CHAPTER 4. AML DOCUMENTATION REQUIREMENTS
1. What is the required detail in the data package submittal for an AML?
a. The detail contained in a data package submittal for an AML approval is agreed on between the applicant and the responsible ACO at the beginning of the AML approval process. The detail required will be directly related to the complexity and intended function of the installation and the complexity of the models listed on the AML. The data package can be split into a principal design and certification data package for the STC modification and into either a “master” installation package for all eligible typecertificated products, or into separate installation packages for each eligible typecertificated product.
b. According to Order 8110.4B, and 14 CFR, part 21, § 21.101, there are STC procedures in place to reduce unnecessary administrative burdens on the applicant and the FAA. Once an applicant has shown that a design change meets the airworthiness requirements necessary for FAA approval, later similar alterations may not require the same data package detail and may not require the same tests as the first approval. This philosophy is used to allow an applicant to benefit from previous work.
c. A key element of the AML process is a single set of compliance data to be applied potentially to multiple models. The intent is to avoid duplication of testing and data gathering while honoring the agency's primary responsibility to determine the airworthiness of the altered product. The compliance data package must be detailed enough to allow a compliance finding by the responsible ACO. However, it may be used to show compliance for multiple models on the AML if the Model Qualification Process clearly documents similarity between the models. For example, it may be possible to address electrical load analysis issues, hazard analysis issues, and other certification requirements in a generic fashion for the entire AML. The responsible ACO and the applicant must agree on this approach.
d. The FAA may minimize or waive the need for the applicant to provide supporting data for specific AML approval requirements. This is based on prior FAA knowledge gained from the first installation done by an applicant for the first model on the AML.
This depends on the criticality and intended function of a particular component and the similarity or identicality of the installations. This agreement should be documented in the AML STC Certification Plan. However, the intent is not to allow an applicant to use compliance data from another applicant's approval unless written permission is obtained to do so from the original STC holder. As with other STC approvals, the FAA will not supply an applicant with information submitted by a previous applicant.
e. The generic approach to the conformity plan should be well defined in the Certification Plan or Model Qualification Process document and must have FAA concurrence. FAA Order 8110.4B and AC 21-40, application guide for obtaining a STC, provide more details on conformity inspections.
f. The ACO and applicant must agree whether an Aircraft Flight Manual (AFM) supplement is necessary. This will depend on the need for an aircraft limitation
(23.1583) based on the equipment, operational complexity and the compelling nature of the equipment to draw the pilot’s attention. If it is determined that an AFM supplement is necessary, it should include a description of the system, aircraft limitations, emergency procedures, abnormal procedures, and normal procedures, and any changes to the performance of the airplane. The AFM supplement may also refer to the equipment user manuals for more detailed instructions on operating the equipment. For simple systems, a general supplement would be suitable for all approved models. The general supplement is then inserted into the existing flight manual with the cover page completed for make and model, registration number, and serial number. AC 23-8B, Flight Test Guide for Certification of Part 23 Airplanes, chapter 6, section 3, provides added guidance on AFM and approved manual material. If the airplane does not require an AFM, a “Supplemental Flight Manual” or pilot handbook should be developed to provide the same information.
Order 8110.4B paragraphs 4-2.a. (4) (c) and (e) also set limits on expanding AFM model eligibility for an AML STC.
2. What is the required detail in the installation instructions?
a. The installation instructions and the Model Qualification Process are vital parts of the AML process. The installation instructions should be suitable for the intended function of the system. These instructions must describe the installation in adequate detail such that the installation shop can determine if a particular serial number airplane is eligible. Follow-on installations are repeatable, so the installation will meet airworthiness requirements, and a conformity inspection can be performed to equipment lists and drawings, if required. If the system being certified is simple, it may be possible to use one set of generic installation instructions and apply them to all the models on the AML. The generalized installation guidelines could reference standard practices used in the installation, for example aircraft electrical wire selection as specified in Advisory Circular 43-13.
b. For more complex systems, a more detailed set of installation instructions may be necessary. This may include a general section, with model specific appendices to address model specific installation considerations. New model specific sections may also be added to the instructions and approved by the FAA as necessary when each system is “prototyped” or when the system is installed on a new model as an amendment to the AML. The procedures for revising the installation instructions should be part of the AML amendment procedures between the responsible ACO and the applicant and should be clearly documented.
c. In developing the installation instructions, the applicant may consult local avionics repair stations, the ACO, and Aviation Safety Inspectors from the FAA local Flight Standards District Office. Their support may provide insight into what is required for the installation instructions. The resulting AML STC should reduce the potential 16
need of Flight Standards to issue follow-on field approvals for similar equipment installations.
