Federal Aviation Administration (FAA), Department of Transportation (DOT).
Notice of proposed rulemaking (NPRM).
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 777-200, -200LR, -300, and -300ER series airplanes. This proposed AD would require revising the Airworthiness Limitations (AWLs) section of the Instructions for Continued Airworthiness by incorporating new limitations for fuel tank systems to satisfy Special Federal Aviation Regulation No. 88 requirements. This proposed AD also would require the initial performance of certain repetitive inspections specified in the AWLs to phase in those inspections, and repair if necessary. This proposed AD results from a design review of the fuel tank systems. We are proposing this AD to prevent the potential for ignition sources inside fuel tanks caused by latent failures, alterations, repairs, or maintenance actions, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.
We must receive comments on this proposed AD by August 17, 2007.
Use one of the following addresses to submit comments on this proposed AD.
- DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
- Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
- Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590.
- Fax: (202) 493-2251.
- Hand Delivery: Room W12-140 on the ground floor of the West Building, 1200 New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for the service information identified in this proposed AD.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Kathrine Rask, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, Washington 98057-3356; telephone (425) 917-6505; fax (425) 917-6590.End Further Info End Preamble Start Supplemental Information
We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “FAA-2007-28389; Directorate Identifier 2006-NM-171-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date Start Printed Page 36374and may amend the proposed AD in light of those comments.
We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.
Examining the Docket
You may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Operations office (telephone (800) 647-5527) is located on the ground floor of the West Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.
The FAA has examined the underlying safety issues involved in fuel tank explosions on several large transport airplanes, including the adequacy of existing regulations, the service history of airplanes subject to those regulations, and existing maintenance practices for fuel tank systems. As a result of those findings, we issued a regulation titled “Transport Airplane Fuel Tank System Design Review, Flammability Reduction and Maintenance and Inspection Requirements” (66 FR 23086, May 7, 2001). In addition to new airworthiness standards for transport airplanes and new maintenance requirements, this rule included Special Federal Aviation Regulation No. 88 (“SFAR 88,” Amendment 21-78, and subsequent Amendments 21-82 and 21-83).
Among other actions, SFAR 88 requires certain type design (i.e., type certificate (TC) and supplemental type certificate (STC)) holders to substantiate that their fuel tank systems can prevent ignition sources in the fuel tanks. This requirement applies to type design holders for large turbine-powered transport airplanes and for subsequent modifications to those airplanes. It requires them to perform design reviews and to develop design changes and maintenance procedures if their designs do not meet the new fuel tank safety standards. As explained in the preamble to the rule, we intended to adopt airworthiness directives to mandate any changes found necessary to address unsafe conditions identified as a result of these reviews.
In evaluating these design reviews, we have established four criteria intended to define the unsafe conditions associated with fuel tank systems that require corrective actions. The percentage of operating time during which fuel tanks are exposed to flammable conditions is one of these criteria. The other three criteria address the failure types under evaluation: Single failures, Single failures in combination with a latent condition(s), and in-service failure experience. For all four criteria, the evaluations included consideration of previous actions taken that may mitigate the need for further action.
We have determined that the actions identified in this AD are necessary to reduce the potential for ignition sources inside fuel tanks caused by latent failures, alterations, repairs, or maintenance actions, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.
Relevant Service Information
We have reviewed the following sections of Boeing 777 Maintenance Planning Data (MPD) Document D622W001-9, Section 9, Revision March 2006 (hereafter referred to as “Revision March 2006 of the MPD”):
- Section D., “AIRWORTHINESS LIMITATIONS—SYSTEMS, FUEL SYSTEMS AIRWORTHINESS LIMITATIONS”; and
- Section E., “PAGE FORMAT: SYSTEMS AIRWORTHINESS LIMITATIONS.”
