Aerospace Engineering Services UK

STC Twenty One

STC Twenty One Limited is a Design Organisation (DOA) located in the East Midlands. Our aerospace engineering services are approved and regulated under the UK Civil Aviation Authority (CAA).

Aerospace Engineering ServicesUK


STC Twenty One Limited provides UK CAA approved major STC (Supplemental Type Certificate) and minor changes/repairs for a wide variation of aeroplane and rotorcraft types.

Modifications Search

Modifications Search

Search over a thousand projects undertaken by STC Twenty One, to see if we already have a design that would suit your needs or to see what other modifications could be of use to your fleet.

Simply enter the aircraft type you have or a keyword that describes the type of modification you plan on adding to your aircraft, such as “life vests” or “lighting” and see what we have on file.

Then get in touch to see how we can help.

Aerospace Engineering Services UK


Our aviation engineering services hold a Part 21 Subpart J DOA enabling it to certify UKCAA approved STCs and Major Repairs. Additionally, where a design change or repair is classified as minor, STC Twenty One Limited is authorised to approve them under the DOA using approval reference UK.21J.0198 through CAA.

Aerospace Engineering Services UK


The go-to source for the latest aircraft industry news in the UK and internationally. Stay informed about groundbreaking developments and trends shaping the aviation landscape.

Aerospace Engineering Services UK


STC Twenty One is dedicated to providing career pathways in the aerospace and aviation community. Apply for jobs directly with qualifications and experience, plus you can find out more about positions in aerospace engineering from by clicking the link below.