October 2012
At the end of the last episode Bob Berg, the owner of the 1939 Piper J-3 Cub and I had just driven to Lompoc, Calif. to attend the West Coast Cub Fly-in. That annual event took place July 6-8, 2012.
I had hoped when I agreed to join the resurrection team in mid-February to fly the 60-odd statute miles to the Lompoc airport (KLPC) in our newly resurrected J-3. That hope was wildly optimistic. As I write this, it’s now Labor Day—and we haven’t yet turned a prop. I was warned by the Cub expert I contacted through the Cub Club that it would be prudent to budget between 200 and 250 hours of labor.
On the 11th of April I wrote a “To-Do” list. It included labor items such as patch the belly fabric (I cut it in order to install rudder pedal return springs); install instrument panel; install and plumb instruments; install boot cowl; install new rear stabilizer tube; install horizontal stabilizer and elevators, install rudder, install tailwheel, install STC’d Globe brake kit; and decide on what magnetos to use.
MAGNETOS—OVERHAUL OR NEW?
Old mailbox-style Bendix SF4RN-8 magnetos were on the A-65-8 engine in Berg’s Cub when it last flew. I was told by some old-timers that mailbox mags “would shoot a spark across the room.”
According to the records the magnetos had been in service for only 120 hours since the last overhaul. How would 11 years of inactivity affect them? I felt that we needed to either overhaul them, or go with a new set of Slick mags. Al Marucci at Savage Magneto Service in Hayward, Calif. quoted an overhaul on each SF4RN at $750; parts extra. I could get a complete Slick (Champion Aerospace) ignition system consisting of two new magnetos with impulse couplings, ignition harnesses, eight spark plugs and gaskets, etc. for about $500 more than the estimated cost of overhauling the Bendix mags.
We weren’t trying to restore Berg’s Cub to original condition; we were working to make it safe and dependable. I decided on the new Slicks and installed them.
ENGINE AND PROP
Hanging the engine was pretty easy; we picked it up with a loading arm that notched into the front bucket of a front loader. We drove that loader right into the workshop, ran a length of chain through the engine lifting eye, chocked the Cub’s wheels, and got the engine and mount close enough to wrestle the mount into position on the firewall. Then I torqued the nuts and installed cotter pins.
Later I had to go back and lift the engine with a cable come-along I had looped over the shop’s roof beam in order to install eight fiber washers (part number 80122-43)—one on each side of four conical rubber engine mounts. Studying the parts book showed they were needed.
The throttle control had developed a friction point during the decade since removal. After routing it out through the firewall, around the engine, and connecting it to the carburetor throttle arm, we found that it was bound up—a healthy push was required before it finally moved.
This push-push-push harder action resulted in almost no movement at the carburetor arm until—bang—the friction was overcome and the throttle went full. No good. I soaked it down with AeroKroil—the best penetrating oil I know of—but that wasn’t the problem. We finally gave up and bought a new cable from Univair.
An article in Cub Clues showed that I needed to determine which needle valve was installed in the Stromberg NA-S3 carburetor. Was it the original stainless steel needle? The neoprene-tipped needle? Or the post-1963 Delrin needle? If the Delrin needle valve was installed—it was impervious to chemicals—a small weight had to be installed on the float to guarantee a tight seal between the needle and the needle seat.
We were in luck! The Delrin needle was installed and the needed weight had been previously installed.
Berg had already removed the Sensenich wood prop, but since we weren’t using the original engine, we needed to remove the prop hub from the tapered crankshaft. These hubs are designed with a built-in self-pulling feature. As the nut is backed off, a flange on the nut bears against a thick snap ring that transfers pressure to the hub, pulling it off the shaft.
We started backing off the nut but nothing was moving. We looked more closely—the propeller nut had pushed the hub into position on the tapered shaft of the engine—but the snap ring required to remove it was nowhere in sight.
Dana Osmanski of the Cub Club directed us to Doug Combs at Classic Aero. He had them. Cost $35. We got one, and—following the directions written by Bob Gehring and Steve Krog on this very topic for the March 2005 issue of Vintage Airplane—popped the hub loose.
The spark plug leads supplied with the Slick magneto kit weren’t the correct length. They were what I call “fits-all” leads since they were made long so that the kit would fit a large number of four-cylinder engines. The only tool I knew of that would make quick work out of changing lead lengths was a Slick T-200 harness assembly tool kit. I found one on eBay for $95. We were back in business.
I fabricated a flexible hose for the gascolator-to-carburetor connection, routed the oil pressure tube and oil temperature Bourdon tube through the firewall, and fabricated a new wiring harness for the magneto “P” leads.
RIGGING THE TAIL FEATHERS
Clyde Smith Jr. is known as The Cub Doctor. He worked for Piper in Lock Haven for years. Smith writes maintenance articles for the Cub Club newsletters. He also manufactures and sells a number of items for tube and fabric Pipers including instrument panels, cowlings and firewalls.
Between the pages of the Cub Club newsletter, Cub Clues, and Smith’s patient and helpful counsel, Bob Berg and I found answers and received the guidance needed to press on.
Work on the tail feathers included the installation of a new stabilizer trim yoke (part number 42692-000), the new rear stabilizer tube and installation of the surfaces. Smith wrote about tail surface rigging in Cub Clues (Issue #41, December 1990). These tips guided me as I adjusted the tensions on the four brace wires.