Those sections of Revision March 2006 of the MPD describe new airworthiness limitations (AWLs) for fuel tank systems. The new AWLs include:
- AWL inspections, which are periodic inspections of certain features for latent failures that could contribute to an ignition source; and
- Critical design configuration control limitations (CDCCL), which are limitation requirements to preserve a critical ignition source prevention feature of the fuel tank system design that is necessary to prevent the occurrence of an unsafe condition. The purpose of a CDCCL is to provide instruction to retain the critical ignition source prevention feature during configuration changes that may be caused by alterations, repairs, or maintenance actions. A CDCCL is not a periodic inspection.
Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.
FAA's Determination and Requirements of the Proposed AD
We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. For this reason, we are proposing this AD, which would require revising the AWL section of the Instructions for Continued Airworthiness by incorporating the information in the service information described previously. The proposed AD also would require the initial performance of certain repetitive inspections specified in the AWLs to phase in those inspections, and repair if necessary.
Explanation of Compliance Time
In most ADs, we adopt a compliance time allowing a specified amount of time after the AD's effective date. In this case, however, the FAA has already issued regulations that require operators to revise their maintenance/inspection programs to address fuel tank safety issues. The compliance date for these regulations is December 16, 2008. To provide for efficient and coordinated implementation of these regulations and this proposed AD, we are using this same compliance date in this proposed AD, instead of the 18-month compliance time recommended by Boeing.
Rework Required When Implementing AWLs Into an Existing Fleet
The AWL revision for the fuel tank systems specified in paragraph (g) of this proposed AD, which involves incorporating the information specified in Revision March 2006 of the MPD, would affect how operators maintain their airplanes. After doing that AWL revision, operators would need to do any maintenance on the fuel tank system as specified in the CDCCLs. Maintenance done before the AWL revision specified in paragraph (g) would not need to be redone in order to comply with paragraph (g). For example, the AWL that requires fuel pumps to be repaired and overhauled per an FAA-approved component maintenance manual (CMM) applies to fuel pumps repaired after the AWLs are revised; spare or on-wing fuel pumps do Start Printed Page 36375not need to be reworked. For AWLs that require repetitive inspections, the initial inspection interval (threshold) starts from the date the AWL revision specified in paragraph (g) is done, except as provided by paragraph (h) of this proposed AD. This proposed AD would require only the AWL revision specified in paragraph (g), and initial inspections specified in paragraph (h). No other fleet-wide inspections need to be done.
Changes to Fuel Tank System AWLs
Paragraph (g) of this proposed AD would require revising the AWL section of the Instructions for Continued Airworthiness by incorporating certain information specified in Revision March 2006 of the MPD into the MPD. Paragraph (g) allows accomplishing the AWL revision in accordance with later revisions of the MPD as an acceptable method of compliance if they are approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. In addition, Section E. of Revision March 2006 of the MPD specifies that any deviations from the published AWL instructions, including AWL intervals, in that MPD must be approved by the Manager, Seattle ACO. Therefore, after the AWL revision, any further revision to an AWL or AWL interval should be done as an AWL change, not as an alternative method of compliance (AMOC). For U.S.-registered airplanes, operators must make requests through an appropriate FAA Principal Maintenance Inspector (PMI) or Principal Avionics Inspector (PAI) for approval by the Manager, Seattle ACO. A non-U.S. operator should coordinate changes with its governing regulatory agency.
Exceptional Short-Term Extensions
Section D. of Revision March 2006 of the MPD has provisions for an exceptional short-term extension of 30 days. An exceptional short-term extension is an increase in an AWL interval that may be needed to cover an uncontrollable or unexpected situation. For U.S.-registered airplanes, the FAA PMI or PAI must concur with any exceptional short-term extension before it is used, unless the operator has identified another appropriate procedure with the local regulatory authority. The FAA PMI or PAI may grant the exceptional short-term extensions described in Section D. without consultation with the Manager, Seattle ACO. A non-U.S. operator should coordinate changes with its governing regulatory agency. As explained in Revision March 2006 of the MPD, exceptional short-term extensions must not be used for fleet AWL extensions. An exceptional short-term extension should not be confused with an operator's short-term escalation authorization approved in accordance with the Operations Specifications or the operator's reliability program.
