GUIDANCE FOR APPROVED MODEL LIST (AML)
SUPPLEMENTAL TYPE CERTIFICATE (STC) APPROVAL OF PART 23 AIRPLANE AVIONICS
INSTALLATIONS
AC 23-22
JANUARY 27, 2005
Initiated By: ACE-100
FOREWORD
The advisory circular (AC) system became effective in 1962. It provides a single, uniform, agency-wide system that the Federal Aviation Administration (FAA) uses to deliver advisory material to FAA customers, industry, the aviation community, and the public. This AC sets guidelines for using the Approved Model List (AML) Supplemental Type Certificate (STC) process for the installation approval of avionics for 14 CFR, part 23 airplanes.
S/
David R. Showers Acting Manager, Small Airplane Directorate Aircraft Certification Service
i (and ii)
CONTENTS
SECTION PAGE
Foreword
Chapter 1. General Information
1. What is the purpose of this AC?1
2. Who does this Advisory Circular (AC) apply to?1
3. What is incorporated or cancelled by this AC?1
Chapter 2. Introduction
1. Why write this AC?3
2. What documents are re lated to this AC?4
3. What are common definitions for the terms used in this AC?6
4. What is an AML STC?6
5. What does existing guidance say about AML STC approvals?7
6. What avionics can be approved under the AML STC process?8
7. What are some limits of the AML STC process?9
Chapter 3. AML STC Process
1. What are the key process steps to an AML STC?11
2. How is the AML created?11
3. What is the Model Qualification Process?13
4. How is an avionics AML STC amended?14
Chapter 4. AML Documentation Requirements
1. What is the required detail in the data package submittal for an AML?15
2. What is the required detail in the installation instructions?16
3. What must the installati on instructions address?17
4. What Continued Airworthiness Considerations must be addressed?19
Chapter 5. Model Qualification Process Requirements
1. Evaluation of Physical Location of Installed Equipment21
2. Evaluation of the Applicability of the Proposed STC21
3. Evaluation of Intended Function of the Proposed Equipment21
4. Evaluation of the Installation Complexity of the Proposed Equipment22
5. Evaluation of Operational Requirements of the Proposed Equipment22
6. Pilot Evaluation and Human Factors Issues for the Proposed Equipment23
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Appendix 1 Generic Model Qualification Process Sample DocumentA1-1
Appendix 2 Example AML STCA2-1
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CHAPTER 1. GENERAL INFORMATION
1. What is the purpose of this AC?
a. This advisory circular (AC) sets guidelines for using the Approved Model List (AML) Supplemental Type Certificate (STC) process for the installation approval of avionics for 14 CFR, part 23 airplanes. It also applies to airplanes certified under a prior certification basis, such as Civil Air Regulations (CAR) part 3 or Aeronautics Bulletin 7-A.
Guidance provided in this AC applies only to avionics installations using the AML STC process. For other types of modifications to part 23 airplanes seeking to use the AML STC process, the Aircraft Certification Office (ACO) should coordinate with the Small Airplane Directorate. Avionics AML STC guidance provided in this AC addresses the following:
(1) Avionics eligible for the AML STC process
(2) Model Qualification Process used by the STC holder and the FAA to either create or edit the AML
(3) Level of Detail required for the installation instructions for an AML STC, including a list of acceptable equipment that can be integrated under the STC.
b. Material in this AC is neither mandatory nor regulatory in nature and does not constitute a regulation. In addition, this material is not to be construed as having any legal status and should be treated accordingly. However, it is designed to provide standardization guidelines for AML STC approvals. The AML STC process may be used whenever the ACO and the applicant agree that it is suitable. This AC is not applicable to any products certified under part 25, 27, or 29.
c. This guidance does not replace the ability of an applicant to get a field approval for a major alteration, as outlined in FAA order 8300.10, Volume 2, Chapter 1. It is meant to provide an alternative path for installation approval of avionics equipment and to promote standardization through Certification Engineering involvement on multiple-model installations of the same equipment.
