engine. The ASTM subcommittee that is responsible for these specifications will not consider the suitability of the fuel for use on aircraft or aircraft engines. In this case, the impact of minor revisions (see paragraph 8(b)(3)(a) of this AC) to the fuel specification, on the fuel’s suitability for aircraft and aircraft engines, must be evaluated by the applicant. The operating limitation must reference both the specification root number and the issue suffix number or revision level to allow for the evaluation and approval of each minor revision. TC/STC holders must apply for a TC/STC amendment each time the revision number changes. Non-applicable ASTM fuel specifications that have been approved as operating limitations are listed below:
1 ASTM D4814, “Standard Specification for Automotive SI Engine Fuel.”
2 ASTM D4806, “Standard Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel.”
3 D1655 for Aircraft Diesel Engines Using Jet Fuel. Reciprocating compression ignition engines (diesel engines) are typically designed to operate on aviation turbine fuel due to the wide availability of this fuel at airports. The ASTM specification for aviation turbine fuel is D1655. This is a non-applicable specification for diesel engines because the specification scope does not specifically include aviation diesel engines. Therefore, the operating limitation needs to reference both the specification root number and the issue suffix number or revision level. This will require the TC/STC holder to apply for a TC/STC amendment each time the revision number changes. For example, the operating limitation is listed as D1655-10 for a project initiated in CY 2010.
(d) Aviation Fuel Sub-Grades. ASTM International aviation fuel specifications may specify certain fuel grades that are subsets of existing grades. These sub-grades meet all of the performance requirements of other existing grades, but specify a narrower range or more stringent criteria for some of those properties. For example, in ASTM International specification D910, grade 100VLL is identical to grade 100LL in all aspects, except that the maximum lead content is reduced by about 19%. Because the specification criteria for 100LL lead content is expressed as only a maximum value, the lower maximum of 100VLL will always meet 100LL’s specification requirements. Also, in ASTM International specification D1655, grade Jet A-1 is identical to grade Jet A, except that Jet A-1 specifies a lower freezing point (-47°C) than Jet A (- 40°C). Because the freezing point is specified as a maximum criterion, Jet A-1 will always meet the specification requirements of Jet A.
1 Sub-grades such as Grade 100VLL or Jet A-1 are acceptable for use on those aircraft and engines that are approved to operate with other grades that encompass all of the specification criteria of the sub-grade, unless otherwise prohibited by the TC/STC holder. The TC/STC holder may communicate the acceptability of sub-grades to operators via routine service information documents.
2 If TC/STC holders choose to add sub-grades to existing operating limitations in aircraft flight manuals, pilot operating instructions, or TCDSs that specify other grades that encompass all of the specification criteria of the sub-grade, they may substantiate their showing of compliance to the applicable aircraft or engine airworthiness standards by submittal of the
subject ASTM International aviation fuel specification(s). If the sub-grade is added to the operating limitations, then aircraft placards, operating, maintenance, and other service documents must also be revised to specify the sub-grade.
d. Other Governmental, Military or Industry Voluntary Consensus-Based Standards, or Specifications as Operating Limitations for Aviation Fuel. If an applicant proposes to specify an aviation fuel identified by another governmental, military or industry voluntary consensus-based standard, designation, or specification, then the applicant should present sufficient information to show that the specification provides an equivalent level of property, performance, and quality control.
e. Independent Specifications as Operating Limitations for Aviation Fuel.
(1) The FAA has determined that independent fuel specifications may be acceptable for definition of aviation fuel operating limitations if they provide an equivalent level of property, performance, and quality control as governmental, military, or industry voluntary consensus- based standards.
(2) The intent of this guidance is to provide an acceptable level of property, performance, and quality control for fuels produced to independent specifications. Fuels used for certification compliance testing must meet all of the requirements of the independent specification.
(3) Fuel Production Requirements. Independent specifications must include criteria to ensure that fuels produced to these specifications are controlled in a manner consistent with the fuel used during the certification testing. Production processes and facilities, quality control systems, manufacturing processes, materials and feedstocks, additives, and test methods must all be consistent with the fuel used for certification testing. Production traceability and control of non-compliant or contaminated fuel batches must be provided to allow for continued operational safety planning.
(4) Additives. Additives permitted for use in fuels identified by independent specifications must be sufficiently specified to limit the variability of additive chemical composition. The independent specification must provide a means for detecting the presence of any additive permitted for use in the fuel defined by the specification.
