U.S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Guidance for Certification of Military and Date: 9-30-2010 AC No: 20-169 Special Mission Modifications and Equipment for Initiated by: AIR-100 Commercial Derivative Aircraft (CDA) This advisory circular (AC) provides guidance for the certification of commercial derivative aircraft (CDA). CDA are aircraft that have been modified with specialized equipment to perform military and other non-civil missions. CDA are operated-by, or under the operational control of, governmental entities. With certain limited exceptions, they are operated as public aircraft. This advisory circular (AC) sets forth acceptable means, but not the only means, to show compliance to the provisions of Title 14 of the Code of Federal Regulations (14 CFR) parts 23, 25, 27, and 29 regarding type certification requirements for commercial derivative aircraft (CDA). This AC is presented as companion material to the procedures outlined in Order 8110.101, Type Certification Procedures for Military Commercial Derivative Aircraft.” The guidance provided in this AC is for use on certification projects for Military CDA. Certain provisions of this AC may also be applicable to certification projects for non-military CDA e.g., aircraft operated by state or local governments under public-use or aircraft owned by a foreign government.
For David W. Hempe Manager, Aircraft Engineering Division Aircraft Certification Service
TABLE OF CONTENTS
INTRODUCTION
1. Purpose4
2. Applicability4
3. Cancellation4
4. Related guidance4
CHAPTER 1. COMMERCIAL DERIVATIVE AIRCRAFT (CDA)
1. What is a CDA?6
2. Why does the FAA accept military commercial derivative aircraft (MCDA) certification
projects?6
3. What is the FAA MCO?7
4. Can the FAA certify all CDA?7
5. How are applications for sponsored military projects handled? Can applications be made for
CDA at other ACOs?8
6. What is different about a military project versus a typical civil project?8
7. How does The FAA Aircraft Certification Service manage complex integrations which
involve multiple approvals?9
CHAPTER 2. COMPLIANCE AND CERTIFICATION FOR CDA PROJECTS
1. Can the FAA certify a CDA that requires special utility arrangements necessary for the
mission, such as operator stations in the passenger compartment or troop carriage?10
2. What special mission equipment (SME), by definition, cannot be certified to civil
regulations?11
3. Can other SME be certified to civil regulations?12
4. What performance and/or environmental qualification standards should be applied to new
SME?13
5. What if the proposed SME package includes existing off-the-shelf hardware?14
6. Can the applicant submit, and will the FAA accept, previously accomplished equipment
qualification data (test analysis, reports, etc.) to be used in support of compliance findings?15
7. What happens if the COTS/ MOTS equipment fails to meet minimum qualification
requirements for the environment or function for the intended use?15
8. What about approvals for software embedded in GFE/SME?15
TABLE OF CONTENTS (Continued)
9. To what depth does the FAA participate in finding compliance with 14 CFR § XX.1309(a),
for SME?16
10. What reliability must GFE/SME have?17
11. Can the FAA approve provisions for unapproved SME as part of the type certification
process?17
12. For SME that will be FAA certified, but is not required by FAA regulations, what areas may
need to be covered by the military airworthiness authority (MAA)?18
CHAPTER 3. CONFORMITY INSPECTIONS AND PRODUCTION APPROVALS
1. How is FAA conformity inspection achieved for SME during the type certification process?19
2. Can SME be provided as an FAA-approved part if it has not been produced under an FAA
production approval?19
3. What about SME supplied as government or customer furnished equipment?20
4. Does the FAA accept used parts from the military or other U.S. government entities?20
5. What about parts and components that are installed as military deviations (i.e. not included in
the type design)?20
CHAPTER 4. MILITARY DEVIATIONS TO FAA APPROVED TYPE DESIGN
1. Can the FAA establish that uncertified SME (appearing on FAA Form 8130-31 as a military deviation) does not interfere with the airplane and/or flight crew performance for normal
operation or a failure case?21
2. Why is it required that the FAA find compliance for an aircraft configuration (as defined in type design) even though that FAA-approved configuration may be superseded by military
deviations and may never be produced?21
3. Do items identified in the FAA-approved type design, that will not be used in the delivered
aircraft need to be manufactured, conformed, and tested to receive certification?22
APPENDICES
APPENDIX A, AcronymsA-1
APPENDIX B, Discussion of required/essential versus non-required/non-essential electrical
equipmentB-1
APPENDIX C, Example (14 CFR part 25)C-1
INTRODUCTION
1. Purpose.
a. This advisory circular (AC) sets forth acceptable means, but not the only means, to show compliance to the provisions of Title 14 of the Code of Federal Regulations (14 CFR) parts 23, 25, 27, and 29 regarding type certification requirements for commercial derivative aircraft (CDA). CDA are aircraft that have been modified with specialized equipment to perform military and other non-civil missions. CDA are operated-by, or under the operational control of, governmental entities. With certain limited exceptions, they are operated as public aircraft.
b. The extensive variety of CDA applications and equipment often present challenges for civil type certification because they may not have a comparable civil function or purpose.