3. What must the installation instructions address?
a. Definition of Intended Function for the System - The intended function of the system must be clearly stated so compatibility can be determined with existing equipment for each model on the AML. Also, the intended function should be the same for all the models on the AML, or it may be necessary to split the AML into different sections.
There has been a trend to install equipment, mainly navigation related equipment such as moving maps, as nonrequired, “Not approved for primary navigation” or “SA-Only.”
The basis for their installation approval has been that they must perform their intended function and not present a hazard to other equipment or the airplane. However, it is not acceptable to label an instrument as “SA-Only” and assume its failure in normal operation is acceptable. A safety assessment conducted by guidelines in AC 23.1309-1C is required to help define the potential safety concerns for a particular installation for the models on the AML.
b. Human Factors Considerations - The FAA recognizes the need to address human factors issues. Human factors considerations must be addressed in the AML Certification Plan. Guidance to aid in this effort and other human factors considerations is contained in the FAA policy statement, PS-ACE100-2001-004. Also, AC 23.1523 addresses pilot workload, which should be considered for all the models on the AML.
c. Wiring Considerations - This includes system schematics and wiring diagrams to describe adequately the connectivity of the equipment, including antennas. For simple installations, it may be acceptable for the applicant to reference specific sections and figures in AC 43-13 to document accepted installation practices, including wire routing and wire separation. For more complex installations, more detailed wiring information may be necessary. For example, specific wiring instructions are required to maintain HIRF and lightning compliance for follow-on installations of critical equipment. If these practices are not followed for a particular installation, the potential for safety hazards may exist. Wire routing and separation considerations must also be addressed according to accepted practices for the certification basis of the model being altered. However, depending on the installation, exact three-dimensional wire routing diagrams may not be value added, even for critical systems. The applicant and ACO must agree early in the approval process on the acceptable means to document wiring installation. Also, only wire specifically designed for airborne use should be installed in the aircraft, such as wire presented in AC 43.13-1B.
d. Structural Considerations - If required, structural substantiation data must be submitted for antenna installations, and box mounting. AC 43-13 is not a satisfactory reference for antenna installations on pressurized airplanes. Also, depending on the certification basis of the airplane (Amendment 23-45 or later), damage tolerance issues must be addressed.
e. STC Assumptions and Limitations - Assumptions and limitations in the supporting data for the original approval of the STC must be clearly stated in the installation instructions. This is because an installation shop can address serial number specific considerations and seek further approval, if needed. For example, a particular serial number may have existing equipment or modifications that would preclude installation of the proposed modification or would require further FAA approval, despite being listed on the AML.
f. Interface to Other Equipment - Data must be provided to document what equipment is approved to interface with the proposed system under the AML STC.
Enough detail must be provided to document interface compatibility and interoperability assurance with other equipment. This should include any approved variations in protocol or data word formats that might influence proper functionality, operational characteristics, or changes to intended function. This may also include a list of equipment that is specifically not approved to interface with the equipment being installed.
g. Electrical Load Analysis and Functional Hazard Assessment. Installation procedures should clearly state that electrical load analysis, functional hazard assessment, and other certification requirements remain in compliance. It is possible to apply a generic approach to the functional hazard assessment if worst-case assumptions are made for a typical installation. For example, the functional hazard assessment is performed during design approval with certain assumptions on system redundancy and back-up systems. The STC must contain details of these assumptions as limits to assure all models on the AML meet the terms of the original design approval assumptions.
h. Pre- and Post-Installation Check Procedures
(1) Provide either pre or post installation ground test or flight check procedures, or both, with clear and concise pass/fail criteria to verify the intended function of the system. Include a post-installation approval for return to service by the responsible party so a maintenance record entry can be made documenting the installation has been performed.
(2) The ground test or flight check procedures, or both, should 1) evaluate operation of the system, 2) determine if the system is interfaced properly with other systems, 3) determine if the system performs its intended function, and 4) determine if there is unacceptable interference with other systems. For example, day/night lighting considerations must be addressed for a particular installation.
(3) AC 23-8B, Flight Test Guide for Certification of Part 23 Airplanes, provides further guidance. Also consider part 91, § 91.407, to determine flight check requirements for post-installation test to verify intended function. In accordance with § 91.407(a) and
(b)An operational flight check should be conducted by the applicant or designee to verify proper system function. Installations intended for Instrument Flight Rules (IFR) may be initially limited to Visual Flight Rules (VFR) until the proper functionality is shown to 18
avoid the requirement for a special airworthiness certificate in experimental category before conducting an operational flight check.