(5) Fuel Properties and Compositional Definition. Independent specifications must specify a very narrow range of composition and properties to minimize the variability of performance of fuels produced to the specification.
(6) Trace Materials. Criteria to limit trace materials, such as trace organics, non-metals, and metals, must be established based on the feedstock and process characteristics. Test methods must be specified to measure trace materials.
(7) Test Methods. Test methods must be specified for each criterion used to measure the properties of the fuel. The reproducibility and repeatability of each specified test method must be defined, and must be valid for the specific chemistry of the fuel. A referee test method must
be specified if more than one test method is defined for a particular criterion. Only those test methods used during the certification compliance program may be listed in the specification.
(8) Test Laboratories. The specification must define the accreditation requirements for laboratories used to conduct test methods specified in the specification.
(9) Transfer. Independent specifications must specify requirements to measure and document fuel properties at each transfer of ownership, storage facility, and transportation mode.
(10) Change Control. A change to any of the requirements included in the specification will be subject to FAA design change oversight and approval. Independent specifications must be listed in the operating limitations in the TCDS and AFM/RFM, and must provide a means for change tracking, i.e., a revision number.
f. Operating Limitations for Aviation Fuel: Certification Compliance Plans.
(1) Applicable airworthiness requirements are those FAA aircraft, aircraft engine, or APU regulatory standards for which showing compliance is contingent on fuel properties and product performance using the fuel. Applicable regulations may include, but are not limited to, those regulations listed in appendices 2 and 3 of this AC.
(2) Applicants must present either an issued industry consensus-based, governmental or military fuel specification as specified in paragraphs 8.c and 8.d of this AC, or an independent specification that meets the criteria specified in paragraph 8.e. of this AC, and a compliance plan to the FAA.
(3) An applicant’s compliance plan must address all applicable airworthiness certification standards, some of which are discussed below. Sound testing techniques and thorough data analysis should be well documented in the compliance plan. Accordingly, close contact and frequent coordination with the FAA are recommended to ensure the plan is developed with minimal delay.
(4) An applicant’s compliance plan must address the effects of mixing the proposed new aviation fuel with other existing types of aviation fuel, for example, mixing conventional Jet A fuel with synthetic Jet A fuel. Data generated during development of the industry consensus- based, governmental or military fuel specification may be used to support this task.
(5) New TSO APU approvals, or major changes or STCs to existing APU TSO approvals, that include a new fuel operating limitation should include the applicable requirements and performance standards from the latest revision of TSO-C77 in the compliance plan.
(6) Applicable Regulations for Engines and APUs. See appendix 2 of this AC, paragraphs 1, 2, and 3 for a list of some regulations that may apply to projects adding an aviation fuel specification as an operating limitation. Additional guidance on some airworthiness standards follows in appendix 3. The following is not all-inclusive and is provided as a recommended starting point only. Applicants should obtain guidance from the FAA on the regulations with which they will need to show compliance.
(a) To ensure the operating limitation for the new fuel is acceptable (refer to § 33.7 and paragraph 5.b.(4) of TSO-C77b), applicants must show that the new fuel is compatible with existing fuels, additives, and oils specified in the operating limitations and instructions for continued airworthiness (ICA). If applicable, compatibility data generated during the ASTM fuel specification development may be used.
(b) To ensure the operating limitation for the new fuel is acceptable (refer to § 33.7 and paragraph 5.b.(4) of TSO-C77b), applicants must show that the new fuel exhibits acceptable storage stability. Fuel performance related to such items as gum formation, potential gums, water reaction, microbial contamination, and fuel stability over time must be evaluated to determine the impact on fuel performance over long-duration storage.
(c) Fuel composition can significantly affect material properties and durability (refer to §§ 33.15, 33.53, and 33.91, and TSO-C77b, appendix 1, section 4.2). Applicants should demonstrate materials compatibility of the fuel-wetted materials, including elastomers, seals, and metallic components. This can be accomplished with a combination of soak testing and component testing (for example, in accordance with RTCA DO-160C), or by other methods the applicant proposes, and should become part of the applicant's compliance plan. In some cases, materials compatibility data generated during development of the ASTM fuel specification may be used. This may require testing of both used and unused non-metallic parts, such as elastomers and seals, if using the fuel on engines previously operated with other types of fuel.
