05-1587. Airworthiness Directives; Boeing Model 757-200, -200PF, and -300 Series Airplanes, Powered by Pratt & Whitney PW2000 Series Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 757 series airplanes. This proposed AD would require repetitive inspections for loose or damaged components of the support brackets and associated fasteners for the hydraulic lines located in the nacelle struts, and any related investigative and corrective actions. This proposed AD is prompted by reports of damage and subsequent failure of the support brackets and associated fasteners for the hydraulic lines located internal to the upper fairing cavity of the nacelle struts. We are proposing this AD to prevent flammable fluids from leaking into the interior compartment of the nacelle struts where ignition sources exist, which could result in the ignition of flammable fluids and an uncontained fire.

DATES:

We must receive comments on this proposed AD by March 14, 2005.

ADDRESSES:

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: [phone].
• 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.

For service information identified in this proposed AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

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.

FOR FURTHER INFORMATION CONTACT:

Technical information: Tom Thorson, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

Plain language information: Marcia Walters, [e-mail].

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

The FAA has implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, new AD actions are posted on DMS and assigned a docket number. We track each action and assign a corresponding directorate identifier. The DMS AD docket number is in the form “Docket No. FAA-2004-99999.” The Transport Airplane Directorate identifier is in the form “Directorate Identifier 2004-NM-999-AD.” Each DMS AD docket also lists the directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

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-2005-20137; Directorate Identifier 2004-NM-96-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 comment 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.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/​language and http://www.plainlanguage.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 [phone]) 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.

Discussion

We have received reports of damage and subsequent failure of the support brackets and associated fasteners for the hydraulic lines located internal to the upper fairing cavity of the nacelle struts. These failures occurred on certain Model 757 series airplanes powered by Pratt & Whitney PW2000 series engines. These failures resulted in damage to the adjacent fuel lines and fuel leaks in the engine strut due to a fastener migrating through a support bracket and retainer channel, allowing the fastener to wear through the fuel supply tube. The hydraulic lines supply pressure from the hydraulic pumps to the airframe and are subject to high frequency pressure oscillations/vibrations. Investigation by the manufacturer revealed that the operating pressure and surge loads from the hydraulic pumps are higher than originally expected and exceed the capability of the design for the support bracket structure.

The hydraulic lines are located in the upper fairing compartment of the nacelle struts. The upper fairing compartment is a flammable leakage zone and is isolated from other strut compartments by a protective vapor barrier. The vapor barrier acts as a seal to keep flammable fluids and vapors from hydraulic and fuel line leaks out of the interior portion of the strut where pneumatic bleed air ducts are located. The surface temperature of the bleed air ducts is hot enough to be an ignition source. The reported condition of sheared or loose fasteners, or damage to the strut webs adjacent to the support brackets and associated fasteners, compromises the vapor barrier, which in turn could allow flammable fluids to leak into the interior compartments of the nacelle struts. Such a condition, if not corrected, could result in ignition of flammable fluids and an uncontained fire.

Relevant Service Information

We have reviewed Boeing Service Bulletins 757-29-0064 (for Model 757-200 and -200PF series airplanes) and 757-29-0065 (for Model 757-300 series airplanes), both dated February 29, 2004. The service bulletins describe procedures for repetitive detailed inspections for loose or damaged components of the support brackets and associated fasteners for the hydraulic lines located in the nacelle struts, and related investigative and corrective actions. Evidence of damage includes excessive wear, fatigue cracks, or elongated fastener holes in the strut webs. If no damaged or loose parts are found, the service bulletins specify repeating the inspection of the support brackets and associated fasteners for the hydraulic lines at the intervals specified.

The procedures for the related investigative and corrective actions include:

• Inspecting the fuel and hydraulic lines and strut webs for evidence of damage (e.g., chafing or holes) caused by a loose support bracket or line.
• Replacing or repairing damaged fuel lines.
• Replacing damaged hydraulic lines with new lines.
• Repairing damaged areas of the strut webs.
• Contacting the manufacturer for damage that is beyond the repair limitations specified in the service bulletin.
• Replacing damaged components with new, improved nickel alloy components.

