Reinstalling Removed Equipment...require a new 337?

Discussion in 'Avionics and Upgrades' started by hish747, Jun 29, 2020.

  1. hish747

    hish747 Pre-takeoff checklist

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    An STEC-50 and Garmin 430 were installed in an aircraft and the STCs and old 337s are present. Over time, they both became INOP and were removed. Years later would a new 337 form be required to reinstall working versions of the same units or are the old STCs/337s still valid?
     
  2. Witmo

    Witmo Pattern Altitude

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    If nothing was filed removing the old STCs/337s. then reinstalling the equipment would just be putting the aircraft back into it's properly altered configuration. Just a logbook entry required.
     
  3. Tom-D

    Tom-D Taxi to Parking

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    You must understand what was written on the 337 in block #8.
     
  4. Tom-D

    Tom-D Taxi to Parking

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    disagree
     
  5. Witmo

    Witmo Pattern Altitude

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    Another drive-by posting from Tom. If you disagree it would be nice to hear a rationale for your opinion. Section 8 is a description of the work performed. Tell us how this would apply to the question asked. Why would a second 337 be required?
     
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  6. Bell206

    Bell206 En-Route

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    It depends on extent of the unit's removal and how it was documented. Technically, when a major alteration is completely removed it requires a 2nd 337 to show its removal unless the original 337 approved data has instructions to return the product back to its original configuration. Then no 2nd 337 required per existing guidance. For example, if the 430/STEC was completely removed except for the wire harnesses/hard provisions then there should have been a 2nd 337 submitted for the equipment removal and/or AFM Supplement removal. So the original 337 would be invalid for any "new" installations. Where the gray-area comes in is if say only the control heads were removed under 91.213 and you only re-installed replacement control heads. So without more info hard to make a call.
     
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  7. bradg33

    bradg33 Pattern Altitude

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    From a practical perspective, if there was no 337 prepared and filed showing the removal, anyone looking at the logs would never know the airplane flew for a time without those parts installed. They'd see a 430 and STEC autopilot in the airplane, and there'd be a 337 on file showing/approving the installation. Exceptionally unlikely anyone would ever look into it any further than that, making the discussion of whether it's "valid" somewhat moot.
     
  8. Witmo

    Witmo Pattern Altitude

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    Written more eloquently but essentially agreeing with my earlier post. Tom disagrees.
     
  9. Bell206

    Bell206 En-Route

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    I guess it depends on how you define moot. If I was reviewing the records and saw a 337 from say 1990 for a STEC-50/430 then saw a write up to install a STEC-50/430 in 2020 then I would question that. Why the date difference? And if further review finds "new" AP servos or GPS antenna installed or both with a mfg date later than 1990 I'd definitely red flag it. Have seen this scenario one too many times.
     
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  10. Bell206

    Bell206 En-Route

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    Only from the standpoint if the interface items were removed under 91.213. Even then it is still very gray from a mx sign-off angle to simply sign it off especially if there are no proper removal writeups. When I have crossed this path, I usually did a completely new install sign off with new 337 if needed to keep the paper trail intact.
     
    Last edited: Jun 30, 2020
  11. Tom-D

    Tom-D Taxi to Parking

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    Until we know that, we don't know what anyone should do.
    once again the issue is confused.
     
  12. hish747

    hish747 Pre-takeoff checklist

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    For the sake of this hypothetical. Let's assume that the equipment was removed with a log entry and no 337 filed. The only thing that remain are the gps antenna and wiring.
     
  13. Bell206

    Bell206 En-Route

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    Always enjoy a good hypothetical every now and then....;)

    With this scenario, new 337 required. But I don't know if the original STC permission letters would still be valid. And you still have a paperwork continuity issue with the missing removal 337s, provided there were no removal instructions with the original approval. However, those could easily be dealt with in several ways.
     
  14. Dana

    Dana Pattern Altitude

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    I know it's not the same thing, but I had to put my experimental back into phase 1 testing for 5 hours when I installed a new prop. The FSDO told me that if I reinstalled the original prop it would need another 5 hour test period.
     
  15. Dana

    Dana Pattern Altitude

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    No, you need to go back to phase 1 for any "major change", which is defined as any change that can have an appreciable impact on performance, which a prop change certainly could. Fixed pitch to CS is a different requirement to notify the FAA for a records change.
     
  16. Ravioli

    Ravioli Final Approach PoA Supporter

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    For the OP - My dumb opinion is what happened in the 'removal'. was is it just pulling the inop 430 and A/P head, or was re-wiring, new tray, etc. done and documented? In that case I would expect the installation paperwork for those in-op items are no longer valid. So, do all it took to put them in the first time. OTHOH, if you were just flying with empty holes you could slide in and "probably" be fine.

    For @Dana and @unsafervguy - I think Dana is right. I switched from a two blade Warnake prop to a three blade Catto and went to phase 1. FP vs C/S doesn't factor in.
     
  17. unsafervguy

    unsafervguy Pattern Altitude

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    Yes, I screwed that one up. Wasn’t thinking straight. If it is a different part number it doeas require a phase 1, replacement doesn’t. Brain fart time