Airworthiness Directives; The Boeing Company Model 767 Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain Model 767 airplanes. This proposed AD would require installing new panel assemblies in the main equipment center and removing certain relays from some panels in the main equipment center. This proposed AD would also require revising the maintenance program to incorporate airworthiness limitations (AWLs) No. 28-AWL-27 and No. 28-AWL-28. This proposed AD results from fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent possible sources of ignition in a fuel tank caused by electrical fault or uncommanded dry operation of the main tank boost pumps and center auxiliary tank override and jettison pumps. An ignition source in the fuel tank could result in a fire or an explosion and consequent loss of the airplane.

DATES:

We must receive comments on this proposed AD by February 12, 2010.

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 proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-544-5000, extension 1; fax 206-766-5680; e-mail me.boecom@boeing.com; Internet https://www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221 or 425-227-1152.

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:

Louis Natsiopoulos, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6478; fax (425) 917-6590.

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-2009-1221; Directorate Identifier 2008-NM-097-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” (67 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 AD are necessary to reduce the potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.

Boeing advised us that wiring deterioration or damage in the main tank boost pumps or center auxiliary tank override and jettison pumps can result in electrical faults. Internal electrical faults in the pump or inside the pump wire bundle conduit could cause an ignition source in the fuel tank from an overheat condition or electrical arcs. There is also a safety concern that the center auxiliary tank override and jettison pumps might continue to operate dry for an extended period due to electrical faults or a single failure in the pump switch. The extended dry operation of the pump could cause overheating, electrical arcs, or frictional sparks in the fuel tank. An ignition source in the fuel tank could result in a fire or an explosion and consequent loss of the airplane.

Other Related Rulemaking

On May 8, 2008, we issued AD 2008-11-01, amendment 39-15523 (73 FR 29414, May 21, 2008), for certain Model 767-200, -300, -300F, and -400ER series airplanes. That AD requires revising the maintenance program to incorporate new airworthiness limitations (AWLs) for fuel tank systems to satisfy Special Federal Aviation Regulation No. 88 requirements. That AD also requires an initial inspection to phase in certain repetitive AWL inspections, and repair if necessary. That AD resulted from a design review of the fuel tank systems. We issued that 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. Incorporating AWLs No. 28-AWL-27 and No. 28-AWL-28 into the maintenance program in accordance with paragraph (g)(2) of AD 2008-11-01 would terminate the action required by paragraph (h) of this proposed AD.

On July 24, 2009, we issued AD 2009-16-06, amendment 39-15989 (74 FR 38905, August 5, 2009), for all Model 767 airplanes. That AD requires installing an automatic shutoff system for the auxiliary fuel tank override/jettison fuel pumps (also referred to as center tank fuel pumps in the airplane flight manual (AFM)), revising the AFM to advise the flightcrew of certain operating restrictions for airplanes equipped with an automatic auxiliary fuel tank pump shutoff control, and, for certain airplanes, installing a placard to alert the flightcrew of certain fuel usage restrictions. That AD provides optional terminating actions for certain requirements. That AD results from a design review of the fuel tank systems. We issued that AD to prevent an overheat condition outside the center tank fuel pump explosion-resistance area that is open to the pump inlet, which could cause an ignition source for the fuel vapors in the fuel tank and result in fuel tank explosions and consequent loss of the airplane. That AD requires installing the automatic shutoff system in accordance with Boeing Service Bulletin 767-28A0083, Revision 2, dated February 12, 2009, for Model 767-200, -300, and -300F series airplanes; or Boeing Service Bulletin 767-28A0084, Revision 1, dated April 26, 2007, for Model 767-400ER series airplanes. Those service bulletins would be required to be done prior to or concurrently with the installation of the panel assemblies proposed in this NPRM.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 767-28A0085, dated January 10, 2008; and Boeing Service Bulletin 767-28A0085, Revision 1, dated June 25, 2009. Those service bulletins describe procedures for installing new P140 and P141 panel assemblies (including all applicable parts and components) in the main equipment center and removing certain relays. Applicable parts and components include, but are not limited to, support brackets and wiring supports. Removing certain relays involves removing the fuel boost pump control relays from the P33, P36, and P37 panels.

Boeing Alert Service Bulletin 767-28A0085 specifies that installing an automatic shutoff system for the auxiliary fuel tank pump specified in Boeing Service Bulletin 767-28A0083 should be done before or at the same time as installing the new P140 and P141 panel assemblies.

Boeing Service Bulletin 767-28A0085, Revision 1, dated June 25, 2009, adds Boeing Service Bulletin 767-28A0084 to the concurrent requirements described above, includes information derived from a service bulletin validation process, and corrects some part numbers and work-hour estimates provided in Boeing Alert Service Bulletin 767-28A0085, dated January 10, 2008.

We have also reviewed Section 9 (“AIRWORTHINESS LIMITATIONS (AWLs) AND CERTIFICATION MAINTENANCE REQUIREMENTS (CMRs)”) of the Boeing 767 Maintenance Planning Data (MPD) Document, D622T001-9, Revision March 2009 (hereafter referred to as “the MPD”). Subsection E of the MPD contains fuel system AWL No. 28-AWL-27 that specifies, for certain airplanes, repetitive operational testing of the main fuel tank boost pumps and all ground fault indication (GFI) control relays for the center auxiliary tank override/jettison fuel pump. Subsection E of the MPD also contains fuel system AWL No. 28-AWL-28, that specifies, for certain airplanes, repetitive functional testing of the center auxiliary fuel tank override/jettison fuel pump uncommanded-on system.

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 same type design. This proposed AD would require the following actions:

• Installing new P140 and P141 panel assemblies and all applicable parts and components in the main equipment center and removing certain relays.
• Installing an automatic shutoff system for the center wing tank override boost pumps before or concurrently with the installation of the new P140 and P141 panel assemblies.
• Revising the maintenance program to incorporate AWL No. 28-AWL-27 that specifies, for certain airplanes, repetitive operations testing of the main fuel tank boost pumps and all GFI control relays for the center auxiliary tank override/jettison fuel pump.
• Revising the maintenance program to incorporate AWL No. 28-AWL-28, that specifies, for certain airplanes, repetitive functional testing of the uncommanded-on system for the override/jettison fuel pump of the center auxiliary fuel tank.

Costs of Compliance

We estimate that this proposed AD would affect 416 airplanes of U.S. registry. The following table provides the estimated costs, at an average labor rate of $80 per work-hour, for U.S. operators to comply with this proposed AD.

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
• Incorporation by reference
• 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.