37 materials in the connector are compatible with the operating environment and to determine if a design life or periodic inspections for the pump connector are needed.
11 AIRWORTHINESS LIMITATIONS FOR THE FUEL TANK SYSTEM.
11.1 Based upon the evaluations required by § 25.981(a), amendment 25-102 also added a requirement to § 25.981(b), that CDCCLs, inspections, or other procedures be established as necessary to prevent development of ignition sources within the fuel tank system, and that they be included in the Airworthiness Limitations section of the ICA required by § 25.1529. This requirement is similar to that contained in § 25.571 for airplane structure. Amendment 25-102 also added a new requirement to part 25, appendix H, Instructions for Continued Airworthiness, requiring that each mandatory replacement time, inspection interval, related inspection procedure, and all CDCCLs approved under § 25.981 for the fuel tank system be included in the section titled “Airworthiness Limitations” of the ICA.
11.2 The preamble of amendment 25-102 (66 FR 23097) states:
Critical design configuration control limitations include any information necessary to maintain those design features that have been defined in the original type design as needed to preclude development of ignition sources.
This information is essential to ensure that maintenance, repairs, or alterations do not unintentionally violate the integrity of the original fuel tank system type design. An example of a critical design configuration control limitation for current designs discussed previously would be maintaining wire separation between FQIS wiring and other high power electrical circuits. The original design approval holder must define a method to ensure that this essential information will be evident to those that may perform and approve repairs and alterations. Visual means to alert the maintenance crew must be placed in areas of the airplane where inappropriate actions may degrade the integrity of the design configuration. In addition, this information should be communicated by statements in appropriate manuals, such as Wiring Diagram Manuals.
11.2.1 CDCCLs may include any maintenance procedure that could result in a failure, malfunction, or defect endangering the safe operation of the airplane, if not performed properly or if improper parts or materials are used. This information is essential to ensure that maintenance, repairs, or alterations do not unintentionally violate the integrity of the original type design of the fuel tank system.
11.2.2 CDCCLs are intended to identify only critical features of a design that must be maintained. CDCCLs have no intervals; they establish configuration limitations to maintain and to protect the “critical design feature” identified in the CDCCLs. CDCCLs can also include requirements to have placards on the airplane with information about critical features. For example, certain components of a fuel pump (or all components) may include critical features that are identified as CDCCLs. These critical features must be identified in the Airworthiness Limitations section of the ICA and should also be
38 identified in the component maintenance manual (CMM) as CDCCLs to provide awareness to maintenance and repair facilities.
11.2.3 Certain CDCCLs apply to elements of fuel system components. As such, maintenance of those critical features may be covered in a CMM. When airworthiness limitations need to call out aspects of CMMs, it is a best practice to limit the CDCCL-controlled content to only those maintenance tasks directly impacting a CDCCL feature, rather than requiring the complete CMM to be a CDCCL. (See the CMM deviation definition in appendix C of this AC.)
11.2.4 Any component that is the subject of a CDCCL is considered a critical part. Therefore, new parts manufacturer approvals issued for fuel tank system components that are the subject of CDCCLs should be treated as “critical parts” in accordance with FAA Order 8110.42D, Parts Manufacturer Approval Procedures.
11.3 Any fuel tank system components that are determined to require periodic maintenance, inspection, or overhaul to maintain the integrity of the system or maintain protective features incorporated to preclude a catastrophic fuel tank ignition event must be defined and included in the Airworthiness Limitations section of the ICA. An inspection airworthiness limitation has a specific task and interval (such as 10 years). The inspection interval should be established based on the standard practices defined in AC 25.1309-1A for evaluation of component failures. The inspection could also be required following maintenance to verify a CDCCL feature is maintained. Examples of inspection airworthiness limitations include the following:
11.3.1 Aging Fuel Line Couplings Seals/O-Rings.
In certain instances, materials used in fuel line couplings may lose flexibility and harden with age. Under pressurized operation, the seal may allow fuel leakage. This will allow spraying of fuel in the tanks or other areas of the airplane where spraying fuel could create a fire hazard. Repetitive inspections, functional checks, or mandatory replacement intervals may be required to prevent leakage.
Note: While not related to compliance with § 25.981, hazards associated with the aging of fuel coupling O-rings, resulting in air entering fuel lines during suction feed operation, should also be addressed when developing the fuel system maintenance program.
