[Federal Register Volume 65, Number 185 (Friday, September 22, 2000)]
[Rules and Regulations]
[Pages 57282-57285]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-24110]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-259-AD; Amendment 39-11909; AD 2000-19-08]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 777 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to all Boeing Model 777 series airplanes. The existing 
AD requires repetitive detailed visual inspections to detect cracking 
of the coveskin on the outboard leading edge slats; a slat adjustment 
check; and corrective actions, if necessary. This amendment reduces the 
repetitive inspection interval, but also provides for an optional 
modification that would significantly increase the repetitive 
inspection interval. This amendment also revises the applicability of 
the existing AD to remove certain airplanes. This amendment is prompted 
by findings of increased vibration of the coveskins due to air leaking 
and resonating within the cavity between the fixed leading edge and the 
coveskin; the vibration can result in fatigue cracking and high fatigue 
loads. The

[[Page 57283]]

actions specified in this AD are intended to detect and correct 
cracking and/or missing pieces of the coveskin on the outboard leading 
edge slats on the wings, which could result in skin separation or 
structural damage to the leading edge slats and consequent reduced 
controllability of the airplane.

DATES: Effective October 10, 2000.

    The incorporation by reference of Boeing Alert Service Bulletin 
777-57A0034, Revision 3, dated May 4, 2000, and Boeing Alert Service 
Bulletin 777-57A0034, Revision 4, dated July 20, 2000, as listed in the 
regulations, is approved by the Director of the Federal Register as of 
October 10, 2000.
    The incorporation by reference of Boeing Alert Service Bulletin 
777-57A0034, Revision 2, dated November 19, 1998, as listed in the 
regulations, was approved previously by the Director of the Federal 
Register as of March 8, 1999 (64 FR 8230, February 19, 1999).
    Comments for inclusion in the Rules Docket must be received on or 
before November 21, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-259-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-259-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    The service information referenced in this AD may be obtained from 
Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 
98124-2207. This information may be examined at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Stan Wood, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2772; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: On February 9, 1999, the FAA issued AD 99-
04-19, amendment 39-11044 (64 FR 8230, February 19, 1999), applicable 
to all Boeing Model 777 series airplanes, to require repetitive 
detailed visual inspections to detect cracking of the coveskin on the 
outboard leading edge slats; a slat adjustment check; and corrective 
actions, if necessary. That action was prompted by reports of fatigue 
cracking and/or missing pieces of the coveskin on the outboard leading 
edge slats. The actions required by that AD are intended to detect and 
correct such discrepancies, which could result in skin separation or 
structural damage to the leading edge slats and consequent reduced 
controllability of the airplane.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, Boeing has conducted flight tests 
with instrumented slats. The testing revealed that the spanwise bulb 
seals of the slats can allow air to leak and resonate in the cavity 
between the fixed leading edge and the coveskin, which can cause the 
coveskin to vibrate. Testing also showed that this vibration resulted 
in fatigue loads much higher than expected. The vibration of the 
coveskin can also result in fatigue cracking of the slats. Undetected 
cracking of the slats could eventually lead to damage or skin 
separation on the slat trailing edge wedge of an outboard slat, and 
consequent loss of pieces of the trailing edge wedge. In addition, the 
maneuver margins and the speed margins to airplane stall will be 
decreased if a trailing edge wedge is lost or sufficiently damaged. A 
lost or sufficiently damaged wedge can cause the airplane to roll, with 
no warning, before the stall system operates.
    Testing further revealed that the installation of foam inserts in 
the spanwise bulb seal resulted in increased compression and 
significantly reduced vibration of the coveskin.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
777-57A0034, Revision 3, dated May 4, 2000; and Revision 4, dated July 
20, 2000. Revision 2 of this alert service bulletin was cited in AD 99-
04-19 as the appropriate source of service information for the coveskin 
inspection and certain corrective actions.
    Revision 3 of the alert service bulletin was issued to, among other 
things, recommend that an internal inspection and slat adjustment check 
be done only if a cracked slat is found. In addition, Revision 3 
describes procedures for installing seal inserts into the spanwise bulb 
seals for the slats; if accomplished, the installation would 
significantly increase the repetitive inspection interval. Certain 
airplanes have received the seal inserts in production.
    Revision 4 of the alert service bulletin was issued to recommend a 
compliance time(s) in terms of flight hours as well as flight cycles 
because the subject vibration occurs mainly during cruise, which is 
related to flight hours. Revision 4 also clarifies certain instructions 
for the slat adjustment check and internal inspection.

