Aircraft have to be certified with specific airworthiness requirements. You will find here the airworthiness standards for aircraft, the United States Airworthiness Standards (FAA FAR) and the European Aviation Safety Agency (EASA).
These Airworthiness Standards are to be used as a reference, as in actual designs the requirement is frozen in a certain date and amendment.The Airworthiness Standards available for download:
Airworthiness Standards for Normal, Utility, Acrobatic and Commuter Category Airplanes
Airworthiness Standards for Transport Category Airplanes
Certification Specifications Normal, Utility, Acrobatic and Commuter Category Aeroplanes
Certification Specifications for Large Aeroplanes
Certification Specifications for Large Aeroplanes, Amendment 10, December 2010
Aircraft engines have to be certified with specific airworthiness requirements.
FAA FAR Part 33 - AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES
EASA CS-E - Certification Specifications for Engines, Amendment 3 (pdf)
Many other countries have their specific regulations. From an engineering point of view, an aircraft that complies with the FAA or EASA requirements is basically qualified for compliance with all other requirements.
For access to all EASA regulations, including the ones with links here and all the others (light airplanes, sailplanes, gas balloons and so on) click EASA ALL