2. Who does this Advisory Circular (AC) apply to?
This AC provides guidance to Federal Aviation Administration (FAA) personnel, equipment manufacturers, and avionics equipment installers.
3. What is incorporated or canceled by this AC?
a. This guidance does not address design approval for part 23 avionics systems, which is already addressed in existing FAA documents, such as Order 8150.1B. It is meant to clarify installation approval under the AML process for part 23 avionics.
b. The guidance in this AC augments and clarifies the information provided in cancelled Notice 8110.43, Supplemental Type Certificates Applicable to Several Type 1
Certificated Products, issued 3/6/1992. The information from Notice 8110.43 has been incorporated into this AC in Appendix 2.
c. This AC also cancels Policy Statement PS-ACE100-2002-002 on the installation approval of Multifunction Displays (MFD) using the AML STC process. PS-ACE100- 2002-002 did not address Primary Flight Displays or other avionics systems and limited the use of the AML process to non-flight critical applications. This AC incorporates the information in PS-ACE100-2002-002 and provides guidance to expand the use of the AML to other types of avionics systems and standardize the AML approval process.
CHAPTER 2. INTRODUCTION
1. Why write this AC?
a. The Safer Skies initiative and the Advanced General Aviation Transportation Experiment (AGATE) program determined that modern avionics could provide pilots with better information and reduce general aviation accidents. Until recently, hardware costs and certification costs made it impractical to build new technology avionics systems for part 23 use. As new technology is introduced, hardware costs continue to come down. In contrast, the avionics installation approval process has increasingly become more rigorous for applicants seeking installation approval of new systems in part 23 and CAR 3 airplanes. Also, the existing approval processes often provide an inconsistent level of FAA oversight.
b. Applicants sought the approval path of least resistance, which has increased the number of follow-on field approvals for installation of avionics systems in small airplanes. Field approvals are typically based on a single STC with little or no follow-on ACO involvement, which may only be suitable for certain types of installations. For more complex avionics installations, a follow-on field approval may not properly address interface considerations to existing equipment. This warrants a change in the avionics approval process for part 23 and CAR 3 airplanes. The resulting streamlined process needs to provide the proper measure of certification oversight, but it must provide similar advantages to the field approval process.
c. The “Industry and FAA Avionics Approval Guide” describes the certification process for design and installation approval and suggests expanded use of the AML process to streamline part 23 avionics installation approvals. However, the lack of clear guidance on AML approvals has led ACOs to develop their own avionics approval procedures, resulting in a lack of standardization. There is a clear need for a standardized approach to the AML avionics approval process, including criteria for the suitable use of the process, which this AC is designed to provide.
d. Existing AML approvals range in complexity from simple “single wire” installations of supplemental systems to complex Primary Flight Display (PFD) systems that provide flight critical information. Each avionics system presents a unique set of certification requirements. Complex systems require greater certification detail to deal properly with compliance issues for models with slightly different certification bases.
For example, showings of compliance to part 23, § 23.1331 requirements for electrical power may be slightly different from model to model and must be clearly documented under the AML process.
e. This AC serves to clarify the AML process for part 23 avionics approvals. It clearly outlines the requirements for creating a Model Qualification Process, determining a suitable certification basis, creating detailed installation instructions with equipment suitable integration procedures, determining data package details, creating procedures for amending the AML, and other items. The AML process is designed to allow a single set of compliance data to be applied to multiple models, where suitable. The intent is to 3
avoid duplication of testing and data gathering while honoring the agency's primary responsibility to determine the airworthiness of the altered product.
f. It is important the applicant and the FAA ACO agree to the use of the AML process early in a certification project. The resulting STC, with its associated AML, should lessen the need for installers to request field approvals, but is not meant to lower the certification requirements for a particular installation approval. If done properly, an AML STC may save valuable resources for both industry and the FAA by reducing the number of individual STC approvals.