11.3.2 Wear of Pump Bushings, Bearings, and Seals.
Wearing of pump bushings, bearings, and seals may significantly affect the performance of fuel pumps and degrade the features necessary to maintain the explosive-proof qualification. In most cases, these failure conditions are latent;
therefore, incorporation of other fail-safe features, as discussed earlier in this AC, would likely be required. If fail-safe features, such as installation of feeder tanks that are filled using ejector pumps, are incorporated, functioning of those features would need to be ensured by indications or periodic functional tests. Installation of fuel level sensors in the feeder tanks would provide continuous monitoring of the function.
Another means could be installation of flow indicators in the flow line of the ejector
39 pump that can be viewed by maintenance personnel, and a mandatory periodic inspection of this function is one example of a method of mandatory maintenance action.
11.3.3 Fuel Pump Electrical Power Protective Features.
If failure of an AFCB or GFI protective feature and/or a thermal fuse (closed) is latent and this feature is needed to maintain fail-safe features, periodic checks would likely be needed. The inspection interval, and need for built-in test features with indication of failures, should be established through the safety analysis process and should consider factors described in paragraph A.3.4.3 of appendix A.
11.3.4 Transient Suppression/Energy Limiting Devices.
If failure of the device is latent and this feature is needed to maintain fail-safe features, periodic checks will likely be needed.
11.3.5 Wire Shield Grounding.
Component grounds and wires will likely require inspections and measurements to determine proper grounding.
11.3.6 Fuel Tank Access Panel/Door Seals.
Maintenance tasks should adequately provide procedures for inspection and checks of access panels and door seals.
11.3.7 Corrosion, Wear, and Damage to Fuel Pump Connectors.
Maintenance tasks should provide adequate procedures for inspecting and checking fuel pump connectors for wear, corrosion, and damage.
11.3.8 Integrity of Fuel Pump Electrical Supply Conduit.
Maintenance tasks should provide adequate procedures for inspecting the integrity of the structure, sealing, drain holes, and bends of the electrical supply conduit to the fuel pump.
11.4 Maintainability of Design and Procedures.
Maintainability, both in the design and procedures (i.e., master minimum equipment list, airplane maintenance manual, etc.), should be verified by the applicant. This should include, as a minimum, verification that the system and procedures support the safety analysis assumptions and are tolerant to anticipated human errors, and that any critical procedures are highlighted for consideration as required inspection items. (See 14 CFR
121.369(b) for considerations of a “required inspection item.”)
11.5 Incorporation by Reference into Airworthiness Limitations.
11.5.1 Where the words “in accordance with” or “per” are cited in the airworthiness limitations, the procedures in the referenced document must be followed to ensure that the critical design feature is maintained. Any changes to these procedures require
40 approval from the responsible Aircraft Certification Service office before they can be used.
11.5.2 Where the words “refer to” are cited in the airworthiness limitation, the procedures in the referenced document represent one method of complying with the airworthiness limitation. An accepted alternative procedure may be developed by the operator in accordance with its procedures in its maintenance program/manual. Prior approval from the responsible Aircraft Certification Service office is not required for this action.
11.5.3 See AC 120-97A, Incorporation of Fuel Tank System Instructions for Continued Airworthiness into Operator Maintenance or Inspection Programs, for guidance regarding procedures operators should use when requesting approval of changes to documents referenced in airworthiness limitations and for examples of fuel tank system airworthiness limitations.
11.6 Visible Identification of CDCCLs.
11.6.1 Section 25.981(d) establishes a requirement for visibly identifying critical features of a design that are located in certain areas. The DAH should define a method of ensuring that this essential information will be communicated with statements in the appropriate manuals, such as wiring diagram manuals, and be evident to those who perform and approve such repairs and alterations and are identified as a CDCCL.
11.6.2 An example of a CDCCL that would result in a requirement for visible means would be maintaining wire separation between FQIS wiring and other high-power electrical circuits where separation of the wiring was determined to be a CDCCL. Acceptable methods of providing visible means would include color coding and labeling the wiring.
For retrofit of markings onto existing wiring, placement of identification tabs at specific intervals along the wiring would be acceptable. Standardization within the industry for color coding of wiring used for the fuel tank system would assist maintenance personnel in functional identification of wiring. Some manufacturers use pink wiring for fuel tank system wiring, and FAA recommends using this color as a standard for fuel tank system wiring.
Appendix A A-1 Appendix A. Certification of Arc Fault Circuit Breaker (AFCB) or Ground Fault Interrupter (GFI) A.1 PURPOSE.
