[Federal Register Volume 64, Number 33 (Friday, February 19, 1999)]
[Rules and Regulations]
[Pages 8230-8232]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-3726]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-320-AD; Amendment 39-11044; AD 99-04-19]
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 adopts a new airworthiness directive (AD) that 
is applicable to all Boeing Model 777 series airplanes. This action 
requires repetitive detailed visual inspections to detect cracking of 
the cove skin on the outboard leading edge slats; a slat adjustment 
check; and corrective actions, if necessary. This amendment is prompted 
by reports of fatigue cracking and/or missing pieces of the cove skin 
on the outboard leading edge slats. The actions specified in this 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.

DATES: Effective March 8, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 8, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before April 20, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-320-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    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, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2772; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: The FAA has received several reports of 
fatigue cracking and/or missing pieces of the cove skin and on the 
outboard leading edge slats on the left and right wings on Boeing Model 
777 series airplanes. On four airplanes that had accumulated between 
3,000 and 14,000 flight hours and 650 and 2,800 flight cycles, cracking 
was located on slat numbers 4, 5, and 9. On one airplane that had 
accumulated 4,530 total flight hours and 685 total flight cycles, the 
cracked and missing pieces were located on slat numbers 5 and 10. On 
another airplane that had accumulated 1,140 total flight hours and 
1,525 total flight cycles, a portion of the leading edge wedge was 
missing, and cracking in the cove skin at the deflection control ribs 
on slat number 5 was detected. At this time, the exact cause of the 
cracking is unknown. These conditions, if not detected and corrected, 
could result in skin separation or structural damage to the outboard 
leading edge slats, and consequent reduced controllability of the 
airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
777-57A0034, Revision 2, dated November 19, 1998, which, among other 
things, describes procedures for repetitive detailed visual inspections 
to detect cracking of the cove skin on the outboard leading edge slats; 
a slat adjustment check to verify proper adjustment of the slat 
rigging; and corrective actions, if necessary. The corrective actions 
include stop drilling of any crack that is 1.5 inches or less as an 
interim action; replacement of the leading edge slat; and adjustment of 
the slat, if necessary. Accomplishment of the actions specified in the 
alert service bulletin is intended to adequately address the identified 
unsafe condition.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, this AD is 
being issued to detect and correct cracking and/or missing pieces of 
the cove skin on the outboard leading edge slats on the left and right 
wings, which could result in skin separation or structural damage to 
the leading edge slats, and consequent reduced controllability of the 
airplane. This AD requires accomplishment of the actions specified in 
the alert service bulletin described previously, except as discussed 
below.

Differences Between This Rule and Alert Service Bulletin

    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.
    The alert service bulletin also specifies that the inspection of 
the interior structure of the cove skin be accomplished repetitively. 
This AD does not require repetitive interior inspections of this area, 
because the FAA has determined that the repetitive detailed visual 
inspections of the exterior structure of the cove skin required by this 
AD are adequate to detect cracking in the subject area.
    The flow chart in Figure 1. of the alert service bulletin does not 
accurately describe the mandatory corrective actions addressed in this 
rule. There have been recent instances involving cracking of the slats 
where it was determined that the slats were properly rigged, therefore, 
the FAA is uncertain of the cause for the cracking and is not relying 
on the rigging checks to assure crack free structure. The FAA has 
determined that the slat adjustment check cited in the flow chart does 
not adequately address the identified unsafe condition; therefore, this 
AD does not require accomplishment of this action at the intervals 
specified.

Interim Action

    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

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 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

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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.
    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 98-NM-320-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects 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, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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 adding the following new 
airworthiness directive:

99-04-19 Boeing: Amendment 39-11044. Docket 98-NM-320-AD.

    Applicability: All Model 777 series airplanes, certificated in 
any category.

    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 cove 
skin on the outboard leading edge slats on the left and right 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:

    Note 2: Where there are differences between the alert service 
bulletin and the AD, the AD prevails.

    (a) Prior to the accumulation of 500 total flight cycles, or 
within 30 days after the effective date of this AD, whichever occurs 
later: Perform a detailed visual inspection to detect cracking of 
the cove skin 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. Repeat the inspection 
thereafter at intervals not to exceed 350 flight cycles.
    (b) If any cracking is detected during any inspection required 
by paragraph (a) of this AD, prior to further flight, accomplish the 
actions specified in paragraph (b)(1), (b)(2), or (b)(3) of this AD, 
as applicable, in accordance with Boeing Alert Service Bulletin 777-
57A0034, Revision 2, dated November 19, 1998.
    (1) For any crack that is less than or equal to 1.5 inches in 
length, stop drill the crack. Within 5 days following accomplishment 
of the stop drilling accomplish paragraphs (b)(1)(i) and (b)(1)(ii) 
of this AD.
    (i) Perform a detailed visual inspection of the interior 
structure of the cove skin 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.
    (A) If no crack is detected, prior to further flight, accomplish 
a slat adjustment check, and if any slat is not adjusted within the 
limits, adjust the slat to within the limits; in accordance with 
Part 3 of the Accomplishment Instructions of the alert service 
bulletin.
    (B) If any crack is detected, prior to further flight, replace 
the slat with a new slat, and accomplish a slat adjustment in 
accordance with Part 2 of the Accomplishment Instructions of the 
alert service bulletin.
    (ii) Repair any cracked cove skin in accordance with a method 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA, Transport Airplane Directorate.
    (2) For any crack that is greater than 1.5 inches in length, 
prior to further flight, accomplish paragraphs (b)(2)(i) and 
(b)(2)(ii) of this AD.
    (i) Perform the inspection required by paragraph (b)(1)(i) of 
this AD in accordance with Part 2 of the Accomplishment Instructions 
of the alert service bulletin.
    (A) If no crack is detected, prior to further flight, accomplish 
a slat adjustment check, and if any slat is not adjusted within the 
limits, adjust the slat to within the limits; in accordance with 
Part 3 of the Accomplishment Instructions of the alert service 
bulletin.
    (B) If any crack is detected, prior to further flight, replace 
the slat with a new slat and accomplish a slat adjustment in 
accordance with Part 2 of the Accomplishment Instructions of the 
alert service bulletin.
    (ii) Repair any cracked cove skin in accordance with a method 
approved by the Manager, Seattle ACO.
    (3) Replace the slat with a new slat and accomplish a slat 
adjustment in accordance with Part 2 of the Accomplishment 
Instructions of the alert service bulletin.
    (c) 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.

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

    (d) 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.
    (e) The actions shall be done in accordance with Boeing Alert 
Service Bulletin 777-

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57A0034, Revision 2, dated November 19, 1998. This incorporation by 
reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 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.
    (f) This amendment becomes effective on March 8, 1999.

    Issued in Renton, Washington, on February 9, 1999.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-3726 Filed 2-18-99; 8:45 am]
BILLING CODE 4910-13-U