Would you pay this man to help you upgrade your airplane? We did and it worked out much better then the picture would suggest.

This blog is not a how-to. There have been plenty of well done how-to blogs. It’s just some pictures with a few words attached.

Three years ago my brother Alan and I (with lots of help) built a pair of 601s from Super-Quick-build kits in 4 months at Quality Sport Planes in Cloverdale California. You can read about that adventure here.

So who is that guy with the Michelin tire hat? That’s Doug Dugger who, with his wife Lori, operates Quality Sport Planes. Doug has owned many planes and has built a 601, a 701 and is half done with a 750. How does he do all that and help folks with their projects at the same time? With lots of energy, experience and a sense of humor, obviously.

When Alan and I decided to install the upgrade to our experimental 601s we considered a few options but in the end it was clear that the why to go was another high-energy project at QSP.

We talked to Doug and he blocked time out on his calendar and arranged the resources to get the task done in as short a period as possible. We were hoping to get most of the work done in 9 days, which was the amount of time Alan could get off of work. Well it took about 400 man-hours and 13 days to get both planes done. I snuck a few extra projects in during the upgrade: New battery, landing & taxi lights, main tires, 650 style L angles in the back.

Now, more pictures, fewer words...

Here I am draining the gas with Sedrick’s help. Sedrick is not officially part of the crew but he pitched in from time to time. Sedrick is building a Subaru powered 801 at QSP.

Alan’s ailerons come off. Can’t fly this thing no mo.
Here is a view of our crowed hanger. Mike and Gracie’s 701 project on the right, Sedrick’s 801 project and the left and our 601 upgrade project in the front of the hanger.
Wings come of quickly and the skins too. Below a template is being used to correctly position the nose ribs. The template is custom made for each wing before the ribs are removed.

From time-to-time it’s good to READ THE PLANS. Here Doug and I actually do that.

Here the main spare is being upgraded on Alan’s wing.
Here is my longer web doubler positioned above the stock one. I made mine 5 inches longer which was what could be done easily. This mod is not sanctioned by Zenith.

Here is the longer web doubler installed.

Working into the evening. We started each day at 8:00am and ended no earlier then 6:00pm, sometimes much later. No days off.

Here Alan and Ron Asbill install the bottom skin doubler. Ron and his wife Sharon dropped by for a few days. They are good company and great help. They have a flying 601, and have the upgrade kit already – just need to find the time.

Here I am back-drilling the center spar.

Ron and Alan riveting in the center spar.

Steve Barnes, Alan Smith and Doug Dugger work on a center spar. Steve builds and flies RV airplanes. He has logged thousands of flight hours.

Alan Smith, Steve Barnes and Ed Dalbec work on a center spar. Ed Dalbec is a flight instructor and an A&P. He worked for American airlines as a mechanic. He has built several airplanes including a 601.

Speaking of the center spar, you can’t see it in this picture but in my dual-stick airplane, the front torque tube barring was quite worn. Apparently it was not greased when originally assembled. Keep in mind that the tension on the elevator cables is pulling against this surface as you operate the ailerons back and forth. Grind, grind, grind takes it toll.

Don Shaw works on a main spar. Don has built several airplanes. He was an international pilot for a major airline. In the background is Russ Bens, a 601 driver who is part way through his upgrade. He is about half done building his 750 also.

Man, this thing used to fly? Sure is torn up now! Good thing we did not run any wire through the center spar – ok two little wires did run through the center spar. Could have been much worse!

Upgraded bellcrank.

Our factory-built wings allowed the wire to rub on the bottom skin. You can see the dark splotches on the skin. We made standoffs attached to the new L angles to keep the wires from touching the skins.

Here is an aileron balance.

Ed is working on fitting the L angles.

Sharon is removing the old paint around each rivet hole. This was done with a paint removing tool Doug made by welding a nut onto a drill bit which is loaded into the drill upside down so it does not cut. It worked quite well. We called it the paint twirler (as in, "ok who has the paint twirler now?"). It got used a lot!

Here Doug is asking for Divine guidance - silence. In the end we had to read the plans

Ron, Alan and Doug putting a tank back into a wing. All 4 tanks had leaks at the welds and needed rework at the welding shop ($480). The two that had been "inspected by RM" were not so bad: one leak in one, two in the other. The two tanks from Alan's plane did not claim to have been inspected by anyone: 4 leaks in one, 6 in the other.

The leaks were noticed because of the blue stains the evaporated fuel left behind. While it was disconcerting to see these I suspect they posed no real safety hazard. I say this because the stains seem to indicate the fuel evaporated before it could run very far. From that evidence I conclude the leaks were very slow and the fumes dissipated quickly.

Also of concern in the factory wings; no cork was used between the back of the tank and the bottom row of rivets on the main spar. On two tanks, the rivets had been rubbing on the backs of the tanks and small indentations on the tanks were evident. Perhaps this could have gone on for a long time before something bad happened. Anyway, cork is cheep - use it well to prevent metal to metal contact.

New rear spar attachment is in. Much beefier - just push it in: it fits ok.

Alan's wing is all ready to rivet. Now that's a lot of clecos.

I don’t think it will fly like that. More work to do.

Don gives Doug words of encouragement as Doug gets those pesky bolts in. What helped is that we trial-fitted the center spar and bolts to each wing before the center spar was re-installed into the plane. It actually went well. Doug has a set of pointy little fitting pins that help. I did a little grinding and polishing on them things: pointier pointy things are more better.