2. What documents are related to this AC?
a. Orders, regulations, policy statements, and other FAA documents:
HBAW 98-18 Checklist for Instructions for Continued Airworthiness for Major Alterations
Order 8100.5A Aircraft Certification Service Mission, Responsibilities, Relationships, and Programs
Order 8110.4B Type Certification
Order 8150.1B Technical Standard Order Procedures
Order 8300.10 Airworthiness Inspector’s Handbook Volume 2, Chapter 1, Perform Field Approval of Major Repairs and Major Alterations, Change 16
Order 8110.37C Designated Engineering Representative (DER) Guidance Handbook
Order 8110.48 How To Establish The Certification Basis For Changed Aeronautical Products
Order 8110.49 Software Approval Guidelines
Title 14 CFR, part 21 Certification Procedures for Products and Parts
Title 14 CFR, part 23 Airworthiness Standards: Normal, Utility, Acrobatic, and Commuter Category Airplanes 4
b. Advisory Circulars
You may get copies of the current publication of the ACs listed below from the U.S.
Department of Transportation, Subsequent Distribution Office, Ardmore East Business Center, 3341 Q 75th Avenue, Landover, MD 20785. The ACs are also available on the Internet at http://www.faa.gov/certification/aircraft.
AC 21-40 Application Guide for Obtaining a Supplemental Type Certificate
AC 23.1309-1C Equipment, Systems, and Installation in Part 23 Airplanes
AC 23.1311-1A Installation of Electronic Displays in Part 23 Airplanes
AC 23-15A Small Airplane Certification Compliance Program
AC 23-17A Systems and Equipment Guide for Certification of Part 23 Airplanes
AC 23-8B Flight Test Guide for Certification of Part 23 Airplanes
AC 43.13-1B Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair
AC 43.13-2A Acceptable Methods, Techniques, and Practices - Aircraft Alterations
AC 20-138A Airworthiness Approval of Global Navigation Satellite System (GNSS) Equipment
c. Other Applicable FAA and Industry Documents or Job Aids The FAA and Industry Guide to Product Certification, January 1999, located on the web at: http://www.faa.gov/certification/aircraft/av-info/dst/CPIGUIDE.pdf
The FAA and Industry Guide to Avionics Approvals, April 2001, available on the web at: http://www.faa.gov/certification/aircraft/AVCPIcov.pdf
GAMA Publication Number 10, Recommended Practices and Guidelines for Part 23 Cockpit/Flight Deck Design, available on the web at:
http://www.gama.aero/pubs/onlineCatalog.php 5
GAMA Publication No. 12 - Recommended Practices and Guidelines for an Integrated Cockpit/Flightdeck in a Part 23 Airplane, available on the web at:
http://www.gama.aero/pubs/onlineCatalog.php
3. What are common definitions for the terms used in this AC?
AD Airworthiness Directive AML Approved Model List CFR Code of Federal Regulations CPI Certification Process Improvement DER Designated Engineering Representative FHA Functional Hazard Assessment GAMA General Aviation Manufacturers Association GPS Global Positioning System ICA Instructions for Continued Airworthiness MFD Multi-Function Display PSCP Project Specific Certification Plan STC Supplemental Type Certificate TC Type Certificate TCDS Type Certificate Data Sheet
4. What is an AML STC?
a. An AML STC is similar to a multimodel STC, which applies to multiple airplanes listed on the same TCDS. However, an AML STC goes one step further by allowing the STC to apply to several different TCs. This allows a single STC to address several different TCs by documenting the data and limits suitable to each of the several different aircraft. This is a more efficient use of resources compared to multiple single-model approvals for an installation that is similar or identical for several different models. See Order 8110.4B for more information on the STC process.
b. To keep track of the various models, an AML is created and attached to the STC (FAA form 8110-2). Whenever another model is added or a document is amended, the AML is changed and not the STC. This lessens the number of STC approvals and may be a more efficient use of resources compared to multiple single-model approvals.
