[Federal Register Volume 64, Number 227 (Friday, November 26, 1999)]
[Proposed Rules]
[Pages 66426-66428]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-30798]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-307-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 777-200 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 777-200 
series airplanes. This proposal would require one-time inspections to 
detect cracking of the aft wheel well bulkhead, and corrective actions, 
if necessary. This proposal also would require modification of the aft 
wheel well bulkhead. For certain airplanes, this proposal also would 
require a one-time visual inspection to detect excess sealant covering 
the outer flange of the side fitting and lower chord and splice area of 
the aft wheel well bulkhead, and corrective actions, if necessary. This 
proposal is prompted by a report indicating that numerous fatigue 
cracks were found in the aft wheel well bulkhead. The actions specified 
by the proposed AD are intended to prevent fatigue cracking of the aft 
wheel well bulkhead, which could result in rapid in-flight 
decompression of the airplane.

DATES: Comments must be received by January 10, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-307-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    The service information referenced in the proposed rule 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.

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:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice

[[Page 66427]]

must submit a self-addressed, stamped postcard on which the following 
statement is made: ``Comments to Docket Number 99-NM-307-AD.'' The 
postcard will be date stamped and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 99-NM-307-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received a report indicating numerous fatigue cracks 
have been found in the aft wheel well bulkhead of a Boeing Model 777-
200 test airplane. During full-scale fatigue testing of the airplane, 
cracks between 0.15 to 1.5 inches long occurred at 55,186 flight 
cycles. The cracks were detected at the bulkhead web cut-out for the 
air driven pump duct, at the side fitting to lower chord splice area, 
and both sides of the splice joint of the aft wheel well bulkhead. At 
110,000 flight cycles, cracks were detected in the vertical flange of 
the lower chord at the fairing support bracket attachment. Such fatigue 
cracking, if not detected and corrected, could result in rapid in-
flight decompression of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
777-53A0015, dated June 17, 1999, which describes procedures for a one-
time visual inspection to detect cracking of the adjacent structure of 
the aft wheel well bulkhead, and a one-time high frequency eddy current 
(HFEC) inspection to detect cracking of certain fastener holes in the 
web, side fitting, and outer chord of the aft wheel well bulkhead, and 
corrective actions, if necessary. The corrective actions involve, for 
certain airplanes, removing additional fasteners, oversizing the 
cracked fastener holes, performing additional HFEC inspections, and 
replacing the fasteners with new fasteners.
    For certain airplanes, Boeing Alert Service Bulletin 777-53A0015, 
dated June 17, 1999, describes procedures for modification of the aft 
wheel well bulkhead. The modification involves cold working certain 
fastener holes; replacing the fairing support brackets and splice 
plates with revised fairing support brackets and splice plates; and 
installing new web doublers and, if necessary, shims.
    Additionally, for certain airplanes, Boeing Alert Service Bulletin 
777-53A0015, dated June 17, 1999, describes procedures for a one-time 
visual inspection to detect excess sealant covering the outer flange of 
the side fitting and lower chord and splice of the aft wheel well 
bulkhead, and corrective actions, if necessary. The corrective actions 
involve removing the excess sealant between stringers S-27L to S-27R 
prior to accomplishing the inspections and modification of the aft 
wheel well bulkhead.
    Accomplishment of the actions specified in the alert service 
bulletin is intended to adequately address the identified unsafe 
condition.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require accomplishment of the actions specified in 
the alert service bulletin described previously, except as discussed 
below.

Differences Between Proposed Rule and Alert Service Bulletin

    Operators should note that, although the Boeing alert service 
bulletin specifies that the manufacturer may be contacted for 
disposition of certain cracking conditions, this proposal would require 
the repair of those conditions to be accomplished in accordance with a 
method approved by the FAA.
    Additionally, operators also should note that, this proposed AD 
would require, removal of excess sealant in the remaining area between 
stringers S-27L and S-27R, prior to further flight, upon completion of 
the aft wheel well bulkhead modification. The alert service bulletin 
recommends that the excess sealant be removed prior to the threshold 
specified for fatigue inspections in Section 9 of the Maintenance 
Planning Document (MPD). In developing the appropriate compliance time, 
the FAA considered the manufacturer's recommendation and the degree of 
urgency associated with addressing the subject unsafe condition. In 
light of these factors, the FAA finds that the compliance time 
specified by this proposed AD to be appropriate.

Cost Impact

    There are approximately 109 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 35 airplanes of U.S. registry 
would be affected by this proposed AD.
    For all airplanes, it would take approximately 2 work hours per 
airplane to accomplish the general visual and HFEC inspections at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of the these inspections proposed by this AD on U.S. 
operators is estimated to be $120 per airplane.
    For all airplanes, it would take approximately 28 work hours per 
airplane to accomplish the proposed modification at an average labor 
rate of $60 per work hour. Required parts would be approximately $6,013 
per airplane. Based on these figures, the cost impact of the 
modification proposed by this AD on U.S. operators is estimated to be 
$7,693 per airplane.
    For certain airplanes, it would take 3 work hours per airplane to 
accomplish the proposed inspection to detect excess sealant at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of the this inspection proposed by this AD on U.S. 
operators is estimated to be $180 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the proposed requirements 
of this AD action, and that no operator would accomplish those actions 
in the future if this AD were not adopted.

