2011-1119. Airworthiness Directives; The Boeing Company Model 777-200 and -300 Series Airplanes Equipped With Pratt and Whitney Engines

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 777-200 and -300 series airplanes. This proposed AD would require repetitive inspections for hydraulic fluid contamination of the interior of the strut disconnect assembly; repetitive inspections for discrepancies of the interior of the strut disconnect assembly, if necessary; repetitive inspections of the exterior of the strut disconnect assembly for cracks, if necessary; and corrective action if necessary. This proposed AD also provides an optional terminating action for the inspections. This proposed AD results from reports of system disconnect boxes that have been contaminated with hydraulic fluid and, in one incident, led to subsequent cracking of titanium parts in the system disconnect assembly. We are proposing this AD to detect and correct hydraulic fluid contamination, which can cause cracking of titanium parts in the system disconnect assembly, resulting in compromise of the engine firewall. A cracked firewall can allow fire in the engine area to enter the strut and can lead to an uncontained engine strut fire if flammable fluid is present. Cracking of the disconnect box may also reduce the effectiveness of the fire extinguishing system in the engine compartment and could contribute to an uncontained engine fire. In addition, a cracked disconnect box can leak flammable fluids into the engine core, which can initiate an engine fire, and lead to one or both fire conditions discussed above.

DATES:

We must receive comments on this proposed AD by March 7, 2011.

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: [phone].
• 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 [phone], extension 1; fax [phone]; e-mail [e-mail]; 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.

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 [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Kevin Nguyen, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

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-2011-0026; Directorate Identifier 2010-NM-104-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

We have received reports of system disconnect boxes that have been contaminated with hydraulic fluid. One operator has found cracks in the system disconnect assembly bulkheads and lower skin panel. Subsequent analysis at Boeing found hydrogen enbrittlement of the system disconnect assembly bulkheads and lower skin panel. The system disconnect assembly is made from titanium and is located near the hot engine core of the engine where temperatures can exceed 270 degrees Fahrenheit. The presence of hydraulic fluid and temperature above 270 degrees Fahrenheit can result in hydrogen embrittlement of the titanium system disconnect assembly. Hydrogen embrittlement combined with a high sonic vibration environment can result in cracking of the system disconnect assembly. The system disconnect assembly is a box where hydraulic, fuel, and electrical connections are made between the engine and the strut. This box acts as a firewall between the engine compartment and the strut. The engine compartment has a fire extinguishing system while the strut does not. The strut is considered a flammable leakage zone where flammable fluids may be present. These fluids are subsequently drained from the strut and system disconnect box. A cracked firewall can allow fire in the engine area to enter the strut and can lead to an uncontained engine strut fire if flammable fluid is present. Cracking of the disconnect box may also reduce the effectiveness of the fire extinguishing system in the engine compartment and could contribute to an uncontained engine fire. In addition, a cracked disconnect box can leak flammable fluids into the engine core, which can initiate an engine fire, and lead to one or both fire conditions discussed above.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 777-54A0024, Revision 1, dated November 4, 2010. This service bulletin describes procedures for doing repetitive general visual inspections for hydraulic fluid contamination of the interior of the strut disconnect assembly; repetitive detailed inspections for discrepancies (e.g., hydraulic fluid coking, heat discoloration, cracks, and etching or pitting) of the interior of the strut disconnect assembly, if certain conditions are found; repetitive detailed inspections of the exterior of the strut disconnect assembly for cracks; and corrective action, if certain conditions are found. The corrective action is replacing the titanium system disconnect assembly with an Inconel system disconnect assembly. If accomplished, the replacement will eliminate the potential for hydrogen embrittlement and subsequent cracking, and would eliminate the need for the inspections of the titanium strut disconnect assembly.

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 these same type designs. This proposed AD would require accomplishing the actions specified in the service information described previously.

Costs of Compliance

We estimate that this proposed AD would affect 53 airplanes of U.S. registry. We also estimate that it would take about 48 work-hours per product to comply with this proposed AD. The average labor rate is $85 per work-hour. Required parts would cost about $122,617 per product. Based on these figures, we estimate the cost of this proposed AD to the U.S. operators to be $6,714,941, or $122,697 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
• 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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new AD:

The Boeing Company: Docket No. FAA-2011-0026; Directorate Identifier 2010-NM-104-AD.

