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 aircraft restoration projects.
Page created 01/01/2001,
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
before the fabric is reapplied. This view shows the
panel as purchased. Both radios had long since been removed from
FCC's list of approved aircraft transmitters. Narco Superhomers were
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
to restore the instrument panel. Note the original instrument panel
looked as though someone had practiced operating a drill on it. I
all instrument panel pieces. I understand that Univair no longer has
etched aluminum pieces. If you check my Stinson Homepage you will find
a link to new etched instrument panel pieces. Next view shows the
about half way done. Last view, taken much more recently actually,
completed instrument panel.
Another surprise when I had many of the instruments overhauled; many
radium dials, and they were not repairable! I also wanted instruments
would fit the performance of the aircraft. Check the rate of climb
Note how the low end is expanded to achieve greater detail in the low
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
know how the airplane climbed, so I found a WWII TSO'd Bendix
with the expanded low end and had it overhauled. All this takes time.
reason to do the fuselage first, overhauling instruments and buying new
radios is expensive.
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.
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
on with a final finish coat.) The Poly Fiber STC now
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
base finish coat. Plan on using a LOT of masking tape and work at
everything you don't want painted! There are four coats of the Lemon
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
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
insignia which came after this photo).
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
the wings having the finish spray coat it is time for the I.A. to make
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.
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
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.
article deals mostly with the airframe, but I wanted to mention the
must be satisfactory to complete the annual inspection. This view shows
installed engine ready to fly. Note
that the firewall, engine mount, baffles, etc., was all stripped,
inspected and primered during the fuselage preparation.
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
have comments, criticsims, error corrections, or whatever, contact me