Time for the bad news: VERY accurate airplane scales. Sad truth: 830 pounds - both planes match to the pound. How's that for twin airplanes? How much did they gain? We don't know because the original weight and balance was done with Wal-Mart scales. They seem to be designed for folks who don't want the truth.

Two upgraded 601s; mine on the left and Doug's on the right. Doug's 701 is in the background.

As of now, QSP has upgraded 3 601s and they are all flying again. The folks are QSP are very knowledgeable and most accommodating. Where else can you find a group of pleasant, Zenith-knowable people who will put in 13 days straight 8:00am to 6:00pm just to help meet a tight schedule? If you're looking for help on the west coast, look no further then QSP.

How do these upgraded 601s fly? Speaking for myself, I find the plane now has a stiffer, busier ride. It did not take long to get accustom to it. Otherwise, nothing notable.

Handling and installing all these upgrade parts leaves no doubt; the plane is much stronger in key areas. I am glad my upgrade is done and I can get back to flying.


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Comment by Stephen R. Smith on April 16, 2010 at 10:16am
Hello Gary,

Thanks for posting your experience on the upgrade. Reversing the gear seems like a good change for some aircraft. The trainer I learned in also had the gear reversed.

Comment by Gary Ray on April 16, 2010 at 5:49am
Nice post.
I also did not remove the front skins and had no problem completing the upgrade.
The aileron vibration mentioned in the hingeless 601XL is not seen in my 601XL with a 6 cylinder Corvair engine.
The flight characteristics appear to be unchanged except:
I reversed my main gear at the same time which moves the axel 5.75 inches forward and took only 40 minutes to accomplish when the wings were off for the upgrade. This is a big improvement on reducing nosewheel weight and now the aircraft rotates without the need to pull it off. Also during landing it is easy to keep weight off the nose wheel.
Comment by Stan Cooper on March 6, 2010 at 12:06pm
Steve, thanks very much for posting this. I'm taking delivery of my upgrade kit next week, and now feel much better about my ability to perform the surgery. Zenith and Doug and Lori at QSP have really stepped up.

Comment by Phill Barnes on March 3, 2010 at 6:19pm
Thanks Steve. Fantastic blog by the way. If a picture tells a thousand words, your 32 000 words have been a great help to myself and many others I'm sure.

Comment by Stephen R. Smith on March 3, 2010 at 4:42pm
No issue leaving the nose skin on. The team at QSP has done all 6 wings that way so its not as though we can give you a comparison of methods - can only say it worked OK to leave them on.

Comment by Phill Barnes on March 3, 2010 at 4:35pm
Hi Steve
Any dramas with leaving the nose skins attached to the bottom.
I am still hesitating in drilling out all of the bottom spar rivets for the upgrade just to get the nose skin out of the way. I have not heard anyone say so far, leave the nose skins on. Everyone I have asked has said to remove them completely. What are your thoughts.

Comment by Stephen R. Smith on March 3, 2010 at 3:32pm
I am probably not using the correct words for the parts involved...

I am talking about the 4 small bolts that attach the front part of the gear bracket to the plane. There is a heavy doubler that those 4 bolts need to go through so the bolts needed to come out.
Comment by Mark Ertz on March 3, 2010 at 12:36am
Thanks Shephen, That March Kit Plane article spoke to the placing of the mass balance and they seem to be flexible,too. I am thinking about putting an inspection plexiglass plate on the lower skin under the weights. That way I can inspect it daily during preflights. I may patch around the cut holes in both the rear spar and aileron to beef up the area where the bar passes thru. Your fotos are a real help.
Comment by Bob McDonald on March 2, 2010 at 8:16pm
Excellent blog.
Comment by Stephen R. Smith on March 2, 2010 at 4:29pm
Mark E.,
Yes, we moved the balance to just outboard of the last rib. No, this change is not sanctioned by Zenith and I suspect they would want everyone to follow the plans. Our planes are experimental so we experimented. Our rational? We suspect the plans call for the balance at the end of the aileron to minimize the “damage” the hole creates in the rear spar – just guessing. In my view, the hole is close enough to the end of the wing that its exact placement is not much of an issue. The aileron is rather light weight in its construction. I felt that the balance would perform its job better if it was place closer to the center of the aileron. I am not an engineer; I am just doing this my way so to speak.

On a related subject: Doug’s 601 has hingeless ailerons and he placed the balance per the plans. Doug’s ailerons vibrate in a way that make both Doug and I uncomfortable. I have ridden in Doug’s plane at his request just to observe this. We have seen this vibration both while taxing and also in flight while executing some turns. This vibration in the ailerons seems to be excited by engine vibration. Doug’s plane has a 100 hp, 4 cylinder engine. Based on my observations I would replace hingeless ailerons with hinged ones prior to attaching a heavy weight to it. Using a single skin layer for a hinge is an elegant design but it is far less stiff then the hinged design. It stands to reason that it could have a resonant frequency which is different and therefore respond differently to vibration. I understand the factory demo plane is also hingeless however it has a much smother 6 cylinder engine so they do not report seeing these vibrations (as I understand it). In any case I don’t suspect the hingeless design was conceived with the expectation that it would one day have a heavy weight attached at one end. In this paragraph I am just reporting my observations and personal thoughts. I have no inside information and do not intend to set standards for the community of builders.

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