(4) Electromagnetic Interference (EMI) testing may reveal incompatibilities between the installed system and existing systems. For example, there may be potential interference from electric motors or ballasted lighting systems on sensitive navigation and attitude reference system sensors. The applicant should provide model specific checkout procedures for each model on the AML to address possible interference conditions. Laboratory EMI tests performed according to RTCA/DO-160 Section 21 for RF emissions provide confidence that installed equipment will perform without interference to existing aircraft systems. This represents the most efficient way to address the potential for EMI on multiple models. This approach would also account for variations in existing equipment and minimize EMI tests needed on each airplane model.
Procedures for functional ground tests and flight checks should be provided as a final EMI check. Suggested remedies for interference include transfer of equipment, shielding techniques, or external filters. Recurrent EMI issues may warrant changes to the installation instructions that may need to be rolled back into the original AML STC approval.
i. Any other items the responsible ACO considers necessary for a given AML approval
4. What Continued Airworthiness Considerations must be addressed?
The following items should be addressed for each model on the AML to address continued airworthiness considerations:
a. Instructions for Continued Airworthiness (ICA).
(1) An ICA is required as part of the AML STC data package. Part 21, § 21.50(b), states that a holder of an STC must provide at least one set of complete ICA prepared following § 23.1529, including any Airworthiness Limitations.
(2) The ICA provides instructions necessary for authorized personnel to inspect and maintain the added equipment installed by the AML STC under the requirements of 14 CFR, part 43, including procedures to address approved equipment interfaces.
(3) The FAA is responsible under § 21.50 to accept the ICA. The Aircraft Evaluation Group (AEG) will aid the ACO engineer in showing the adequacy of the ICA and determining the acceptability of the ICA.
(4) The ICA must be in a printed form when the first airworthiness certificate is issued, or before delivery of the first product, whichever is later.
(5) FAA Order 8110.4B offers guidance on developing the ICA documents.
(6) The ICA should address maintaining HIRF and lightning protection compliance, including a list of specific wiring, bonding, or strapping requirements that must be maintained for the system.
CHAPTER 5. MODEL QUALIFICATION PROCESS REQUIREMENTS
This chapter is designed to help the user of this AC design a Model Qualification Process. This process is used by the STC holder and the ACO to determine and document the applicability of an AML STC to a given airplane model. In contrast, the installation instructions are intended to be used by the installer to determine applicability of the STC to a particular serial number airplane. The Model Qualification Process is designed to be used to: 1) include a given aircraft model on the existing AML (to determine if the installation is appropriate under the AML), 2) determine if a particular model would require further compliance showing to be added to the AML, or 3) determine if an installation is complex enough to warrant an individual STC. The following list of items is meant only as a guideline and does not represent an exhaustive list of potential issues that must be addressed to qualify a model for an AML approval.
1. Evaluation of Physical Location of Installed Equipment
a. Will the equipment for the proposed modification fit in the model being considered? This should include considerations for available space for new equipment and for systems that will need to be moved or displaced to complete the modification.
b. Is the proposed installation location, or proposed alternate mounting locations, compatible with the criticality and visibility of displayed information, including required announcements and warnings?
c. Is the environment suitable for the limitations of the equipment? This should include cooling considerations.
2. Evaluation of the Applicability of the Proposed STC
a. Is a particular model airplane configured in such a way that would preclude it from being eligible for the STC, although it is listed on the AML? This might be caused by existing equipment, where the interface is not covered in the installation instructions for the system, inadequate electrical capacity because of existing equipment, or other factors.
b. Are the operational characteristics of a particular model airplane compatible with the assumptions made during the initial certification? For example, an airplane may be approved for CAT II approach from the factory, where adding new equipment and replacing it with the new system might cancel this ability.
3. Evaluation of Intended Function of the Proposed Equipment
a. Will the proposed equipment be able to perform its intended function in the model being considered?
b. Is the intended function compatible with the equipment approval for the system, including software and hardware design assurance levels?
c. Is the software development level of the proposed equipment compatible with the intended function for the category/classification of the model in question?
d. Does the intended function change for the model being considered compared to other models already on the AML? If so, the applicant may need to split the AML into sections or seek separate approvals.
4. Evaluation of the Installation Complexity of the Proposed Equipment
a. Will the proposed modification present unique model specific installation challenges for the models being considered? This should include an analysis of the complexity of the proposed modification with consideration to existing equipment that would typically appear on a given model.
b. Will the proposed installation affect the electrical load analysis, the functional hazard assessment, or the calibration/operation of existing systems?
c. How will calibration issues for the new equipment, EMI related issues, and the possible effects to the HIRF and lightning certification of the proposed model be addressed?
d. How will the proposed modification interface with other existing systems on the model being proposed? What existing equipment is acceptable to interface with the new equipment?
e. Is specific training needed to install the system? Consider the existing installation instructions to see if more model specific details are needed to include the model in question.
f. Are there continued airworthiness issues that should also be evaluated to see if any model specific issues exist? For example, consider the installation location of the equipment and whether this might influence inspection, calibration, or maintenance schedules of the equipment.
