2-6 Table 2-4. Airplanes Authorized By OpSpec A570 to Use Ground-Conditioned Air Boeing Airbus 747 Series A300, A310 Series 737 Series A318, A319, A320, A321 Series 777 Series A330, A340 Series 767 Series 757 Series
2.10.2 OpSpec A570 Authorized Airplanes. If the operator applied for the ground conditioned air provision, it is controlled on OpSpec A570, One Year Extension of Compliance Times in Section 121.1117(e). The operator’s manual must contain any applicable airplanes in Table 2-4 that are authorized on OpSpec A570 to use ground conditioned air.
This must include a listing by N registration number and fleet type of airplanes that require retrofit with FRM or IMM. As airplanes are retrofitted, they should be removed from the list. The OpSpec A570 authorization terminates on December 26, 2018, or when all of the operator’s airplanes listed in its manual are retrofitted, whichever occurs first.
2.11 Service Instructions.
2.11.1 Install FRM or IMM. In order for the operators to install FRM or IMM, the DAHs are required to develop airplane model specific design change service instructions (Service Bulletins (SB)) that are FAA Oversight Office-approved. Operators will use these service instructions along with installation kits to install FRM or IMM. The FAA Oversight Office-approved FRM/IMM SBs are part of the airplane type design. Therefore, certain changes must be FAA Oversight Office-approved in accordance with the following procedures.
2.11.2 Deviation/Changes to FAA Oversight Office-Approved FRM SBs. The retrofit requirements contained in 14 CFR § 121.1117 require installation of an IMM or FRM, if required by 14 CFR § 26.33, § 26.35, or § 26.37, that is “approved by the FAA Oversight Office.” Unlike an Airworthiness Directive (AD) that typically requires accomplishment of corrective actions “in accordance with” a manufacturer’s SB, 14 CFR § 121.1117 does not require strict adherence (“in accordance with”) to the manufacturer’s SB. As with any SB that implements a change to type design, the manufacturer’s SBs for the Nitrogen Gas System have been FAA-approved. Although the entire SB is identified as approved, only the technical data (type design) associated with the SB is FAA-approved. Therefore, deviations to the SBs that revise the technical data contained within the SB would have to be approved. Major changes to the technical data include, but are not limited to, any deviation/change to the SB that could affect the performance/reliability/operation of the Nitrogen Gas System. Minor deviations/changes to non-AD FAA-approved SBs should be handled in accordance with the procedures in the operator’s manual acceptable to the PI. Operators should refer to AC 120-77, Performance Rules: Provisions Contained in an
2-7 Operator Manual Under § 43.13(c), for guidance regarding considerations in making major/minor decisions and the needed analysis or justification.
2.11.2.1 Proposed Deviations. Operators should have coordinated with the PI of their FAA certificate management office (CMO) or the responsible Flight Standards office in requesting and implementing approval of major deviations/revisions directly by the FAA Oversight Office to the FRM SBs.
2.11.2.2 Procedures That Address Major and Minor Changes. The operator must have procedures in its manual that address both major and minor changes to FAA Oversight Office-approved FRM/IMM service instructions/bulletins.
2.12 Airworthiness Limitations.
2.12.1 DAH-Developed Airworthiness Limitations. The DAH is required to develop FAA Oversight Office-approved airworthiness limitations which include critical design configuration control limitations (CDCCL), inspections, or other procedures to prevent increasing the flammability exposure of any tanks equipped with FRM or FIMM above the certification limits, or to prevent degradation of the performance of any IMM installed throughout the operational life of the airplane. The DAH is required to include these airworthiness limitations in the Airworthiness Limitations Section (ALS) of the instructions for continued airworthiness (ICA). These airworthiness limitations are part of the type design of the modified airplane. This requirement is similar to that contained in 14 CFR § 25.571. Airplane fuel tank system airworthiness limitations are intended to be treated the same as airplane structure airworthiness limitations. Title 14 CFR part 25 Appendix H, requires including fuel tank system airworthiness limitations in the airworthiness limitations of the ICA.
