AMC1 21.A.101(ba) Type-certification basis for changes to large aeroplanes subject to point 26.300 of Part-26

CAA ORS9 Decision No. 48

Compliance with point 21.A.101(ba) is demonstrated through compliance with Amdt 19 to CS 25.571 or subsequent amendments, or with the following:

  1. For turbine-powered large aeroplanes with a certified maximum take-off weight (MTOW) greater than 34 019 kg (75 000 lbs):

    1. For changes that affect or introduce fatigue critical structures susceptible to widespread fatigue damage (WFD), WFD evaluations should substantiate freedom from WFD up to the existing limit of validity (LOV) or a new reduced LOV approved by CAA;

    2. The extension of an existing LOV is a major change.

    3. The extent of the test evidence required in support of the WFD evaluation should be agreed with CAA;

    4. Inspections and other maintenance actions upon which the LOV is dependent are established and submitted to CAA for approval in accordance with point 21.A.7 of Part 21;

    5. Additional AMC which are relevant to this subject appear in paragraph 8 to AMC 20-20B.

  2. For turbine-powered large aeroplanes certified to carry 30 passengers or more, or with a payload capacity of 3 402 kg (7 500 lbs) or more:

    1. For changes that affect or introduce fatigue critical structures, damage-tolerance evaluations must be performed according to the certification basis of the aeroplane unless it precedes JAR 25.571 Change 7 or 14 CFR §25.571 Amendment 45, in which case the certification basis for the change should be:

      1. JAR 25.571 Change 7 or 14 CFR §25.571 Amendment 45, or later amendments; or

      2. the specifications used for compliance with the applicable points of Part-26 for the structures affected by the change.

    2. Develop or amend the list of fatigue-critical modified structures (FCMS) as necessary and make it available to aircraft operators as part of the ICA of the change.

  3. For turbine-powered large aeroplanes, the baseline corrosion prevention and control programme should be amended or supplemented to address the influence of the change on the effectiveness of the programme, as necessary.