04-20210. Airworthiness Directives; Boeing Model 747-400, -400D, and -400F Series Airplanes

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 747-400, -400D, and -400F series airplanes. This proposed AD would require replacing at least one flap control unit (FCU) in the main equipment center with a new or modified FCU. This proposed AD is prompted by a report indicating that, after takeoff, an airplane was required to return to the airport because the autopilot disengaged. The report also indicated that, upon selecting flaps for landing, the flaps indication display did not indicate the flap setting, requiring the airplane to land in alternate flap mode. We are proposing this AD to prevent disconnection of autoland/autopilot functions and loss of primary flaps control and flaps indication display due to disengagement of all three FCUs at the same time, which could lead to a non-normal high speed landing with the flaps retracted, increased pilot workload, and possible runway departure at high speeds during landing.

DATES:

We must receive comments on this proposed AD by October 22, 2004.

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 the 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 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: Douglas Tsuji, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, 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 written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-18999; Directorate Identifier 2003-NM-259-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 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 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.

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 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 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 a report indicating that, after takeoff, a Boeing Model 747-400 series airplane was required to return to the airport because the autopilot disengaged. The report also indicated that, upon selecting flaps for landing, the flaps indication display did not indicate the flap setting, requiring the airplane to land in alternate flap mode. The root cause of these conditions has been determined to be the susceptibility of the flap control units (FCUs) to certain external failures of the position switch circuit of the leading edge flap. These external failures can cause all three FCUs to disengage at the same time, which could result in disconnection of autoland/autopilot functions and loss of primary flaps control and flaps indication display. These conditions, if not corrected, could lead to a non-normal high speed landing with the flaps retracted, increased pilot workload, and possible runway departure at high speeds during landing.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-27A2386, dated March 13, 2003, which describes procedures for replacing FCUs having part number (P/N) 285U0011-207, located in the main equipment center, with new or modified FCUs having P/N 285U0011-208. The service bulletin specifies that at least one FCU per airplane must be replaced to prevent the malfunction of the primary flaps control and flaps indication display.

Boeing Alert Service Bulletin 747-27A2386 refers to Boeing Component Service Bulletin 285U0011-27-06, dated March 13, 2003, as an additional source of service information for modifying an FCU having P/N 285U0011-207 to P/N 285U0011-208.

Boeing Alert Service Bulletin 747-27A2386 also specifies prior or concurrent accomplishment of Boeing Service Bulletin 747-27-2319, dated January 24, 1991, which describes procedures for replacing FCUs having P/N 285U0011-205 or 285U0011-206, located in the main equipment center, with new or modified FCUs having P/N 285U0011-207.

Boeing Service Bulletin 747-27-2319 refers to Boeing Component Service Bulletin 285U0011-27-04, dated January 24, 1991, as an additional source of service information for modifying an FCU having P/N 285U0011-205 or 285U0011-206 to P/N 285U0011-207.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

Clarification of FCU Replacement Specified in Boeing Alert Service Bulletin

Although the Accomplishment Instructions of Boeing Alert Service Bulletin 747-27A2386 specify to “replace the FCUs as shown in Figure 1” (which illustrates replacement of three FCUs), only a minimum of one FCU for each airplane must be replaced as specified in paragraph 1.E., “Compliance,” of the service bulletin. In paragraph 1.D., “Description,” the service bulletin specifies that “a minimum of one FCU for each airplane must be replaced to prevent the malfunction of the primary flaps control and flaps indication display.” Replacing a minimum of one FCU having P/N 285U0011-207 with P/N 285U0011-208 addresses the unsafe condition specified in the proposed AD.

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 replacing at least one FCU having P/N 285U0011-207, located in the main equipment center, with an FCU having P/N 285U0011-208. For certain airplanes, the proposed AD would first require replacing the three FCUs having P/N 285U0011-205 or 285U0011-206 with FCUs having P/N 285U0011-207. The proposed AD would require you to use Boeing Alert Service Bulletin 747-27A2386, dated March 13, 2003; and Boeing Service Bulletin 747-27-2319, dated January 24, 1991; described previously to perform these actions.

Costs of Compliance

This proposed AD would affect about 614 airplanes worldwide and 87 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Replacement	Work hours	Average labor rate per hour	Parts	Cost per airplane
Estimated Costs
With new -208 FCU	2	$65	$78,550	$78,680
With modified -208 FCU	10	65	975	1,625
Estimated Concurrent Service Bulletin Costs
With new -207 FCU	3	65	235,650	235,845
With modified -207 FCU	87	65	2,925	8,580

Regulatory Findings

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.

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-2004-18999; Directorate Identifier 2003-NM-259-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by October 22, 2004.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Model 747-400, -400D, and -400F series airplanes, as listed in Boeing Alert Service Bulletin 747-27A2386, dated March 13, 2003; certificated in any category.

Unsafe Condition

(d) This AD was prompted by a report indicating that, after takeoff, an airplane was required to return to the airport because the autopilot disengaged. The report also indicated that, upon selecting flaps for landing, the flaps indication display did not indicate the flap setting, requiring the airplane to land in alternate flap mode. We are issuing this AD to prevent disconnection of autoland/autopilot functions and loss of primary flaps control and flaps indication display due to disengagement of all three flap control units (FCUs) at the same time, which could lead to a non-normal high speed landing with the flaps retracted, increased pilot workload, and possible runway departure at high speeds during landing.

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.

Replace FCU

(f) At the earliest of the times specified in paragraphs (f)(1), (f)(2), and (f)(3) of this AD: Replace at least one FCU having P/N 285U0011-207 with a new or modified FCU having P/N 285U0011-208 in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-27A2386, dated March 13, 2003.

(1) Within 60 months after the effective date of this AD.

(2) Within 25,000 flight hours after the effective date of this AD.

(3) Within 4,000 flight cycles after the effective date of this AD.

Note 1:

Boeing Alert Service Bulletin 747-27A2386, dated March 13, 2003, refers to Boeing Component Service Bulletin 285U0011-27-06, dated March 13, 2003, as an additional source of service information for modifying an FCU having P/N 285U0011-207 to P/N 285U0011-208.

Actions Required Before or Concurrently With Paragraph (f)

(g) For airplanes listed in Boeing Service Bulletin 747-27-2319, dated January 24, 1991: Before or concurrent with the accomplishment of paragraph (f) of this AD, replace the three FCUs having P/N 285U0011-205 or 285U0011-206 with new or modified FCUs having P/N 285U0011-207 in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2319, dated January 24, 1991.

Note 2:

Boeing Service Bulletin 747-27-2319, dated January 24, 1991, refers to Boeing Component Service Bulletin 285U0011-27-04, dated January 24, 1991, as an additional source of service information for modifying the FCUs having P/N 285U0011-205 or 285U0011-206 to P/N 285U0011-207.

Parts Installation

(h) As of the effective date of this AD, no person may install on any airplane an FCU having P/N 285U0011-205 or -206.

Alternative Methods of Compliance (AMOCs)

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

Issued in Renton, Washington, on August 25, 2004.

Kevin M. Mullin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.