Methods for showing compliance with civil regulations may not have accepted precedence or appropriate guidance material. The intent of this AC is to answer frequently asked questions regarding acceptable certification approaches for CDA projects. This information should assist applicants in developing certification plans by providing acceptable means of compliance for unique CDA modifications. This AC is presented as companion material to the procedures outlined in Order 8110.101, Type Certification Procedures for Military Commercial Derivative Aircraft.” The guidance provided in this AC is for use on certification projects for Military CDA. Certain provisions of this AC may also be applicable to certification projects for nonmilitary CDA, e.g., aircraft operated by state or local governments under public-use or aircraft owned by a foreign government. The information contained herein is for guidance purposes only and is not mandatory or regulatory in nature. Acronyms used throughout this AC are defined in appendix A. Whenever specific airworthiness st andards are cited in this AC, we have made reference to the rule as implemented in part 25. Contact the FAA Military Certification Office for applicability to part 23, 27, or 29.
2. Applicability. The audience for this AC may include applicants, type certificate (TC)/production approval holders, aircraft modifiers, military contractors, parts manufacturers, maintenance and repair organizations, or operators of military or other government CDA.
3. Cancellation. This AC does not supersede other existing FAA guidance and policy material related to approvals for specific civil aircraft mission operations.
4. Related Guidance. The material contained herein applies to military CDA (certain section of this AC may also be used for non-military CDA) proposed to be FAA certified as normal, utility, acrobatic, commuter, transport, or restricted category aircraft; type-certificated under Civil Aviation Regulations (CAR) 3, 4b, 6, 7; or 14 CFR parts 23, 25, 27, and 29; and produced under 14 CFR part 21, § 21.125 or § 21.143, as may be appropriate. Specific FAA type certification procedures are contained in Order 8110.4C, Type Certification, and supplemented by Order 8110.101. FAA directives and guidance are refere nced at their revision level at the time of publication of this AC. The most current FAA directives and guidance should be used. Other references and guidance material for certification of systems and equipment include, but are not limited to:
a. AC 25-10, Guidance for Installation of Miscellaneous, Non-Required Electrical Equipment
b. RTCA/DO-178B, Software Considerations in Airborne Systems and Equipment Certification
c. AC 20-115B, RTCA, Inc., Document RTCA/DO-178B
d. RTCA/DO-160, Environmental Conditions and Test Procedures for Airborne Equipment
e. AC 21-16F, RTCA Document DO-160 versions D, E and F, “Environmental Conditions and Test Procedures for Airborne Equipment”
f. RTCA/DO-254, Design Assurance Guidance for Airborne Electronic Hardware
g. AC 20-152, RTCA, Inc., Document RTCA/DO-254, Design Assurance Guidance for Airborne Electronic Hardware
h. RTCA/DO-313, Certification Guidance for Installation of Non-Essential, Non-Required Aircraft Cabin Systems & Equipment
i. AC 20-168, Certification Guidance for Installation of Non-Essential, Non-Required Aircraft Cabin Systems & Equipment 5
CHAPTER 1. COMMERCIAL DERIVATIVE AIRCRAFT (CDA)
1. What is a CDA? For purposes of this AC, a CDA is defined as a commercial typecertificated aircraft converted for operational use by the U.S. Armed Forces or other U.S.
government agencies, with associated mission modifications or equipment approved to civil airworthiness standards through the FAA type certification process. Typically a CDA is owned/leased and operated by a government agency. However a CDA may also be owned by a private commercial entity and operated under contract to a government agency as a public-use aircraft. These operations are referred to as contracted air services. CDA are utilized in operations for which the baseline commercial aircraft was originally designed such as training, transportation, and carriage of passengers or cargo. CDA are also used to conduct other special missions. Special missions are defined as aircraft operations conducting unique military, law enforcement, or other government operations not typically conducted as civil operations. Unique military special missions include patrol, surveillance, target towing, aerial refueling, intelligence collection, military training, and military support missions. Some examples for special missions that have shared applications for the civil and military sectors include medevac, parachute operations, aerial spraying, flight inspection, search and rescue, aerial photography, and survey or mapping. In order to conduct special mission operations, CDA may be equipped with modifications and special mission equipment (SME) not typically used in the civil sector. Some special missions cannot be conducted under civil operational rules, but are permissible as publicuse aircraft operations. These lim itations will be prescribed as part of the FAA airworthiness certification.