2.12.1.1 Title 14 CFR §§ 26.33 and 26.35 require the DAH to develop airworthiness limitations to prevent increasing the flammability exposure of any tanks equipped with FRM or FIMM and to prevent degradation of the performance of any IMM.
2.12.1.2 Title 14 CFR § 121.1117 and similar provisions in 14 CFR parts 125 and 129 require the operator to incorporate the airworthiness limitations required by 14 CFR §§ 26.33 and 26.35, if required, into their maintenance or inspection program.
2.12.2 Types of FRM/IMM Limitations. There are three types of fuel system airworthiness limitations.
2.12.2.1 An airworthiness limitation item (ALI) inspection which has a specific task and interval, such as 10 years.
2.12.2.2 An ALI procedure that could have specific task intervals.
2.12.2.3 A CDCCL which has no interval but establishes configuration limitations to maintain and to protect the critical design feature identified in the CDCCL.
2-8 CDCCLs can also include requirements to have placards on the airplane with information about critical features. (Refer to AC 25.981-1, Fuel Tank Ignition Source Prevention Guidelines, or AC 25.981-2, Fuel Tank Flammability Reduction Means, for additional information on CDCCLs.)
Figure 2-1. Example of an FRM/IMM CDCCL Title: Center Fuel Tank Vent System – Auxiliary Tanks The Concern: The addition of an auxiliary fuel tank system via a Supplemental Type Certificate (STC) may reduce the effectiveness of the Nitrogen Gas System resulting in an increase in flammability exposure of the center tank.
Reason for Concern: The Nitrogen Gas System installation is designed to provide the proper level of nitrogen to the center wing fuel tank (CWT) in order to reduce the fleet wide average flammability exposure to levels equal to that of wing fuel tanks. Auxiliary fuel tank installations typically transfer fuel and ullage gases to and from the CWT.
The Critical Design Feature: Any auxiliary fuel tank system that allows transfer of ullage directly to or from the CWT must not significantly affect the performance of the Nitrogen Gas System.
2.12.3 Critical Design Feature. Title 14 CFR § 121.1117 and similar provisions in 14 CFR parts 125 and 129 require the operator to incorporate the airworthiness limitations required by 14 CFR §§ 26.33 and 26.35, if required, into their maintenance or inspection program. The FAA Oversight Office-approved FTFR airworthiness limitations make the CDCCL the primary source for the critical design feature information. While the critical design feature may also be in the Aircraft Maintenance Manual (AMM) reference, it is not to be used as the primary source of information for the CDCCL critical design feature. The primary source is the CDCCL.
2.13 Operator Maintenance/Inspection Program Requirements.
2.13.1 Procedures for Development Personnel. Operators must have procedures in their maintenance/inspection program/manual that include all information from the fuel system airworthiness limitations. The operator’s maintenance/inspection program/manual shall state that personnel who edit maintenance manuals, job/task cards, and Engineering Orders (EO) must include the entire text of the airworthiness limitations, including the AMM standard wiring practice manual (SWPM) text that is required to be followed.
(Merely referencing the AMM, SWPM, etc. is not acceptable.)
2.13.2 CDCCL Incorporation. Operators must ensure that the CDCCL critical design features are incorporated into the maintenance/inspection program/manual and are adhered to as written. Any proposed operator changes must be approved by the FAA Oversight Office.
The CDCCL critical design feature identified above is just one of many that are included in the airworthiness limitations for the airplane. The CDCCLs critical design features must be included on the operators’ EOs and job/task cards.
2-9
2.13.3 Airplanes With FRM or IMM Installed. Operators who have taken delivery of new production airplanes (14 CFR § 121.1117(b)), manufactured either on or prior to December 27, 2010, or manufactured after December 27, 2010 that have either FRM or IMM installed must have FAA Oversight Office-approved airworthiness limitations
(i.e., CDCCLs, inspections, or other procedures) from the ICA incorporated into their maintenance/inspection program/manual prior to putting the airplane into service.
