[Federal Register Volume 63, Number 68 (Thursday, April 9, 1998)]
[Proposed Rules]
[Pages 17344-17346]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-9337]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-326-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 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 747 series 
airplanes. This proposal would require repetitive detailed visual 
inspections for corrosion, and repetitive high frequency eddy current 
(HFEC) inspections for cracks, of the upper link assembly on the number 
2 and number 3 engine struts, and corrective actions, if necessary. 
This proposal is prompted by reports of corrosion and cracks located at 
the four fasteners that attach to the aft end to the upper link 
assembly on the number 2 and number 3 engine struts. The actions 
specified by the proposed AD are intended to prevent failure of the 
upper link due to cracking or corrosion, subsequent damage to other 
strut support structure, and in-flight separation of an engine from the 
airplane.

DATES: Comments must be received by May 26, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-326-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: Tamara L. Dow, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2771; 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.

[[Page 17345]]

    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 97-NM-326-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. 97-NM-326-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that nine operators have 
found seven instances of corrosion and three instances of cracks on 10 
airplanes that had accumulated between 7,400 and 19,800 flight cycles 
and between 37,100 and 81,600 flight hours. One operator reported a 1-
inch crack from one fastener hole location at the aft end of the upper 
link of the strut to the part edge. The corrosion and cracks were 
located at the four fasteners which attach the aft end of the upper 
link assembly of the number 2 and number 3 engine struts. Such 
corrosion and cracking, in the struts upper link, at the aft end 
attachment for the number 2 and 3 engine struts, if not detected and 
corrected in a timely manner, could result in failure of the upper 
link, subsequent damage to other strut support structure, and in-flight 
separation of an engine from the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-54A2187, dated May 22, 1997, which describes procedures for 
repetitive detailed visual inspections for corrosion, and high 
frequency eddy current (HFEC) inspections for cracks, on the upper link 
assembly on the number 2 and number 3 engine struts, and corrective 
actions, if necessary. The corrective actions include repair or 
replacement of the upper link in accordance with Parts 2 and 3 of the 
Accomplishment Instructions of the alert service bulletin. 
Accomplishment of the actions specified in the alert service bulletin 
are 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 described 
below.

Differences Between Proposed Rule and Alert Service Bulletin

    The alert service bulletin specifies that certain corrective 
actions required by this proposed AD may be accomplished in accordance 
with an operator's ``equivalent procedure.'' However, the alert service 
bulletin also specifies that operators may accomplish those actions in 
accordance with certain chapters of the Airplane Maintenance Manual. 
This proposed AD would require that any such actions be accomplished 
only in accordance with the procedures specified in the Airplane 
Maintenance Manual. An ``operator's equivalent procedure'' may be used 
only if approved as an alternative method of compliance in accordance 
with the provisions of this proposed AD.

Cost Impact

    There are approximately 567 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 173 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
12 work hours per airplane to accomplish the proposed inspections, and 
that the average labor rate is $60 per work hour. Based on these 
figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $124,560, or $720 per airplane.
    The cost impact figure discussed above is 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.

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 97-NM-326-AD.

    Applicability: Model 747 series airplanes, line positions 1 
through 886 inclusive; equipped with Pratt & Whitney JT9D-3 or -7, 
or General Electric CF6-45 or -50 engine struts; 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 (e) 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

[[Page 17346]]

been eliminated, the request should include specific proposed 
actions to address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the upper link due to cracking or 
corrosion, subsequent damage to other strut support structure, and 
in-flight separation of an engine from the airplane, accomplish the 
following:
    (a) Perform a detailed visual inspection for corrosion, and a 
high frequency eddy current (HFEC) inspection for cracks, of the 
upper link assembly on the number 2 and number 3 engine struts, in 
accordance with Boeing Alert Service Bulletin 747-54A2187, dated May 
22, 1997, at the applicable time specified in either paragraph 
(a)(1) or (a)(2) of this AD.
    (1) For airplanes with upper link assemblies that were 
overhauled in accordance with Overhaul Manual, 54-00-01, and on 
which the four aft end attach bolts were installed with sealant: 
Perform the inspections required by paragraph (a) of this AD, at the 
later of the times specified in paragraphs (a)(1)(i) and (a)(1)(ii) 
of this AD.
    (i) Within 6,000 flight cycles or 8 years after the date of 
overhaul of the upper link assembly, whichever occurs first.
    (ii) Within 600 flight cycles or 6 months after the effective 
date of this AD, whichever occurs first.
    (2) For airplanes other than those identified in paragraph 
(a)(1) of this AD: Perform the inspections required by paragraph (a) 
of this AD, at the later of the times specified in paragraphs 
(a)(2)(i) and (a)(2)(ii) of this AD.
    (i) Within 6,000 total flight cycles, or 8 years after the date 
of manufacture of the airplane, whichever occurs first.
    (ii) Within 600 flight cycles, or 6 months after the effective 
date of this AD, whichever occurs first.
    (b) If no crack or corrosion is detected during any inspection 
required by paragraph (a) of this AD, repeat the inspections 
specified in paragraph (a) of this AD, thereafter, at intervals not 
to exceed 18 months.
    (c) If any crack or corrosion is detected during any inspection 
required by this AD, prior to further flight, accomplish either 
paragraph (c)(1) or (c)(2) of this AD, in accordance with Boeing 
Alert Service Bulletin 747-54A2187, dated May 22, 1997. Thereafter, 
repeat the inspections required by paragraph (a) of this AD, at 
intervals not to exceed 6,000 flight cycles or 8 years, whichever 
occurs first.
    (1) Repair the upper link within the limits specified in the 
alert service bulletin, in accordance with Part 2 of the 
Accomplishment Instructions of the alert service bulletin. (Complete 
corrosion and crack removal must be achieved within the limits 
specified in the alert service bulletin.) Or
    (2) Replace the upper link with a new upper link assembly, in 
accordance with Part 3 of the Accomplishment Instructions of the 
alert service bulletin.

    Note 2: If any cracking or corrosion is found, and Boeing Alert 
Service Bulletin 747-54A2187, dated May 22, 1997, specifies that 
corrective actions may be accomplished in accordance with an 
operator's ``equivalent procedure:'' The actions must be 
accomplished in accordance with the chapter of the Boeing 747 
Airplane Maintenance Manual (AMM) specified in the alert service 
bulletin.

    (d) Accomplishment of the modifications required in AD 95-13-07, 
amendment 39-9287 (for General Electric CF6-45 or -50 engine 
struts); or AD 95-10-16, amendment 39-9233 (for Pratt & Whitney 
JT9D-3 or -7 engine struts); constitutes terminating action for the 
requirements of this AD.
    (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 Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. 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.

    (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 April 3, 1998.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-9337 Filed 4-8-98; 8:45 am]
BILLING CODE 4910-13-U