Frequently Asked Questions

A change made to an aircraft; including its components, systems, engines, radios, instruments, furnishings, flight manual etc. Changes may be either physical or documentation based.

A ‘minor change’ is approved directly by the 21J Design Organisation and is defined under 21.A.91 as having no appreciable effect on the mass, balance, structural strength, reliability, operational characteristics, operational suitability data, or other characteristics affecting the airworthiness of the product or its environmental characteristics. All other changes are major.

A ‘major change’ is usually approved by the Authority e.g. CAA / EASA and is defined as any change not being classified ‘minor’.

A ‘repair’ is defined under 21.A.431A as the elimination of damage and/or restoration to an airworthy condition following the initial release to service by the manufacturer of any product, part or appliance. This could also include the assessment of damage to allow continued operation without physical repair of that damage.

A ‘minor repair’ is defined under 21.A.435 as having no appreciable effect on the mass, balance, structural strength, reliability, operational characteristics, operational suitability data, or other characteristics affecting the airworthiness of the product or its environmental characteristics. Repairs whose effects are considered minor and require minimal or no assessment of the original certification substantiation data to ensure that the aircraft still complies with all the relevant requirements, are to be considered ‘minor’.

As per GM 21.A.435(a) a repair is classified as ‘major’ if the result on the approved type design has an appreciable effect on structural performance, weight, balance, systems, operational characteristics or other characteristics affecting the airworthiness of the product, part or appliance. In particular, a repair is classified as major if it needs extensive static, fatigue and damage tolerance strength justification and/or testing in its own right, or if it needs methods, techniques or practices that are unusual (i.e., unusual material selection, heat treatment, material processes, jigging diagrams, etc.)

Repairs that require a re-assessment and re-evaluation of the original certification substantiation data to ensure that the aircraft still complies with all the relevant requirements, are to be considered as major repairs.

The Trade and Cooperation Agreement between the UK and EU states that minor changes and minor repairs approved by UK CAA or a UK CAA approved design organisation are accepted by EASA and vice versa without a need for issuance of an additional certificate. Further details can be found in Annex 30 Airworthiness and Environment Certification, Article 13: Acceptance, Page 818.

The Trade and Cooperation Agreement between the UK and EU states that non-significant major changes, STC’s and major repairs approved by UK CAA will require validation. Further details can be found in Annex 30 Airworthiness and Environment Certification, Article 13: Acceptance.

The Trade and Cooperation Agreement between the UK and EU states that minor changes and minor repairs approved by UK CAA or a UK CAA approved design organisation are accepted by EASA and vice versa without a need for issuance of an additional certificate. Further details can be found in Annex 30 Airworthiness and Environment Certification, Article 13: Acceptance, Page 818.

The Trade and Cooperation Agreement between UK and EU states that non-significant supplemental type certificates, approvals of non-significant major changes, repairs and technical standard order authorisations issued by EASA or an EASA approved design organisation are accepted by the UK CAA without a need for issuance of an additional certificate. Significant major changes will require validation. Further clarification on classification is provided in the UK CAA/EASA TIP. Further details can be found in Annex 30 Airworthiness and Environment Certification, Article 13: Acceptance.

The Implementation Procedures for Airworthiness document CAP1780IPA between the USA and UK states that all design changes classified as minor in accordance with UK Part 21.A.91 shall be accepted without further review. Section 3.2.2 & 3.3.5.2 Refers.

The Implementation Procedures for Airworthiness document CAP1780IPA between the USA and UK states that major changes and STC’s will require validation, however major repairs are accepted by the FAA if the criteria set out in Section 3.3.5.2 is met.

The Implementation Procedures for Airworthiness document CAP1780IPA between the USA and UK states that all design changes classified as minor in accordance with 14 CFR Section 21.93 shall be accepted without further review. Section 3.2.2 & 3.3.5.3 Refers.

The Implementation Procedures for Airworthiness document CAP1780IPA between the USA and UK states that major changes and STC’s will require validation, however major repairs are accepted by the CAA if the criteria set out in Section 3.3.5.3 is met.

A Form 1 is an Authorised Release Certificate which certifies that an aircraft part has been produced or maintained in conformity with approved design data. In accordance with 21.A.307 parts can only be installed on type-certified aircraft if accompanied by a Form 1. Standard parts and certain other parts as identified by the design approval holder in the instructions for continued airworthiness are exempt from this.