2.13.4 Retrofitted Airplane Fleets. Operators who retrofit their fleet must incorporate the FAA Oversight Office-approved airworthiness limitations (i.e., CDCCLs, inspections, or other procedures) from the ICA into their maintenance/inspection program/manual prior to putting the airplane back into service.
2.13.5 Procedures to Maintain Placards. Operators must have procedures in their maintenance/inspection program/manual to maintain placards that have information about critical design features on the airplane as required by the airworthiness limitations.
2.13.6 Airworthiness Limitations With Approved CDCCLs. Airworthiness limitations that included FAA Oversight Office-approved CDCCLs, inspections, and other procedures are part of the airplane type design and, therefore, any changes must be approved by the FAA Oversight Office. Operators must have procedures in their maintenance/inspection program/manual that address any changes to airworthiness limitations. The procedures must include notification and be acceptable to the PI.
2.14 Maintenance/Inspection Program Revisions After Alterations.
2.14.1 Before Return to Service. Title 14 CFR § 121.1117(h) and similar provisions in 14 CFR parts 125 and 129 state, in part, after the maintenance/inspection program is revised before returning an airplane to service after any alteration for which airworthiness limitations are required, the operator must revise the maintenance/inspection program for the airplane to include those airworthiness limitations prior to putting the airplane back in service.
2.14.2 Incorporate Type Certificate Holder (TCH)-Developed Revisions. The operator must have incorporated the TCH-developed Maintenance Review Board Report (MRBR) or Maintenance Implementation Document (MID) revisions and/or other FAA Oversight Office-approved fuel tank system airworthiness limitations (i.e., CDCCLs, inspections, and other procedures) into its maintenance/inspection program. The operator will submit to the PI for review the revisions to their maintenance/inspection program incorporating the MRBR, MID, and/or FAA Oversight Office-approved airworthiness limitations changes. The PI review ensures that the operator’s maintenance/inspection programs are in compliance with the fuel tank system and Aging Aircraft Program rules. When the review is complete, the PI will issue or amend OpSpec/Management Specification (MSpec)/LOA D097, Aging Aircraft Programs.
2.14.3 Operators That are Authorized OpSpec/MSpec/LOA D097. The issuance of this OpSpec signifies the FAA has reviewed the operator/certificate holder (CH)/program manager’s policy and procedures incorporated into their maintenance/inspection programs for
2-10 compliance with the Aging Aircraft Program rules. OpSpec/MSpec/LOA D097, Table 1, Aging Aircraft Maintenance Programs, will consist of three columns that list:
• The Aging Aircraft Program rules;
• The manual and section where the policy and procedures are located for the applicable Aging Aircraft Program; and
• The date of the manual and section where the current policy and procedures are located for the applicable Aging Aircraft Program.
Note: Table 2-5 below illustrates a sample OpSpec D097 Table 1 that lists the various 14 CFR part rules. The operator/CH/program manager will have a specific OpSpec D097 template for their operation.
Table 2-5. Sample OpSpec D097, Table 1 – Aging Aircraft Maintenance Programs Aging Aircraft Program Rules Operator/Certificate Holder/Program Manager’s Maintenance and/or Inspection Program Procedures (Manual and Section) Date Repairs Assessment for Pressurized Fuselages — § 91.1505, § 121.1107, § 125.505, § 129.107
Supplemental Inspections — § 121.1109, § 129.109 Electrical Wiring Interconnection Systems (EWIS) Maintenance Program — § 121.1111, § 129.111
Fuel Tank System Maintenance Program — § 121.1113, § 129.113
Flammability Reduction Means — § 121.1117, § 125.509, § 129.117
Fuel Tank System Inspection Program — § 91.1507, § 125.507
2.14.3.1 Initial submission and any later revisions to the operator/CH/program manager’s maintenance/inspection program policy and procedures must be submitted to the PI for review for compliance with the Aging Aircraft Program rules.
