We are Efficiency.

We provide integral engineering services for the aeronautical sector worldwide.

We are focused on aircraft modifications and repairs market.
Additionally, we manage aeronautical production, follow aerospace sector companies quality procedures, we offer our expertise as aeronautical consultants and are dealers for some equipment and systems.


We are recognized by the excellence of the working processes and our devotion for customer service, we do our best to respond to our customers’ needs adapting us to their standards and peculiarities, which allows us to answer any request in a very brief period of time, keeping competitiveness and high quality standards as far as results are concerned.


Since our company started operations back in 2007, over 4000 engineering projects have been developed and certified worldwide, over 2000 aircraft fly with our designs and we have work in over 100 different aircraft models.


Another of our main pilars is our commitment with people, and that is why we provide an integral development for our team of professionals.

We are DOA

S4A is the first company in Spain granted as Design Organization by EASA.


To be a world leader in the development of efficient and innovative aeronautical solutions that enable our customers’ aircraft to operate continuously, sustainably and safely.


To passionately build a business ecosystem focused on stakeholders, with a focus on achieving day-to-day excellence and continuous innovation, thanks to the best trained and committed talent.


At S4A, our relentless passion for the customer drives proactive engagement and continued resilience. Fueled by intellectual curiosity, we embrace exponential transparency, shaping our culture and defining our success.

Our certificates

EN ISO 9001 – Quality Management

EN 9100 – Aerospace Standards

EASA Part 21J DOA – Trusted Certification

If you want to enjoy the advantages of S4A,
click the button below






Projects carried out

Aircraft models

More than 380 customers trust us.

Aircraft Modifications

Our expertise lies in designing and certifying both minor and major (STC’s) aircraft modifications. STC’s are certified by EASA and may be validated by other authorities (FAA, etc).

Aerospace Testing

A history of excellence in producing comprehensive test plans, procedures, and execution for aerospace industry needs.

Aircraft Repairs

Expertise in designing repairs for both metallic and composite materials, covering structural damages, as well as functional and decorative aspects.

Turnkey Aviation Projects

Comprehensive solutions from design, installation, to global certification of aircraft repairs and modifications.

Mastering EASA/FAA validations

We expertly navigate the cross-approval of aircraft modifications, ensuring your FAA-approved changes are EASA-validated, and the other way around. By customer’s request, our modifications can be certified in front other certification authorities (Transport Canada, Bermuda, Isle of Man, San Marino, etc)

Aerospace Consulting

Offering time-bound or ongoing aerospace consulting by a dedicated team of industry experts.