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Thread: Need door frame

  1. #1

    Need door frame

    My mechanic called me to help him locate a right side
    rear door frame for a 1974 Sundowner that has corrosion
    issues. The part number is 169-400026-25. Anyone have
    this part or know of a salvage yard that may have this piece
    to get another one of our planes back in the air?

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  2. #2

    Need door frame

    > My mechanic called me to help him locate a right side
    > rear door frame for a 1974 Sundowner that has corrosion
    > issues. The part number is 169-400026-25.
    *** My condolences. The same thing happened to me. Your mechanic
    will have to fabricate doublers for the door frame, because all the
    rivet holes will be in the wrong place.

    Here is the log of my experiences with this repair:
    -------------- snip ---------------

    How I learned,
    Not to buy an airplane,
    Based at an airport,
    Whose name contains,
    the word ISLAND

    It was January. I was about 15 hours into earning my Instrument rating.
    I was making good progress. We were already well into the approaches. I
    still remember being vectored around exactly at the top of the clouds,
    bashing in and out of them. For the first time, the Sundowner felt *fast*.

    Then it happend. It was the rainy season. I was engaged in a neverending
    battle to keep water out of the airplane. I was making progress. I was
    *winning*. Each rainstorm I made improvements to the cast-on-site silicone
    sealing system. And each time, there was less and less water to bail out of
    the airplane.

    This one fateful afternoon, I was poking around at my silicone, and noted
    that the door post, aft of the pilot's side door, was just a little crumbly.
    I didn't think much about it - Beech "rounded" the corners of the door
    opening with Bondo - I figured some of the bondo was getting worn.

    Well, it wasn't the Bondo. I poked at that little crumbly edge with a
    screwdriver, and to my shock and surprise, the tool went right through the

    I called my IA: "We've got a problem...". I called my CFII and
    cancelled the instrument training. I started pulling things apart.
    * The seats.
    * The window surround
    * The side upholstery panel.
    ( whups, it won't come out unless you take out the floor )
    * OK, the floor

    Things looked pretty clean with the exception of a bit of corrosion at the
    door latch. Surely fixable with a gusset.

    Then I pulled out the fresh air duct, which was snuggled inside the "U" of
    the door post, and all hell broke loose.

    There was a corroded area about the size of my fist, going almost all the
    way through the door post. It was deep. It was bad. Structural aluminum
    had turned into flaky cardboard.

    Apparently, the following effects had occured:

    1. The door snugged in a bit deep. The shoulder of the post was exposed
    to the air ( & water! )blast in flight.

    2. The window was leaky. Apparently the P.O. would just bail out the
    airplane to go flying.

    3. The fresh air duct was leaky, delivering a fine mixture of water and
    air to
    the airframe. It had rotted away not only the door post but the
    longeron above the window.

    4. Beech apparently made the "skeleton" of 2024T6 aluminum, NOT ALCLAD.
    So it was very prone to corrosion.

    5. The space between the aircraft skin and the interior panels was filled
    with fiberglass insulation. When things got wet, this stuff would
    absorb moisture and hold it lovingly up to the aluminum.

    At first, we thought about doing a doubler. It would have been hard.
    The doorpost was a compound curve of 2024T6 aluminum. We would have had
    to metalwork a patch up, and then get it heat treated. I called around
    California. Found one shop that could do the job, for a mere $150.

    I called further afield. "Trade-a-Plane is my Bible, and I shall not
    Want." A wrecking yard on the East Coast had a good door post for the same
    price as the heat treat for my patch. A complication was the part number:
    there was none. The Sundowner parts book listed a part with an effectivity
    code of "4". I don't remember what S/Ns "4" covered, but I do remember that
    it didn't cover mine! The yard had a close S/N to mine. They guaranteed
    that the part would fit, otherwise I could just send it back. I'd be out
    shipping, but it seemed like a good bet. I also ordered the longeron.