The service bulletin also includes procedures for a functional test of the hydraulic and fuel systems.

Service Bulletin 757-29-0064 recommends prior or concurrent accomplishment of Boeing Service Bulletin 757-29-0043, dated June 21, 1990. Service Bulletin 757-29-0043 describes procedures for replacing aluminum brackets, retainer channels, and attachment hardware for the hydraulic lines located in the nacelle struts. Service Bulletin 757-29-0043 also describes procedures for replacing certain fuel and hydraulic lines with new lines if necessary.

Accomplishing the actions specified in the service information is intended to adequately address the identified 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. Therefore, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously, except as discussed under “Difference Between the Service Bulletins and Proposed AD.”

Difference Between the Service Bulletins and Proposed AD

Although the service bulletins specify that operators may contact the manufacturer for disposition of certain repair conditions, this proposed AD would require operators to repair those conditions per a method approved by the FAA.

Costs of Compliance

This proposed AD would affect about 432 airplanes worldwide and 377 airplanes of U.S. registry. The proposed inspection/test would take about 35 work hours per airplane (including access and close-up), at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $857,675, or $2,275 per airplane, per inspection/test cycle.

Authority for This Rulemaking

The FAA's authority to issue rules regarding aviation safety is found in Title 49 of the United States Code. 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.

This rulemaking is promulgated under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, the FAA is charged with promoting safety 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 proposed AD.

Regulatory Findings

We have determined that this proposed AD will not have federalism implications under Executive Order 13132. This proposed AD will 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. See the ADDRESSES section for a location to examine the regulatory evaluation.

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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2005-20137; Directorate Identifier 2004-NM-96-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by March 14, 2005.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 757-200, -200PF, and -300 series airplanes; powered by Pratt & Whitney PW2000 series engines; certificated in any category.

Unsafe Condition

(d) This AD was prompted by reports of damage and subsequent failure of the support brackets and associated fasteners for the hydraulic lines located internal to the upper fairing cavity of the nacelle struts. We are issuing this AD to prevent flammable fluids from leaking into the interior compartment of the nacelle struts where ignition sources exist, which could result in the ignition of flammable fluids and an uncontained fire.

Compliance

(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.

Repetitive Inspections

(f) Within 6,000 flight hours or 18 months after the effective date of this AD, whichever is first: Do a detailed inspection for loose or damaged components of the support brackets and associated fasteners for the hydraulic lines located in the nacelle struts by accomplishing all of the actions specified in Part 1, Part 2, and Part 3 of the Accomplishment Instructions of Boeing Service Bulletin 757-29-0064 (for Model 757-200 and -200PF series airplanes) or Boeing Service Bulletin 757-29-0065 (for Model 757-300 series airplanes), both dated February 29, 2004; as applicable. Repeat the inspection thereafter at intervals not to exceed 6,000 flight hours or 18 months, whichever is first.

Note 1:

For the purposes of this AD, a detailed inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

Concurrent Service Bulletin

(g) Prior to or concurrently with the accomplishment of paragraph (f) of this AD: Accomplish all of the actions specified in the Accomplishment Instructions of Boeing Service Bulletin 757-29-0043, dated June 21, 1990.

Related Investigative and Corrective Actions

(h) Except as required by paragraph (i) of this AD: If any loose or damaged parts are found during any inspection required by paragraph (f) of this AD, before further flight, do all of the related investigative and corrective actions specified in Part 1 and Part 2 of the Accomplishment Instructions of Boeing Service Bulletin 757-29-0064, or Boeing Service Bulletin 757-29-0065, both dated February 29, 2004; as applicable.

Repair Information

(i) If any damage is found during any inspection required by this AD, and the service bulletin specifies contacting Boeing for appropriate action: Before further flight, repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. For a repair method to be approved, the approval letter must specifically refer to this AD.

Note 2:

There is no terminating action currently available for the repetitive inspections required by paragraph (f) of this AD.

Alternative Methods of Compliance (AMOCs)

(j) 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.

Issued in Renton, Washington, on January 18, 2005.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.