A new tailwheel steering spring and link kit was installed. New landing gear bungees were installed (using a bumper jack that we modified in accordance with drawings in a Cub Clues newsletter.) New front and rear seat slings were purchased from Airtex and laced into position.
FUEL SYSTEM
When Berg disassembled the Cub, the fuel system consisted of one 12-gallon tank situated between the instrument panel and the firewall. According to the FAA Type Certificate Data Sheet (TCDS) all J-3s came out of the factory with this 12-gallon tank; the fuel tank for the PA-11 (the Cub Special, approved in April 1947) upgraded the system to a single 17-gallon wing tank.
Berg had one wing tank installed while the wing was disassembled for recovery. That tank will be plumbed into the system near the end of this project.
I attempted to free up the main fuel selector with an AeroKroil bath. I soon was able to move the valve freely but the shutoff wasn’t complete. Inspection revealed scoring on the tapered plug of the bronze-to-bronze valve. A replacement valve was purchased from Aircraft Spruce and Specialty and installed.
THE FAMOUS CUB LIGHTNING BOLT
When I started the project the fuselage lacked the trim stripe, the N-number and the famous Cub lightning bolt. We could purchase vinyl appliqués, or paint them. Smith sent us drawings illustrating the proper layout.
Berg invited Tom Horwath, one of the painting experts at Ellis Paint, the company owned by Berg, to lay out the striping. We researched the N-numbers—did we want to put them on the wings like Piper did in 1939? Should the ones on the rudder be three inches in height, or four inches? Smith sells four-inch vinyl N-number appliqués, so we bought a set of four-inch-tall letters and numbers from Moody Aero-Graphics.
UNIVAIR
The Cub decal is available from both Univair and the Cub Club. We bundled a set with an order from Univair. Univair is very easy to work with. In an early flurry of activity I ordered parts we didn’t need—and returns were handled seamlessly.
We opted to purchase a set of new sealed and oiled wing lift struts from Univair. This eliminated the repetitive inspections for internal strut corrosion required by AD 99-01-05. I was also able to download a complete list of Piper Service Publications (Service Bulletins and Letters) for the J-3 from the Univair website.
THE PREMATURE MOVE
We somehow came to the conclusion that it was time to move from the shop on Berg’s property to a hangar on the Paso Robles airport (KPRB). We wanted to install the wings and get flying.
We found a hangar owner who thought that his PA-28-180 (a low-wing) and our Cub (a high-wing) could coexist in his hangar. He was a great guy and the rent was right; we could stay as long as needed—and it was all done on a handshake.
These seemed like auspicious signs. For sure, we thought, it must be time to put on the wings, put some fuel in the tank and oil in the engine and get going. Enthusiasm filled the shop.
A farm trailer was modified, and while I was away in Seattle wrapping up some family affairs, Berg and “Balloon” John Warren trundled the Cub up the trailer. And early one Saturday morning they eased out to the airport. After a couple of hours of wrestling airplanes this way and that, the Cub was pushed back up on the trailer and pulled back to Berg’s shop.
When I got back on the job (I committed to work Friday and Saturday on the Cub until we finished) Berg filled me in on the sad details of the “move.” He suggested and I quickly agreed that the best plan of action for the future would be to finish everything we could in the shop before we even thought about moving to the airport.
The next couple of weeks I focused on fabricating the many small trim pieces required to finish the windows installation and enclose and finish the forward spar attachment area in the fuselage.
After looking at dozens of J-3 Cubs at the West Coast Cub Fly-in we concluded that no two Cubs were finished the same way. Some Cubs left the front spar attach tubing cluster completely exposed; others wrap the area in sheet metal; still others use both sheet metal and fabric.
Smith sent pictures that showed how the forward upper fuselage was originally finished. In the past a large skylight had been installed in Berg’s J-3 so we couldn’t adhere to following the original configuration. We worked with what we had—and in the end, made the spar enclosure out of aluminum.
As this chapter of Cub Resurrection goes to press, all the trim pieces and the pieces of the spar enclosure are at the paint shop. Next week all those parts and the windshield and skylight glass will be installed.
Next month I’ll tell you about ground running the engine to check for fuel and oil leaks. And how we finally got to the final stage in the resurrection—final assembly, final checking (I’ve asked Jeff Byard, vintage sailplane enthusiast and part owner of the Mountain Valley airport (L94) to do a final inspection before we take to the air) and first flight.
Berg and Warren each have logged over 500 hours in tailwheels; I’m the pokey one with 140 hours. We have found a flight instructor to help us all get back up to speed and leads are popping up for hangar space so we’re finally beginning to believe the end is in sight. I’ll update you next month.
Steve Ells has been an A&P/IA for 39 years and is a commercial pilot with Instrument and Multi-Engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as Associate Editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960 Piper Comanche. He lives in Paso Robles, Calif. with his wife Audrey. Send questions and comments to editor@www.piperflyer.com.
RESOURCES >>>>>
Aircraft Spruce and Specialty Co.
aircraftspruce.com
Airtex Products, Inc.
airtexinteriors.com
Classic Aero
classicaero.com
Cub Club
cubclub.org
Clyde Smith Jr., The Cub Doctor
www.cubdoctor.com
Kroil (Kano Laboratories)
www.kanolabs.com
Moody Aero-Graphics
moodyaero.com
Univair Aircraft Corp.
univairparts.com
