Daily Rules, Proposed Rules, and Notices of the Federal Government
You may examine the AD docket on the Internet at
We invite you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the
We will post all comments we receive, without change, to
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
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 proposed 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.
A fuel pump may cause an ignition source in a fuel tank when it has internal electrical faults, or when the pump overheats due to prolonged dry running in an empty fuel tank. Electrical faults inside fuel pumps may cause arcing and burn through the pump housing. Electrical arcs entering an empty fuel tank may cause the fuel vapors to ignite. If a pump is not shut off in a timely manner when the tank is emptied, the dry-running pump may cause excessive heat and become an ignition source inside the tank.
During the SFAR 88 safety assessment, it was determined that each electrically powered fuel pump installed in the center wing tank and/or auxiliary fuel tank must have a protective device installed to detect electrical faults, which can cause arcing and burn-through of the fuel pump housing. That same device must shut off the pump by automatically removing electrical power from the pump when such faults are detected. It was also determined that design features must be added to detect when a center wing tank or auxiliary tank is emptied such that each pump is manually or automatically shut off within 60 seconds after it is emptied. The design features must also preclude undetected running of a fuel pump in an empty tank, after the pump was commanded off manually or automatically. The design features must also ensure that a fuel pump cannot be shut off due to system failures sooner than a specified length of time.
We are proposing this AD because we evaluated all the 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 prohibit operation of an affected airplane as of 60 months after the effective date of the AD, unless an amended type certificate or supplemental type certificate that incorporates the following design features and requirements has been approved by the FAA, and those design features are installed on the airplane.
• A protective device for each electrically powered fuel pump that will detect electrical faults and shut off the pump automatically when such faults are detected
• Additional design features to detect any center wing tank or auxiliary fuel tank pump running in an empty fuel tank and to shut off each pump within a specified time
• Means to ensure that a fuel pump cannot be shut off due to system failures sooner than a specified length of time.
This proposed AD would also prohibit operation of any airplane affected by this AD unless the FAA-approved design features specified in the certification plans are installed within a specified time.
We estimate that this proposed AD affects 1,288 airplanes of U.S. registry. We estimate the following costs to comply with this proposed AD:
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 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
(3) Will not affect intrastate aviation in Alaska, and
(4) 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.
Air transportation, Aircraft, Aviation safety, Incorporation by Reference, Safety.
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:
1. The authority citation for part 39 continues to read as follows:
49 U.S.C. 106(g), 40113, 44701.
2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):
We must receive comments by December 29, 2011.
This AD applies to The Boeing Company airplanes, certificated in any category, as identified in paragraphs (c)(1) through (c)(8) of this AD, and equipped with auxiliary fuel tanks.
(1) Model DC-9-11, DC-9-12, DC-9-13, DC-9-14, DC-9-15, and DC-9-15F airplanes.
(2) Model DC-9-21 airplanes.
(3) Model DC-9-31, DC-9-32, DC-9-32 (VC-9C), DC-9-32F, DC-9-33F, DC-9-34, DC-9-34F, and DC-9-32F (C-9A, C-9B) airplanes.
(4) Model DC-9-41 airplanes.
(5) Model DC-9-51 airplanes.
(6) Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) airplanes.
(7) Model MD-88 airplanes.
(8) Model MD-90-30 airplanes.
Joint Aircraft System Component (JASC)/Air Transport Association (ATA) of America Code 28: Fuel.
This AD was prompted by fuel system reviews conducted by the manufacturer. We are issuing this AD 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.
Comply with this AD within the compliance times specified, unless already done.
As of 60 months after the effective date of this AD, no person may operate any airplane affected by this AD unless an amended type certificate or supplemental type certificate that incorporates the design features and requirements described in paragraphs (g)(1), (g)(2), and (g)(3) of this AD has been approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, and those design features are installed on the airplane.
(1) Each electrically powered fuel pump installed in the center wing tank or auxiliary fuel tank must have a protective device installed to detect electrical faults that can cause arcing and burn through the fuel pump housing. The same device must shut off the pump by automatically removing electrical power from the pump when such faults are detected. When a fuel pump is shut off as the result of detection of an electrical fault, the device must stay latched off until the fault is cleared through maintenance action and verified that the pump and the electrical power feed is safe for operation.
(2) Additional design features must be installed to detect when any center wing tank or auxiliary fuel tank pump is running in an empty fuel tank. The prospective pump shutoff system must shut off each pump no later than 60 seconds after the fuel tank is emptied. The pump shutoff system design must preclude undetected running of a fuel pump in an empty tank, after the pump was commanded off manually or automatically.
(3) The implementation of the design features defined in paragraphs (g)(1) and (g)(2) of this AD must ensure that a fuel pump cannot be shut off due to system failures including nuisance shutoffs sooner than 100,000 hours' mean time between failures (MTBF).
(1) The Manager, Los Angeles ACO, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in the Related Information section of this AD.
(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.
For more information about this AD, contact Serj Harutunian, Aerospace Engineer, Propulsion Branch, ANM-140L, FAA, Los Angeles ACO, 3960 Paramount Boulevard, Lakewood, California 90712-4137; phone: (562) 627-5254; fax: (562) 627-5210; email: