STC Twenty One Limited is an EASA approved Design Organisation located in the East Midlands. STC Twenty One Limited provides EASA approved major (Supplemental Type Certificate) and minor changes/repairs for a wide variation of aeroplane and rotorcraft types.

The scope of approval held by STC Twenty One Limited permits design changes for the following:

Avionic Systems

Electrical Systems

Radio & Navigation Systems

Hydro Mechanical

Environmental Control Systems




Flight Conditions and Permit to Fly Approval

Our contact details are

Address:   The Waldorf Centre, 1290 London Road, Alvaston, Derby DE24 8QP .

Tel: +44 (0) 1332 576 830    Fax: +44 (0) 1332 576 831