Page 33 - UK Regulation Part 21 Initial Airworthiness Annex I (consolidated) March 2022

PART 21 - INITIAL AIRWORTHINESS (ANNEX I)

purpose and results (for example, by providing better performance than the proposed type design, or
masking any potential failure mode or behaviour).
Changes that affect the validity of the statement of conformity (see point 21.A.33(e)(2)): if changes
need to be introduced to the test specimen or to the test and measurement equipment after the
statement of conformity is issued (and before the test is undertaken), the statement of conformity
must be updated. The updated statement of conformity must be made available to the CAA before the
test if the CAA has informed the applicant that it will witness or carry out the tests.
Development versus certification tests: sometimes, tests of specimens that conform to a preliminary
design, but are not intended for certification (known as development tests), are performed as part of a
risk control strategy and to develop knowledge of a subject. Problems and failures found during
development are part of the process of increasing the understanding of the design, including its failure
modes and the potential for optimisation. Such development tests do not need to meet the
requirements of point 21.A.33.
Any planned test event should be classified in advance as either a development test or a certification
test. Tests that support the compliance demonstration should be classified as certification tests.
Nevertheless, if agreed by the CAA, it is acceptable for a development test to finally form part of the
compliance demonstration, and it may be declared afterwards to be a certification test as long as it
meets the requirements of point 21.A.33. For this reason, it is important to keep the configuration of
such tests under the control of the design organisation.
In addition to this, the level of involvement (LoI) notified by the CAA as per 21.B.100(c) should be taken
into account: if the CAA has determined that it will witness or conduct a certain test, this test may need
to be repeated so that the CAA can witness or conduct the test.
If the test specimen used for a certification test has already undergone a series of previous tests that
may affect or ultimately invalidate its acceptance as required by point 21.A.33(b), this aspect should be
considered when issuing the statement of conformity required by point 21.A.33(c), and specific
analyses or inspections may be required to support such a statement.
Because of the above aspects, the CAA advises applicants to inform the CAA if they intend to conduct
a campaign of development tests that may eventually be used as certification tests.
Availability of compliance data (see point 21.A.33(d)(1)): data and information requested from the
applicant for review should be made available in a reliable and efficient way that is agreed between the
applicant and the CAA.
Point 21.A.33(d)(1) refers to any data or information related to compliance data; the scope of that
requirement is therefore not limited to inspections and tests. In particular, point 21.A.33(d)(1) is not
limited to data and information related to compliance demonstration items (CDIs) in which the CAA is
involved.
21.A.33(d) GM Inspections and tests
The applicant should inform the CAA sufficiently in advance about the execution of inspections and
tests that are used for compliance demonstration purposes unless the CAA has explicitly excluded
these inspections and tests from its involvement according to 21.B.100.
Additionally, the applicant may propose to the CAA to perform or witness flight or other tests of
particular aspects of the product during its development and before the type design is fully defined.
However, before the CAA performs or witnesses any flight test, the applicant should have performed
these tests already before the CAA and should ensure that no features of the product preclude the
safe conduct of the evaluation requested.
The CAA may require any such tests to be repeated once the type design is fully defined to ensure that
subsequent changes have not adversely affected the conclusions from any earlier evaluation.
A statement of conformity as per point 21.A.33(c) is also required for the above tests.
21.A.35 Flight Tests
(a) Flight testing for the purpose of obtaining a type-certificate shall be conducted in
accordance with conditions for such flight testing specified by the CAA.
(b) The applicant shall make all flight tests that the CAA finds necessary:
1. to determine compliance with the applicable type-certification basis and
environmental protection requirements; and
2. to determine whether there is reasonable assurance that the aircraft, its parts and
appliances are reliable and function properly for aircraft to be certificated under this
Annex I (Part 21), except for,
(i) sailplanes and powered sailplanes,
(ii) balloons and airships defined in ELA1 or ELA2,
(iii) aeroplanes of 2 722 kg or less maximum take-off mass (MTOM).
(c) (Reserved)
(d) (Reserved)
(e) (Reserved)
(f) The flight tests prescribed in point (b)(2) shall include:
1. for aircraft incorporating turbine engines of a type not previously used in a type-
certificated aircraft, at least 300 hours of operation with a full complement of engines
that conform to a type-certificate; and
2. for all other aircraft, at least 150 hours of operation.
21.A.35 GM Flight Tests
Detailed material on flight testing is included in the applicable CS and GM.
21.A.35(b)(2) GM Objective and Content of Function and Reliability Testing
1. OBJECTIVE
The objective of this testing is to expose the aircraft to the variety of uses, including
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