Regulatory Impact

    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that 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) if promulgated, 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. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

[[Page 66428]]

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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:

Boeing: Docket 99-NM-307-AD.

    Applicability: Model 777-200 series airplanes having line 
numbers 1 through 144; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (c) 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 prevent fatigue cracking of the aft wheel well bulkhead, 
which could result in rapid in-flight decompression of the airplane, 
accomplish the following:

General Visual Inspection

    (a) For Group 1 airplanes, as identified in Boeing Alert Service 
Bulletin 777-53A0015, dated June 17, 1999: Prior to the accumulation 
of 11,000 total flight cycles, or within 4,000 flight cycles after 
the effective date of this AD, whichever occurs later, perform a 
one-time general visual inspection to detect excess sealant covering 
the outer flange of the side fitting and lower chord and splice of 
the aft wheel well bulkhead, in accordance with Part I of the 
Accomplishment Instructions of the alert service bulletin.

    Note 2: For the purposes of this AD, a general visual inspection 
is defined as: ``A visual examination of an interior or exterior 
area, installation, or assembly to detect obvious damage, failure, 
or irregularity. This level of inspection is made under normally 
available lighting conditions such as daylight, hangar lighting, 
flashlight, or drop-light, and may require removal or opening of 
access panels or doors. Stands, ladders, or platforms may be 
required to gain proximity to the area being checked.''

    (1) If no excess sealant is detected, no further action is 
required by this paragraph.
    (2) If any excess sealant is detected, prior to further flight, 
remove the excess sealant from the aft wheel well bulkhead area in 
accordance with the alert service bulletin.

Inspections/Modification

    (b) For Groups 1 and 2 airplanes, as identified in Boeing Alert 
Service Bulletin 777-53A0015, dated June 17, 1999: Prior to the 
accumulation of 11,000 total flight cycles, or within 4,000 flight 
cycles after the effective date of this AD, whichever occurs later, 
perform a one-time general visual inspection to detect cracking of 
the adjacent structure of the aft wheel well bulkhead and perform a 
one-time high frequency eddy current (HFEC) inspection to detect 
cracking of the fastener holes in the web, side fitting, and outer 
chord of the aft wheel well bulkhead, in accordance with Part II of 
the Accomplishment Instructions of the alert service bulletin.
    (1) If no cracking is detected during the general visual and 
HFEC inspections, prior to further flight, modify the aft wheel well 
bulkhead (including cold working; replacing the fairing support 
bracket and splice plates with revised fairing support brackets and 
splice plates; and installing new web doublers and, if necessary, 
shims), in accordance with Part II of the Accomplishment 
Instructions of the alert service bulletin.
    (2) If any cracking is detected during the general visual 
inspection, prior to further flight, accomplish the requirements of 
paragraph (c) of this AD.
    (3) If any cracking is detected during the one-time HFEC 
inspection, prior to further flight, remove additional fasteners, 
and perform a second HFEC inspection to detect cracking of the 
fastener holes, in accordance with Part II of the Accomplishment 
Instructions of the alert service bulletin.
    (i) If no cracking is detected during the second HFEC 
inspection, prior to further flight, oversize all the holes to the 
diameter specified in the alert service bulletin, and perform a 
third HFEC inspection to detect cracking of the fastener holes, in 
accordance with Part II of the Accomplishment Instructions of the 
alert service bulletin.
    (A) If no cracking is detected during the third HFEC inspection, 
prior to further flight, replace the fasteners with new fasteners 
and modify the aft wheel well bulkhead (including cold working; 
replacing the fairing support bracket and splice plates with revised 
fairing support brackets and splice plates; and installing new web 
doublers and, if necessary, shims), in accordance with Part II of 
the Accomplishment Instructions of the alert service bulletin.
    (B) If any cracking is detected during the third HFEC 
inspection, prior to further flight, accomplish the requirements of 
paragraph (c) of this AD.
    (ii) If any cracking is detected during the second HFEC 
inspection, prior to further flight, accomplish the requirements of 
paragraph (c) of this AD.
    (c) For airplanes on which cracking has been detected during any 
inspection required by paragraph (b)(2), (b)(3)(i)(B), or 
(b)(3)(ii), prior to further flight, repair in accordance with a 
method approved by the Manager, Seattle Airplane Certification 
Office (ACO), FAA, Transport Airplane Directorate; or in accordance 
with data meeting the type certification basis of the airplane 
approved by a Boeing Company Designated Engineering Representative 
who has been authorized by the Manager, Seattle ACO, to make such 
findings. 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.
    (d) For Group 1 airplanes, as identified in Boeing Alert Service 
Bulletin 777-53A0015, dated June 17, 1999, on which excess sealant 
was detected and removed in accordance with paragraph (a) of this 
AD: Prior to further flight following the accomplishment of the 
modification required by paragraph (b) of this AD, remove any excess 
sealant in the remaining area of the lower lobe of the aft wheel 
well bulkhead between stringers S-27L and S-27R, in accordance with 
the alert service bulletin.

Alternative Methods of Compliance

    (e) 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.

Special Flight Permits

    (f) Special flight permits may be issued in accordance with 
Secs. 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.

    Issued in Renton, Washington, on November 19, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-30798 Filed 11-24-99; 8:45 am]
BILLING CODE 4910-13-U