Why is a 337 required?

Discussion in 'Maintenance Bay' started by Timbeck2, Feb 21, 2016.

  1. RotorAndWing

    RotorAndWing Final Approach

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    So what's new?
     
  2. GlennAB1

    GlennAB1 Ejection Handle Pulled

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    That's why, when it's questionable or arguable, just do it.
     
  3. GlennAB1

    GlennAB1 Ejection Handle Pulled

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    No, I've been an Inspector for a couple airlines for almost 30 years, and been in aircraft maintenance for almost 40.
     
  4. Tom-D

    Tom-D Taxi to Parking

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    Yes, I'm an IA, I've been in GA on and off since 1954. I do 337s nearly every month. Guess what happens when an A&P brings me a 377 that is not required? No,,, I don't go ballistic on the dude, But I do educate. That is a very rare occasion. most times I am requested to come to some ones hangar to see what they are wanting to do. So, I'm involved from step 1.
     
  5. Tom-D

    Tom-D Taxi to Parking

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    That is never the proper way.
     
  6. Tom-D

    Tom-D Taxi to Parking

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    The question was ...... if it is a drop in replacement, why is a 337 required. IMHO, it isn't
     
  7. GlennAB1

    GlennAB1 Ejection Handle Pulled

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    That's is always the proper way. Better safe than sorry. The airline I work for now uses its documents in place of 337's, but when I worked for ATA, my department was responsible for 337's. I filled out many in ten years of ageing L-1011 and 727 heavy checks, sometimes several 337's per check.
     
  8. Checkout_my_Six

    Checkout_my_Six Touchdown! Greaser!

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    Thank you .....Tom ;)
     
  9. bnt83

    bnt83 Final Approach PoA Supporter

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    Most component repair stations that do work for 121 operators don't even a know what a 337 is. This is usually a problem when a 135 operator has flight control (or other) repairs contracted to them and the 135 operator's RGSOM requires 337s for RTS.
     
  10. Silvaire

    Silvaire En-Route

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    It's not required because of the installation, it's required because of the STC and the STC exists simply because Plane Power decided to create one. They decided to do that so people wouldn't inanely argue over whether or not it is a major modification. With the STC there's nothing left to argue about.

    But that won't stop POA
     
  11. kontiki

    kontiki Cleared for Takeoff

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    PMA approval means a part is manufactured per FAA MIDO rules for manufacturing aircraft parts.

    Incorporation of an STC means you have changed the Type Certificated configuration of the aircraft (by doing something approved by Supplemental Type Certification).

    They are two different processes, often used together. It is one thing to manufacture an aircraft part, it is another to approve it's installation on any given airplane.

    You have to read the paperwork very carefully.
     
  12. Timbeck2

    Timbeck2 Final Approach PoA Supporter

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    In my defense having asked the question: I've owned my plane, my FIRST plane since June of last year so I'm completely new to this process. Its 45 years old and it needs new parts. I find a part which claims "no 337 required....only need a log entry...." yet they include the STC in the box the new alternator came in along with installation instructions and PMA paperwork which lists my particular aircraft. I don't claim to know all the ins and outs of getting parts and putting them on a certified aircraft, hence why I asked the question here. I'm STILL confused because I'm getting two different answers/opinions. My mechanic is out of pocket and my plane is down for maintenance and the weekend is coming up.

    I'm gonna go take a bunch of pills and wash it down with a bottle of scotch. Goodbye cruel world.
     
  13. Checkout_my_Six

    Checkout_my_Six Touchdown! Greaser!

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    sounds like yer screwed.....:D

    either way...you need a mechanic to fix it.
     
  14. Timbeck2

    Timbeck2 Final Approach PoA Supporter

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    Finding parts is part of the problem. The bracket that holds the alternator and adjusts the belt tension is Piper part 63531-00 according to the parts catalog I have. The one that is on it isn't straight but has a couple of bends in it (from the factory) which doesn't seem to match the picture in the catalog. I've googled that part number for images and came up with one (1) picture and although it has a bend in it, the angle doesn't help. The alternator I took off has NO part number on it whatsoever so it doesn't match the Prestolite OR the Chrysler part numbers listed for my aircraft.

    What a cluster....:confused:
     
  15. Checkout_my_Six

    Checkout_my_Six Touchdown! Greaser!

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    50 shades of gray.....lol
     
  16. Silvaire

    Silvaire En-Route

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    Actually they are both right. You don't have to use the STC but, like I said, you've already paid for it by purchasing the PP alternator. The advantage of using it is that no idiot A&P or FAA goon can come along at some time in the future and kick up a fuss about it, all of the gray has been erased and it's right there in black and white. That's why even Rosin Visors have an STC. Yes, it's ludicrous but it puts an end to the seemingly endless stream of varied opinions out there. No more arguments.

    As for the bracket, why are you looking for another one? Doesn't the existing one fit? Your mechanic sounds a little gun shy. Is he new at this?
     
    midlifeflyer likes this.
  17. kontiki

    kontiki Cleared for Takeoff

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    If you compare all the aircraft Types listed on the PMA with all the aircraft Types the STC is applicable for use on do you see any differences? I'm just guessing here.
     
  18. Timbeck2

    Timbeck2 Final Approach PoA Supporter

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    Silvaire - The old bracket had too much of a bend in it requiring so much tension on it when tightened that it could snap. I looked up the part number in my catalog and found one in Chandler (KRN.com) Ironically, the "right" part number bracket was different (less bend) than the one installed previously and it fit perfectly with no tension. My mechanic said that the old one if used wouldn't last 100 hours before it snapped.

    Kontiki - the difference was that instructions and hardware were included in the alternator box for a baffle to be manufactured. I don't have baffling in front of my alternator so it wasn't needed.

    My mechanic bought off on just a log entry so all is well.
     
  19. N801BH

    N801BH Touchdown! Greaser! Gone West

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    Which is exactly would should happen.... Glad common sense prevailed......