(d) Applicants should consider several factors when demonstrating that an engine operating with a new fuel does not result in an unsafe condition. For example, differences or changes in combustion characteristics such as temperature and pressure, deposit accumulation, octane demand, fuel lubricity, fuel vaporization, material responses or effects, and others should be evaluated by test or analysis. The applicant must substantiate that any time-between-overhaul (TBO) established for the engine, or the existing engine’s TBO, whichever is applicable, is valid with the new fuel. This may require analysis or testing to show compliance with §§ 33.15,
33.19, 33.49, and 33.87 (refer to §§ 33.15, 33.19, 33.49, and 33.87 and TSO-C77b, appendix 1, sections 4.2, 4.3 and 6.3).
(e) Applicants should evaluate engine-cooling requirements since different fuels may change combustion characteristics and thereby impact cooling requirements. This is particularly important for reciprocating engines where fuel characteristics can affect cylinder temperatures (refer to § 33.21 and TSO-C77b, appendix 1, section 5.7).
(f) The engine fuel system must function properly with the proposed fuel throughout its complete operating range under all flight and atmospheric conditions. Fuel density, vaporization, and low temperature properties may affect fuel system performance under certain conditions (refer to § 33.51). For SI reciprocating engine fuels, carburetor icing and vapor lock tendencies should be evaluated (refer to §§ 33.35, 33.67, and TSO-C77b, appendix 1, section
5.5).
(g) Avoiding engine detonation and demonstrating acceptable detonation margins are critical requirements for SI reciprocating engines. A fuel must demonstrate adequate anti-knock
margin under the worst-case operating conditions to prevent destructive detonation. Due to the variation in accuracy and responsiveness of detonation measurement systems, the detonation measurement test method the applicant intends to use must be approved by the FAA (refer to § 33.47 and see AC 33.47-1).
(h) Compression Ignition (CI) reciprocating engines require fuel with an acceptable cetane number to ensure stable combustion across the entire operating envelope. These engines typically specify Jet A fuel as the aviation fuel operating limitation. The ASTM specification for Jet A fuel, D1655, does not specify a minimum cetane number. Therefore, CI engines must demonstrate operability at the minimum expected (worst case) cetane number of Jet A fuel (refer to § 33.51).
(i) Fuel composition and properties can significantly affect the ability to support combustion at certain points in the engine-operating envelope. Applicants must therefore evaluate engine operability with the new fuel at all operating and atmospheric conditions approved for the engine. Engine starting, acceleration, deceleration, and steady-state operation must be evaluated by test or analysis for all approved operating conditions (refer to §§ 33.51,
33.89, and TSO-C77b, appendix 1, section 4.4).
(j) The applicant must identify any changes to the ICA, including, but not limited to, safety precautions, fluid compatibility, changes to placards, changes to service intervals, and changes to maintenance practices (refer to § 33.4).
(7) Applicable Regulations for Airplanes and Rotorcraft. For a list of regulations that may apply to projects adding a new aviation fuel as an operating limitation, see appendix 2 and appendix 3, of this AC. Additional guidance on airworthiness standards follows in paragraphs
(7)(a) through (g) below. The following is not all-inclusive and is only provided as a recommended starting point. Applicants must obtain guidance from the FAA on the regulations they will need to show compliance.
(a) Applicants must evaluate the effect of differences in fuel properties, such as density on aircraft weight, center of gravity, and aircraft structure (refer to §§ 25.23,
25.25, 25.27, 25.29, 23.23, 23.25, 23.29, 27.25, 27.27, 27.29, 29.25, 29.27, and 29.29).
(b) Applicants must evaluate the effect of differences in fuel properties, such as density, energy content, and combustion characteristics on aircraft performance (refer to §§ 23.53, 23.69, 23.77, 25.105, 25.117, 25.119, 25.121, 27.51, 27.65, 27.67, 29.51, 29.65, and
29.67).
(c) Applicants must demonstrate materials compatibility of the fuel wetted materials, including elastomers, seals, metallic components, fuel bladders, and fuel tanks. This can be done with a combination of soak testing and component testing (refer to §§ 23.603, 25.603, 27.603, and 29.603). This may require testing of both used and unused non-metallic parts, such as elastomers and seals, if using the fuel on aircraft previously operated with other types of fuel.