5. Evaluation of Operational Requirements of the Proposed Equipment
a. Will the proposed equipment change the operational capabilities of the model being considered? This should include an evaluation of possible changes to the following: 1) existing precision approach capabilities, 2) navigational accuracy and procedures, 3) current pilot workload, 4) special certification conditions, and 5) operational approvals for the model being proposed, such as RVSM or CAT II approval.
b. Are there model specific limits and possible additions or changes to the AFM or AFM Supplements?
6. Pilot Evaluation and Human Factors Issues for the Proposed Equipment
Will the proposed modification create any issues that would warrant a pilot evaluation or any human factors concerns for the model being considered? This should include an evaluation of existing equipment, how the modification will affect the pilot's primary field of view, and how the system will be ground and flight tested after installation.
Ground and flight test procedures should contain exact test procedures and expected response data, with clear pass/fail criteria for each test.
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Appendix 1 APPENDIX 1 - GENERIC MODEL QUALIFICATION PROCESS SAMPLE DOCUMENT
Disclaimer:
The following sample document provides an example of a generic framework for the process used to show applicability of a given STC to a particular airplane model. The document proposes a structure for the formal engineering process that must be followed before a model can be added to the AML for a given STC.
The sample Model Qualification Process document is provided only as an example for the agreement between the STC holder and the ACO. It is not meant to capture all the possible information that would be required to determine applicability or use of a particular airplane for a given STC. Depending on the complexity of the system being approved, the detailed steps of this process may need to be reduced or expanded in scope to allow suitable installation and certification requirements for a particular approval.
A1-1
Appendix 1
CONTENTS
1 INTRODUCTIONA1-3
1.1 SummaryA1-3
1.2 Definitions and AcronymsA1-3
1.3 Applicable Documents and ReferencesA1-3
2 CERTIFICATION CONSIDERATIONSA1-3
2.1 AML STC DefinitionA1-3
2.2 AML STC Limitations and AssumptionsA1-3
2.3 Installation OverviewA1-4
2.4 AML Revision ProcessA1-4
3 DETERMINATION OF APPLICABILITYA1-4
3.1 Certification BasisA1-5
3.2 Prior ConsiderationsA1-5
3.3 Operational ConsiderationsA1-5
3.4 Installation ConsiderationsA1-6
3.5 Final ApprovalA1-6
4 SPECIFIC AIRCRAFT EVALUATIONSA1-6
4.1 Intended FunctionA1-7
4.2 Applicability Across Serial NumbersA1-7
4.3 Physical Location of Installed EquipmentA1-7
4.4 Interface to Existing EquipmentA1-8
4.5 Electromagnetic InterferenceA1-8
4.6 Human FactorsA1-8
5 ACCEPTANCE PROCESSA1-9
5.1 Model Qualification DiagramA1-9
List of Tables and Figures
Figure A1-1 AML Model Qualification Process DiagramA1-10
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Appendix 1 APPENDIX 1 - GENERIC MODEL QUALIFICATION PROCESS
SAMPLE DOCUMENT (CONTINUED)
1 Introduction
1.1 Summary
This section should contain a brief summary of the scope and purpose of the document, including a brief description of the certification approval project itself.
1.2 Definitions and Acronyms
This section should contain any project specific definitions and acronyms applicable for the approval.
1.3 Applicable Documents and References
This section should contain a listing of applicable certification documentation for the STC being considered, any applicable regulatory references, and other guidance suitable for a particular approval.
2 Certification Considerations
This section should contain an outline of the certification philosophy used by the ACO to approve the proposed modification. This information is provided so the reader is familiar with the basic certification assumptions surrounding the approval of the proposed modification.
2.1 AML STC Definition
This section should contain a clear definition of the AML STC as defined for the project approval in question. This includes a clear definition of the intended function of the equipment as provided in other certification documentation for the approval.
2.2 AML STC Limitations and Assumptions
This section should contain a summary list of assumptions made about the airplane, or equipment, for the initial certification that would influence the decision to include a given model on a proposed AML. One example would be the assumption that electromechanical back-up instruments are maintained and considered in the System Safety Assessment for a Primary Flight Display installation. Another example would be the software development assurance level that relates to the failure condition classification and airplane classification under AC 23.1309-1C.
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