This appendix provides guidance for certification of AFCB or GFI devices that have been shown to be a practical means to protect the circuits of electric-motor fuel pumps and other fuel tank components that use higher than intrinsically safe electrical power (for example, motor operated valves).
A.2 BACKGROUND.
A.2.1 Service experience has shown that failures in the power supply circuit of the fuel pump, discussed in the body of this AC, can result in ignition sources and, therefore, must be assumed as a foreseeable failure condition. Traditional thermal circuit breakers are sized to prevent nuisance trips during fuel pump transient power demands and have not tripped when intermittent electrical arcs occur. Intermittent arcing can erode metallic barriers such as conduit, electrical connectors, and the pump housing, resulting in loss of the integrity of explosion-proof features, or create ignition sources outside in areas adjacent to the fuel tank. Addressing the failure modes discussed in this AC has resulted in the need to provide fast-acting GFI or AFCBs in traditional fuel pump electrical circuits in order to show compliance with § 25.981.
A.2.2 AFCBs have been used as a practical means to protect against arcing in the power circuits of fuel pump motors powered by both alternating current and direct current.
SAE International issued two aerospace standards for AFCBs—one for alternating current circuits and one for direct current circuits. (See paragraph B.7 of appendix B of this AC).
A.2.3 Fuel pump housings and metallic conduits are grounded to the airframe, and any arcing to the cavity wall or conduit creates a ground fault. Therefore, GFI have been used in AC pump power circuits as a practical means to ensure that power is quickly disconnected from the fuel pump in the event of a ground fault in the pump or associated power wiring.
A.3 CERTIFICATION GUIDANCE.
One means for the applicant to show compliance with the applicable regulations is to demonstrate, through design, review, analysis, and test, that the AFCB or GFI performs as intended under any foreseeable operating conditions and addresses the following guidance:
A.3.1 Fault Detection Trip Levels.
A.3.1.1 The applicant should show that the AFCB or GFI can distinguish between actual fault events and events characteristic of the normal airplane pump start up operating loads
Appendix A A-2 and environmental conditions. Laboratory testing and/or airplane ground/flight testing should be performed to show the “intended function” of AFCB or GFI. The test methods chosen should reproduce the most common types of arcing in fuel pumps that occur in an airplane environment due to ground or arc faults. The AFCB or GFI should be designed to prevent nuisance tripping due to normal airplane electrical loads and electrical bus switching; and to operate continuously with normal and abnormal airplane electrical bus switching characteristics associated with master minimum equipment list dispatch relief configurations.
A.3.1.2 Installation of the AFCB or GFI should not result in an appreciable increase in the loss of fuel pump function. A reliability requirement on the order of 100,000 hours mean time between failures may be satisfactory, but the applicant should show that failure of the AFCB or GFI does not result in an appreciable increase in the occurrence of failures that result in the loss of fuel pump function.
A.3.1.3 Sufficient laboratory testing and airplane testing should be conducted to show AFCB or GFI nuisance trip performance, including tests for lightning, HIRF, and electromagnetic compatibility. In addition, sufficient laboratory testing should be conducted to show that the AFCB or GFI trips before arcing in the fuel pump can lead to ignition of fuel vapor in the fuel tank.
A.3.1.4 A means should be provided to latch the AFCB or GFI in a state that removes power from the fuel pump motor in the event that a ground fault has been detected, until the AFCB or GFI is reset. A trip of a single AFCB or GFI should not be reset until the reason for the trip has been determined and repaired, or until it has been determined that no ground fault exists. Intermittent arcing can cause tripping of circuit protection devices resulting from failures that are difficult to isolate during maintenance actions.
Single trip events may be attributed to a nuisance fault. However, maintenance instructions should include notes that state repeated tripping of devices indicates an intermittent fault exists, and the circuit should not be energized until the fault is isolated and repaired.
A.3.2 Software.
Inadvertent operation of multiple AFCB or GFI devices has the potential to affect the continued operation of more than one engine, a condition that the FAA considers to be hazardous. Software used by the AFCB or GFI devices should be developed and verified in accordance with the latest version of RTCA DO-178.
A.3.3 Complex Hardware.
Application-specific integrated and complex circuits used by the AFCB or GFI devices should be developed and tested in accordance with RTCA DO-254 and FAA Order 8110.105A, Simple and Complex Electronic Hardware Approval Guidance, dated April 5, 2017.
Appendix A A-3 A.3.4 System Safety Assessment.
A.3.4.1 AFCB or GFI devices installed in circuits that perform essential or critical functions and/or their performance could impact the safety of flight. The applicant should perform an installation SSA in accordance with §§ 25.901(c), 25.981(a) and (d), and 25.1309.
