Replies to This Discussion

Permalink Reply by Richard Rost on November 11, 2009 at 8:00pm

Mathieu,
Please define stiffening. I'm working on the elevator right now. Should I hold off on installing any of the trim parts?

Thanks, Rich

Permalink Reply by Matt Heintz on November 12, 2009 at 5:42am

Yes, hold off until you have the drawings. We are just adding 2 "L" angles on either side of the trim servo motor so that the motor does not flex the skin. This can be done from the access panel. We are doing the same for the aileron trim servo.

Permalink Reply by Craig Payne on November 11, 2009 at 6:56pm

We have heard conflicting reports on how 6-ZU-1-2 fits inside the center spar without changing the spacing of the front and rear portions of the spar. Can you comment on this?

-- Craig Payne, QBK

Permalink Reply by Matt Heintz on November 12, 2009 at 7:50am

Yes, 6-ZU-1-2 is bolted to the wing spar root and slides into the centre spar. What makes this possible is by removing the front wing attachment uprights 6-W-13-1. Once these are removed, the front spar caps are quite flexible and makes it possible to slide the wing into the centre spar very easily. The new front spar uprights (extrusions) are fitted once the wing is on the fuselage. This is part number 6-ZU-2-4. This all sounds rather confusing but Zenith will be doing this installation on their demo aircraft very soon where they will have a detailed procedure.

Permalink Reply by Craig Payne on November 11, 2009 at 6:59pm

In the wing spars if we replace the solid rivets with bolts and seal up the wings how will we check the torque on the bolts in the future?

Permalink Reply by Matt Heintz on November 12, 2009 at 7:59am

We will be recommending a high torque SL nut, such as the AN310, to be torqued 50-70 inch-pounds. This will not loosen over time. Many certified aircraft use internal bolts that cannot be inspected and have not had problems with this. We are still evaluating the exact type of bolts to be used. Our first recommendation will be to replace the solid rivets with new solid rivets of the same diameter if the hole size is not to large. Zenith will see how hard that is to do in the next few days.

Permalink Reply by Matt Archer on November 12, 2009 at 8:42am

Suggestion for consideration. Might want to have an alternate to new solid rivets. Installation of the bolts would seem more straight forward than bucking the rivets. Why not use an AN365 as apposed to the AN310 castle nut?

Permalink Reply by Matt Heintz on November 12, 2009 at 9:51am

Correction to the 310 nut. We will be recommending the MS20365 nuts to be torqued 50-70 inch-pounds.

Permalink Reply by Gabriel Kremer on November 16, 2009 at 12:03am

Have you looked into using Hi-lok or Hi-lite fasteners for the rivet replacement. Hi-lock being titanium might be overkill but the hi-lite being steel might fit the bill. Being that they are a close tolerance when installed properly I would think they would be superior to the bolts. They also might eleviate the concerns builders have with the bolts and nuts seeing the nut only hold the pin in the hole and normally you have to tap them with a hammer to seat the head before installing the collar or nut wichever method found to be fit for securing them. Also people would probably be pleased to know that they hold the wing spars together in the CRJ 200, 700 and 900 airliners. Anyway just an idea I came up with from my experiance with larger aircraft maintenance.

Permalink Reply by Chris Sinfield on November 11, 2009 at 7:12pm

Mathieu
I have the Duel stick system I already have 2 spar uprights on the front spar box to support the flight controls. Do I now need the other 4 uprights on thr front with a total of 6 or just 2 more? If just 2, what locatons/ spacing ? as drawaing 6_-ZU-2 does not show Duel Stick mod stuff shown
chris Sinfield
Australia

Permalink Reply by Matt Heintz on November 12, 2009 at 8:01am

Yes, you need to add the spar uprights 6-ZU-2-3, front and rear. Top and bottom are bolted, with rivets into the spar web.

Permalink Reply by Herbert E. Heaton on November 11, 2009 at 8:26pm

I, like many other builders, have already drilled the center wing spar to the cabin floor. By making the spar thicker, the front row of holes is offset by 0.063". I made a spar mock up today where I drilled holes for A5 rivets in two matching peices of Al sheet. I then offset the parts by 0.063". Using a small step drill I drilled out each pair of holes to 0.1875". The 1/8" drill at the end of the step drill acts as a pilot to keep the drill from wandering. The holes were then reamed to #11 or 0.191". The holes are not perfect but well within the maximum hole size for an A6 rivet as shown in the Zenith construction manual.
This process would eliminate the alleged problem of forcing the wing spar into the center wing spar.

Herb Heaton - Plans Builder

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