2.14.3.2 Any proposed revisions or deletions of FAA Oversight Office (Aircraft Certification Service office)-approved ICAs must be coordinated with the PI for review and concurrence. The PI will then forward the proposed revisions or deletions to the responsible Aircraft Certification Service office for
2-11 approval prior to implementation or incorporation into the maintenance/inspection program.
2.14.3.3 An operator/CH/program manager must have procedures to ensure that ICAs are incorporated into their maintenance/inspection program.
Appendix A A-1 APPENDIX A. ACRONYMS A4A Airlines for America AC Advisory Circular AD Airworthiness Directive AED Aircraft Evaluation Division AFM Aircraft Flight Manual ALI Airworthiness Limitation Item ALS Airworthiness Limitation Section AMM Aircraft Maintenance Manual APU Auxiliary Power Unit ASI Aviation Safety Inspector C of A Certificate of Airworthiness CDCCL Critical Design Configuration Control Limitation CFR Code of Federal Regulations CH Certificate Holder CMO Certificate Management Office CWT Center Wing Fuel Tank DAH Design Approval Holder DRS Dynamic Regulatory System EO Engineering Order EWIS Electrical Wiring Interconnection System FAA Federal Aviation Administration FIMM Flammability Impact Mitigation Means FQIS Fuel Quantity Indicating System FRM Flammability Reduction Means FS Flight Standards Service FTFR Fuel Tank Flammability Reduction FTS Fuel Tank Safety ICA Instructions for Continued Airworthiness IMM Ignition Mitigation Means LOA Letter of Authorization
Appendix A A-2 MID Maintenance Implementation Document MRBR Maintenance Review Board Report MSG-3 Maintenance Steering Group – 3rd Task Force MSI Maintenance Significant Items MSpec Management Specification MWG Maintenance Working Group NTSB National Transportation Safety Board NWS National Weather Service OpSpec Operations Specification PI Principal Inspector (This may include any or all of the affected Airworthiness or Operations) PMA Parts Manufacturer Approval SB Service Bulletin SFAR Special Federal Aviation Regulations STC Supplemental Type Certificate SWPM Standard Wiring Practice Manual TC Type Certificate TCH Type Certificate Holder TSOA Technical Standard Order Authorization
Appendix B B-1 APPENDIX B. DEFINITIONS
1. Actual Gate Time. The time that the airplane is parked at a gate for servicing and passenger egress and ingress.
2. Aircraft Evaluation Division (AED). The Federal Aviation Administration (FAA) Flight Standards Service (FS) representatives who know the operational and maintenance aspects of the certification project and are responsible for determining the operational acceptability and continuing airworthiness requirements of newly certified or modified aircraft, engines, and propellers intended to be operated under the provisions of the Code of Federal Regulations (CFR). This function includes providing the FAA Oversight Office support in the review and approval of the initial and subsequent changes to the type design.
3. Aircraft Maintenance Manual (AMM). A manual developed by the manufacturer of a particular airplane that contains information necessary for the continued airworthiness of that airplane.
4. Airport Ambient Temperature. The official National Weather Service (NWS) temperature at the airport.
5. Airworthiness Limitations (AL). In terms of this advisory circular (AC), mandatory maintenance of the fuel system that can include critical design configuration control limitation (CDCCL), inspections, or other procedures determined necessary to ensure that unsafe conditions do not occur and are not introduced into the fuel system as a result of maintenance actions, repairs, or alterations throughout the operational life of the airplane.
6. Applicant. In the context of this AC, an applicant is a person applying for design approval.
7. Available. In this AC, “available” relates to the requirement to use ground-conditioned air. In this regard, it means a ground-conditioned air hookup is installed and is operational at the gate. (Mobile ground-conditioned air carts are not required to be used.)
8. Center Wing Fuel Tank (CWT). A fuel tank located in the center of an airplane’s wing box. These tanks are typically located within the fuselage contour but may extend outside the fuselage contour into the wing.