2. Why does the FAA accept military commercial derivative aircraft (MCDA) certification projects? Aircraft operated by the military are by statute public-use aircraft and are not subject to the civil regulatory requirements for certification, maintenance, and operation. Aircraft operated by U.S. government agencies (including the FAA) are also public-use aircraft and may also be exempt from compliance with civil airworthiness regulations, and to some extent, operational regulations. Though not required by FAA regulations, some governmental agencies have policies to maintain the airworthiness of the baseline aircraft by requiring FAA approval for any modifications. Some U.S. government agencies do not have the necessary aeronautical airworthiness expertise to evaluate aircraft modifications. They may rely upon the FAA or a military airworthiness authority (MAA) to approve their aircraft. Each U.S. Armed Force has a competent MAA responsible for ensuring their aircraft are airworthy. These MAA could complete airworthiness approvals for MCDA using their own processes. However, it is recognized by the military and the FAA that approving modifications to CDA should consider the original civil design and airworthiness criteria for the baseline aircraft. The MAA have issued policies requiring FAA certification be obtained for their MCDA when it is efficient or practical to do so. The FAA and the U.S. Armed Forces have signed a Memorandum of Agreement (MOA) to support that need. A special FAA aircraft certification office (ACO) designated as the FAA Military Certification Office (MCO) was created for this purpose. In the FAA certification process, the modifications and SME installed on CDA are found to comply with applicable civil airworthiness regulations. The MAA then uses the FAA certification to support their airworthiness approval for MCDA.
3. What is the FAA MCO? The MCO, located in Wichita, Kansas, was established in October 2004. The MCO provides certificati on, continued airworthiness, and technical assistance services for MCDA acquired by U.S. Armed Forces. Under the MOA, upon request by a sponsoring U.S. Armed Force, the MCO may also execute certification programs for the following entities: other U.S. Government agencies, foreign military/government under a U.S.
security assistance program, or private entities operating under contract to the U.S. military.
Military sponsored projects are accomplished by the MCO, through the responsible directorates, and other ACOs may be utilized. The MCO also assists the FAA Aircraft Engineering Division, AIR-100, in developing unique policy and guidance for military and special mission projects.
4. Can the MCO certify all CDA? There are situations where the MCO may find that an application for military CDA is inappropriate for civil certification. If any one of the following conditions applies, the MCO may determine that civil type certification is impractical for a military CDA and, as provided for in the MOA, may not accept the application, or may find the project is not executable as proposed:
a. If the modifier cannot produce an adequate certification plan, does not have the technical resources, or a sufficient schedule is not available to allow conduct of the type certification project in accordance with prescribed MCO procedures, the MCO may determine the project is not executable as proposed and may return the application and close the project.
The applicant must have the ability and technical competence to show compliance with applicable regulations, and the FAA must be allowed the time required to perform its duties.
b. If the changes required for the proposed aircraft cannot be certified to existing regulatory airworthiness criteria (with limited exceptions) to the extent that the basic airworthiness and continued operational safety of the aircraft is assured, the MCO may decline to execute the project.
c. If the changes required for the proposed aircraft are so extensive that a substantially complete investigation of compliance is required, thus requiring application for a new TC in accordance with 14 CFR § 21.19, the aircraft is a new aircraft and no longer defined as a derivative aircraft. A TC application for a new aircraft that has no civil utility or purpose must be reviewed and approved by the Aircraft Certification Service, Aircraft Engineering Division, AIR-100. Applications submitted for this purpose will likely require a Program Specific Service Agreement with the sponsoring U.S. Armed Force (see Chapter 2 of Order 8110.101).
d. If the proposed aircraft will be routinely or intentionally operated outside the airworthiness limitations published in the approved airplane flight manual (e.g., operating weights, load factors, airspeeds, altitudes, or other environmental limitations, etc.), the FAA type certification is not valid assurance for continued airworthiness. The existing instructions for continued airworthiness are not viable, and continued operational safety support cannot be provided by the FAA. This is contradictory to th e rationale and principles for obtaining the civil airworthiness certification for a military CDA. These aircraft will require airworthiness approval from the MAA, including the possibility that a full military qualification will be required.
