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Modification
of Canadian Aircraft
What
is a design change
The maintenance release for a modification
design change
You
have made a change to the type design of the aircraft and it is
time to make the logbook entry so the aircraft can go flying. The
decision that the person completing the maintenance release has
to make is if design change is a major or minor modification? Remember
that the purpose of this exercise is to determine the type of applicable
data that the design change has to “comply” with. Hopefully
this exercise was thought about before the work was completed.
Here
are the definitions straight from CAR 571.06:
“major
modification” - means an alteration to the type
design of an aeronautical product in respect of which a type certificate
has been issued that has other than a negligible effect on the
weight and centre-of-gravity limits, structural strength, performance,
power plant operation, flight characteristics or other qualities
affecting its airworthiness or environmental characteristics;
"major
repair" - means a repair to an aeronautical product
in respect of which a type certificate has been issued, that causes
the aeronautical product to deviate from the type design defined
by the type certificate, where the deviation from the type design
has other than a negligible effect on the weight and centre-of-gravity
limits, structural strength, performance, power plant operation,
flight characteristics or other qualities affecting the aeronautical
product's airworthiness or environmental characteristics;
Don’t
feel bad if these definitions leave you more confused than before.
The determination of a minor and a major design change has been
a gray area for many people since its conception. If you are having
a hard time about this one I recommend one of two approaches, call
Transport Canada and ask, or feel free to call AV8 Design.
Here
is the data that Transport Canada allows to be used for major and
minor modifications CAR 571.06:
The
criteria to be used to determine which data applies to modifications
and repairs is as follows:
(a)
All major modifications and major repairs shall be performed in
accordance with either “approved” data or “specified”
data. A statement of “No technical objection”, or
similar wording, by the manufacturer does not constitute “approved”,
“acceptable”, or “specified” data and
shall not be used without further approval by the Minister.
(b)
All other modifications and repairs shall be performed in accordance
with “acceptable” data.
Sparing
you any more definitions here is how it breaks down in regards to
what data can be used to complete the maintenance release for a
design change.
Minor |
Major
|
Acceptable
Data |
Specified
Data |
Approved
Data |
OEM Data
TC
Advisory Material
Advisor
Documents of foreign authorities which Canada has airworthiness
agreements with
|
Manufactures SRM
AC
43.23-1 and 43.13-2 with conditions
AD’s
SB’s
with regulatory approval
|
|
If
the design change is a major modification or major repair don’t
forget to report the design change to Transport Canada. This is
a requirement as stated in CAR 571.12. You can find a report form
in CAR 571 Appendix L.
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
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
|
