Our Services

DAVIDSON AEROWORKS

1936 Beechcraft C-17 Staggerwing. Some steel tube structure, all wood, and all sheet metal replaced by Davidson Aeroworks.

Transport Canada, our CAA or FAA equivalent, has issued Aircraft Maintenance Organization AMO 83-04 to Davidson Aeroworks to sanction the issue of Form One certification for the following relevant activities.

-The “Modification, Repair, and Overhaul of “Sheet Metal, Tubular, and Wooden Structures”.

-The overhaul of Gipsy Major Engines, including cylinder head overhauls

-The repair and overhaul of BTH magnetos for De Havilland Gipsy engines.

BTH-AG4 Magnetos

We can supply both shielded or non-shielded. Please contact us for current prices.

Davidson Aeroworks has been overhauling BTH AG-4 magnetos for over thirty years. The overhaul of this magneto requires a great many separate operations. Over time it became clear that as skilled labor became more difficult to find, the incentive to overhaul these in ever increasing quantities grew. So that we might all benefit in the economies of scale we have just completed our largest batch ever..28 magnetos.

All magnetos have been carefully disassembled, all parts inspected for cracks, all tapped holes checked for clean threads, all parts glass beaded, and measured for wear and distortions. Armatures are re-wound, bearings are replaced, magnets are re-magnetized, lock-tabs are replaced, and HT pickups in the distributor caps replaced and machined to match the rotor. The threaded hardware is all replaced or renewed, and cadmium plated. All components are ultra-sound cleaned.

So that we can continue, we offer this service on an exchange basis only. That is, we must receive a complete magneto in return. It is not expected that the core be in undamaged condition, but a good effort at packaging for its shipment to our facility is greatly appreciated. Bakelite items such as the distributor and the points cover are particularly vulnerable.

For the asking, we will supply several articles on the installation, care, precautions, and operation of these magnetos.

We stock all the required tab-washers, cork and felt washers, and are willing to supply others who are also in need.

Hobson Carburetors

Davidson Aeroworks overhauls Hobson A.J.48H carburetors in batches of a minimum of four on an exchange basis only.

All carburetors, with their flame traps, are carefully disassembled, crack inspected, all tapped holes checked for clean threads, glass beaded, and measured for wear and distortion. Float assemblies are disassembled, the cork finish is carefully stripped, and the displacement measured and corrected as necessary. They are then reassembled, and the assembly weight is measured and corrected with custom rivets. Floats are refinished and sealed with catalyzed fuel tank sloshing compound. Jet sizes are matched to the dash no. and are measured for size. All parts are ultra-sound cleaned. All painted surfaces are epoxy primed and painted black with acrylic urethane.

Cylinder Heads

Overhauled Seats

Davidson Aeroworks overhauls Gipsy Major cylinder heads, with a focus on those that require the exhaust seat insert replaced. We have a full set of the required special threaded dies, and a supply of six progressively oversized exhaust seat inserts. When we receive a head, I like to receive it as a complete assembly to be able to go through the entire process of examining the complete head. This involves disassembling, glass beading, crack inspecting, and assessing. Worn guides are replaced, valves are reground and fitted to re-cut seats. I prefer to reassemble the entire head. The tappet cover and base will be reshaped to new shape, epoxy primed and acrylic urethane painted.

Aircraft Woodwork

Tiger and Gypsy Moth Spars

We have been doing “fabricated repairs” on Tiger and Gipsy Moth wooden components since the 1980s and shipping them all over the world. The aircraft that appear in this website have had all their sheet metal and woodwork replaced by Davidson Aeroworks.

Airworthiness “Form One Certification” of wing spars have been a special challenge. I am not aware of any organization that has acquired a Parts Manufacturing Approval (PMA) for Tiger Moth and Gipsy Moth wing spars since the end of DeHavilland factory production. Worldwide there are a few competent firms that are authorised to conduct repairs to these spars, but not to manufacture complete spars, serialize them, and sell them as new. Therefore, a new spar must replace a spar on an existing aircraft and be entered into the airframe logbook as a “Fabricated Replacement Part”, and the DH drawing referenced to conduct the work. If the aircraft is to be registered without a Certificate of Airworthiness, the fabrication standards remain, but the Form One issue does not.

Aircraft quality Spruce has become a major issue. I live near the only part of the world in which magnificent Sitka Spruce trees grew in abundance. Our needs require old-growth trees that measure a minimum of 120 cm diameter at chest height and are straight and with no visible limbs to a height of at least 20 metres. Humanity has squandered these trees to where there are almost none left. Those that are remaining have become protected or must be harvested by helicopter. Many Tiger spars were engineered and produced by DeHavilland that were laminated, yet many of us believe a solid spar is superior to one that is laminated. A spar that is made up of laminates creates a greater certainty of being free of flaws that are not visible on the surface (see ANC-19 Wood Aircraft Inspection and Fabrication). Another consideration is that a compression failure, split, or shake that has developed in service will tend to progress and stop at a glue line. To achieve better utilization of the timber stock we also offer laminated spars which are fabricated to approved DeHavilland British drawings. Each of these spars require at least six hours extra labour and are sold at a lower price than our solid spars.

Shop Products

Davidson Aeroworks has produced the fixtures and dies to fabricate parts for specific in-house repairs. We have used these to repair our assemblies, and to enable other restorers to do the same. These are:

Wing tip bows

Wing upper trailing edge root transition fittings, both Gipsy and Tiger Moth

Wing strut-end fittings

Wing internal bracing wire assemblies

Rib Clips

Pricing, Payment, and Shipping

When shipping smaller items such as magnetos and carburetors, the overhauled item will be shipped to you with its Form One Maintenance Release documentation. I ask that the core is shipped to us in the box in which I have sent your overhauled item. The box is purpose built and will have adequate protection for your core.

Payment would be made in full, including the Surface Post shipping cost of the core to Davidson Aeroworks before the overhauled item is sent. I will send the purchaser Bank E-Transfer instructions.

We stock wing spars and other wing and tail wooden parts in Kimberley BC, Canada and on consignment from Aero Vintage in Southampton U.K.

If you require additional information or wish pricing, payment or shipping details please email me. Please include your name and reason for contacting me.

davidsonaeroworks@gmail.com