Milman Product
Milman Spar Conversion
Leading Edge
Smoke System
Tapping Machines

Are you the owner of a:
Are your wing spars made of wood and do they have cracks, heading for failure?

Our kit comes complete with STC papers, installation instructions, two front and two rear spars predrilled from our master fixture. Including all necessary spacers, drill jig and screws for attaching rib flanges.

The models included starts with the 7AC Aeronca up to and including the 7GCBC Citabria with flaps, and the 11AC Chief through the S11CC.  The problem with wood spars is a tendency for cracks to develop near doubler plates following the grain, compression cracks which run perpendicular to the grain and cracks which run between rib nail holes.  One other common problem with wood spars is the loosening and subsequent loss of rib nails.

BHM aircraft assembled the first prototype wing and performed sandbag testing with an FAA representative observing the test.  Finally, after three years of paper shuffling and waiting, the FAA issued BHM aircraft the STC No. SA3829NM with only one restriction.  The restriction is not to mix BHM STC metal spars with wood spars or non-BHM metal spars.

Our STC aluminum spar conversion kit uses all of the existing parts from the aircraft’s wings, except of course for the wood spars.  Precision CNC machined aluminum billet spacers are used at all high stressed attach points and five ply birch plywood (for weight saving) is used on the lightly loaded rib attach points.  AN526-632R12 screws and locknuts are supplied in the kit to attach the ribs and spacers to the I-beam spar shear web area.  The Aluminum spars are supplied pre-drilled to fit the customers model specific aircraft hole patterns.  Canadian and International orders require an FAA form 8130-3 which increases the cost for the necessary DAR inspection fee and paperwork for these forms.  Our normal delivery is around four - six weeks.

No AD’s have been issued for our STC spar kit or leading edge kit.  Metal spar AD’s currently issued are for a different manufacturer and do not apply to STC No. SA3829NM or No. SA4773NM.