Comments Due Date

(a) We must receive comments by March 7, 2011.

Affected ADs

(b) None.

Applicability

(c) This AD applies to The Boeing Company Model 777-200 and -300 series airplanes, certificated in any category; equipped with Pratt and Whitney engines; as identified in Boeing Alert Service Bulletin 777-54A0024, Revision 1, dated November 4, 2010.

Subject

(d) Air Transport Association (ATA) of America Code 54: Nacelles/Pylons.

Unsafe Condition

(e) This AD results from reports of system disconnect boxes that have been contaminated with hydraulic fluid, in which one case a crack was found. The Federal Aviation Administration is issuing this AD to detect and correct hydraulic fluid contamination, which can cause cracking of titanium parts in the system disconnect assembly, resulting in compromise of the engine firewall. A cracked firewall can allow fire in the engine area to enter the strut and can lead to an uncontained engine strut fire if flammable fluid is present. Cracking of the disconnect box may also reduce the effectiveness of the fire extinguishing system in the engine compartment and could contribute to an uncontained engine fire. In addition, a cracked disconnect box can leak flammable fluids into the engine core, which can initiate an engine fire and lead to one or both fire conditions discussed above.

Compliance

(f) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Inspections and Corrective Actions

(g) Within 12 months after the effective date of this AD: Do a general visual inspection for hydraulic fluid contamination of the interior of the strut disconnect assembly, in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-54A0024, Revision 1, dated November 4, 2010.

(1) For airplanes on which no hydraulic fluid contamination is found (Condition 1): Repeat the general visual inspection required by paragraph (g) of this AD thereafter at intervals not to exceed 6,000 flight cycles or 750 days, whichever occurs first.

(2) For airplanes on which hydraulic fluid contamination is found (Condition 2): Before further flight, do a detailed inspection for discrepancies (e.g., hydraulic fluid coking, heat discoloration, cracks, and etching or pitting) of the interior of the strut disconnect assembly, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-54A0024, Revision 1, dated November 4, 2010.

(i) For airplanes on which no discrepancy is found during the inspection required by paragraph (g)(2) of this AD (Condition 2A): Repeat the detailed inspection required by paragraph (g)(2) of this AD thereafter at intervals not to exceed 6,000 flight cycles or 750 days, whichever occurs first.

(ii) For airplanes on which hydraulic fluid coking or heat discoloration is found but no cracking, etching, or pitting is found during the inspection required by paragraph (g)(2) of this AD (Condition 2B): Do the actions required by paragraph (g)(2)(ii)(A) and (g)(2)(ii)(B) of this AD.

(A) Within 300 flight cycles after doing the inspection required by paragraph (g)(2) of this AD: Do a detailed inspection of the exterior of the strut disconnect assembly for cracks, in accordance with Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-54A0024, Revision 1, dated November 4, 2010; and repeat the detailed inspection thereafter at intervals not to exceed 300 flight cycles.

(B) Within 6,000 flight cycles or 750 days after hydraulic fluid coking and/or heat discoloration was found during the inspection required by paragraph (g)(2) of this AD, whichever occurs first: Replace the titanium system disconnect assembly with an Inconel system, in accordance with Part 4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-54A0024, Revision 1, dated November 4, 2010.

(h) For airplanes on which any crack, etching, or pitting is found during any inspection required by paragraph (g)(2) or (g)(2)(ii)(A) of this AD (Condition 3): Before further flight, replace the titanium system disconnect assembly with an Inconel system, in accordance with Part 4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-54A0024, Revision 1, dated November 4, 2010.

Optional Terminating Action

(i) Replacing the titanium system disconnect assembly with an Inconel system disconnect assembly in accordance with Part 4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-54A0024, Revision 1, dated November 4, 2010, terminates the actions required by this AD.

Credit for Actions Accomplished in Accordance With Previous Service Information

(j) Actions accomplished before the effective date of this AD according to Boeing Alert Service Bulletin 777-54A0024, dated April 1, 2010, are considered acceptable for compliance with the corresponding actions specified in this AD.

Alternative Methods of Compliance (AMOCs)

(k)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Kevin Nguyen, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]. Information may be e-mailed to: [e-mail].

(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.

Issued in Renton, Washington, on January 12, 2011.

Jeffrey E. Duven,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.