[Federal Register Volume 64, Number 120 (Wednesday, June 23, 1999)]
[Proposed Rules]
[Pages 33437-33439]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-15931]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-72-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 767 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 767 
series airplanes, that currently requires repetitive inspections to 
detect cracking or damage of the forward and aft lugs of the diagonal 
brace of the nacelle strut, and follow-on actions, if necessary. That 
AD also provides optional terminating action for the repetitive 
inspections. This proposal would require accomplishment of the 
previously optional terminating action. This proposal is prompted by a 
report that a fractured diagonal brace lug was found during a routine 
maintenance inspection. The actions specified by the proposed AD are 
intended to prevent cracking of the diagonal brace of the nacelle 
strut, which could result in failure of the diagonal brace, and 
consequent fatigue failure of a strut secondary load path and 
separation of the engine and strut.

DATES: Comments must be received by August 9, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-72-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: James G. Rehrl, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2783; 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 must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 99-NM-72-AD.'' The

[[Page 33438]]

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-72-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On March 17, 1999, the FAA issued AD 99-07-06, amendment 39-11091 
(64 FR 14578, March 26, 1999), applicable to certain Boeing Model 767 
series airplanes, to require repetitive inspections to detect cracking 
or damage of the forward and aft lugs of the diagonal brace of the 
nacelle strut, and follow-on actions, if necessary. That action also 
provides optional terminating action for the repetitive inspections. 
That action was prompted by a report that a fractured diagonal brace 
lug was found during a routine maintenance inspection. The requirements 
of that AD are intended to detect and correct cracking of the diagonal 
brace of the nacelle strut, which could result in failure of the 
diagonal brace, and consequent fatigue failure of a strut secondary 
load path and separation of the engine and strut.

Actions Since Issuance of Previous Rule

    In the preamble to AD 99-07-06, the FAA specified that the actions 
required by that AD were considered ``interim action'' and that further 
rulemaking action was being considered. The FAA has determined that 
further rulemaking action is indeed necessary; this proposed AD follows 
from that determination and would require accomplishment of the 
previously optional terminating action, in accordance with Boeing Alert 
Service Bulletin 767-54A0094, dated May 22, 1998. (That service 
bulletin was referenced in AD 99-07-06 as the appropriate source of 
service information for accomplishment of the replacement.)

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 supersede AD 99-07-06 to continue to require 
repetitive inspections to detect cracking or damage of the forward and 
aft lugs of the diagonal brace of the nacelle strut, and follow-on 
actions, if necessary. In addition, this proposed AD would require 
accomplishment of the previously optional terminating action for the 
repetitive inspection requirements.

Cost Impact

    There are approximately 208 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 105 airplanes of U.S. registry 
would be affected by this proposed AD.
    The inspections that are currently required by AD 99-07-06, and 
retained in this proposed AD, take approximately 1 work hour per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the currently required 
inspections on U.S. operators is estimated to be $6,300, or $60 per 
airplane, per inspection cycle.
    The replacement that is proposed in this AD action would take 
approximately 8 work hours (4 work hours for each strut) per airplane 
to accomplish, at an average labor rate of $60 per work hour. Required 
parts would cost approximately $50,000 per airplane.
    Based on these figures, the cost impact of the proposed replacement 
required by this AD on U.S. operators is estimated to be $5,300,400, or 
$50,480 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or 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.

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 removing amendment 39-11091 (64 FR 
14578, March 26, 1999), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 99-NM-72-AD. Supersedes AD 99-07-06, amendment 39-
11091.

    Applicability: Model 767 series airplanes; as listed in Boeing 
Alert Service Bulletin 767-54A0094, dated May 22, 1998; 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 (f) 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 cracking of the diagonal brace of the nacelle strut, 
which could result in failure of the diagonal brace, and consequent 
fatigue failure of a strut secondary load path and separation of the 
engine and strut, accomplish the following:

Restatement of Requirements of AD 99-07-06

Initial Inspection

    (a) Perform a detailed visual inspection to detect cracking or 
damage of the forward and aft lugs of the diagonal brace of the 
nacelle strut, on the left and right sides of the airplane, in 
accordance with Boeing Alert Service Bulletin 767-54A0094, dated May 
22, 1998. Perform the inspection at the time specified in paragraph 
(a)(1) or (a)(2) of this AD, as applicable.

