This page created 3/13/99.
Click on photos for larger image.
Andy Baker, age 7, uses a palm
sander to work on the edges of the birch ply panel
Compared to earlier Stinsons, there is not a great deal of wood in the 108 series. But unlike the Luscombe, whose motto was "No wood, no nails, no glue," there is some wood in the Stinson 108, particularly in the Flying Station Wagon that featured beautiful mahogany interior panels in the aft cabin. Windshield framing pieces, floorboards, baggage floor, etc., are also important and likely to have deteriorated after half of a century. What follows is a general discussion of woodwork in the Stinson based on my experiences and what I have learned from others. Special thanks to the late Rich Tweedie of San Jose, California. Rich and his wife Judith restored N175C and Rich graciously shared his photos and knowledge. Additional information and tips are welcome.
Windshield top frame/mount. This piece is located at the upper edge of the windshield. It serves as a support for the windshield and as an attach point for the forward edge of the headliner. Made of spruce on Rich's N175C, it had been replaced when Rich recovered the plane in 1969, and needed replacement again this time. The original style "Tee" nuts are available from Schultz Engineering. Cost is $2.50 for a bag of 24. The originals were oblong in shape and have two spurs. Suitable replacements with three spurs and a round base are available at many hardware stores according to Rich. During the 1969 recover job, Rich had installed half stainless steel windshield screws and half standard AN screws in the windshield mount on N175C. Where the cad plated AN screws were installed, the screws had rusted right into the "Tee" nuts and were totally jammed. Also the top aluminum windshield frame was corroded under these screws, but not under the stainless screws. All of the stainless screws turned freely, and the "Tee" nuts were much less corroded than the others. Being tied down outside with the occasional salt fog did not help the situation any. Rich is convinced that if the wood had been preserved with Minwax polyurethane oil, that there would not have been much deterioration of the wood. All of the wood in 175C has now been treated with the Minwax oil.
Wing root pieces. These consist of Philippine mahogany plywood with plywood and basswood attachments. They are attached to the sheet metal with steel staples. Rich Tweedie used 1/16 inch stainless steel welding rod to make his own stainless staples to prevent rust damage to the wood over the years. For 97M, I was fortunate to obtain an original, unused pair of wing root pieces (stamped with the Stinson part number) from a friend who had some parts on hand.
Supports for upholstery and headliner. These are made of spruce, pine, or plywood and are installed along the upper door and window frames. A tapered piece along the upper door frame is sectioned to provide clearance for the fuel lines. There are additional wood pieces at the rear of the cabin that support the headliner. Tom Messeder, restorer of NC903C, cautions against using hardwood plywood (such as birch) for the pieces along the window and door frames as it will be difficult to staple or tack the upholstery and headliner. I used a combination of woods for these pieces on NC6197M, including some pine, spruce, and even construction grade plywood. Use the old pieces at patterns.
The above photo shows wood
supports for headliner/upholstery above passenger door frame.
In this photo we see the wood
support pieces above and below the window frame.
The garage door track serves
as a drying rack for the
Dome Light/Speaker Grill support. I duplicated this hexagon shaped piece using 1/8" aircraft mahogany. Both Rich Tweedie and I discovered that you can easily attach nutplates to the thin ply for attaching the speaker grill. Countersink the ply slightly and back rivet using flush rivets. Works great!
The birch floorboards that
go under the back seat are on the left.
Front Floorboards. Made of plywood, these tend to go bad over the years, with help from brake fluid, etc. Originals were 3/16" mahogany ply. Replacements on N175C were made with 5 mm Philippine Mahogany plywood, heavily coated with the Minwax oil, including the small pine strips (1/2" square) that are screwed and glued to the edges as supports for the side panels. Tom Messeder used Baltic Birch for the floorboards on NC903C. On NC6197M I used aircraft grade birch plywood for the front and the pieces under the front seats, 5 mm thickness, purchased from Harbor Sales, located until recently in Baltimore. You can use the old floorboards as patterns but I suggest you wait until the new boards are in place to mark and drill the mounting holes. The floorboards are mounted, for the most part, to J-clips that snap onto the fuselage tubing. The floorboards are then secured to the J-clips with U-type tinnerman nuts and screws. For accurate placement of the mounting holes, set the boards in place and center punch the holes from the bottom, through the J-clips. I used all stainless hardware.
Front floorboards on 97M from 5 mm birch ply, unfinished in this photo.
The front floorboards after several coats of varnish.