Explanation of Requirements of Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of this same type design, this AD 
supersedes AD 99-04-19 to continue to require repetitive detailed 
visual inspections to detect cracking of the coveskin on the outboard 
leading edge slats; a slat adjustment check; and corrective actions, if 
necessary. This AD reduces the repetitive inspection interval, but also 
provides for an optional modification that would significantly increase 
the repetitive inspection interval. In addition, this AD removes 
certain airplanes from the applicability. The actions are required to 
be accomplished in accordance with the alert service bulletin described 
previously, except as discussed below.

Differences Between AD and Relevant Service Information

    The alert service bulletin specifies that the manufacturer may be 
contacted for disposition of certain repair conditions. However, this 
AD requires the repair of those conditions to be accomplished in 
accordance with a method approved by the FAA.

Interim Action

    This is considered to be interim action. The FAA is currently 
considering further rulemaking action to revise the applicability of 
this AD to include additional airplanes; however, the planned 
compliance time for the additional airplanes is sufficiently long so 
that notice and opportunity for prior public comment will be 
practicable.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements

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affecting flight safety and, thus, was not preceded by notice and an 
opportunity for public comment, comments are invited on this rule. 
Interested persons are invited to comment on this rule by submitting 
such written data, views, or arguments as they may desire. 
Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the AD is 
being requested.
     Include justification (e.g., reasons or data) for each 
request.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-259-AD.'' The postcard will be date stamped 
and returned to the commenter.

Regulatory Impact

    The regulations adopted herein 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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 it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-11044 (64 FR 
8230, February 19, 1999), and by adding a new airworthiness directive 
(AD), amendment 39-11909, to read as follows:

2000-19-08  Boeing: Amendment 39-11909. Docket 2000-NM-259-AD. 
Supersedes AD 99-04-19, Amendment 39-11044.

    Applicability: Model 777 series airplanes, certificated in any 
category; having line numbers 1 through 265 inclusive.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (d) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct cracking and/or missing pieces of the 
coveskin on the outboard leading edge slats on the wings, which 
could result in skin separation or structural damage to the leading 
edge slats and consequent reduced controllability of the airplane, 
accomplish the following:

Inspection

    (a) At the applicable time specified by paragraph (a)(1) or 
(a)(2) of this AD: Perform detailed visual inspections to detect 
cracking of the coveskin on the outboard leading edge slats of the 
left and right wings at slat numbers 1 through 6 inclusive, and 9 
through 14 inclusive; in accordance with Boeing Alert Service 
Bulletin 777-57A0034, Revision 2, dated November 19, 1998; Revision 
3, dated May 4, 2000; or Revision 4, dated July 20, 2000. Repeat the 
inspections thereafter at intervals not to exceed 100 flight cycles 
or 400 flight hours, whichever occurs first.
    (1) For airplanes on which the repetitive inspections required 
by paragraph (a) of AD 99-04-19 HAVE been initiated prior to the 
effective date of this AD: Inspect at the earlier of the times 
specified by paragraphs (a)(1)(i) and (a)(1)(ii) of this AD.
    (i) Within 350 flight cycles after the most recent inspection.
    (ii) At the later of the times specified by paragraphs 
(a)(1)(ii)(A) and (a)(1)(ii)(B) of this AD.
    (A) Within 100 flight cycles or 400 flight hours, whichever 
occurs first, after the most recent inspection.
    (B) Within 30 days after the effective date of this AD.
    (2) For airplanes on which the repetitive inspections required 
by paragraph (a) of AD 99-04-19 have NOT been initiated prior to the 
effective date of this AD: Inspect at the earlier of the times 
specified by paragraphs (a)(2)(i) and (a)(2)(ii) of this AD.
    (i) Prior to the accumulation of 500 total flight cycles.
    (ii) Prior to the accumulation of 2,000 total flight hours, or 
within 30 days after the effective date of this AD, whichever occurs 
later.