(d) Applicants must evaluate the effect of differences in fuel properties, such as density, energy content, and combustion characteristics on installed engine and APU performance, including in-flight restarting. Refer to §§ 23.901(f), 23.903, 23.903(d),
23.903(e), 23.903(f), 23.903(g), 23.939, 25.901(d), 25.903(e), 25.903(f), 25.939, 27.903(d),
27.939, 29.903(e), 29.923(p), and 29.939.
(e) Fuel system performance in high temperature conditions and in suction feed conditions can be influenced by fuel properties such as vapor pressure, liquid/vapor ratio, and thermal conductivity. Applicants must therefore, evaluate fuel system hot weather and engine cooling performance when operating with the new fuel. Refer to §§ 23.961, 23.1041, 23.1043,
23.1045, 23.1047, 25.961, 25.1041, 25.1043, 25.1045, 27.961, 27.1041, 27.1043, 27.1045,
29.961, 29.1041, 29.1043, 29.1045, 29.1047, and 29.1049).
(f) Applicants must show that the fuel is compatible with aircraft fuel system components, and that the fuel does not have any adverse effect on fuel system performance. This demonstration must include an evaluation of fuel properties, such as flash point or vapor pressure, for their effect on the fuel in the fuel tank, including flammability.
1 Fuel properties, such as the dielectric/density relationship, can change the gauging system function since some gauging systems do not have densitometers and are based on an assumed relationship for typical aviation fuels.
2 Some fuel types can also cause corrosion and adversely affect material properties and durability of engine fuel system components as discussed in paragraph 8f.(6)(c) above.
3 Some fuel types can also have an affinity for water retention and icing, which could lead to stoppage of fuel flow or corrosion.
4 A comprehensive compliance plan must also include an analysis of the effect of fuel properties, such as viscosity on fuel system pressure drop and fuel pump performance.
5 Refer to §§ 23.951, 23.955, 23.959, 23.969, 23.973(e)(f), 23.975, 23.979,
23.997, 23.1001, 23.1305, 23.1337, 25.951, 25.952, 25.955, 25.959, 25.969, 25.975, 25.979,
25.981, 25.997, 25.1001, 25.1305, 25.1337, 27.951, 27.955, 27.959, 27.965, 27.969, 27.997,
29.951, 29.955, 29.959, 29.969, 29.975, 29.979, 29.997, 29.1001, 29.1305, and 29.1337.
(g) The applicant must identify any changes to the ICA, including, but not limited to, safety precautions, fluid compatibility, changes to placards, changes to service intervals, and changes to maintenance practices (refer to appendices G23.3, H25.3, A27.3, and A29.3).
9. Lubricating Oil.
a. Historically Accepted Oil Standards.
(1) Commercial turbine engine type design holders traditionally used performance standard MIL-PRF-23699 to qualify engine oil. Today, SAE International Aerospace Standard
(AS), SAE AS5780, “Specification for Aero and Aero Derived Gas Turbine Engine Lubricants,” replaces MIL-PRF-23699 for commercial turbine engines.
(2) SAE AS5780 defines physical, chemical, and performance limits for gas turbine engine oils along with standard test methods and requirements. It includes specialized laboratory and rig testing to determine if the oil is suitable for aircraft turbine engines. It also defines quality control requirements to ensure batch conformance and materials traceability, and it includes procedures to manage and communicate changes in oil formulation and brand. SAE Technical Committee E-34, Propulsion Lubricants, maintains SAE AS5780. The SAE E-34 committee addresses all facets of aerospace propulsion lubricants; development, maintenance, and in-service experience. This work includes lubricants used for gas turbine engines, aircraft gearboxes, and accessories.
(3) Similarly, commercial and military engine type design holders used MIL-L-6082, Lubricating Oil, Aircraft Piston Engine (Non-Dispersant Mineral Oil) and MIL-L-22851, Lubricating Oil, Aircraft Piston Engine (Ashless Dispersant) for conventional SI reciprocating engines. However, SAE International Surface Vehicle Standard J1899, “Lubricating Oil, Aircraft Piston Engine (Ashless Dispersant),” and SAE International Surface Vehicle Standard J1966, “Lubricating Oils, Aircraft Piston Engine (Non-Dispersant Mineral Oil),” replaced MIL- L-6082 and MIL-L-22851 as the primary standards for conventional SI reciprocating engine oil.