5. How are applications for sponsored military projects handled? Can applications be made for CDA at other ACOs?
a. Applications for sponsored military certification projects must be made directly to the MCO in accordance with Order 8110.101. The MCO will evaluate the applications and certification plans to determine the scope and feasibility of the project and to determine whether it can be conducted using standard certification procedures and practices. Not all CDA military projects are appropriate for FAA certification, and the application may be rejected by the MCO.
The MCO will issue a unique FAA military certification project number and Certification Program Notification to coordinate with the directorate and other ACOs that may be involved.
The MCO determines if the project will be retained and worked by the MCO or if it will be worked by another ACO. If the project involv es an amended TC, the MCO will coordinate for the project to be administered and conducted through the Certificate Management ACO for that TC. The MCO will work with the applicant and the ACO to determine the best possible use of FAA and designee resources to support the project. If the project is complex or has many military unique issues, the MCO will conduct or may retain partial involvement in the project. If the project has limited military issues and is best served by the applicant’s local ACO, the project may be delegated and conducted at the applicant’s local ACO. However, the military project number must be used to collect data and identify it as work done that is eligible for reimbursement by the U.S. Armed Forces.
b. Applications for other CDA which are NOT sponsored by the U.S. Armed Forces (other U.S. government agency, foreign military, or commercial special mission aircraft) are considered to be civil projects, and the applicant submits the application to its geographic ACO in accordance with Order 8110.4C.
6. What is different about a military project versus a typical civil project? Military CDA certification projects are similar to standard civil certification projects, but are conducted in accordance with Order 8110.101. The applicant must demonstrate that the design of the aircraft (new TC) or design changes/modifications to an existing approved design (amended TC, or supplemental TC (STC)) meet minimum safety standards by showing compliance to the applicable civil airworthiness requirements. The differences between an FAA military project and a civil project depend on the modifications and SME installed on the CDA platform. Some military off-the-shelf (MOTS) SME may be shown to meet civil safety standards and may be fully certified. Other SME or modifications may not meet civil certification requirements, and the FAA may only be able to establish that structural or system provisions meet applicable civil standards. SME may also pose hazards to the aircra ft, other aircraft, personnel, or property that exclude consideration for FAA approval (e.g., self-defense systems such as flare and chaff dispensers). Military modifications or equi pment may require first investigating whether certification is possible, and then considering what suitable means of compliance the applicant must show to meet applicable regulations. In some cases, the FAA may make agreements with the responsible MAA to accept technical data, provide expertise for SME, or otherwise assist the FAA in obtaining the information needed to find compliance with civil regulations. It must be shown that the type design changes meet all applicable regulatory requirements for the modified aircraft to be eligible for a civil standard airworthiness certificate, if required. (Some military aircraft and other U.S. government agencies operate under civil registration and maintain 8
standard airworthiness certificates.) The MAA is obligated under their system to issue an airworthiness approval, clearance, or flight release that is similar in purpose and effect (if not format) to an FAA airworthiness certificate. FAA approval of modifications on CDA projects may be used to satisfy all or part of their airworthiness requirements and is used by the MAA to support their airworthiness approval. When full FAA certification cannot be completed on a MCDA because applicable civil standards do not exist or civil certification is not possible for certain systems, then military airworthiness qualification and approval are required. MCDA platforms can become “hybrid” aircraft because some type design changes have been FAA certified, and some modifications have been approved by the military. Management of that “seam” between the civil and military approvals is required to ensure that all aspects affecting airworthiness of the CDA platform are addressed, but not duplicated.