    A lecture on rivet removal was delivered by my IA. "Take a new, sharp
    1/8" drill bit. Drill through the top, right at the dimple. Don't drill too
    deep, just to the shoulder. Take a pin punch - or turn the drill bit
    backward - and twist the head of the rivet off. Then pound the tail of the
    rivet through with a punch and hammer. Repeat one hundred times." The
    door post is a fairly large part. It starts at the floor and goes up
    to the middle of the roof. Kind of like a half bow from a Conestoga wagon.

    One issue that always comes up with repairs is - how far up the FAA food
    chain do you have to go to get them approved? It's always best to do it as
    low as possible. The hierarchy is something like:

    1. Owner maintenance - changing oil etc. You do it and log it.
    2. A&P maintenance - say, changing a fuel pump. Unbolt, bolt. A&P
    does it and logs it.
    3. Major repair - requires a power drill. A&P does it, files a 337.
    has to sign.
    4. Field Approval - Weird stuff, changing the airplane. You make up a
    337 BEFORE doing the work, FAA looks at it, puts a
    stamp on it, signs it. Then A&P does the work, IA
    signs the 337. A surprising amount of things are
    viewed by the FSDO as "weird stuff" and therefore
    requiring field-approval.

    We decided that since we were just replacing Beech parts with Beech
    parts, it would be a "2". More about that later.

    In due time, the "new" parts arrived from the wrecking yard. I spent a
    day cleaning, alumiprepping, alodining, and painting them with epoxy zinc

    When I went out to install them, the first of many nasty surprises was
    delivered to me: the @#$# rivet holes didn't match! Well, some did, and
    some didn't. Worst case were the ones that were right next to where they
    should be, or went halfway through where they should be. Apparently,
    some rivet holes were part of the original tooling of the part. Others
    were drilled at will by Beech when they hand-assembled my airplane.

    The fix for this was to "fabricate" ( that's A&P talk for "make" ) a
    set of doublers. ("Doubler" is a piece of metal that lays next to another
    piece of metal. You wind up with a sandwich two pieces of metal thick ).
    The doublers would have all the rivet holes in the "right" place, to match
    the rivet holes in the skin.

    "Hello, Aircraft Spruce? Please send me a sheet of 2024T3, fifty thou
    thick". This was to be the first of many many calls to Aircraft Spruce.

    "Fabrication" is very time consuming. You measure twice. You cut the
    metal to size with, depending on its thickness, a big pair of snips, or a
    saber saw. You round off the corners. You Alumiprep it. You alodyne it.
    You paint it zinc chromate. Time passes....

    But wait! There's more. In order to punch the holes in the doublers,
    you need to know where they are. EXACTLY where they are. That's not
    knowable unless you have holes in the door post. So I

    * Filled the existing holes in the post with aluminum. Actually, bits of
    rivet, squashed into the holes with a rivet squeezer.
    * Installed the door post in the airplane.
    * Drilled new holes through the post, in exactly the right places through
    How was this possible? Well, Dremel makes an attachment for the moto
    tool that converts it into a little tiny router. And they make little
    tiny bits with ball ends. I took the "router" and stuck the ball end
    bit through the skin hole and and used it to grind the hole in the post
    - since at the skin was the smooth surface of the shaft behind the
    ball, the skin hole was not damaged.

    Once the "new" post was drilled, holes for the doublers were scribed by
    sticking a sharp tool through the skin from the outside. Clecos were
    invaluable for this work. Scribe one hole, punch it, cleco the doubler
    in, scribe the next hole, punch it..... Did I mention that this work is

    Some time around all this, my IA said

    "Jerry, you better check the other side...."

    OK, I checked the other side. GAAK! Corrosion there too!

