This page shows the process, with text and images, of restoring a Stinson 108 airframe. While the Stinson 108 is the primary subject, the steps shown apply to most light fabric covered aircraft restoration projects.

Page created 01/01/2001, Last updated 01/16/2024

Stinson 108-3 N6968M as purchased

• Step 1 - selecting a candiate airplane for restoration. A number of criteria was considered when I decided to purchase an airplane to restore. A couple were - first the airplane must have a reasonable cost to purchase and rebuild. Second in priority was to purchase an airplane which was basically complete. This view shows the airplane as I first saw it. Complete but in serious need of attention. Here is another image of the airplane as purchased. As this view shows, the condition of the instrument panel as purchased. Note that when purchased the airplane was equipped with a 12 channel Narco Superhomer "coffee grinder" tuneable radio on the right side. The Narco Superhomer worked, the Cessna ARC crystal controlled radio on the left side did not work. Both were tube type radios replaced during restoration.
  
• Step 2 - get the airplane to where it will be restored. To reduce costs I decided the restoration would take place at my home, not the airport. This required disassembly of the airplane and transportation to my home from the airport. Originally I planned to put the tail wheel in the back of my truck and tow the airplane home. I learned that my personal auto insurance did NOT cover towing unless the vehicle being towed has a vehicle license plate. Because of time restraints I hired a flat bed truck to bring the airplane from airport to my home. I later found out it is not too difficult to locate a trailer specially made to haul aircraft. I previously removed and brought home all pieces of the airplane which would fit into my Ford Ranger pickup. I was able to get all except the fuselage and wings home before hiring the truck. This image shows the truck arriving at my California home. I was fortunate that I lived (this complete restoration occurred while I lived in California, before our move to Maine) on a little traveled street.
  
• Step 3 - Get the airplane under cover. With the aircraft home, the restoration begins by removing the engine so the airplane will fit in the garage. A hydraulic hoist was rented to remove the engine. One of the most difficult aspects of aircraft restoration is to convince your wife she really doesn't need to have her car in the garage. Good Luck.
  
• Step 4 - Fuselage preparation. This is the most time consuming and expensive part of the restoration. A major advantage of a fabric airplane is the ability to strip down the airframe and wings and see the inside. This view shows beginning to strip the fabric. You also begin to learn about the non standard parts which may have been installed during the life of the airplane. Look close and you can see non standard, very uncomfortable, front seats. Also notice the mildew buildup on the bottom of the fabric.

CAUTION - several publications suggest keeping the old fabric to use as a pattern, especially to locate inspection holes. The airplane I purchased was covered with the first Ceconite process. Problem here is that the early Ceconite process this airplane was covered with used nitrate dope as the first brush coats. Nitrate dope sticks better to synthetic fabric (which is the reason for using nitrate dope rather than the less flammable butyrate dope), but nitrate dope is extremely flamable. Be careful with the original fabric, store it carefully. As for me I documented the location of the inspection holes then disposed of the old fabric.

SUGGESTION #1 - before continuing you need to locate an individual with a FAA Inspection Authorization (A&P with IA). This individual must be experienced with fabric covered aircraft. Before an individual can obtain an FAA Inspection Authorization they must first have an FAA Airframe and Powerplant mechanic license. There are times during the restoration where an A&P license alone is insufficient to meet FAA requirements, wile at other time the IA rating for some inspections is essential. After each inspection make certain to have the IA make an appropriate entry in the airplane's airframe log book. Recovering a fuselage or wings also requires completion of the FAA Form 337, and for this the IA inspection and signature is required.

SUGGESTION #2 - keep a detailed record of what you remove, include drawings of how you take pieces apart. I know it seems obvious when you remove it, but write it down in a notebook anyway. Don't loose the notebook! When you go to reassemble it will help a LOT to review your notes on how you disassembled the airplane! Most likely it will be quite a period of time from disassembly to reassembly.

Once everything, that is every nut bolt, former, everything, is removed, you can now bring the basic frame down to bare metal. This view shows the fuselage completely stripped ready for sandblasting. Note the wooden jig used to support the fuselage in the pick up truck to/from the sandblaster's shop. Very soon after sandblasting the fuselage will need to be inspected by the IA as 4130 steel rusts very fast. The IA will be looking for problems in the 4130 steel frame of the fuselage. If there is a problem now is the time to fix it. In California the maximum load height is 10 feet. In the configuration shown the maximum height is 9 feet 6 inches. Check your local laws before moving the fuselage.