However, any change to the AML requires FAA approval.
c. STC approvals with an AML have the same data requirements as an STC applicable to a single model of aircraft. However, when making avionics modifications it is possible to combine the current approval process with some of the advantages of the field approval process. Field approvals typically allow for data from a single STC to be reused for multiple approvals where similarity can be clearly shown. However, they are often carried out with little or no follow-on ACO involvement, which may only be suitable for simple installations where Part 43 “acceptable data” clearly addresses differences between the existing approval and the follow-on installation. The AML provides an advantage, since ACO engineering involvement is required for each 6
installation on each model on the AML and differences are evaluated and documented clearly in the installation instructions.
d. For more complex avionics installations (See Chapter 1, Section 6.c), it may be more suitable for the applicant to address interface considerations to existing equipment upfront for each proposed model on an AML through a prototyping approach.
e. This process allows portions of the compliance data to be reused, and new showings of compliance for each model to be provided as needed. The AML process is meant to provide the proper measure of certification oversight, but also provide a streamlined approval process for part 23 avionics. Further guidance on the STC process is available in AC 21-40.
5. What does existing guidance say about AML STC approvals?
a. Order 8110.4B, section 4-2a(4), clearly provides for a single STC data package to be used for multiple airplane models, provided the following conditions are met:
(1) The STC data package consists of a principal design and certification data package for the change and either a master installation package for all eligible type certificated products or a separate installation package for each eligible type certificated product.
(2) Any design or installation differences between eligible products are identified in the design and installation data.
(3) Installation complexity is similar on all eligible products.
(4) The change does not require a large reevaluation of the type-certificated product's airworthiness.
(5) Either the flight or operational characteristics, or both, of the type-certificated product remain unchanged.
(6) The change does not create an acoustical change to the type-certificated product (See §21.93 and FAR Part 36 to define an acoustical change).
(7) The eligible type certificated products, applicable FAA approved documents, and the certification basis for each model are listed on a special page known as the “Approved Model List (AML)” attached to the STC under the following conditions:
(a) Whenever a type certificated product is added or one of the FAA approved documents is amended, deleted, or added, the AML itself is amended and approved by the FAA, not the STC.
(b) An AD is required to remove a product from an AML in the case where some unsafe condition exists unless the STC holder can prove no installation was made.
The applicant should always coordinate with the responsible ACO to determine the best course of action for removing a model from the AML using existing FAA process.
Existing installations may be affected if the ACO determines that an unsafe condition exists for a particular model, which may require the removal of the equipment in question.
(c) An STC with an AML can be transferred in total to another holder but cannot be split into more than one STC.
b. The “Industry and FAA Avionics Approval Guide” states that, for avionics equipment with similar installation requirements on several aircraft models, a generic approach to the approval process should be considered. The goal of the generic STC approval process is to develop installation instructions that can be used to install avionics equipment in several different aircraft models. These installation instructions will not repeat complete STC programs and will allow the reuse of compliance data where suitable. Title 14 CFR, part 21, § 21.101, also supports this idea.
c. This AML STC approach can reduce the effort for follow-on approvals the avionics installers must get and should reduce the number of field approvals that are performed. It will streamline the STC approval process and allow multiple models to be approved at once. However, there has been some confusion of defining “type design” in discussions about this generic approval process. This guidance seeks to clarify that a single compliance data package is suitable for AML approvals if applicability of the data package to different models and likeness between type designs can be clearly shown and documented. By identifying installation requirements up front, the AML STC process simplifies the approval of installation data for other models.
6. What avionics can be approved under the AML STC process?
a. Critical and noncritical avionics system installations can be addressed using the AML process, provided the ACO and applicant agree the process will adequately address the certification requirements for a given system, and its installation on other model aircraft. The term ”critical'' refers to those functions identified by a (§ 23.1309) hazard analysis whose failure would contribute to, or cause, a failure condition that would prevent the continued safe flight and landing of the airplane. AML STC approvals can be separated into two classifications, simple or complex, depending on the system installation complexity.
b. A simple system is defined as a stand-alone equipment installation that 1) has well understood requirements for power, antenna, and other interfaces, and 2) does not require substantial model specific configuration settings to be applied. A simple AML STC involves an installation that is repeated easily for all the airplanes listed on the AML using a generic set of installation instructions and a generic configuration setting.
However, before using a generic set of installation instructions, the applicant must clearly document and show similarity between the aircraft on the AML. Further compliance findings and formal conformity inspections may not be required after an initial showing 8