STC Twenty One Limited has extensive experience in aircraft modification services and after market design engineering. We are equally capable of tackling both mechanical and electrical / avionic design tasks.
Aircraft Modification Services
Avionic & Electrical Systems
View our solutions for avionic and electrical systems including communications, navigation, monitoring, flight control systems, fuel systems, collision avoidance systems, flight recorders, weather systems and aircraft management systems.
Environmental Control Systems
View our experience in changes to air conditioning and pressurisation systems, bleed air systems, avionic & target acquisition cooling systems, water / waste systems and oxygen systems.
STC Twenty One Limited can produce approved designs for interior changes, from minor LOPA changes, to full VIP interior or passenger to freighter conversion. We have approved design changes for cabin security systems, cabin refurbishments and VIP consulting services.
STC Twenty One Limited has the skills, experience and approval privilege to design changes to all structure, including primary elements, on large and small aircraft and rotorcraft. In support of such changes we perform stress analysis, fatigue and damage tolerance analysis in order to demonstrate compliance with the necessary requirements and to ensure safety and continued airworthiness of the aircraft. Our engineers and CVEs have in excess of 60 years of experience in aerospace structures.
Supporting you to achieve valid test results for the safe operation of the test aircraft. We assess flight test procedures and organisations that perform them. STC Twenty One understands Part 21 core issues relating to the establishment and approval of flight conditions – as is required from a DOA member holding the respective privilege. The development involves testing of new aircraft or modifications, testing of new concepts of airframe, engine, propeller and equipment, and testing of new operating techniques.
Permit to Fly / Flight Conditions
Assisting you in the approval of flight conditions. A Permit to Fly (PtF) on which this based is issued by the Competent Authority of the State of Registry, or of the State prescribing the identification marks of an aircraft. PtF are authorised when a certificate of airworthiness is temporarily invalid, or when one can’t be granted, but the aircraft is capable of safe flight.
EASA Approved Design Organisation
STC Twenty One
All Aircraft modifications and Aircraft repairs are managed by our EASA approved Design Office represented by STC Twenty One (EASA DOA.21J.198).