- 3 - AIRP-WG/WHL/9-WP/2

/ International Civil Aviation Organization / AIRP-WG/WHL/9-WP/2
25/10/05
WORKING PAPER

AIRWORTHINESS PANEL (AIRP)

WORKING GROUP OF THE WHOLE

NINTH MEETING

Beijing 14 to 18 November 2005

Agenda item 6: Review of Proposed Amendments to Annex 8 in response to the requests of the ANC and State’s comments

TITLE: RESPONSIBILITIES OF STATE OF DESIGN FOR STCs

(Presented by Eugene Holzapfel)

SUMMARY
WP 5 was formed to consider an ANC direction regarding issues relating to the responsibilities of the holders of an STC approval. This paper contains the results of discussions to date.

1. INTRODUCTION

Annex 8, Part II, paragraph 4.2.1.2 requires that the State of Design of an engine or a propeller, where it is different from the State of Design of the aircraft, shall transmit any continuing airworthiness information to the State of Design of the aircraft and to any other Contracting State upon request. The ANC received a comment that there should be an obligation on a State that has approved a design change developed by an organization that is not responsible for the type design of the aircraft to transmit information for the continuing airworthiness of the aircraft (e.g. an STC issued by a State that is not the aircraft State of Design). The ANC requested AIRP to study this issue and report.

2. ISSUES

The question appears to have two primary issues as follows:

·  holders of STCs and States to have responsibility for continuing airworthinessof their STC, and

·  procedures to enable those responsibilities to be satisfied.

3. REVIEW OF CURRENT SITUATION

SARP Requirements For Aircraft / SARP Requirements For STCs
Annex 8 para 1.2.1, design standards to comply with Annex 8 standards. / Annex 6 para 8.6 requires that all modifications and repairs shall comply with airworthiness requirements acceptable to the State of Registry.
Annex 8 para 1.3.4 requires States approving a modification to do so on the basis of the airworthiness standard used for type certification of that aircraft.
Annex 8 para 4.3.c)i) requires States of Registry to have requirements to ensure that the aircraft continues to comply with the appropriate airworthiness requirements after a modification (not defined as original or latest design standard).
Aircraft production must accord with Annex 8, Chapter 2 / Annex 8 Para 2.2.3 requires contracting states to ensure that the production of aircraft and aircraft parts is performed in a controlled manner
CofA to be issued in accordance with Annex 8 Chapt 3. A flight manual is required stating approved limitations and instructions for safe operation. / No change to CofA is required and no statement on flight manual. In practice, a supplement may be required.
Annex 7, Section 6, Register of nationality, common and registration marks, of Aircraft Nationality and Registration Marks, requires contracting states to maintain a current register of each aircraft. / Annex 6, para 8.4 requires operators to ensure aircraft records include appropriate details of modifications. No known requirement for NAAs to record incorporation of STCs.
Defect reports forwarded to holder of aircraft type design, Annex 8 para 4.3.5 / No separate requirement for STCs, presumably all defect reports are forwarded to the holder of the aircraft.
Annex 8 para 4.2.1.1 requires State of Design for aircraft to forward Continuing Airworthiness Information to all States with the aircraft on their register. / No specific requirement for forwarding of continuing airworthiness information for STCs.

3.1 The Airworthiness Manual Volume II Part A, Chapter 2, para 2.8 details how STCs are issued. The Airworthiness Manual Volume II, Part B, Chapter 5.2.9 lists continuing airworthiness responsibilities for the holder of an STC, including:

·  Immediately advise the airworthiness authority of any safety deficiency reported;

·  Prepare appropriate design changes and make available to the authority for mandatory continuing airworthiness action; and

·  Make the descriptive data (SB) available to all operators of products affected by the mandatory action.

3.2 Annexes 6 and 8 and the Airworthiness Manual therefore have substantial information about the certification of an STC, and the responsibilities of States and the holder of an STC, but appears to have deficiencies in how those responsibilities are exercised. Also, the detail in the Airworthiness Manual is not well supported by requirements in Annex 8.

3.3 Aircraft manufacturers may consider that the difficulty in enforcing the responsibilities of the holder of an STC unfairly weighs against them. The aircraft manufacturer is clearly identified, and highly visible for raising defect reports and mandatory continuing airworthiness action. In contrast, the State of Registry may not have visibility of the holder of an STC incorporated in an aircraft on their register.

3.4 Many STCs can be substantial, and can change the role of the aircraft, for example, passenger to cargo conversions. Hence, it is sensible to ensure there are clear requirements in the Annexes and Advisory Material regarding the responsibilities of the States and holders of an STC, and how those responsibilities can be exercised effectively. However, there have not in practice been a large number of problems with STCs, and there are many more STCs than aircraft type certificates, so the effort required to implement any corrective action must be related to the benefits gained.

4. IMPLEMENTATION ISSUES

4.1 Annex 8 para 4.2.3 requires the State of Registry to advise the State of Design it has entered an aircraft on its register, which enables the State of Design to know where continuing airworthiness information should be sent. Unfortunately, this does not extend to knowing where STCs have been incorporated, and the State of Design of a modification when different from the State of Design of the product may not know where continuing airworthiness information should be sent to?

4.2 In considering this issue, some possible solutions were considered:

·  The holder of the STC could approve each application of their STC, and be able to advise the NAA of the STC State of Design where to send the information.

·  The State of Design of the modification could forward continuing airworthiness information to all contracting States, which can be discarded as irrelevant by NAAs that do not have the STC incorporated in aircraft on their register.

·  The STC State of Design forward any continuing airworthiness information to only those States that have the parent equipment on their register, possibly through the State of Design for the parent equipment.

4.3 Some major STCs could include a new data plate, and extension to the aircraft model number, to ease a data base search for aircraft incorporating these major modifications.

4.4 Given the large numbers of STCs, and that many are small in size, there is also an increased possibility that the holder of the STC will cease to support the STC, resulting in some aspects of an aircraft that are not supported by a type certificate holder.

5. RECOMMENDED ACTION

5.1 Despite the practical issues noted above, AIRP believes Annex 8 Amdt 100 Chapt 2 should be amended to include a new para 4.2.1.3, similar to:

When the State of Design of a modification is different from the State of Design of the product being modified, the State of Design of the modification shall transmit mandatory continuing airworthiness information to the State of Design for the aircraft, engine or propeller, and to any other contracting State upon request.

5.2 If this is agreed, and Annex 8 is amended, AIRP can then develop suitable supporting material for the Airworthiness manual, covering the responsibilities of the STC State of Design and the State of Design for the parent certificated product, and may include specific requirements for major STCs which change the fundamental assumptions of the original aircraft certification.

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