Rear Floorboards for the Flying Station Wagon. The rear floorboards on the Flying Station Wagon are designed to support 600 pounds. They are reinforced with aluminum channels set on the diagonal. The original one half inch thick floorboards are of sandwich construction - a basswood core ply faced with mahogany, according to Rich Tweedie. Most others, including Dave Talley and Robert Hadow, have indicated that the rear floorboards use a balsa core. The rear floorboard is in two pieces, a main section at the rear and a forward section that contains the slot for the rear cabin heat vent. Don't try to be clever and make the floorboard in one piece (as I did originally). If you do, you will not be able to get it into the airplane and in place!
After removing many years worth of dirt and glue, Rich found the rear floorboards on 175C to be in excellent condition, and were the only wood pieces re-used. Rich treated them with the Minwax oil and replaced the old cad plated flush washers with identical stainless pieces (many were badly rusted). The stainless washers are available from Aircraft Spruce.
Main rear floorboard on Rich
Tweedie's 108-2 Station Wagon.
The rear floorboards on 97M were beyond repair, so I built new ones using Birch ply. I used 6 mm birch, and laminated strips of 5 mm birch roughly 3" wide along the perimeter and along the diagonals to maintain the original strength and to duplicate the original 1/2" thickness of the floorboards. Even though the panels are a half inch thick only along the perimeters and diagonals, they are heavier than the originals by about two pounds. Robert Hadow made floorboards using hobby store balsa for the core sandwiched between mahogany ply from Aircraft Spruce. I might make new rear floorboards using this method to save weight.
Two piece rear floorboard on NC6197M. Cutout is for rear cabin heat vent.
Another view of the rear floorboards
on 97M. 1/2" Square wood strips support side panels.
Here you can see the heavy
aluminum channel attached to the bottom of the rear floorboard main (aft)
Another shot of the main rear flloorboard for 97M, this time from the top.
This is the forward portion of the rear floorboard with the cabin vent installed.
Bottom of the same piece. Flexible tubing will run from this vent to the firewall fitting.
The rear floorboards on the Voyagers were not as elaborate. Barrie Bouwman of Rocky Mountain House, Alberta, Canada, has a 108 Voyager and reports that the originals are of 3/16" mahogany ply. He replaced his with baltic birch of similar dimensions. Since Barrie is in a cold climate, he also modifed the front floorboards in the area of the rudder pedals. To reduce drafts, he fabricated alumimum sheet fairings that are attached to the bottom of the floorboards around the rudder pedals. These fairings reduce the size of the openings but provide full travel of the pedals. He also plans to fabricate vinyl "boots" for the pedals, reducing drafts further. Barrie used foil backed helicopter insulation below his floorboards to help keep things warm.
Woody Panels for the Flying Station Wagon. "Woody" panels consist of mahogany plywood with basswood overlays. Side panels on the 108-2 are flat. The side panels also have pine attachments on the sides to accept screws from the back panel. Rich Tweedie says the basswood was a real surprise. He thought it was birch until taking the old panels in to the local exotic wood emporium, where they told him they were basswood. Having never heard of basswood, Rich was amazed when purchasing it to find its extraordinary light weight. When finished with many coats of Minwax Oil, (sounds like a commercial) they indeed looked like beautiful hardwood overlays. Basswood shaves pounds off of the weight of the interior. I used Minwax polyurethane spray on all of the wood for 97M and it took many, many coats. Rich says the Minwax oil is wiped on, goes much quicker, and looks great.
The rear panel for Rich Tweedie's
The old side panels on Rich's 108-2 would have been OK to refinish, except that the staples had badly rust-stained the wood, all the way through. In constructing the new panels, Rich removed the staples after the glue dried on the basswood. To attach the carpet strip along the lower edge of the panels, new homemade stainless staples of 1/16th inch welding rod were used.
Woody side panels on the 108-3 are more of a challenge and are not covered here.
Baggage Compartment. The original baggage compartment walls were of cardboard and in very poor condition. I used 3 mm aircraft Birch ply for the floor, forward wall and stub wall on 97M. The canvas portion of the baggage compartment came from Airtex and fit well. The sewing department of the local five and dime provided new snaps as needed. Tom Messeder used nylon straps and buckles from a local backpacker's equipment supplier in the baggage compartment. I plan to do the same. Rich Tweedie used 5 mm Philippine mahogany for the floor and 3 mm mahogany for the bulkheads on N175C. He added a Grimes reading light to the upper forward bulkhead of the luggage compartment to help with finding things after dark. Rich reports that the 108-2 did not have baggage hold down straps but thinks they are a great idea. He says, "Sometimes the luggage has been REALLY shaken up over the Sierra's (1500-2000 ft/min up and downdrafts)."
Baggage compartment on NC6197M. Birch ply is finished with clear Minwax polyurethane varnish.
Stub wall on the pilot's side of the baggage compartment. Snaps came from the local five and dime.
The final piece of wood on
97M - a mount for the ACK ELT,