Airworthiness Directives; McDonnell Douglas Model 717-200 Airplanes; Model DC-9-10 Series Airplanes; Model DC-9-20 Series Airplanes; Model DC-9-30 Series Airplanes; Model DC-9-40 Series Airplanes; Model DC-9-50 Series Airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) Airplanes; Model MD-88 Airplanes; and Model MD-90-30 Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for all McDonnell Douglas airplanes identified above. This proposed AD would require revising the FAA-approved maintenance program, or the Airworthiness Limitations (AWLs) section of the Instructions for Continued Airworthiness, as applicable, to incorporate new AWLs for fuel tank systems to satisfy Special Federal Aviation Regulation No. 88 requirements. 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 a fuel tank explosion and consequent loss of the airplane.

DATES:

We must receive comments on this proposed AD by March 3, 2008.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: 202-493-2251.
• 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.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this AD, contact Boeing Commercial Airplanes, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Data and Service Management, Dept. C1-L5A (D800-0024).

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov;; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (telephone 800-647-5527) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Serj Harutunian, Aerospace Engineer, Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5254; fax (562) 627-5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2008-0032; Directorate Identifier 2007-NM-314-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

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 another 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 proposed AD are necessary to reduce the potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of the airplane.

Relevant Service Information

We have reviewed the following appendixes of the Boeing Twinjet Special Compliance Items Report, MDC-92K9145, Revision G, dated June 7, 2007 (hereafter referred to as “Report MDC-92K9145”):

• Appendix B, Critical Design Configuration Control Limitations (CDCCLs)
• Appendix C, Airworthiness Limitation Instructions (ALIs)
• Appendix D, Short-Term Extensions

Appendixes B and C of Report MDC-92K9145 describe new airworthiness limitations (AWLs) for fuel tank systems. The new AWLs include:

• CDCCLs, 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 change that may be caused by alterations, repairs, or maintenance actions. A CDCCL is not a periodic inspection; and
• AWL inspections, which are inspections of certain features for latent failures that could contribute to an ignition source.

FAA's Determination and Requirements of This Proposed AD

We are proposing this AD because we evaluated all relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the(se) same type design(s). This proposed AD would require revising the FAA-approved maintenance program, or the AWLs section of the Instructions for Continued Airworthiness, as applicable, by incorporating the information in Appendixes B, C, and D of Report MDC-92K9145.

Difference Between the Proposed AD and Service Information

Although Report MDC-92K9145 specifies to submit certain information to the manufacturer, this proposed AD does not include that requirement.

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.

Rework Required When Implementing AWLs Into an Existing Fleet

The maintenance program revision specified in paragraph (g) of this proposed AD, and the AWLs revision specified in paragraph (h) of this proposed AD, for the fuel tank systems, which involve incorporating the information specified in Report MDC-92K9145, would affect how operators maintain their airplanes. After doing the maintenance program revision or AWLs revision, as applicable, operators would need to do any maintenance on the fuel tank system as specified in the CDCCLs. Maintenance done before the maintenance program revision specified in paragraph (g), or the AWLs revision specified in paragraph (h), as applicable, would not need to be redone in order to comply with paragraph (g) or (h). For example, the AWL that requires fuel pumps to be repaired and overhauled per the FAA-approved component maintenance manual (CMM) applies to fuel pumps repaired after the maintenance programs are revised; spare or on-wing fuel pumps do not need to be reworked.

Changes to Fuel Tank System AWLs

For certain airplanes, paragraph (g) of this proposed AD would require revising the FAA-approved maintenance program by incorporating certain information specified in Report MDC-92K9145. For certain other airplanes, paragraph (h) of this proposed AD would require revising the AWLs section of the Instructions for Continued Airworthiness by incorporating certain information specified in Report MDC-92K9145. Paragraphs (g) and (h) allow accomplishing the revision in accordance with later revisions of Report MDC-92K9145 as an acceptable method of compliance if they are approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA. In addition, Appendix B of Report MDC-92K9145 specifies that any deviations from the published AWL instructions, including AWL intervals, must be approved by the Manager, Los Angeles ACO. Therefore, after the maintenance program or AWLs 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, Los Angeles ACO. A non-U.S. operator should coordinate changes with its governing regulatory agency.

Exceptional Short-Term Extensions

Appendix D of Report MDC-92K9145 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 Appendix D without consultation with the Manager, Los Angeles ACO. A non-U.S. operator should coordinate changes with its governing regulatory agency. As explained in Appendix D, 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 the 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.

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. The AWLs contained in Appendix C of Report MDC-92K9145 are inspections for which the applicable sections of the operating rules apply. The AWLs contained in Appendix B of Report MDC-92K9145 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 Component Maintenance Manuals (CMMs) Cited in Fuel Tank System AWLs

Some of the AWLs in Appendix B of Report MDC-92K9145 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 AWL because of the volume of that information. As a result, the Manager, Los Angeles 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 need to be approved by the Manager, Los Angeles ACO, or governing regulatory authority. For example, certain pump repair/overhaul manuals must be approved by the Manager, Los Angeles ACO.

Changes to Airplane Maintenance Manual Referenced in Fuel Tank System AWLs

In other AWLs in Report MDC-92K9145, 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, Los Angeles 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

We estimate that this proposed AD would affect 780 airplanes of U.S. registry. We also estimate that it would take about 1 work-hour per product to comply with this proposed AD. The average labor rate is $80 per work-hour. Based on these figures, we estimate the cost of this proposed AD to the U.S. operators to be $62,400, or $80 per product.

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.

Regulatory Findings

We 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 this 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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.