    Note 2: For the purposes of this AD, a detailed visual 
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.''

Corrective Action

    (b) If any cracking is detected during any inspection required 
by paragraph (a) of this AD, prior to further flight, accomplish all 
applicable corrective actions specified by and in accordance with 
Boeing Alert Service Bulletin 777-57A0034, Revision 2, dated 
November 19, 1998; Revision 3, dated April 4, 2000; or Revision 4, 
dated July 20, 2000. The corrective actions include stop drilling 
the crack and performing detailed visual inspections, slat 
adjustment checks, and

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replacement of the slats. Where the alert service bulletin specifies 
to contact Boeing for appropriate action: Prior to further flight, 
repair in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office, FAA. For a repair method to be 
approved by the Manager, Seattle ACO, as required by this paragraph, 
the Manager's approval letter must specifically reference this AD. 
After the effective date of this AD, only Revision 4 of the alert 
service bulletin may be used.

Optional Modification

    (c) Accomplishment of the actions specified by paragraphs (c)(1) 
and (c)(2) of this AD extends the repetitive inspection interval 
specified by paragraph (a) of this AD to 8,000 flight cycles.
    (1) Install a seal insert into the spanwise bulb seals for the 
slats in accordance with Part 4 of Boeing Alert Service Bulletin 
777-57A0034, Revision 3, dated May 4, 2000; or Revision 4, dated 
July 20, 2000.
    (2) Within 750 days or 4,000 flight cycles, whichever occurs 
first, after installing the seal insert as specified by paragraph 
(c)(1) of this AD: Perform a detailed visual inspection of the 
interior structure of the coveskin at slat numbers 1 through 6 
inclusive, and 9 through 14 inclusive, in accordance with Part 2 of 
the Accomplishment Instructions of the alert service bulletin.

Alternative Methods of Compliance

    (d)(1) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle ACO. Operators shall submit 
their requests through an appropriate FAA Principal Maintenance 
Inspector, who may add comments and then send it to the Manager, 
Seattle ACO.
    (2) Alternative methods of compliance, approved previously in 
accordance with AD 99-04-19, amendment 39-11044, are approved as 
alternative methods of compliance with paragraph (b) of this AD.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (e) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

Incorporation by Reference

    (f) Except as provided by paragraph (b) of this AD: The actions 
shall be done in accordance with Boeing Alert Service Bulletin 777-
57A0034, Revision 2, dated November 19, 1998; Boeing Alert Service 
Bulletin 777-57A0034, Revision 3, dated May 4, 2000; and Boeing 
Alert Service Bulletin 777-57A0034, Revision 4, dated July 20, 2000; 
as applicable.
    (1) The incorporation by reference of Boeing Alert Service 
Bulletin 777-57A0034, Revision 3, dated May 4, 2000, and Boeing 
Alert Service Bulletin 777-57A0034, Revision 4, dated July 20, 2000, 
is approved by the Director of the Federal Register, in accordance 
with 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) The incorporation by reference of Boeing Alert Service 
Bulletin 777-57A0034, Revision 2, dated November 19, 1998, was 
approved previously by the Director of the Federal Register as of 
March 8, 1999 (64 FR 8230, February 19, 1999).
    (3) Copies may be obtained from Boeing Commercial Airplane 
Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be 
inspected at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Effective Date

    (g) This amendment becomes effective on October 10, 2000.

    Issued in Renton, Washington, on September 14, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-24110 Filed 9-21-00; 8:45 am]
BILLING CODE 4910-13-P