The SSA should include a functional hazard assessment to determine the effects of failures of the AFCB or GFI devices on the safety of the airplane and to verify that the design limits the probability of undesirable failure conditions to acceptable levels. In addition, the applicant should address the potential for possible common cause trips due to hardware/software errors and common cause trips due to environmental conditions such as HIRF (§ 25.1317), lightning (§§ 25.954 and 25.1316), and electromagnetic compatibility (§§ 25.1301, 25.1309(e), and 25.1353(a)).
A.3.4.2 Failure to provide fuel pump power due to unintended activation of multiple AFCB or GFI devices has the potential to affect the continued operation of more than one engine.
A circuit protective device failure, cascading failure, or common cause failure that affects multiple engines would be non-compliant with § 25.903(b) if it prevents continued operation of the remaining engines, or requires immediate crew action to prevent a multiple engine power loss.
A.3.4.3 Failure of an AFCB or GFI device to detect an arc or ground fault condition in a fuel pump circuit can contribute to a catastrophic failure condition. Assuming the loss of explosion-proof features of the pump (examples discussed in paragraph A.2.1) or arcing at the electrical connector could result from a single failure, the FAA considers the undetected failure of an AFCB or GFI alone, which prevents its detection of or response to an arc or ground fault, to be a severe-major (hazardous) failure condition. The loss of arc or ground fault protection should either be shown to be extremely remote (if latent, consistent with the requirement of § 25.981(a)(3)) or annunciated to the flightcrew prior to flight. If failures of the AFCB or GFI can contribute to severe-major (hazardous) or catastrophic failure conditions, the safety assessment should analyze common cause failures or design errors that could result in these conditions and verify that appropriate protection to prevent them is provided. Due to the nature of AFCB and GFI devices, special attention should be given to protection from lightning, EMI, and HIRF.
A.3.4.4 As discussed in section A.3.7 below, the FAA expects there will be a means for the flightcrew to reset the AFCB or GFI in the event that more than one fuel pump AFCB or GFI trips simultaneously in flight.
A.3.4.5 Further, the applicant should show by design, analysis, and fault insertion testing, if applicable, the validity of failure analysis assumptions, and show that the probability of the failure of AFCB or GFI to detect the existence of a ground or arc fault condition and remove power from a pump is extremely remote (10-7 or less). In order to make this showing, AFCB and GFI installations have typically required an automatic built-in test feature that verifies the AFCB or GFI is operational before applying power to the fuel pump prior to each flight (see section 9.3.3 of this AC).
Appendix A A-4 A.3.5 Power and Ground Requirements.
AFCB or GFIs are active devices and require power to function. The applicant should show that AFCB or GFI power and ground connections are implemented such that all airplanes load margins are sufficient and that proper circuit protection or other methods are used to protect AFCB or GFI power and ground wiring. The applicant should also show that there are no hazards to maintenance or flightcrews due to possible hot shorts to electrical panels containing AFCB or GFI. In addition, if the installation of AFCB or GFI involves the direct replacement of devices on a given electrical panel, the applicant should show adequate power/heat dissipation and ensure safe touch temperature.
A.3.6 Built-In Test.
AFCB and GFI devices should incorporate built-in test and annunciation features needed to meet the reliability requirements for showing compliance with § 25.981(a)(3).
For example, if single or cascading failure in the fuel pump electrical circuit can result in an ignition source, a circuit protection feature failure rate less than extremely remote (1 x 10-7), would be required in order to comply with § 25.981. Traditional protective devices without built-in test and annunciation of failures have not been shown to achieve this level of reliability. Applicants have installed multiple protective devices in series or provided built-in test with annunciation in order to comply.
A.3.7 Troubleshooting Procedures.
A.3.7.1 Because AFCB or GFIs are capable of detecting ground paths on pumps and airplane wiring that may not be detected by visual inspection, the applicant should define the operational and maintenance philosophies and methodology associated with an AFCB or GFI trip that does not rely solely on visual inspections. The applicant should show how the maintenance procedures would be able to safely distinguish and diagnose an AFCB or GFI trip and nuisance trip without causing a fuel tank explosion. Operational instructions and maintenance procedures should be provided to prevent resetting of tripped AFCB or GFIs until it can be assured that resetting an AFCB or GFI will not cause the occurrence of a fuel tank explosion. Human factors should be taken into account to minimize the possibility of human error during airplane operation and maintenance.