SAE Standards J1899 and J1966 define physical, chemical, and performance limits for conventional SI reciprocating engine oils along with standard test methods and requirements.
They include specialized laboratory and rig testing to determine if the oil is suitable for aircraft conventional SI reciprocating engines. They also define quality control requirements to assure batch conformance and materials traceability. The SAE E-38 Aviation Piston Engine Fuels and Lubricants Committee maintains SAE Standards J1899 and J1966.
(a) Guidance for oil qualification programs performed in accordance with SAE J1899 is provided in Appendix 1, “Horizontally Opposed Reciprocating Engine Oil Approvals: The SAE J1899 Program”. This appendix applies only to Continental Motors, Inc. (CMI) and Lycoming Engines (LE) horizontally opposed reciprocating engines.
b. Operating Limitations for Lubricating Oil.
(1) FAA regulations require the Administrator to establish engine operating limitations related to oil. These operating limitations are also included in the engine TCDS for each type certificated design. Operating limitations for oil are related to oil grade, brand name, and specifications for reciprocating and turbine engines.
The FAA determined that SAE grade, specification known as an SAE standard, or oil formulation brand designation(s) based on SAE standards, are acceptable to include as engine operating
limitations related to oil. Once the compliance plan is successfully completed, the oil formulation brand designation or the standard number will be listed in the engine TCDS or in manufacturers’ documents referenced in the TCDS. For STC projects, the oil formulation brand designation or the standard number will be listed in the limitations section of the STC.
(2) Special Considerations.
(a) Oil Formulation Brand Name Designation. Turbine engines generally require lubricating oils meet the SAE AS5780 standard, but the operating limitation specified in the engine TC is most often listed as the brand name(s) of specific oil formulations. Similarly, conventional SI piston engine lubricating oil typically meets SAE J1899 or J1966 standards with the operating limitations listed as brand name(s) of specific oil formulations. This is a more specific means of identification than simply referencing SAE AS5780, J1899, or J1966, and, therefore, specifying the brand name is generally acceptable for establishing an operating limitation related to oil, as required by §§ 33.7(b)(3) and (c)(3). Specifying SAE AS5780, J1899, or J1966 is also acceptable if the engine manufacturer has demonstrated that any oil with properties that fall within the range of criteria in the specification is acceptable for use in the subject engine.
(b) Changes to SAE Approved Oil Formulation. Oil manufacturers may change oil formulation, base stock composition, additive composition, or manufacturing plant location.
SAE requires brand re-identification if these changes have a significant potential to adversely impact the engine oil system. This brand re-identification will result in applicants requesting a change to the TC or STC to add the new brand as an operating limitation.
1 If SAE determines the change does not require a change to the brand name, then the specified operating limitation is still valid, and accordingly, no change to the TC or STC is required. This is because operating limitations relative to oil are typically defined in terms of the brand name.
2 If SAE determines the change requires a brand name re-identification, then the SAE industry oversight group generally evaluates the change in parallel with the engine manufacturer’s FAA design change control process. The industry oversight group’s report and associated evidence can be used to support the FAA’s review process.
(c) Other governmental military or industry voluntary consensus-based standards or specifications. If an applicant proposes to specify aviation oil identified by another governmental, military, or industry voluntary consensus-based standard, or specification, then the applicant must present sufficient information to show that the oil grade, brand name, or specification provides an equivalent level of property, performance, and quality control.
c. Operating Limitations for Oil: Certification Compliance Plans.
(1) Applicable airworthiness requirements are those FAA regulatory standards for which the showing of compliance is contingent on oil properties. Once applicants present the industry consensus-based, governmental, or military oil brand, standard, grade, or specification to the FAA, the FAA will aid applicants as they develop their compliance plan.
(2) An applicant’s compliance plan must address all applicable airworthiness certification standards, some of which are discussed paragraph 9.c(5) below. Sound testing techniques and thorough data analysis must also be well documented in the compliance plan. Accordingly, close contact and frequent coordination with the FAA are recommended to ensure the plan is developed with minimal delay.
(3) An applicant’s compliance plan must also address the effects of mixing the proposed new oil with other types of oil, such as mixing a new brand with an existing brand. Data generated during the development of the industry consensus-based, military, or governmental oil specification may be used to support this task.
(4) Applicants using engine oil for airplane or rotorcraft systems must demonstrate that the airplane or rotorcraft the engine is installed on continues to meet all certification standards.