Ensuring Compliance With Fuel Tank System AWLs
Boeing has revised applicable maintenance manuals and task cards to address AWLs and to include notes about CDCCLs. Operators that do not use Boeing's revision service should revise their maintenance manuals and task cards to highlight actions tied to CDCCLs to ensure that maintenance personnel are complying with the CDCCLs. Appendix 1 of this proposed AD contains a list of Air Transport Association (ATA) sections for the revised maintenance manuals. Operators might wish to use the appendix as an aid to implement the AWLs.
Recording Compliance With Fuel Tank System AWLs
The applicable operating rules of the Federal Aviation Regulations (14 CFR parts 91, 121, 125, and 129) require operators to maintain records with the identification of the current inspection status of an airplane. Some of the AWLs contained in Section E of Revision March 2006 of the MPD are inspections for which the applicable sections of the operating rules apply. Other AWLs are CDCCLs, which are tied to conditional maintenance actions. An entry into an operator's existing maintenance record system for corrective action is sufficient for recording compliance with CDCCLs, as long as the applicable maintenance manual and task cards identify actions that are CDCCLs.
Changes to CMMs Cited in Fuel Tank System AWLs
Some of the AWLs in Section E of Revision March 2006 of the MPD refer to specific revision levels of the CMMs as additional sources of service information for doing the AWLs. Boeing is referring to the CMMs by revision level in the applicable AWL for certain components rather than including information directly in the MPD because of the volume of that information. As a result, the Manager, Seattle ACO, must approve the CMMs. Any later revision of those CMMs will be handled like a change to the AWL itself. Any use of parts (including the use of parts manufacturer approval (PMA) approved parts), methods, techniques, and practices not contained in the CMMs needs to be approved by the Manager, Seattle ACO, or governing regulatory authority. For example, pump repair/overhaul manuals must be approved by the Manager, Seattle ACO.
Changes to AMMs Referenced in Fuel Tank System AWLs
In other AWLs in Section E of Revision March 2006 of the MPD, the AWLs contain all the necessary data. The applicable section of the maintenance manual is usually included in the AWLs. Boeing intended this information to assist operators in maintaining the maintenance manuals. A maintenance manual change to these tasks may be made without approval by the Manager, Seattle ACO, through an appropriate FAA PMI or PAI, by the governing regulatory authority, or by using the operator's standard process for revising maintenance manuals. An acceptable change would have to maintain the information specified in the AWL such as the pass/fail criteria or special test equipment.
Costs of Compliance
There are about 564 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 125 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD at an average labor rate of $80 per work hour.
|Actions||Work hours||Cost per airplane||Fleet cost|
|Maintenance program revision||8||$640||$80,000|
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.
For the reasons discussed above, I certify that the proposed regulation:
1. Is not a “significant regulatory action” under Executive Order 12866;
2. Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and
3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.Start List of Subjects
List of Subjects in 14 CFR Part 39End List of Subjects
The Proposed Amendment
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:Start Part
PART 39—AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
2. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):
Boeing: Docket No. FAA-2007-28389; Directorate Identifier 2006-NM-171-AD.
Comments Due Date
(a) The FAA must receive comments on this AD action by August 17, 2007.
(c) This AD applies to Boeing Model 777-200, -200LR, -300, and -300ER series airplanes; certificated in any category; with an original standard airworthiness certificate or original export certificate of airworthiness issued before June 1, 2006.
Airplanes with an original standard airworthiness certificate or original export certificate of airworthiness issued on or after June 1, 2006, must be already in compliance with the airworthiness limitations specified in this AD because those limitations were applicable as part of the airworthiness certification of those airplanes.
This AD requires revisions to certain operator maintenance documents to include new inspections and maintenance actions. Compliance with these limitations is required by 14 CFR 43.16 and 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by these limitations, the operator may not be able to accomplish the actions described in the revisions. In this situation, to comply with 14 CFR 43.16 and 91.403(c), the operator must request approval for revision to the airworthiness limitations (AWLs) in the Boeing 777 Maintenance Planning Data (MPD) Document D622W001-9 according to paragraph (g) or (i), as applicable, of this AD.