A.3.7.2 If multiple boost pumps are protected with AFCB or GFI devices such that the continued operation of multiple engines could be affected, there should be a means for the flightcrew to reset tripped AFCB or GFI devices in flight. Loss of fuel pump capability due to inadvertent tripping in some fuel tanks could result in loss of fuel reserves needed to complete an Extended Operations (ETOPs) flight or safe diversion.
To prevent causing an ignition source, the applicable airplane flight manual should contain a limitation against the reset of a single AFCB or GFI. However, in order to address common cause inadvertent tripping, procedures should be provided for resetting AFCB or GFI devices when multiple AFCB or GFIs have tripped simultaneously in flight.
Appendix A A-5 A.3.8 Hardware Qualification.
Environmental testing—including thermal, shock and vibration, humidity, fluid susceptibility, altitude, decompression, fungus, waterproof, salt spray, and explosionproof—should be performed in accordance with RTCA DO-160G or equivalent standards. The applicant should define an insulation, dielectric, and electrical grounding and bonding standard acceptable to the FAA for the AFCB or GFI. Appropriate test categories in each section of RTCA DO-160G should be chosen based on the AFCB or GFI installation environment defined for the specific airplane. Particular attention should be given to the normal and abnormal power input tests outlined in section 16 of RTCA DO-160G. The system with AFCB or GFI installed must comply with §§ 25.954 and 25.1316 for lightning protection; §§ 25.1301, 25.1309(e), and 25.1353(a) for electromagnetic compatibility; and § 25.1317 for HIRF.
A.3.9 Airplane Tests.
The applicant should show by ground tests, flight tests, or both that all AFCB or GFIs remain armed during normal and abnormal electrical power bus and load switching as described in paragraph A.3.1.1 of this AC, and are not adversely affected by the operation of other airplane systems. The airplane tests should also show that the AFCB or GFI would not produce electromagnetic interference on other airplane systems.
A.3.10 Instructions for Continued Airworthiness (ICA).
A.3.10.1 The applicant must submit ICAs required by § 25.1529 in order to provide the necessary procedures to service and maintain AFCB or GFI installations. As required by appendix H25.4, the Airworthiness Limitations section of the ICA must include each mandatory replacement time, inspection interval, related inspection procedure, and all critical design configuration control limitations (CDCCLs) approved under § 25.981 for the AFCB or GFI installation. Inspection intervals determined from the safety analysis would be included for the detection of latent failures that would prevent the AFCB or GFI from tripping during a ground or arc fault event.
A.3.10.2 AFCB or GFIs used for showing compliance to § 25.981 requirements for preventing ignition sources are typically a CDCCL in these installations. As required by § 25.981(d), the applicant must provide visible means of identifying the AFCB or GFI as a CDCCL and should provide design features to minimize the inadvertent substitution of an AFCB or GFI with a non-AFCB or GFI device.
A.3.11 Airplane Flight Manual Limitations.
The airplane flight manual Limitations section should address any limitations related to AFCB or GFI intended function and any self-test features of the AFCB or GFI design.
Appendix B B-1 Appendix B. Related Documents The following related documents are provided for information purposes and are not necessarily directly referenced in this AC.
B.1 REGULATIONS.
The following 14 CFR regulations prescribe requirements for the design, substantiation, and certification relating to prevention of ignition sources within the fuel tanks of transport category airplanes. You can download the full text of these regulations at the U.S. Government Printing Office e-CFR website. Or you can order a paper copy by sending a request to the U.S. Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402-0001; by calling telephone number (202) 512-1800; or by sending a request by fax to (202) 512-2250.
Section 21.50, Instructions for continued airworthiness and manufacturer’s maintenance manuals having airworthiness limitations sections.
Section 25.729(f), Protection of equipment on landing gear and in wheel wells.
Section 25.863, Flammable fluid fire protection.
Section 25.901, Powerplant: Installation.
Section 25.903(b), Engine isolation.
Section 25.951, Fuel System: General.
Section 25.954, Fuel system lightning protection.
Section 25.973, Fuel tank filler connection.
Section 25.981, Fuel tank explosion prevention.
Section 25.1301, Equipment: Function and installation.
Section 25.1309, Equipment, systems, and installations.
Section 25.1316, Electrical and electronic system lightning protection.
Section 25.1317, High-intensity Radiated Fields (HIRF) Protection.
Section 25.1353, Electrical equipment and installations.
Section 25.1521, Powerplant limitations.
Section 25.1529, Instructions for Continued Airworthiness.
