Federal Aviation Administration (FAA), Department of Transportation (DOT).
Notice of proposed rulemaking (NPRM).
The FAA proposes to adopt a new airworthiness directive (AD) for all Boeing Model 707, 720, and 720B series airplanes. This proposed AD would require revising the Limitations section of the airplane flight manual (AFM). The AFM revisions include instructions for monitoring the low pressure lights for the center tank fuel pumps, and a statement prohibiting the resetting of a tripped circuit breaker for a fuel pump in any tank. This proposed AD is prompted by the results of fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent dry operation of the fuel pumps in the center fuel tank, which could result in high temperatures or sparks inside the fuel tank, ignition of fuel vapors, and consequent fire or explosion. We are also issuing this AD to prohibit the resetting of a tripped circuit breaker for a fuel pump in any tank, which could allow an electrical fault to override the protective features of the circuit breaker, and result in sparks inside the fuel tank, ignition of fuel vapors, and consequent fire or explosion.
We must receive comments on this proposed AD by May 16, 2005.
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: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, Washington, DC 20590.
- By fax: (202) 493-2251.
- Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
You can examine the contents of this AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC. This docket number is FAA-2005-20785; the directorate identifier for this docket is 2005-NM-002-AD.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Sulmo Mariano, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6501; 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 under ADDRESSES. Include “Docket No. FAA-2005-20785; Directorate Identifier 2005-NM-002-AD” in the subject line 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 submitted by the closing date and 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 website, 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 Start Printed Page 16768comment on behalf of an association, business, labor union, etc.). You can review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.
Examining the Docket
You can examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.
The FAA has examined the underlying safety issues involved in recent 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.
As a result of the fuel system reviews associated with SFAR 88, the airplane manufacturer has determined that, if the fuel pumps in the center fuel tank of Boeing Model 707, 720, and 720B series airplanes are allowed to run when the fuel quantity is low, high temperatures or sparks caused by metal-to-metal contact may occur, resulting in an ignition source for fuel vapors and consequent fire or explosion. The airplane manufacturer has also determined that, if a tripped circuit breaker for a fuel pump in any tank is reset, an ignition source may be created in the fuel tank. The tripping of a circuit breaker indicates an electrical fault, and resetting the circuit breaker may result in the electrical fault overriding the protective features of the circuit breaker, resulting in sparks inside the fuel tank, an ignition source for fuel vapors, and consequent fire or explosion.
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. Therefore, we are proposing this AD, which would require revising the Limitations section of the airplane flight manual. The AFM revisions include instructions for monitoring the low pressure lights for the center tank fuel pumps, and a statement prohibiting the resetting of a tripped fuel pump circuit breaker.
Costs of Compliance
There are about 225 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.
|Action||Work hours||Average labor rate per hour||Parts||Cost per airplane||Number of U.S.-registered airplanes||Fleet cost|
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. Start Printed Page 16769
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. See the ADDRESSES section for a location to examine the regulatory evaluation.Start List of Subjects
List of Subjects in 14 CFR Part 39
- Air transportation
- Aviation 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:Start Part
PART 39—AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):
Boeing: Docket No. FAA-2005-20785; Directorate Identifier 2005-NM-002-AD.
Comments Due Date
(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by May 16, 2005.
(c) This AD applies to all Boeing Model 707, 720, and 720B series airplanes, certificated in any category.
(d) This AD was prompted by the results of fuel system reviews conducted by the manufacturer. We are issuing this AD to prevent dry operation of the fuel pumps in the center fuel tank, which could result in high temperatures or sparks inside the fuel tank, ignition of fuel vapors, and consequent fire or explosion. We are also issuing this AD to prohibit the resetting of a tripped circuit breaker for a fuel pump in any tank, which could allow an electrical fault to override the protective features of the circuit breaker, and result in sparks inside the fuel tank, ignition of fuel vapors, and consequent fire or explosion.
(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.
Airplane Flight Manual (AFM) Revisions
(f) Within 30 days after the effective date of this AD: Revise the Limitations section of the Boeing 707 Airplane Flight Manual to include the following information. This may be done by inserting a copy of this AD into the AFM. Thereafter, operate the airplane in accordance with the limitations specified in these AFM revisions.
“OPERATION WITH BOOST PUMPS INOPERATIVE. For ground and flight operations, a fuel pump circuit breaker which has tripped must not be reset.
CENTER TANK FUEL PUMPS. Center tank fuel pumps must not be ‘ON’ unless personnel are available in the flight deck to monitor the low pressure lights.
Each center tank fuel pump switch must be positioned to ‘OFF’ without delay when the respective center tank fuel pump low pressure light illuminates.”
When information identical to that in paragraph (f) of this AD has been included in the general revision of the AFM, the general revision may be inserted into the AFM, and the copy of this AD may be removed from the AFM.
Actions Accomplished Previously
(g) Incorporation of the information in Approval Reference Number 045151 of the Boeing Model 707 Airplane Flight Manual is considered acceptable for compliance with the corresponding action specified in this AD.
Alternative Methods of Compliance (AMOCs)
(h) The Manager, Seattle Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.
Issued in Renton, Washington, on March 23, 2005.
Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 05-6448 Filed 3-31-05; 8:45 am]
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