If a qualification project for a new operating limitation for oil for an APU is required for a new TSO, major change, or STC, then the compliance plan must include the applicable requirements and performance standards from the latest revision of TSO-C77.
(5) Applicable Regulations for Engines and APUs. For a list of regulations that may apply to oil projects, see appendix 2 of this AC, paragraphs 4, 5, and 6. Additional guidance on airworthiness standards follows in paragraphs 9.c(5)(a) through (d). The following list is not allinclusive, and is provided as a recommended starting point only. Applicants must therefore, obtain from the FAA, guidance on regulations with which they will need to show compliance.
(a) Applicants must review the design of the turbine engine oil system and provide data that shows that the new turbine engine oil will not result in harmful build-up of carbon deposits for compliance with §§ 33.19 and 33.71. This can be done with any combination of engine test, rig test, and analysis based on prior service experience or testing. The applicant must substantiate that any time-between-overhaul (TBO) established for the engine, or the existing engine’s TBO, whichever is applicable, is valid with the new oil. This may require analysis or testing to show compliance with §§ 33.15, 33.19, 33.49, and 33.87. Refer to §§ 33.15, 33.19, 33.49, and 33.87 and TSO-C77b, appendix 1, sections 4.2, 4.3, and 6.3.
(b) Applicants must also include in the ICA, if applicable, instructions for inspections, repair, and cleaning of turbine engine areas or components shown to be susceptible to carbon deposit build-up. These instructions must be derived by reviewing the oil system design accomplished during compliance with §§ 33.71, 33.19, and TSO-C77b, appendix 1, sections 5.4 and 4.3.
(c) If all oil-wetted materials on the specific engine model under review were not evaluated during the SAE qualification process, additional materials compatibility testing will be necessary (refer to § 33.15 and TSO-C77b, appendix 1, section 4.2).
(d) The applicant must identify any changes to the ICA, including, but not limited to, safety precautions, fluid compatibility, changes to placards, changes to service intervals, and changes to maintenance practices (refer to § 33.4).
(6) Applicable Regulations for Airplanes and Rotorcraft. For a list of regulations that may be applicable for oil projects, see appendix 3 of this AC, paragraph 2. Additional guidance on airworthiness standards follow in paragraphs 9.c.(6)(a) through (c). The following list is not allinclusive, and is provided as a recommended starting point only. Applicants must therefore, obtain from the appropriate directorate guidance on regulations with which they will need to show compliance.
(a) Applicants must show that the oil is compatible with aircraft or propeller systems that use the oil. Refer to §§ 23.901(e), 23.901(f), 23.903(b)(2), 23.905(d), 23.909, 25.901(d),
25.903, 25.903(f), 25.905, 25.943, 25.1011(b), 25.1019, 27.903, and 29.903.
(b) Applicants must show that the oil has no adverse effect on engine cooling. Refer to §§ 23.1041, 23.1043, 23.1045, 23.1047, 25.1041, 25.1043, 25.1045, 27.1041, 27.1043,
27.1045, 29.1041, 29.1043, 29.1045, 29.1047, and 29.1049.
(c) The applicant must identify any changes to the ICA, including, but not limited to, safety precautions, fluid compatibility, changes to placards, changes to service intervals, and changes to maintenance practices (refer to appendices G23.3, H25.3, A27.3 and A29.3).
10. Additives.
a. Additive Specification.
(1) Fuel additives that are incorporated into ASTM, governmental or military specification, or other industry-based consensus organization specification, are considered to be identified in sufficient detail to be accepted by the FAA under existing operating limitations on TCs, amended TCs, STCs, or ASTCs, provided there are no changes to those operating limitations.
(2) Oil additives that are incorporated into an SAE oil standard, or a brand name that meets an SAE standard, governmental or military specification, or other industry-based consensus organization specification, are considered to be identified in sufficient detail to be accepted by the FAA under existing operating limitations on TCs, amended TCs, STCs, or ASTCs provided there are no changes to those operating limitation.
(3) The FAA will accept fuel or oil additives that are not incorporated into fuel or oil specifications according to paragraph 10.a.(1) or (2) above, provided the additive is identified and controlled to a single compositional definition.
b. Additive Approval.
