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Modification of Canadian Aircraft

What is a design change
The maintenance release for a modification design change
The AC 43.13 as specified data for major modifications
Approved data for major modifications
How do you obtain a design change approval
What is a DAR and a DAO

DAR - Design Approval Representative - A delegated individual
DAO - Design Approval Organization - A delegated company
DE - Delegated Engineer - A delegated individual within a company
AEO - Airworthiness Engineering Organization - A delegated company with limited delegation to the aircraft they operate

The above Transport Canada delegations allow an individual or a company the authority to make findings of “compliance” on behalf of the minister. A delegated individual or company determines if a given aeronautical product design change complies with the certification requirements. Summing it up, the DAR or DAO ensures that all data defining the design change “complies” with all the pertinent certification requirements and the licensed aircraft mechanic (AME) ensures that the actual installation “conforms” to the data the DAR or DAO approved.

CAR Airworthiness Manual Chapter 505 states the standards for DAR and DAO delegation. To receive DAR delegation, licensed professional engineer (P.Eng) status is not required. If fact, the majority of DAR’s and DE’s are not engineers at all, but are individuals with considerable experience in there chosen field of expertise. This is a bit of a contradiction considering that the professional engineers acts (Part of Canadian Legislation) defines the practice of professional engineering as:

"practice of professional engineering" means any act of designing, composing, evaluating, advising, reporting, directing or supervising wherein the safeguarding of life, health, property or the public welfare is concerned and that requires the application of engineering principles, but does not include practicing as a natural scientist; ("exercise de la profession d'ingénieur")

Being both a Engineer with a degree in aerospace engineering and a licensed AME I must admit that I rely much more on my practical background than my engineering training. I do find it interesting though that the CAR’s are very strict and definitive on the requirements for an individual to become a licensed AME on the other hand an individual could in “theory” become a DAR on the basis of experience alone without the requirement for any training or licensing. These are the requirements for DAR eligibility, CAR 505.203:

To obtain a delegation of authority as a DAR an applicant shall:

(a) Be a graduate in an engineering discipline from a recognized University or be registered or eligible for registration by a Provincial Association as a professional engineer in Canada or have knowledge and experience which, in the opinion of the Minister, is equivalent to the foregoing;

(b) Have, in the opinion of the Minister, a thorough knowledge gained by working experience of the applicable Canadian airworthiness requirements in his specialty and, where required, a thorough knowledge of Canadian operational requirements;

(c) Provide a service with respect to regulatory compliance of designs for aeronautical products in Canada;

(d) Have not less than a one year working relationship, satisfactory to the Minister, with the Department of Transport Airworthiness Branch Staff, in processing engineering information for the approval of an aeronautical product design;

(e) Have not less than six years of progressively more responsible related aeronautical engineering or flight test experience;

(f) Be a Canadian citizen or a permanent resident as defined in the Immigration Act and have an ordinary place of business in Canada;

(g) In addition to 505.203 (a) through (f) the specialty of test pilot must:

(1) have a current pilot's license;
(2) be a graduate of a recognized test pilot school or have, in the opinion of the Minister, an equivalent qualification gained through engineering test flying; and
(3) have current experience acceptable to the Minister.

One last note about delegation, to receive delegation an individual or company must submit a procedures manual defining the scope of delegated authority. Usually this means that the delegated individual or company will be granted authority to make aeronautical product design change findings of “compliance” with certification requirements pertaining to there field of expertise.

Why use a DAR or DAO
Standards and Approvals
Mechanics, Engineers and good design
Whose responsibility is the aircraft modification
Change Product Rule and the basis of certification