you insist on a field approval good luck, you will need alot of it! Datum now has over 600 sets out their all over the world, he is about a year behind on orders; and has no intention of ever trying to get them certified, so you can use them from an insurance angle, but legal with the powers to be: if you crash it .. that's another story ??? Yet another great reason to fly experimental.....Click image for larger version. 

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    Good luck
    E
    Last edited by TurboBeaver; 12-02-2022 at 05:08 AM.

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    All good information. I appreciate the insight.

    Thanks,
    DT

  29. #29
    TurboBeaver's Avatar
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    Your Welcome. The Datum ski has no peers in performance, unfortunately we are now living in a society
    Where trying to get procurement of a government run approval, is not possible............ Like the Catto prop there
    Is absolutely no reason both should not be easily approved, but in our present environment just not a possibility.
    E

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