    Luckily, it wasn't as bad. I was able to clean off the lower longeron
    (under the window) completely with scotchbrite & alumiprep. The door post
    got a bit cut off at the door latch, and a gusset. The upper longeron
    got its corrosion cut out, scotchbrite & alumiprep, and a pair of doublers
    - one shaped like a "U" that fit snugly into the "U" of the longeron, the
    other flat, up under the longeron. The "U" doubler was especially time
    consuming. I made about seven of them before I got the width of the "U"
    just right. Then there was that large oval hole to make for the air duct.
    The Dremel mototool and a little abrasive cut-off wheel was the perfect
    tool for this. Then Alumiprep, Alodine, zinc chromate. Time passed....

    The IA and I decided that I should change out ALL the fresh air ( & water
    ) ducting. And a miserable dirty job it was, too. More time passed.

    Rivet holes in the new door post & longeron did not match rivet holes in
    the seat belt mounting point gussets. So I had to fabricate new gussets.
    I duplicated them in 0.080" 2024T3 alclad that I had left over from an
    instrument panel project. A complication was that the gussets are gently
    curved to match the interior of the airplane. The proper & easy way to
    gently curve things is to use a "slip roll", which is a large floorstanding
    metalworking tool. I don't have a "slip roll", so I did the following:

    1. Cut a two-foot-long strip of aluminum, the width of the desired part.
    2. Clamp the end of the strip in the bench vise.
    3. Grab the free end of the strip with a smaller vise or vise-grips and
    4. Slide the old part up and down the long bent strip.
    5. Repeat (3) & (4) until a spot on the long bent strip is found that
    precisely matches the curve of the old part. Mark the strip.
    6. Cut out a new part out of the bent strip at the mark.
    7. Discard the rest of the strip.

    ( Another weekend passed )

    Finally, I was ready to rivet. I got together with the IA and an A&P
    friend. The IA brought his trailer mounted generator/compressor set and we
    went to town. IA bucked. A&P hammered ( with the rivet gun ). I undid
    Clecos, cut rivets, and did whatever else was required to keep the work flow
    going. I lost count of how many times I hopped on & off the wing. In six
    and a half hours, we had all the exterior rivets in. I went home and almost
    fell down the stairs, I was so tired.

    Time passed. Just for variety, I changed the engine oil, and greased
    the wheel bearings. There was still a good deal of interior rivetting to
    be done. I attacked the interior with my own rivetting setup. Got it all
    done. Called the IA - there were about ten rivets he didn't like. Some of
    those constricted spaces are the devil to get bucked without bending the
    rivet stem over. I tried over & over, it just wasn't happening.

    So then I got a bright idea - what about those Cherrymax rivets? I
    figured out what sizes I needed, ordered them from Aircraft Spruce. Ten bux
    well spent, if it greases the skids on this job! The IA approved.
    The Cherrymax rivets saved the day.

    It was all downhill after that. Vacuuming the bejeezus out of the
    subfloors. Reinstalling the ceiling, interior panels, window surrounds.
    Re-routing the antenna coax and putting the instrument panel back together
    ( because I'd had to undo the antenna coax to in order to remove the door
    post ).

    All that done, I went to the IA with my logbook entry sticker.
    "Where's your 337?"
    "Uh, you said it was going to be a logbook entry, because we were
    replacing Beech parts with Beech parts"
    "Oh, no. This is a major, MAJOR repair. Gotta have a 337. Call me when
    it's done".
    Two days of spare-time paper shuffling later, he had his 337. In
    quadruplicate. One copy for the FAA, one copy for him, one copy for me, and
    one copy because - well - "stuff" happens.

    Well, the 337 is in, the logbook is signed off, the weight & balance is
    in, I have new charts & AF/D in hand, it's time to call that CFII again.
    I'm feeling a little rusty.

    "Hey Bob, what's that steering wheel thingie in front of the panel for?"

    - Jerry Kaidor ( jerry at )

    -------------- endsnip ------------

    Anyone have
    > this part or know of a salvage yard that may have this piece
    > to get another one of our planes back in the air?
    > Thanks,
    > Pete
    > _______________________________________________
    > BAC-Mail mailing list

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