[[Page 33439]]

    (1) For airplanes in Groups 1, 3, and 4: Inspect prior to the 
accumulation of 12,000 total flight cycles, or within 90 days after 
April 12, 1999 (the effective date of AD 99-07-06, amendment 39-
11091), whichever occurs later.
    (2) For airplanes in Group 2: Inspect prior to the accumulation 
of 24,000 total flight cycles, or within 90 days after April 12, 
1999, whichever occurs later.

Follow-On Actions

    (b) If no cracking or damage is detected during the inspection 
required by paragraph (a) of this AD, repeat the inspection 
thereafter at the interval specified in paragraph (b)(1) or (b)(2) 
of this AD, as applicable, in accordance with Boeing Alert Service 
Bulletin 767-54A0094, dated May 22, 1998. Repeat the inspection 
until the actions specified by paragraph (d) or (e) of this AD have 
been accomplished.
    (1) For airplanes in Groups 1, 3, and 4; and for airplanes in 
Group 2 on which the diagonal brace has accumulated more than 32,000 
total flight cycles: Repeat the inspection at intervals not to 
exceed 1,000 flight cycles.
    (2) For airplanes in Group 2 on which the diagonal brace has 
accumulated 32,000 or fewer total flight cycles: Repeat the 
inspection at intervals not to exceed 3,000 flight cycles.
    (c) If any cracking or damage is detected during any inspection 
required by paragraph (a) or (b) of this AD, prior to further 
flight, remove the diagonal brace and perform additional inspections 
to detect damage of the strut secondary load paths, in accordance 
with Part 4 of Boeing Alert Service Bulletin 767-54A0094, dated May 
22, 1998; and accomplish the requirements of paragraphs (c)(1) and, 
if applicable, (c)(2) of this AD.
    (1) Prior to further flight, replace the one-piece diagonal 
brace with a new three-piece diagonal brace, in accordance with Part 
3 of the Accomplishment Instructions of the alert service bulletin. 
Such replacement constitutes terminating action for the requirements 
of this AD.
    (2) If any additional damage of the alternate load paths is 
detected, prior to further flight, repair in accordance with a 
method approved by the Manager, Seattle Aircraft 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.
    (d) For airplanes on which no cracking is detected during the 
inspection required by paragraph (a) of this AD, in lieu of 
accomplishing repetitive inspections in accordance with paragraph 
(b) of this AD, rework of the forward and aft lugs of the diagonal 
brace may be accomplished in accordance with Part 2 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 767-
54A0094, dated May 22, 1998. If such rework is accomplished: Within 
12,000 flight cycles after the rework, repeat the inspection 
required by paragraph (a) of this AD; and, prior to the accumulation 
of 37,500 total flight cycles on the diagonal brace, replace the 
one-piece diagonal brace with a new three-piece diagonal brace, in 
accordance with Part 3 of the Accomplishment Instructions of the 
alert service bulletin. Such replacement constitutes terminating 
action for the requirements of this AD.

New Requirements of This AD

Terminating Action

    (e) Prior to the accumulation of 37,500 total flight cycles, or 
within 180 days after the effective date of this AD, whichever 
occurs later: Replace the one-piece diagonal brace with a new three-
piece diagonal brace, in accordance with Part 3 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 767-
54A0094, dated May 22, 1998. Such replacement constitutes 
terminating action for the requirements of this AD.

Alternative Methods of Compliance

    (f) 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

    (g) 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.

    Issued in Renton, Washington, on June 17, 1999.
Dorenda D. Baker,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-15931 Filed 6-22-99; 8:45 am]
BILLING CODE 4910-13-U