(1) For additives incorporated into an ASTM, SAE oil standard, or a brand name that meets an SAE standard, governmental or military specification, or other industry-based consensus organization specification:
(a) Further FAA testing or approval is not required if the current specified operating limitations are adequate to accommodate the fuel, or oil specification or standard. TC/STC holders do not need to revise aviation fuel operating limitations to use the additive.
(b) If the current specified operating limitations are not adequate to accommodate the fuel, or oil specification or standard, then a regulatory showing of compliance according to paragraph 8.f. or 9.c. of this AC, whichever applicable, is necessary to incorporate the fuel or oil as a new operating limitation on a TC or STC.
(2) For additives not incorporated into an ASTM, SAE oil standard, or a brand name that meets an SAE standard, governmental or military specification, or other industry-based consensus organization specification:
(a) If the FAA determines that a demonstration of compliance for each certificated product for which the additive is intended to be used on is n ecessary, then the applicant must follow the process described in paragraph 7.f. of this AC to add the additive to each product’s TC or STC.
(b) In special cases, the FAA may determine that sufficient data is available to support a broad-based approval for use of the additive on an identifiable population of engines or aircraft.
For example, an additive with an identical composition to an existing, approved additive may have extensive service experience on a specific category, or type of aircraft or engine. In this case, the FAA may conduct the evaluation and approval in accordance with § 21.8(d).
(c) For approvals conducted according to paragraphs (a) or (b) above, the showing of compliance must address the following:
1 It must be demonstrated that the additive does not have any adverse effects on the operation, performance, durability, or materials of the products intended for use.
2 It must be demonstrated that the additive does not have any adverse effects on the performance of the base fuel or oil that it is intended for use with.
3 It must be demonstrated that the additive is compatible with all other additives, or combination of all other additives, permitted for use in the base fuel or oil that the additive is intended for use with.
If you have any suggestions for improvements or changes, you may use the template provided at the end of this AC.
//ORIGINAL SIGNED BY PETER A. WHITE ON 6/30/14// Peter A. White Manager, Alternative Fuels Program Staff Aircraft Certification Service
Appendix 1 A1-1
Appendix 1
Horizontally Opposed Reciprocating Engine Oil Approvals:
The SAE J1899 Program
1. Introduction. This appendix provides guidance for oil qualification programs performed in accordance with SAE J1899, “Lubricating Oil, Aircraft Piston Engine (Ashless Dispersant).”
This appendix provides guidance specific to SAE J1899 qualified piston engine lubricating oils.
It applies only to Continental Motors, Inc. (CMI) and Lycoming Engines (LE) horizontally opposed reciprocating engines.
2. Background.
a. This appendix applies to a single engine model or a family of engine models if the applicant can show that the tested engine represents the most severe case. The costs associated with such a substantiation program are prohibitive for single reciprocating engine models;
therefore, a broader applicability for lubricating oil approvals is required for these engines.
b. The Naval Air Warfare Center (NAWC) developed a standardized procedure to qualify a particular engine oil across engine models, based on similarities of materials and design operating parameters. Today, this procedure applies only to horizontally opposed reciprocating engines manufactured by CMI and LE.
c. The NAWC’s procedure is captured in SAE J1899. It provides specific requirements for laboratory testing, engine bench testing, and engine flight testing. It represents an acceptable method of showing the FAA that applicable airworthiness certification standards are retained when the oil is used.
3. FAA Oversight of SAE J1899 Qualification Program. The SAE J1899 qualification program consists of: Step 1—all laboratory analysis and testing and engine endurance testing;
and Step 2—flight testing of the oil using the specified engine model. The SAE technical team (oil manufacturer, engine manufacturers, the FAA, and the U.S. Navy) oversees both steps.
Under Step 1, applicants conduct sufficient testing and analysis to obtain an STC, which approves the use of the oil for flight testing on designated TCM and LE engines in Step 2. Step 1 requires direct FAA participation. Step 2 relies on delegated oversight performed by the engine manufacturers under their design change approval system. The following provides an overview of each step.
a. Step 1: Preliminary Data and Ground Testing.
(1) The objective of this step is to provide proof of compliance to obtain an STC that authorizes flight testing of the LE and CMI engine models specified in SAE J1899. For this step, applicants must submit a compliance plan to the FAA that identifies the applicable regulations from part 33 (or CAR 13). The applicant must also provide the FAA with analyses, data, test plans, and test reports to demonstrate compliance with each regulation.