Complete CH 640 Errata

From Matronics


Overview / Disclaimer

Solutions provided on this page are the opinions of those who write them, and are not approved or endorsed by Zenith Aircraft unless noted in the official drawings and/or manuals. The problems and solutions presented on this page are intended to give builders the hints they need at points in the documentation that may seem sparse.

This is a "living" document. Please add any and all details that would be helpful to other builders.

Wing Discrepancies

  • Drawing 640V1, Revision 4 - Item 1, Wing Spar Extension. The plans dimension "~405" to the first lightening hole. Change this to 350 mm.
640V2 wing spar extension assembly shows the lightening hole half-way between the two (L) pieces.
Adding the dimensions: 25 mm for spar cap overlap + 225 mm from overlap bend to first (L) + 100 mm from first (L) to center of lightening hole = 350 mm.
  • Drawing 640V1, Revision 4 - Item 4, Upper Rear Spar Cap. Minor typo on plans. Length should be 3390 mm, not 3391 mm. Lower spar caps should be 21 mm longer than upper spar caps. See 640V6 spar root detail.
  • Drawing 640V4, Revision 10 - Item 4, Rear Spar Upright. The top "dl=87" dimension should be to the left phantom line, not to the left corner of the cut piece.
  • Drawing 640V5, Revision 12 - Center Web and Spar Cap Assembly.
    • Upper assembly drawing has a callout for 640V3-1, yet points to the 640V3-5. Change this callout text to "640V3-5".
    • The lower assembly drawing shows an (L) callout for the short angles riveted to the 640V3-5. An (L) is defined using 0.025 material, yet these angles should be 0.032 thick 640F40-12 material. See 640F41 Rear Floor Support + Tunnel Installation detail.
    • The lower assembly drawing shows a callout for the "rear spar upright 640V4-3". The part number should be 640V4-4.
  • Drawing 640V6, Revision 8 - Wing Spar Assembly.
    • The top-right corner of the drawing shows a dimension of 102 mm from corner of the web to the first rivet hole. This should be 118 mm. See the Spar Root Detail dimension stack-up: 40+30+30+18.
    • A similar error just below the last one. The 103 mm dimension from the bottom corner of the web to the AN5 bolt hole should be 120 mm. See the Spar Root Detail dimension stack-up: 35+30+30+22 to end of cap + 3 to corner of web.

Tail Discrepancies

  • Drawing 640T7, Revision 3 - Items 1 and 2 Rear Skin and Nose Skin. The drawing shows a 2 mm dimension between the ~1277 horizontal dimension on Item 1 and the horizontal dimension of item 2. This implies that the item 2 dimension should be 1275 mm. The item 2 dimension should be 1315 mm, symetrical to the bottom of this piece. The 2 mm dimension should be to a phantom 1317 mm dimension on item 1 before the corner notch is cut.

Fuselage Discrepancies

  • Drawing 640F2, Revision 7 - Item 0, H.T. Frame Assembly.
    • An overall reference vertical dimension of 500 mm should be shown on this assembly and the top (L) rivets should be called out to be installed on assembly. The back of the 640F3-1 Rear Side Skin is 500 mm tall. The H.T. Frame needs this same 500 mm height when installed. The 495 mm height of 640F2-4 implies an assembly height of 495 mm.
  • Drawing 640F4, Revision 17 - Vertical position of the 640F4-3 should be 143 mm from the top of the upper longeron to the center line of the 60F4-3. This is calculated from the positions of the 640-F27 H.T. Tail stops and the required deflections shown on 640M50. This dimension was confirmed by the factory on 21 Sep 2009.
  • Drawing 640F14, Revision 12 - The assembly drawing in the upper-left shows a callout to part 640F24-2. This part does not exist and should not be shown on this drawing. The older hand-drawn drawings do not show this callout or part drawing.
  • Drawing 640F18, Revision 7 - Engine Mounts.
    • Item 1, Lower Engine Mount - End plate overall length should be shown as dl=52, not 44 mm.
    • Item 3, Upper Engine Mount - To achieve the 17 degree angle, the dimension for the angle on the body should be changed from 7 x 35 mm to 11 x 35 mm. The end plate overall length should be shown as dl=56, not 44 mm.
  • Drawing 640F19, Revision 8 - In the upper-left corner, the length of the crossbar is shown as "l=306 +1/-0". This should be "l=301 +1/-0" to end up with the dimension shown on the bottom as [300 +1/-0].
  • Drawing 640F20 - The length of the lower Z stiffener on the front side skin is shown as 750 mm. The should be 770 mm.
  • Drawing 640F22, Revision 15 - The fuselage assembly dimensions show "(430)" from the firewall to the instrument panel. This should be "(480)" to match the other dimensions and the length of the 640F14-1.
  • Drawing 640F24, Revision 11 - The upper-right corner shows a dimension of "[360]" between the firewall and the 640F24-6. This should be "[410]" from 640F14 assembly detail.
  • Drawing 640F26, Revision 7 - Item 5, Lower Rear Side Skin Stiffener. Experience shows the top width dimension of 142 mm should be 150 mm. This leaves 11 mm, instead of 15 mm, for the width which is cut. The bottom 172 mm width should be 176 mm.