With the fuselage back home, inspected, and the log book entry complete by the IA, reassembly begins. Shown here is the fuselage primped and landing gear reattached. Here is another view of the beginning efforts to reassemble the fuselage. Note the wheels will not be used on the airplane after restoration. I found cracks in the original wheels early on. The advantage of using wheels without tires is that the wheels alone keeps the fuselage a little lower. Note the vertical pieces on the top of the longerons. These pieces are used to hold the aluminum fabric formers. They are also quite close to the garage door, so every little bit helped and that is why the tires are removed from the wheels with cracked rims. After the formers are installed it is not such a problem.

Fuselage preparation continues. Here my daughter and I are using Scotch Brite pads to clean the top aluminum fabric formers after removing the original paint. Here is a view of my son holding the vertical stabilizer showing original Stinson Logo. We found 12 coats of paint on the vertical stabilizer! Each was removed one coat at a time. You can't inspect the airframe metal with layer upon layer of paint. Get the paint off then inspect.

SUGGESTION #3 - obtain parts and service manuals for your airplane. Univair has good quality reprints available for many Classic airplanes, particularly the Stinson 108. When you purchase parts for the airplane, keep the receipt.

Continue with fuselage preparation. This series of images help show why the fuselage is done first. There are many more little items which need attention in the fuselage compared to the wings. This images shows the trim system disassembled, cleaned, primed and awaiting reassembly. Second image is the flap handle disassembled, cleaned, painted and awaiting reassembly. Note all the small parts. The parts manual is a big help here. In fact unless you are out of the ordinary and have a huge selection of aircraft quality bolts available to you, plan on spending hours with the parts manual writing down each size you need.

With the fuselage bare it is a good time to add avionics and other items. This view shows the installation of the Whelen strobe light power supply. With the fabric cover off it is easy to get at places to install both the equipment and the electrical wiring. Where ever possible use a single point on the airplane for the grounds for all electrical and avionics. This helps considerably in reducing noise in the radios.

The instrument panel is also done before the fabric is reapplied. This view shows the instrument panel as purchased. Both radios had long since been removed from the FCC's list of approved aircraft transmitters. Narco Superhomers were one of the most popular and useful general aviation radios of its time. But the time of 12 channel VHF transmitters with tunable receivers was long gone. This view shows the beginning effort to restore the instrument panel. Note the original instrument panel looked as though someone had practiced operating a drill on it. I replaced all instrument panel pieces. I understand that Univair no longer has the etched aluminum pieces. If you check my Stinson Homepage you will find a link to new etched instrument panel pieces. Next view shows the instrument about half way done. Last view, taken much more recently actually, shows the completed instrument panel. Another surprise when I had many of the instruments overhauled; many had radium dials, and they were not repairable! I also wanted instruments which would fit the performance of the aircraft. Check the rate of climb carefully. Note how the low end is expanded to achieve greater detail in the low range. New rate of climb indicators have the high end of the scale expanded. A Stinson 108 is not going to climb 2000 feet per minute. I wanted to accurately know how the airplane climbed, so I found a WWII TSO'd Bendix instrument with the expanded low end and had it overhauled. All this takes time. Another reason to do the fuselage first, overhauling instruments and buying new radios is expensive.

• CRITICAL Point - when the Stinson 108 was designed light aircraft radios were narrower than is typical today. I had to angle the radios to allow the controls full and free movement. This is a view of the Left side radio stack. It is critical that the contols have full and unobstructed movement. All the radio wiring is directed away, clamped and tied away from the control pulleys. The terminal strips are actually well below the control pulley. During the restoration I replaced every original wire. The wires were still usable, but after almost 50 years, and with the fabric off, it is a good time to replace the wiring.