9. Continued Airworthiness. Certified aircraft, engines, propellers, and appliances are safe to operate for the intended purpose; they are maintained safely throughout their service life; the product meets its type design and is in a condition for safe operation.
10. Critical Design Configuration Control Limitations (CDCCL). An AL that preserves a critical feature of the airplane needed for the flammability reduction means (FRM) or ignition mitigation means (IMM) to perform their intended function and prevent the occurrence of an unsafe condition. The purpose of the CDCCL is to provide instructions to ensure these critical features are present throughout the life of the airplane (e.g., when alterations, repairs, or maintenance actions occur).
Appendix B B-2
11. Design Approval Holder (DAH). The holder of any design approval, including type certificate (TC), amended TC, Supplemental Type Certificate (STC), amended STC, Parts Manufacturer Approval (PMA), Technical Standard Order Authorization (TSOA), letter of TSO design approval, and field approvals. In particular contexts, the term DAH may also refer to applicants for design approvals.
12. FAA Oversight Office. The responsible Aircraft Certification Service office or office of the Transport Airplane Directorate having oversight responsibility for the relevant TC or STC, as determined by the Administrator. (See Appendix C, FAA Oversight Offices, for a listing of appropriate offices.)
13. Field Approval. A design approval of a major repair or major alteration of an individual aircraft, aircraft engine, propeller, or appliance by an aviation safety inspector (ASI). This is documented by completing and signing Block 3 of FAA Form 337, Major Repair and Alteration (Airframe, Powerplant, Propeller, or Appliance). We approve these major repairs or alterations by either examining data only or by physically inspecting, demonstrating, or testing the product.
14. Flammability Impact Mitigation Means (FIMM). Modifications developed by the DAH for auxiliary fuel tanks that are required by Title 14 of the Code of Federal Regulations (14 CFR) part 26 to have an FRM or IMM installed. FIMM are only needed when the DAH or operator has determined that an auxiliary fuel tank installed by STC or field approval could have an adverse impact on the performance of an FRM or IMM.
15. Flammability Reduction Means (FRM). Any system or feature intended and designed to reduce the flammability exposure of a fuel tank either by affecting oxygen levels or by affecting fuel vapor concentration levels.
16. Flammable (With Respect to a Fluid or Gas). Susceptible to igniting readily or to exploding (14 CFR part 1). A non-flammable ullage is one where the fuel-air vapor is too lean or too rich to burn or is inert as defined below. For this AC, a fuel tank vapor space is considered flammable when the bulk average fuel temperature within the tank is within the flammable range for the fuel type being used. For any fuel tank that is subdivided into sections by baffles or compartments, the tank is considered flammable when the bulk average fuel temperature within any section of the tank is within the flammable range for the fuel type being used.
17. Flight Standards Service (FS) Offices. FAA offices responsible for developing guidance and policy applicable to transport category airplanes for AED and FS personnel (Airworthiness and Operations ASIs) in the conduct of their responsibilities.
18. Fuel Types. The Aircraft Flight Manual (AFM) lists the approved-for-use fuels for a given airplane type. Each fuel type has its own properties; those directly related to flammability are flash point and distillation characteristics. Property differences can occur in different batches of a given fuel type because of variations in the properties of the source crude oil and the refining process used to produce the fuel. The most widely used fuel types are JET-A/JET-A1 (with older airplanes approved for use of JET-B
Appendix B B-3 (JP-4)), per ASTM International Specification D1655-11b, Standard Specification for Aviation Turbine Fuels.
19. Hazardous Atmosphere. An atmosphere that may expose maintenance personnel, passengers, or flightcrew to the risk of death, incapacitation, impairment of ability to self-rescue (escape unaided from a confined space), injury, or acute illness.
20. Ignition Energy. The minimum amount of energy required to ignite fuel vapors.
21. Ignition Mitigation Means (IMM). A system or feature intended and designed to prevent overpressure of a fuel tank following ignition of fuel or vapor in the tank.
