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Thread: Old Sheet Metal Cross Reference

  1. #1

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    Old Sheet Metal Cross Reference

    I知 repairing a flap on my 1959 PA-22/20 and I'm trying to identify the kind of aluminum piper used. I know the industry changed the way they identified sheet aluminum alloys from a 2 digit identifier to a 4 digit identifier somewhere along the way. I知 looking for a cross reference of some kind that would help me translate the old identification to the newer alloy identification.

    The only markings I can make out on the original part are;

    3S

    H14 (hardness)

    24S-1

    .02 (thickness)

    Daryl

  2. #2

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    Quote Originally Posted by AVPacer View Post
    I知 repairing a flap on my 1959 PA-22/20 and I'm trying to identify the kind of aluminum piper used. I know the industry changed the way they identified sheet aluminum alloys from a 2 digit identifier to a 4 digit identifier somewhere along the way. I知 looking for a cross reference of some kind that would help me translate the old identification to the newer alloy identification.

    The only markings I can make out on the original part are;

    3S

    H14 (hardness)

    24S-1

    .02 (thickness)

    Daryl
    2024 t3 is what you need . thats the closest to what was used during and just after ww2 not sure when they changed the numbers

  3. #3

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    3003-H14 is what was used for the leading and trailing edges. 2024-T3 for the spar and ribs.

    The old Aircraft Spruce catalogs used to have a chart.

  4. #4
    steveinindy's Avatar
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    Here's the chart Turtle referred to: http://www.aircraftspruce.com/catalo...s/aluminfo.php (Scroll down).

    As Turtle said, 3003 is the equivalent of 3S apparently. I learned something I didn't know previously as a result of the search that turned that up
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  5. #5

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    3003H14 is pretty soft stuff when compared to 2024T3 which feels more like a clockspring. Considering that the harder material drills and cuts better & is a lot stronger, you may want to just use 2024T3. It does cost a little more but those cauliflowered leading edges you see on Cubs are pretty much due to the use of 3003H14.

  6. #6

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    I'd use what Piper used. In most cases when someone made a part with a "better" grade, it didn't last as long as the original due to things like cracking.

    Mr. Piper was almost as smart as he was cheap.

  7. #7

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    Actually, 2024T3 is pretty much approved by the FAA to replace the older grades of aluminum used in most aircraft, including Pipers. 7075 and some other less common grades excepted. Give AC43.13 a read. For a flap, 2024 is certainly the preferred material.

    I will agree that Mr. Piper was cheap.

    Best of luck,

    Wes
    N78PS

  8. #8
    Aaron Novak's Avatar
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    Quote Originally Posted by WLIU View Post
    Actually, 2024T3 is pretty much approved by the FAA to replace the older grades of aluminum used in most aircraft, including Pipers. 7075 and some other less common grades excepted. Give AC43.13 a read. For a flap, 2024 is certainly the preferred material.

    I will agree that Mr. Piper was cheap.

    Best of luck,



    Wes
    N78PS

    Wes,
    I am failing to find any FAA information that even suggests that 2024 can be used as a blanket substitute. Quite the opposite is true as most statements advise to using the same material both in dimension and composition as the original part. This would seem correct to me as it would be foolish to think one could alter a material at their whim with no reguard for the performance of the finished component. AC23-27 covers the subsititution of 4130 for 1020 steel, but has no such approval for any aluminum alloy. 43.13 as well does not seem to grant this approval. I am sure one could do a material change provided the appropriate design and engineering work completed for approval. How this would be worth is I dont know as it seems very straightforward to know what the part was originally designed and approved with. Another option may be to see if there has been any previous approvals done for the same application and follow suit. In any event, my guess is that this would be a major alteration as it is a structural material change. If you have any documention to the contrary you would like to share I would welcome it.

  9. #9

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    Quote Originally Posted by WLIU View Post
    Actually, 2024T3 is pretty much approved by the FAA to replace the older grades of aluminum.
    3S is not necessarily older than 2024.

    The older "grades" still exist under their new numbers, just like 24s = 2024, and are still chosen today based on their properties. The hardness and memory of 2024T3 would be detrimental for a lower cowl, for example. People have done it and most cracked from vibration. Using the original 5052 solved the problem.

    Then there is the issue of the law. This is a certified aircraft. AC43.13 comes in when no other data is available. In this case, we know the original materials and they are still readily available. Even the individual parts for the flap are still available. To substitute materials would be re-engineering the part. Even though the substitution might seem reasonable, I still wouldn't sign it out.

  10. #10
    pylon500's Avatar
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    As mentioned above, although 2024-T3 is todays standard alloy for aircraft use, Piper did use softer (and cheaper) metals back then.
    The 3000 and 5000 series alloys were popular due to being weldable.
    A better replacement than 2024-T3 would be 6061-T6, only (about) two thirds the strength of 2024 but stronger than 3003, is still weldable and cheaper than 2024.
    Many of the light end kit manufacturers use 6061-T6 these days..

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