[Federal Register Volume 64, Number 32 (Thursday, February 18, 1999)]
[Proposed Rules]
[Pages 8024-8026]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-3886]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-286-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-200, -300, and -400 
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 747-200, -
300, and -400 series airplanes. This proposal would require replacement 
of fuse pins in the upper link, midspar fittings, and diagonal brace of 
the nacelle strut with new corrosion-resistant pins. This proposal is 
prompted by reports of cracked fuse pins in the upper link, midspar 
fittings, and diagonal brace of the nacelle strut due to fatigue and 
corrosion. The actions specified by the proposed AD are intended to 
prevent cracking or corrosion of the fuse pins of the nacelle strut, 
which could result in failure of the fuse pin and strut-to-wing 
attachment, and consequent loss of the strut and separation of the 
engine from the airplane.

DATES: Comments must be received by April 5, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-286-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. Anderson, 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.
    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 98-NM-286-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. 98-NM-286-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received numerous reports indicating that cracking of 
various structural members of the strut-to-wing attachment has been 
detected on Boeing Model 747 series airplanes on which certain strut/
wing modifications have not been accomplished. In addition, the FAA has 
received reports indicating that cracking has been detected in 
``bulkhead-style'' fuse pins (made of 4330 or 4340 steel) installed in 
the upper link, midspar fittings, and diagonal brace of the nacelle 
strut. Such cracking has been attributed to fatigue and corrosion. This 
condition, if not corrected, could result in failure of the fuse pin 
and strut-to-wing attachment, and consequent loss of the strut and 
separation of the engine from the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 747-54-
2155, Revision 2, dated June 6, 1996, which describes procedures for 
replacement of the fuse pins in the upper link, midspar fittings, and 
diagonal brace of the nacelle strut with new ``third-generation'' 
corrosion-resistant pins (made of 15-5 steel). In addition to removal 
of the existing pins and installation of new pins, the procedures for 
replacing the pins in the midspar fittings include measurement of the 
distance between the midspar pin, nut, and retainer and the hydraulic 
supply line of the Engine Driven Pump (EDP); and replacement of the 
hydraulic supply line of the EDP with new parts, if necessary.
    Accomplishment of the actions specified in the service bulletin is 
intended to adequately address the identified unsafe condition.

Other Relevant Rulemaking

    Repetitive inspections of the fuse pins of the upper link, midspar 
fittings, and diagonal brace are required by AD 97-14-06, amendment 39-
10064 (62 FR 35953, July 3, 1997); AD 92-24-51, amendment 39-8439 (57 
FR 60118, December 18, 1992); and AD 93-03-14, amendment 39-8518 (58 FR 
14513, March 18, 1993); respectively. Accomplishment of the replacement 
of fuse pins of the upper link, midspar fitting, and diagonal brace in 
accordance with this proposed AD would terminate the repetitive 
inspection requirements for the fuse pins in those areas.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or

[[Page 8025]]

develop on other products of this same type design, the proposed AD 
would require accomplishment of the actions specified in the service 
bulletin described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that the effectivity listing of Boeing 
Service Bulletin 747-54-2155 includes certain Model 747 series 
airplanes regardless of the type of engine. This proposed AD is 
applicable only to Model 747-200 and -300 series airplanes equipped 
with General Electric Model CF6-80C2 series engines, and Model 747-400 
series airplanes; as listed in that service bulletin. The replacement 
of fuse pins in the upper link, midspar fittings, and diagonal brace of 
the nacelle strut with new corrosion-resistant pins is already required 
as part of the modification of the nacelle strut/wing structure for 
earlier Model 747 series airplanes, in accordance with AD 95-10-16, 
amendment 39-9233 (60 FR 27008, May 22, 1995); AD 95-13-05, amendment 
39-9285 (60 FR 33333, June 28, 1995); AD 95-13-06, amendment 39-9286 
(60 FR 33338, June 28, 1995); and AD 95-13-07, amendment 39-9287 (60 FR 
33336, June 28, 1995).
    Operators also should note that Boeing Service Bulletin 747-54-2155 
recommends that the fuse pins in the upper link, midspar fittings, and 
diagonal brace be replaced with new, corrosion-resistant pins at the 
next scheduled inspection of the pins. This proposed AD would require 
that such replacement be accomplished within 10 months after the 
effective date of this AD. In developing an appropriate compliance time 
for this proposed AD, the FAA considered not only the manufacturer's 
recommendation, but the degree of urgency associated with addressing 
the subject unsafe condition, the average utilization of the affected 
fleet, the age of the service information, and the time necessary to 
perform the pin replacement. In light of all of these factors, the FAA 
finds a 10-month compliance time for initiating the required actions to 
be warranted, in that it represents an appropriate interval of time 
allowable for affected airplanes to continue to operate without 
compromising safety.

Cost Impact

    There are approximately 282 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 43 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
105 work hours per airplane to accomplish the proposed replacement, and 
that the average labor rate is $60 per work hour. Required parts would 
be provided by the manufacturer at no cost to the operators. Based on 
these figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $270,900, or $6,300 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 98-NM-286-AD.

    Applicability: Model 747-200 and -300 series airplanes equipped 
with General Electric Model CF6-80C2 series engines, and Model 747-
400 series airplanes; as listed in Boeing Service Bulletin 747-54-
2155, Revision 2, dated June 6, 1996; certificated in any category; 
except those airplanes on which modifications of the strut/wing 
structure have been accomplished in accordance either of the 
following AD's:
     AD 95-13-05, amendment 39-9285 (60 FR 33333, June 28, 
1995), or
     AD 95-13-06, amendment 39-9286 (60 FR 33338, June 28, 
1995).

    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 cracking or corrosion of the fuse pins of the nacelle 
strut, which could result in failure of the fuse pin and strut-to-
wing attachment, and consequent loss of the strut and separation of 
the engine from the airplane; accomplish the following:
    (a) Within 10 months after the effective date of this AD, 
replace the fuse pins in the upper link, midspar fittings, and 
diagonal brace of the nacelle strut with new corrosion-resistant 
pins, in accordance with the Accomplishment Instructions of Boeing 
Service Bulletin 747-54-2155, Revision 2, dated June 6, 1996.

    Note 2: Replacement of the fuse pins accomplished prior to the 
effective date of this AD in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 747-54-2155, dated September 
23, 1993, or Revision 1, dated December 8, 1994, is considered 
acceptable for compliance with the applicable action specified in 
this amendment.

    Note 3: All fuse pins in the strut do not have to be replaced at 
the same time; however, the fuse pins do have to be replaced in 
sets, as specified in Boeing Service Bulletin 747-54-2155, Revision 
2, dated June 6, 1996.

    (b) Accomplishment of the replacement of the fuse pins specified 
in paragraph (a) of this AD constitutes terminating action for the 
repetitive inspections of the fuse pins of the upper link, required 
by AD 97-14-06, amendment 39-10064; of the fuse pins of the midspar 
fitting, required by AD 92-24-51,

[[Page 8026]]

amendment 39-8439; and of the fuse pins of the diagonal brace, 
required by AD 93-03-14, amendment 39-8518.
    (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 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 4: 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.

    Issued in Renton, Washington, on February 10, 1999.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-3886 Filed 2-17-99; 8:45 am]
BILLING CODE 4910-13-P