SUGGESTION #4 - Keep in mind this page shows restoring a certified airplane, not a home built. That means you need certified parts including radios and instruments. The IA can sign off on the mechanical part of the radio installation, but you will need a FAA approved radio shop to sign off on the electrical part of the radio installation. I purchased my radios from a local avionics dealer who is a FAA Approved radio shop. I bought my radios from that shop even though some may have been a little more expensive than buying out of a Trade-A-Plane ad. Some reasons for my choice: the shop guaranteed the radios, knew I was restoring an airplane and the radios I bought would not be tested for many months after I purchased them. I only had a problem with one radio, but it was backed up fully. In addition I got a lot of good advice from an experienced avionics techincian. A Stinson 108 only has a 25 amp generator, so be careful with your electronics (lights - instrument, position and strobe take up more than half the available power). Remember the 80% rule (maximum continuous power drain is limited by AC 43 to 80% of the rated capacity of the generator or alternator). Lastly after showing the shop my wiring diagrams, they came by and inspected my work, then signed it off making the installation legal. In the end I had radios which worked great, didn't have noise problems, were legally installed, and this had a lot to do with suggestions from the experienced avionics techincian who owns the shop. An important point of this suggestion - use a single ground point for all your radios. In the case of this Stinson some were mounted on the left side of the instrument panel, others were mounted on the right side of the instrument panel, but the ground for all was at one point near the center at the throttle bracket. This is a big help to stop radio noise. Grounding the radios and other electronics all over the airplane works, but it also creates ground loops. If you don't want noise in your radios when you finish ground everything at the same point.

• Step 5 - Applying new fabric. BEFORE you apply new fabric be sure to have your IA inspect the fuselage and make an airframe log book entry that he approves the condition of the airframe for recover. With the fuselage preparation phase complete it is time to apply the new fabric. First step is to apply the fabric to the fuselage. There are two basic ways to apply the fabric, an envelope or a blanket. I choose the blanket method for the fuselage. With synthetic fabric it is now time to heat shrink to tighten the fabric. This view shows shrinking the fabric. This heat must be applied with very controlled temperatures. You must calibrate the iron first. If you use cotton you will shrink the fabric using dope. This view shows the fabric applied and shrunk. Be careful not to let water get on the fabric at this point. The fabric is not yet protected. Next step is to apply the first brush coat. The first coat of Poly Brush is applied by brush to make certain the fabric weave is penetrated. The Poly Brush has a red oxide tint to make it easier to see exactly where the Poly Brush has been applied.

After the fabric has the brush coats you apply the tape along all points where the fabric may wear. This image actually shows the tape applied to the wing. For some unknown reason I didn't photograph this step on the fuselage. After the brush coats multiple coats with aluminum powder, called the silver coat, are applied by spray gun. The purpose of the aluminum coating is to keep the suns ultra violet rays off the fabric. I applied 4 coats of aluminum impregnated Poly Spray, sanding between coats after the second coat. Basic test is to hold a 60 watt lamp about a foot from the fabric and check to make sure it doesn't penetrate so you can see it from inside the fuselage.

(This original text is now outdated - At this point, when the fuselage is covered through aluminum, it is legally covered. The outside coat is not required by the FAA, although most (by far most) airplane owners continue on with a final finish coat.) The Poly Fiber STC now requires Poly Fiber finishe coats to comply with the STC.

At this time the IA should again inspect your work and make a log book entry and complete and sign a FAA Form 337 which is required for a fuselage recover job. Be certain to keep a copy of the completed and signed (by the IA) form 337 with the airplane.

Finish coat - This view shows the base finish coat. Plan on using a LOT of masking tape and work at covering everything you don't want painted! There are four coats of the Lemon Yellow finish coat. With the base finish coat on it is time to apply the trim. After the characters are masked the trim is sprayed. It took me about 20 minutes per character to mask. The Stinson logo was a complete mask I purchased from Univair (top of the vertical stabilizer). This view shows the completed trim (except for a small part at the base of the rudder and the cowling insignia which came after this photo).

• Step 6 - Wing preparation. The wings didn't take nearly so long primarily because there were no instruments, instrument panel, radios, power supplies, antennas, etc. Also while there is wiring, it far less extensive. This preparation of the structure is similar to the fuselage. This view shows the fabric removed from the wing. You can early signs of corrosion, and some rust around steel parts, all of which must be cleaned. After cleaning the wing is primed and new hardware, cables, etc. are installed. Next step is to tape all edges. This view shows the wing after the wing is taped. Here is another view of the prepared wing. Now is the time to have your I.A. come by for a visit to inspect the basic wing structure BEFORE the fabric is applied. Have the IA make a log book entry that the airplane has been inspected and is structually ready for recover.
  