7. How does The FAA Aircraft Certification Service manage complex integrations which involve multiple approvals? Military CDA platforms may require extensive modifications and complex integrations of multiple mission systems. Integration of numerous systems on the CDA platform often results in several specialized subcontractors performing a portion of the work on the aircraft. Competition and risk sharing for government contracts has further encouraged the creation of work share partnerships between contractors and subcontractors. The requirement to obtain FAA approval for the platform to the maximum extent possible may result in several companies applying for FAA approval for their portion of the modification to the CDA. There may be several applicants in various locations seeking approval for complex amended TC and/or STC for the same aircraft. The FAA has always held the person installing the aircraft modifications responsible for determining that modifications to an aircraft are compatible with each other and with the existing conditions on the aircraft. The FAA has a regulatory and oversight role, and cannot direct design activity on numerous independent approvals to make sure integration and certification requirements are coordinated for all changes approved for a single model or aircraft serial number. These are the responsibilities of the military contractors as both system integrators and type certification applicants. To ensure that these issues are addressed for complex projects, the FAA may require that certification must be accomplished under a single FAA approval. Or, the FAA may require limitations that link approvals to interdependent or pre-requisite installations. Just as the military must have a prime contractor identified as the system integrator, the FAA may find it necessary to hold one applicant responsible for airworthiness certification compliance in order for the project to be viable.
CHAPTER 2. COMPLIANCE AND CERTIFICATION FOR CDA PROJECTS
1. Can the FAA certify a CDA that requires special utility arrangements necessary for the mission, such as operator stations in the passenger compartment or troop carriage?
a. It is important to note that the civil requirements are generally distinct for passenger compartments, crew compartments, and cargo compartments; combining aspects of these compartments complicates civil certification. Unless the special mission is associated with carrying passengers or dignitaries, military and special mission aircraft may have a need to mix elements of these areas for aircraft utility. If not properly evaluated and executed, this can create compliance problems in civil certification. Aircraft layout, floor plans, and occupied areas must be analyzed to determine which civil regulations may apply, and what must be done to avoid non-compliances. Aircraft layout and interior arrangement drawings should always be submitted with the certification plan for a CDA. The proposed means of compliance for areas designated as occupied areas and cargo compartments should be included, as well as applicant requests for equivalent level of safety (ELOS) findings by the FAA.
b. Civil airworthiness regulations have safety criteria designed for personnel and cargo accommodations. The requirements associated with the safety of crew and passengers in occupied compartments are extensive. These include regulations associated with seating, berths, passenger information, placards, emergency provisions (e.g., emergency exits, evacuation, lighting, and aisle widths), ventilation and heating, pressurization, fire protection, and others.
Passengers on civilian airplanes may be any person, e.g., children, aged, or infirmed, and may be untrained or unfamiliar with the hazards that could affect the aircraft or other occupants. While occupied areas of the aircraft may be equipped with stowage compartments (14 CFR § 25.787), cargo compartments have different requirements and are accessible only by a crew member for specific purpose, but may not be occupied (14 CFR § 25.855.)
c. For purposes of this AC and general guidance for a CDA, it is best to start with basic definitions with respect to civil airworthiness regulations:
(1) A crewmember is defined in 14 CFR part 1 as “a person assigned to perform duty in an aircraft during flight time.” This could include a pilot, copilot, flight engineer, flight attendant, mechanic, mission system operator, mission technician, etc. Crew members will be familiar with the aircraft, their function on board, and be trained in emergency procedures and use of emergency equipment. A crew member may sit in a crew seat or a passenger seat.
(2) A passenger is not a crew member, but may be anyone else that can be an occupant on the aircraft, seated in an area approved for occupancy by a passenger. The passenger may not be familiar with the aircraft, emergency procedures, or emergency equipment, other than what may be provided as a pre-flight safety briefing provided by a crew member. A passenger may only sit in an approved passenger seat.
(3) A supernumerary is a crewmember or employee of the agency operating the aircraft who may be carried on the aircraft as a passenger for transportation or repositioning, but may not necessarily have duties associated with execution of the current mission of the aircraft.
A supernumerary can occupy a passenger seat, or under some circumstances, an unoccupied crew seat if familiar with the aircraft type and trained in emergency procedures and the use of emergency equipment that may be required to occupy that crew seat.
(4) A crew seat is located in the occupied compartment, and the crew seat must meet all the criteria for the occupied compartment in which it is located, i.e., a pilot compartment or passenger compartment.
(5) A passenger seat is located in a passenger compartment.