Section 25.1557, Miscellaneous markings and placards.
Section 25.1701, Electrical Wiring Interconnection Systems (EWIS): Definition.
Section 25.1707, System separation: EWIS.
Appendix H to part 25, Instructions for Continued Airworthiness.
Appendix B B-2 B.2 ADVISORY CIRCULARS.
The following FAA ACs are related to the guidance in this AC. The latest version of each AC at the time of publication of this AC is identified below. If any AC is revised after publication of this AC, you should refer to the latest version for guidance, which can be downloaded from the Internet at http://www.faa.gov/regulations_policies/advisory_circulars/.
AC 20-158A, The Certification of Aircraft Electrical and Electronic Systems for Operation in the High-Intensity Radiated Fields (HIRF) Environment, dated May 30, 2014.
AC 21-40A, Guide for Obtaining a Supplemental Type Certificate, dated September 27, 2007.
AC 25-8, Auxiliary Fuel System Installations, dated May 2, 1986.
AC 25-16, Electrical Fault and Fire Prevention and Protection, dated September 25, 1987.
AC 25-19, Certification Maintenance Requirements, dated October 3, 2011.
AC 25.954-1, Transport Airplane Fuel System Lightning Protection, dated September 24, 2018.
AC 25.981-2A, Fuel Tank Flammability Reduction Means, dated September 19, 2008.
AC 25.1309-1A, System Design and Analysis, dated June 21, 1988.
AC 25.1701-1, Certification of Electrical Wiring Interconnection Systems on Transport Category Airplanes, dated December 4, 2007.
AC 120-97A, Incorporation of Fuel Tank System Instructions for Continued Airworthiness into Operator Maintenance and/or Inspection Programs, dated May 25, 2012.
B.3 ORDERS.
The following FAA orders are related to the guidance in this AC. You can download the latest version from the Internet at http://www.faa.gov/regulations_policies/orders_notices/.
Order 8110.4C, Change 6, Type Certification, dated October 12, 2005.
Order 8110.42D, Parts Manufacturer Approval Procedures, dated March 21, 2014.
Order 8110.105A, Simple and Complex Electronic Hardware Approval Guidance, dated April 5, 2017.
Appendix B B-3 B.4 REPORTS.
The following FAA reports are related to this AC:
Report No. DOT/FAA/AR-98/26, A Review of the Flammability Hazard of Jet A Fuel Vapor in Civil Transport Aircraft Fuel Tanks, dated June 1998. This report can be downloaded from the Internet at http://www.tc.faa.gov/its/worldpac/techrpt/ar98-
26.pdf.
Report No. DOT/FAA/AR-03/61, Silver-Sulfur Deposits on Fuel Quantity Indication System and Attendant Wiring, dated October 2003. This report can be downloaded from the Internet at http://www.tc.faa.gov/its/worldpac/techrpt/ar03-
61.pdf.
Report No. DOT/FAA/AR-TN05/37, Intrinsically Safe Current Limit Study for Aircraft Fuel Tank Electronics, dated October 2005. This report can be downloaded from the Internet at http://www.fire.tc.faa.gov/pdf/TN05-37.pdf.
B.5 MILITARY SPECIFICATIONS.
The following documents are available from the Department of Defense, Document Automation and Production Service, Building 4/D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.
MIL-STD-810N, Environmental Test Methods and Engineering Guidelines, Method
511.5, Explosive Atmosphere, dated October 31, 2008.
MIL-PRF-6106N, General Specification for Electromagnetic Relays, dated September 14, 2009.
B.6 RTCA DOCUMENTS.
You can order of the following documents from RTCA, Inc., 1150 18th Street NW, Suite 910, Washington, DC 20036; telephone: 202-833-9339 or fax: 202-833-9434.
You can also order copies online at http:/www.rtca.org.
RTCA DO-160G, Environmental Conditions and Test Procedures for Airborne Equipment, December 6, 2010.
RTCA DO-178B, Software Considerations in Airborne Systems and Equipment Certification, dated December 13, 2011.
RTCA DO-254, Design Assurance Guidance for Airborne Electronic Hardware, dated April 4, 2000.
B.7 SAE INTERNATIONAL DOCUMENTS.
The versions of the following documents are current at the time of publication of this AC. You can order copies of them from SAE International, 400 Commonwealth Drive, Warrendale, Pennsylvania 15096; or online at http://www.sae.org.
AIR1662, Minimization of Electrostatic Hazards in Aircraft Fuel Systems.