E6-16670. Airworthiness Directives; Boeing Model 777-200LR Series Airplanes Powered by General Electric (GE) Model GE90-110B Engines, and Model 777-300ER Series Airplanes Powered by GE Model GE90-115B Engines

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Final rule; request for comments.

SUMMARY:

This document publishes in the Federal Register an amendment adopting airworthiness directive (AD) 2006-20-51 that was sent previously to all known U.S. owners and operators of certain Boeing Model 777-200LR and -300ER series airplanes by individual notices. This AD requires revising the Airplane Flight Manual to prohibit takeoffs at less than full-rated thrust. This AD is prompted by a report of two occurrences of engine thrust rollback (reduction) during takeoff. We are issuing this AD to prevent dual-engine thrust rollback, which could result in the airplane failing to lift off before reaching the end of the runway or failing to clear obstacles below the takeoff flight path.

DATES:

This AD becomes effective October 16, 2006 to all persons except those persons to whom it was made immediately effective by emergency AD 2006-20-51, issued September 30, 2006, which contained the requirements of this amendment.

We must receive comments on this AD by December 11, 2006.

ADDRESSES:

Use one of the following addresses to submit comments on this 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.
• 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 FURTHER INFORMATION CONTACT:

Margaret Langsted, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

On September 30, 2006, we issued emergency AD 2006-20-51, which applies to all Boeing Model 777-200LR series airplanes powered by General Electric (GE) Model GE90-110B engines, and Model 777-300ER series airplanes powered by GE Model GE90-115B engines.

Background

We have received a report of two occurrences of engine thrust rollback (reduction) during takeoff on Boeing Model 777-300ER series airplanes powered by GE Model GE90-115B engines. In both cases, only one engine was affected. The N1 (fan speed—the normal thrust setting parameter for this engine type) thrust level on the affected engine progressively dropped resulting in a thrust loss of 65 to 77% due to an erroneous N1 command computed by the Full Authority Digital Engine Control (FADEC). In both cases, the engine recovered to the proper N1 thrust level as the airplane climbed beyond 400 feet above ground level. In one case, the operator elected to return to the departure airport after reaching cruise. In the other case, the operator continued to its destination. There were no further anomalies reported during the remainder of the flights. No flight deck messages or maintenance indications occurred as a result of the event.

Investigation indicates that these events are the results of a software algorithm in the FADEC that was introduced in software version A.0.4.5 (GE90-100 Service Bulletin 73-0021). Investigation also indicates that a dual-engine thrust rollback could occur just after V1 (takeoff decision speed after which takeoff is to proceed even after an engine failure), which would result in the airplane not having adequate thrust to safely complete the takeoff. A de-rated or a reduced thrust takeoff, in combination with specific ambient conditions, can result in the FADEC commanding a progressive reduction in the engine thrust. Airplane takeoffs are often performed with engine thrust levels at less than the maximum engine thrust approved for the airplane. This is done to reduce wear on the engines, increase fuel efficiency, and maximize passenger comfort. Operators are permitted to calculate airplane takeoff performance and required engine thrust using two different methods referred to as “derated takeoff thrust” (also known as fixed de-rate) and “reduced takeoff thrust” (also known as the assumed temperature method). Full-rated thrust takeoffs with the thrust levers at the full forward position are not exposed to the potential thrust rollback caused by the software anomaly described above.

A dual-engine thrust rollback, if not corrected, could result in the airplane failing to lift off before reaching the end of the runway or failing to clear obstacles below the takeoff flight path.

The FADEC software, version A.0.4.5, on certain Model 777-200LR powered by GE Model 90-110B engines is identical to that on the affected Model 777-300ER series airplanes powered by GE Model GE90-115B engines. Therefore, both of these airplane models may be subject to the same unsafe condition.

Although the software anomaly was introduced by this version of software, the affected operators have a mixed fleet of airplanes with and without the affected software version. To avoid reliance on flight crews determining which software version is installed as they operate different airplanes, we have determined that this AD should apply to all airplanes equipped with the affected engines. If operators develop an acceptable method to ensure flight crews will consistently perform the correct procedure on affected airplanes, they may request approval for an alternative method of compliance in accordance with paragraph (h) of this AD.

FAA's Determination and Requirements of This AD

Since the unsafe condition described is likely to exist or develop on other airplanes of the same type design, we issued emergency AD 2006-20-51 to prevent dual-engine thrust rollback, which could result in the airplane failing to lift off before reaching the end of the runway or failing to clear obstacles below the takeoff flight path. The AD requires revising the Airplane Flight Manual to prohibit takeoffs at less than full-rated thrust.

We found that immediate corrective action was required; therefore, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual notices issued on September 30, 2006, to all known U.S. owners and operators of all Boeing Model 777-200LR series airplanes powered by General Electric (GE) Model GE90-110B engines, and Model 777-300ER series airplanes powered by GE Model GE90-115B engines. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons.

Interim Action

This is considered to be interim action. The engine manufacturer has advised that it currently is developing a modification that will eliminate the unsafe condition addressed by this AD. Once this modification is developed, approved, and available, we may consider additional rulemaking.

Comments Invited

This AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any relevant written data, views, or arguments regarding this AD. Send your comments to an address listed in the ADDRESSES section. Include “Docket No. FAA-2006-26028; Directorate Identifier 2006-NM-222-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD that might suggest a need to modify it.

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 AD. Using the search function of that Web site, 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 may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Examining the Docket

You may 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 Docket Management System receives them.

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 have determined that this AD will not have federalism implications under Executive Order 13132. This 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.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a “significant regulatory action” under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If this emergency regulation is later deemed significant under DOT Regulatory Policies and Procedures, we will prepare a final regulatory evaluation and place it in the AD Docket. See the ADDRESSES section for a location to examine the regulatory evaluation, if filed.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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):

2006-20-51 Boeing: Amendment 39-14786. Docket No. FAA-2006-26028; Directorate Identifier 2006-NM-222-AD.

Effective Date

(a) This AD becomes effective October 16, 2006, to all persons except those persons to whom it was made immediately effective by emergency AD 2006-20-51, issued on September 30, 2006, which contained the requirements of this amendment.

Affected ADs

(b) None.

Applicability

(c) This AD applies to airplanes in Table 1 of this AD certificated in any category.

Table 1.—Applicability

Boeing model	Powered by General Electric (GE) model
(1) 777-200LR series airplanes	GE90-110B engines.
(2) 777-300ER series airplanes	GE90-115B engines.

Unsafe Condition

(d) This AD results from a report of two occurrences of engine thrust rollback during takeoff. The Federal Aviation Administration is issuing this AD to prevent dual-engine thrust rollback, which could result in the airplane failing to lift off before reaching the end of the runway or failing to clear obstacles below the takeoff flight path.

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.

Revision of the Airplane Flight Manual (AFM)

(f) Within 24 hours after the effective date of this AD, revise the Certificate Limitations Section of the AFM to include the following statement. This may be done by inserting a copy of this AD into the AFM.

“Use of reduced thrust takeoff ratings determined by either the assumed temperature method or the fixed de-rate method or a combination of both, is prohibited. Full-rated thrust must be used for takeoff.”

Note 1:

When a statement identical to that in paragraph (f) of this AD has been included in the general revisions of the AFM, the general revisions may be inserted into the AFM, and the copy of this AD may be removed from the AFM.

Special Flight Permit

(g) Special flight permits, as described in Section 21.197 and Section 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199), are not allowed.

Alternative Methods of Compliance (AMOCs)

(h)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

Issued in Renton, Washington, on October 2, 2006.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.