(d) This AD results from a design review of the fuel tank systems. We are issuing this AD to prevent the potential for ignition sources inside fuel tanks caused by latent failures, alterations, repairs, or maintenance actions, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.
(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
(f) The term “Revision March 2006 of the MPD” as used in this AD, means Section 9 of Boeing 777 MPD Document D622W001-9, Revision March 2006.
Revision of AWLs Section
(g) Before December 16, 2008, revise the AWLs section of the Instructions for Continued Airworthiness by incorporating the information in the sections specified in paragraphs (g)(1) and (g)(2) of this AD into the MPD, except that the initial inspections specified in paragraph (h) of this AD must be done at the compliance times specified in paragraph (h) of this AD. Accomplishing the revision in accordance with a later revision of the MPD is an acceptable method of compliance if the revision is approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA.
(1) Section D., “AIRWORTHINESS LIMITATIONS—SYSTEMS, FUEL SYSTEMS AIRWORTHINESS LIMITATIONS,” of Revision March 2006 of the MPD.
(2) Section E., “PAGE FORMAT: SYSTEMS AIRWORTHINESS LIMITATIONS,” of Revision March 2006 of the MPD.
Initial Inspections and Repair
(h) Do the inspections described in paragraphs (h)(1) and (h)(2) of this AD at the compliance times specified in paragraphs (h)(1) and (h)(2); in accordance with the AWLs described in Section E., “PAGE FORMAT: SYSTEMS AIRWORTHINESS LIMITATIONS,” of Revision March 2006 of the MPD. If any discrepancy is found during this inspection, repair the discrepancy before further flight in accordance with Revision March 2006 of the MPD. Accomplishing the actions in accordance with a later revision of the MPD is an acceptable method of compliance if the revision is approved by the Manager, Seattle ACO.
(1) At the later of the times specified in paragraphs (h)(1)(i) and (h)(1)(ii) of this AD, do a detailed inspection of external wires over the center fuel tank for damaged clamps, wire chafing, and wire bundles in contact with the surface of the center fuel tank, and repair any discrepancy; in accordance with 28-AWL-01.
(i) Before the accumulation of 36,000 total flight cycles, or within 120 months since the date of issuance of the original standard airworthiness certificate or the date of issuance of the original export certificate of airworthiness, whichever occurs first.
(ii) Within 72 months after the effective date of this AD.
For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”
(2) At the later of the times specified in paragraphs (h)(2)(i) and (h)(2)(ii) of this AD, do a special detailed inspection (resistance test) of the lightning shield-to-ground termination of the out tank wiring of the fuel quantity indicating system (FQIS) and, as applicable, repair (restore) the bond to ensure the shield-to-ground termination meets specified resistance values; in accordance with 28-AWL-03.
(i) Before the accumulation of 36,000 total flight cycles, or within 120 months since the date of issuance of the original standard Start Printed Page 36377airworthiness certificate or the date of issuance of the original export certificate of airworthiness, whichever occurs first.
(ii) Within 24 months after the effective date of this AD.
For the purposes of this AD, a special detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. The examination is likely to make extensive use of specialized inspection techniques and/or equipment. Intricate cleaning and substantial access or disassembly procedure may be required.”
Alternative Methods of Compliance (AMOCs)
(i)(1) The Manager, Seattle ACO, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.