(6) The maximum number of occupants approved for the CDA mission configuration consists of the provided crew seats, supernumerary seats, and passenger seats, which may be occupied for takeoff and landing. This cannot exceed the maximum number of occupants limited on the baseline aircraft TC.
d. It is possible to certify a crew station, such as an operator’s console or mission workstation in the passenger compartment. Depending on the hazards associated with the work station, it may be necessary to restrict the seating or unattended access to the equipment from passengers. Cabin safety regula tions must be addressed for crashworthiness, e.g., emergency exits, aisle widths, and head injury criteria. In some cases, mission crew stations or consoles located in a passenger compartment may require an ELOS, special conditions, or an exemption in order to be approved for their intended function in a passenger compartment.
e. Sling seats, bench seats, cargo compartment seating, or seating areas on a floor area designated for carriage of troops are not defined in civil regulations and cannot be certified by the FAA. Current troop seat desi gns do not meet civil airworthiness regulations for cabin safety, crashworthiness, or emergency procedures. While it may be possible to obtain approval for installation of these articles in a CDA to the extent that compliance can be found with some regulations, cargo compartments will not be approved for occupancy, and troop seats will not be approved for carriage of crew or passengers.
2. What special mission equipment (SME), by definition, cannot be certified to civil regulations? Any combat system, component, or store that may be hazardous to the aircraft, its occupants, other aircraft, other personnel or property on the ground is ineligible for FAA certification. Examples of this include weapon sy stems, such as guns, rockets, missiles, or other armament. This can also include defensive combat systems and self protection systems if they utilize active countermeasures that could be considered hazardous. Active countermeasures include chaff, flares, lasers, or other energy sources that could be hazardous to other personnel or aircraft. SME that is designed for jamming radio frequencies are in eligible for civil certification, as well as approvals for hazardous stores, such as ammunition, bombs, flares, or other pyrotechnics. Other types of SME that may be ineligible for certification include active emitters (communications, signal, or tactical), which interfere with the host aircraft or other civil aircraft systems, or civil communication, navigation, or position information. Approvals for these types of SME will be limited to provisions-only, safe-carriage, or military-use-only if design features can be provided to render the equipment inoperable, or operational restrictions are imposed to prohibit unauthorized operation (see Chapter 8 of Order 8110.101). However, if FAA approval 11
for provisions is pursued, the impact to fundamental airworthiness requirements for the end configuration and aircraft envelope should be addressed. See discussion on ‘Provisions-only’ in Order 8110.101 and this AC.
3. Can other SME be certified to civil regulations?
a. The basic tenets of military and civil airworthiness are the same; however, there are real and necessary differences in military approval criteria and civil airworthiness regulations based upon operational need. FAA requirements and standards were developed for civil operations and not for military or special mission operations; although, some military specifications are still used for civil certification. The proposed operation and applicability of specific regulations must be considered to determine the feasibility of certification. The acceptability of any proposed qualification or compliance data are factors to be considered to determine the feasibility of certification. For the FAA to certify any aircraft to civil airworthiness standards, the type design presented to the FAA must comply with all applicable airworthiness regulations and be free from hazards or potential unsafe conditions. If SME cannot be shown to meet these criteria, it cannot receive a complete FAA approval. Existing SME currently in use as airborne equipment has typically been shown to meet military airworthiness requirements on military organic aircraft (military aircraft whose airworthiness was determined by a military qualification process). It must be determined if SME will be examined for compliance as either required or non-required aircraft equipment. These two different approaches for civil certification approval depend upon the equipment function and integration with existing aircraft systems.
(1) Non-Required Equipment. Type certificated commercial aircraft are equipped with all required equipment to meet airworthiness standards. Most SME adds functionality to the airplane but, is not required by the civil airworthiness standards to safely operate the airplane.
Although this installed SME may be mission essential for the military user, the SME is still defined as non-essential equipment for civil certification purposes. Civil certification compliance for non-required systems and equipment focuses on the impact of the SME, its failure modes, and functionality has on the safety of the aircraft and interface with the civil environment. The operational importance of military essential SME often results in robust design criteria for the components (when compared to consumer grade commercial equipment).
Safety and reliability may meet or exceed the civil criteria for certification of the SME as nonrequired aircraft equipment. Although the SME may have no purpose or use in the civil environment, the type design or function itself may not necessarily conflict with civil airworthiness standards. Typical examples can include military tactical communications, encryption systems, and surveillance equipment. Military intelligence gathering equipment and sensors, such as communications intelligence (COMINT), electronic intelligence (ELINT), or image intelligence (IMINT), can often be certified to civil regulations (even though access to the technology, type design, or hardware may be restricted for security reasons). Operation of this SME may also be illegal for the general public. The SME may have been intentionally designed as a benign and passive system to escape detection. Therefore, installations can be designed such that electro-magnetic interference or other safety impacts are eliminated for the host aircraft. Some technologies used for military purposes are similar to those used for civil purposes, such as magnetic anomaly detection (MAD), which has long been used by the military 12