Aviation Engineering UK


Aviation engineering in UK and internationally, holding 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.

Aviation Engineering UK

Our Story

STC Twenty One Limited was founded by John Dent and Peter Gaughan in the roles of Technical Director and Managing Director respectively.

The foundations of STC Twenty One Limited begin with Aero Engineering Design Limited (AED). CAA Approval Number AD/1769/89

AED was founded in 1988 by John Dent and was a UK CAA Approved Design Organisation prior to the inception of EASA.

STC Twenty One Limited continues to support the wide and varied customer base cultivated by AED since 1988 and is responsible for continued airworthiness support for all approved modifications issued prior to September 2003.

aviation engineering services uk company history stc twenty one ltd

Aviation Engineering UK

Mission & Values

  • Safety is our top priority.
  • Communication – Communication – Communication.
  • Flexibility but with due diligence.
  • Professionalism, integrity and honesty.
  • Equal opportunities for
  • ALL staff members.
  • Customer satisfaction for ALL our customers.
  • That hard work and customer satisfaction yields a healthy business.
  • Work together to recover from setbacks.
  • To embrace change and move with the times.

STC Twenty One


Find STC Twenty One aircraft modifications on Modstore.