(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.
|AWL No.||ALI/CDCCL||ATA Section or CMM document 1||Task title||Task|
|28-AWL-01||ALI||AMM 28-11-00/601||External Wires Over the Center Tank—Inspection||28-11-00-210-801.|
|28-AWL-02||CDCCL||SWPM 20-10-11||Wiring Assembly and Installation Configuration.|
|28-AWL-03||ALI||AMM 05-55-54/601||Fuel Quantity Indicator System (FQIS)—Inspection/Check||05-55-54-200-801.|
|28-AWL-04||CDCCL||SWPM 20-10-15||Assemble Shield Ground Wires.|
|28-AWL-05||CDCCL||AMM 28-22-15/401||Install Fuel Line, Fitting and Coupling||28-22-15-400-802-002.|
|28-AWL-06||CDCCL||AMM 29-11-60/401||Install Heat Exchanger||29-11-60-000-801.|
|Bonding Resistances of the Hydraulic Tubes for the Heat Exchanger||29-11-60-765-801.|
|28-AWL-07||CDCCL||CMM 28-20-42, revision 7; CMM 28-20-45, revision 3; CMM 28-20-47, revision 2; or subsequent revisions.|
|28-AWL-08||CDCCL||AMM 28-11-06/401||Install Sump Drain Valve||28-11-06-400-801.|
|28-AWL-10||CDCCL||AMM 28-22-06/401||Install Override/Jettison Pump Motor-Impeller||28-22-06-400-801.|
|Install Override/Jettison Pump Housing||28-22-06-400-802.|
|AMM 28-22-05/401||Install Boost Pump Motor-Impeller||28-22-05-400-801.|
|Install Boost Pump Housing||28-22-05-400-802.|
|28-AWL-11||CDCCL||SWPM 20-10-11||Wiring Assembly and Installation Configuration.|
|28-AWL-12||CDCCL||AMM 28-21-02/401||Install Refuel Valve||28-21-02-400-801.|
|28-AWL-13||CDCCL||CMM 28-47-69, revision 1; CMM 28-47-65, revision 3; or subsequent revisions.|
|28-AWL-14||CDCCL||CMM 28-47-58, revision 4; CMM 28-47-59, revision 1; CMM 28-47-60, revision 4; CMM 28-48-03, revision 2; or subsequent revisions.|
|28-AWL-15||CDCCL||SWPM 20-14-12||Repair FQIS Wire Harness.|
|AMM 28-41-05/401||Install FQIS In-Tank Wire Harness||28-41-05-404-801.|
|28-AWL-16||CDCCL||AMM 28-11-01/401||Install Main Tank Access Door||28-11-01-400-801.|
|AMM 28-11-02/401||Install Center Tank Access Door||28-11-02-400-801.|
|AMM 28-11-07/401||Replace Rubber Door Seal||28-11-07-900-801.|
|AMM 28-11-03/401||Install Surge Tank Access Door||28-11-03-400-801.|
|AMM 28-13-05/401||Install Surge Tank Vent Flame Arrestor||28-13-05-420-801.|
|28-AWL-19||CDCCL||AMM 28-22-02/401||Install Engine Fuel Spar Valve Actuator||28-22-02-400-802.|
|AMM 28-22-01/401||Install Engine Fuel Spar Valve Adapter/Shaft||28-22-01-400-803.|
|AMM 28-22-03/401||Install Engine Fuel Crossfeed Valve Adapter/Shaft||28-22-03-400-803.|
|Start Printed Page 36378|
|AMM 28-22-04/401||Install FWD/AFT Fuel Crossfeed Valve Actuator||28-22-04-400-802.|
|AMM 28-26-01/401||Install Defuel Valve Adapter/Shaft||28-26-01-400-803.|
|AMM 28-26-02/401||Install Defuel Valve Actuator||28-26-02-400-802.|
|AMM 28-31-02/401||Install Fuel Jettison Nozzle Valve Adapter/Shaft||28-31-02-400-801.|
|AMM 28-31-03/401||Install Fuel Nozzle Valve Actuator||28-31-03-400-801.|
|AMM 28-31-04/401||Install Fuel Jettison Isolation Valve Adapter/Shaft||28-31-04-400-803.|
|AMM 28-31-05/401||Install Fuel Jettison Isolation Valve Actuator||28-31-05-400-802.|
|1 CMMs per applicable manufacturer.|
Issued in Renton, Washington, on June 22, 2007.
Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. E7-12835 Filed 7-2-07; 8:45 am]
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