  
• Step 7 - Wing cover. With the wing I choose the envelope method. This is a personal choice which I made because I wanted the wingtip sewed. Many others prefer the blanket method I used on the fuselage. Once the fabric is attached the next step si to heat shrink the fabric to tighten. After heat shrinking the Poly Brush is applied. Next comes taping, and rib stitching.

Since the lift comes from low pressure on top of the wings, there is a requirement to fasten the fabric to the wing. There are actually several means by which different manufactures secure the fabric to the wing. AC 43 shows rib stitching as the primary method. Stinson 108's came from the factory using PK type self taping screws.

After the brush coat comes the aluminum coating. I didn't photograph the wing at that step, but this image shows the fuselage with aluminum spray coat.

(Original text here is outdated - Again, as with the fuselage most people will apply a finish coat.) A finish coat of Poly Fiber finish is required to comply with the STC. With the wings having the finish spray coat it is time for the I.A. to make an inspection. As with the fuselage it is time for both a logbook entry and the completion of a FAA Form 337. Be certain to keep a copy of the completed and signed form 337 with the airplane.

• Step 8 - transport back to the airport and reassembly. Before moving the airplane to the airport, I contacted a shop at the airport and arranged to rent a hangar to reassemble the airplane. Knowing I had a place to reassemble, I then located return transportation. This view shows the purpose built trailer with the airframe and wings loaded which I rented. After safe arrival at the airport the reassembly begins. This views shows the Stinson in the hangar partially reassembled. With basic assembly complete this is the time to ask the I.A. to drop by and make an annual inspection. Even though it has been inspected several times during the process, it is important to see the airplane fully assembled (with inspection covers off).

My son is shown in front of the airplane, now some 7 years older than the earlier view of stipping the paint from the vertical stabilizer.

Both the airframe and engine are inspected. With the all the work accomplished on the airframe it should pass easily. The engine will also need to pass the annuall inspection. For that compression must be good, mags check good, no oil leaks etc. This article deals mostly with the airframe, but I wanted to mention the engine must be satisfactory to complete the annual inspection. This view shows the installed engine ready to fly. Note that the firewall, engine mount, baffles, etc., was all stripped, cleaned, inspected and primered during the fuselage preparation.

• Step 9 - Detail work. After the annual inspection the interior parts are reinstalled. Shown here is the replacement front seats, cleaned, primed and painted. This view shows the covered front seats ready for use. Rear side panels, headliner, and rear seats come last. My seat covers, carpet and the front side panels came from Airtex. They are good quality and fit quite well. My original wooden side panels were in very poor condition. Vic Steelhammer provided the rear side wooden panels (actually for a 108-2), and I made the back panel behind the rear seats.
  
• Step 10 - Finished! This view shows the finished airplane on the ground after its first few flights. My wife did photograph the first flight, however her camera did not produce a photograph of adequate quality to scan.

A couple of parting points. It will take much longer than you think. It will cost more than you budget. You will find that locating the correct part for an old airplane can be time consuming, but you can find those parts, just plan on becoming a "parts detecitve." For the Stinson 108, and many other Classic light aircraft, Univair holds the type certificate, and can supply and or manufacture many if not most of the airframe parts. You will also find on my main Stinson page a list of Stinson and Frnklin Parts and Service Sources. This list will help locate parts and shops who work on classic aircraft.

Training is a start, but there is no substitute for experience. Locate comptent, experienced people to help you. Especially the I.A. and radio technician.

My final suggestion is to always Fly SAFE! Remember the FAR's are minimum requirements. Three miles visibility is a FAA FAR minimum. Based upon your own experience you may well want to set your own personal minimum higher, of say 5 miles or better visibility. Enjoy flying, and do it safely.

Hope you enjoyed this page. If you have comments, criticsims, error corrections, or whatever, contact me, Larry Westin at email westin@westin553.net.

Stinson 108-3 N6968M as completely restored - flown by Larry Westin

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