22. Inert. When the bulk average oxygen concentration within each compartment of the fuel tank is 12 percent or less from sea level up to 10,000 feet altitude, then linearly increasing from 12 percent at 10,000 feet to 14.5 percent at 40,000 feet altitude, and extrapolated linearly above that altitude.
23. Inerting. A process where a noncombustible gas is introduced into the ullage of a fuel tank so that the ullage becomes non-flammable.
24. Instructions for Continued Airworthiness (ICA). Documentation that sets forth instructions and requirements for maintenance that is essential to the continued airworthiness of an aircraft, engine, or propeller.
25. Main Fuel Tank. Title 14 CFR § 25.981(b)(3)(iii) defines the main fuel tank as: “…a fuel tank that feeds fuel directly into one or more engines and holds required fuel reserves continually throughout each flight.” The functions of the main tanks are immediately available and operate without immediate supervision by the flightcrew in the event of failure or inadvertent depletion of fuel in an auxiliary tank. Generally, main tanks are those dedicated to the feed of the engines during engine feed isolation.
26. Maintenance Instructions. Recommended periods for cleaning, inspection, adjustment, testing, lubrication, degree of inspection, applicable wear tolerances, and recommended work necessary for each part of the airplane and its engine auxiliary power units (APU), propellers, accessories, instruments, and equipment to provide for continued airworthiness of the airplane. Recommended overhaul periods and necessary cross-references to the ALS of the maintenance manual are also included (refer to 14 CFR part 25 appendix H and § 25.3(b); and AC 26-1, Part 26, Continued Airworthiness and Safety Improvements, Appendix A, Maintenance Instructions, for additional information).
27. Maintenance Review Board Report (MRBR). Document intended for use by air carriers. It contains the initial minimum scheduled maintenance and inspection requirements for a particular transport category aircraft and on-wing engine program. Air carriers use the MRBR and its associated requirements to develop maintenance programs.
(Refer to AC 121-22, Maintenance Review Boards, Maintenance Type Boards, and Original Equipment Manufacturer/Type Certificate Holder Recommended Maintenance Procedures, for additional information.)
Appendix B B-4
28. Maintenance Significant Items (MSI).
28.1 Under the Maintenance Steering Group – 3rd Task Force (MSG-3), MSI are items identified by the DAH whose failure could cause one of the following effects:
• It could affect safety on the ground or in flight,
• It could be undetectable during operations,
• It could have a significant impact on operations, or
• It could have a significant economic impact.
28.2 In terms of development of maintenance and inspection instructions, MSI include systems, subsystems, modules, components, accessories, units, and parts.
29. Maintenance Steering Group – 3rd Task Force/4th Task Force (MSG-3/MSG-4). A voluntary structured process developed by the industry and maintained by Airlines for America (A4A) to make decisions used to develop maintenance and inspection tasks and intervals for an airplane.
30. Maintenance Working Group (MWG). A working group of maintenance specialists from participating operators, the prime manufacturer, and the regulatory authority whose function is to develop airplane maintenance programs.
31. Maximum Payload Capacity. Is defined in 14 CFR part 119.
32. Normally Emptied. Defined in 14 CFR § 26.31(b) as “…a fuel tank other than a Main Fuel Tank.” Main Fuel Tank is defined in 14 CFR § 25.981(b), and expanded above.
33. Operational. With regard to ground-conditioned air, operational means the ground air source is functional and has the capacity to provide air to the airplane.
34. Operator. Person who uses, causes, or authorizes another to use aircraft for air navigation, including piloting the aircraft.
35. Transport Category Airplanes. For the purposes of this AC, the group consists of turbine-powered transport category airplanes, provided that the TC for the airplane was issued after January 1, 1958, and that the airplane has either a maximum type certificated passenger capacity of 30 or more, or a maximum payload capacity of 7,500 pounds or more, resulting from the original certification of the airplane.