[Federal Register Volume 66, Number 15 (Tuesday, January 23, 2001)]
[Proposed Rules]
[Pages 7433-7435]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-1890]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 66, No. 15 / Tuesday, January 23, 2001 / 
Proposed Rules  

[[Page 7433]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-250-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, -200, -300, and 
747SP 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 747-100, -
200, -300, and 747SP series airplanes. This proposal would require 
certain inspections to find missing and alloy-steel taperlock fasteners 
(bolts) in the diagonal brace underwing fittings; and corrective 
actions, if necessary. For airplanes with missing or alloy-steel 
fasteners, this proposal also would mandate replacement of certain 
fasteners with new fasteners, which would constitute terminating action 
for the repetitive inspections. This action is necessary to prevent 
loss of the underwing fitting load path due to missing or damaged 
alloy-steel taperlock fasteners, which could result in separation of 
the engine and strut from the airplane. This action is intended to 
address the identified unsafe condition.

DATES: Comments must be received by March 9, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-250-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. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-250-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    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, 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 action may be changed in 
light of the comments received.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the proposed 
AD is being requested.
     Include justification (e.g., reasons or data) for each 
request.
    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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-250-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. 2000-NM-250-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received a report indicating that broken taperlock 
fasteners (bolts) were found on the diagonal brace underwing fittings 
on the outboard strut at the Number 1 and Number 4 engine pylons on a 
Boeing Model 747-200 series airplane having titanium underwing 
fittings. According to the manufacturer's drawings, Model 747-200 
series airplanes with titanium underwing fittings should only have 
taperlock fasteners made of A286 corrosion-resistant steel installed on 
the fitting, but investigation has revealed that certain airplanes may 
have taperlock fasteners made from alloy-steel installed. In the case 
mentioned above, both alloy-steel and A286 fasteners were found broken. 
Alloy-steel fasteners are known to be susceptible to corrosion and 
subsequent stress corrosion cracking. The cause of the broken A286 
fasteners has been attributed to fatigue cracking due to certain alloy-
steel fasteners on the same fitting cracking and increasing the load on 
the A286 fasteners. Such conditions, if not corrected, could result in 
loss of the underwing fitting load path and separation of the engine 
and strut from the airplane.
    The subject alloy-steel taperlock fasteners on Boeing Model 747-200 
series airplanes may also be on certain Boeing Model 747-100, -300, and 
SP series airplanes. Therefore, all of these airplanes are subject to 
the same unsafe condition.

[[Page 7434]]

Related Rulemaking

    This proposed AD is related to AD 2000-03-22, amendment 39-11582 
(65 FR 8640, February 22, 2000), which is applicable to certain Boeing 
Model 747-100, -200, and 747SP series airplanes having aluminum 
underwing fittings. These airplanes were delivered with taperlock bolts 
of alloy-steel installed in the underwing fittings. That AD requires 
repetitive detailed visual and ultrasonic inspections to detect 
missing, damaged, or broken taperlock bolts in the diagonal brace 
underwing fittings; and corrective actions, if necessary. That AD also 
requires eventual replacement of the aft 10 taperlock bolts with new 
fasteners, which constitutes terminating action for the repetitive 
inspections. This NPRM proposes similar actions for Boeing Model 747-
100, -200, -300, and 747SP series airplanes having alloy-steel 
taperlock fasteners in titanium underwing fittings.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-57A2312, dated June 15, 2000, which describes procedures for a one-
time detailed visual inspection to find missing taperlock fasteners and 
a one-time magnetic inspection to find alloy-steel taperlock fasteners. 
For airplanes on which alloy-steel or missing taperlock fasteners are 
found, the service bulletin describes procedures for repetitive 
ultrasonic inspections to find damaged (cracked or broken) alloy 
taperlock fasteners, and follow-on actions, if necessary, including 
ultrasonic inspection to find damaged non-alloy taperlock fasteners, 
and replacement of damaged fasteners with new fasteners. Replacement of 
fasteners involves performing an open-hole high frequency eddy current 
(HFEC) inspection to detect cracks at the bolt hole locations, and 
replacing damaged and missing taperlock fasteners with new fasteners. 
Such replacement terminates the repetitive inspections described 
previously. Accomplishment of the actions specified in the 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 service bulletin described previously, except as discussed below.

Differences Between Proposed AD and Service Bulletin

    Incorporation of the terminating action stated in the referenced 
service bulletin is optional, but this AD proposes to mandate, within 
48 months after the effective date of this AD, the open-hole inspection 
and replacement of certain fasteners with new fasteners stated in the 
referenced service bulletin as terminating action for the repetitive 
inspections. The FAA has determined that long-term continued 
operational safety will be better assured by design changes to remove 
the source of the problem, rather than by repetitive inspections. Long-
term inspections may not be providing the degree of safety assurance 
necessary for the transport airplane fleet. This, together with a 
better understanding of the human factors associated with numerous 
continued inspections, has led the FAA to consider placing less 
emphasis on inspections and more emphasis on design improvements. The 
proposed replacement requirement is in consonance with these 
conditions.
    In addition, the service bulletin specifies that the manufacturer 
must be contacted for repair of certain conditions, but this proposal 
would require the repair of those conditions to be accomplished per a 
method approved by the FAA; or per data meeting the type certification 
basis of the airplane approved by a Boeing Company Designated 
Engineering Representative who has been authorized by the FAA to make 
such findings. For a method to be approved, the approval letter must 
specifically reference this AD.

Cost Impact

    There are approximately 363 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 60 airplanes of U.S. registry 
would be affected by this proposed AD.
    It would take approximately 2 work hours per airplane to accomplish 
the proposed visual and magnetic inspections, at an average labor rate 
of $60 per work hour. Based on these figures, the cost impact of the 
proposed inspections on U.S. operators is estimated to be $7,200, or 
$120 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 proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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 2000-NM-250-AD.

    Applicability: Model 747-100, -200, -300, and 747SP series 
airplanes, equipped with titanium diagonal brace underwing fittings; 
as listed in Boeing Alert Service Bulletin 747-57A2312, dated June 
15, 2000; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability

[[Page 7435]]

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

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent loss of the underwing fitting load path due to 
missing or damaged taperlock fasteners, which could result in 
separation of the engine and strut from the airplane, accomplish the 
following:

Repetitive Inspections

    (a) Within 12 months after the effective date of this AD: Do a 
one-time detailed visual inspection of the diagonal brace underwing 
fitting at the Number 1 and Number 4 engine pylons to find missing 
taperlock fasteners (bolts), and a magnetic inspection to find 
alloy-steel fasteners per Part 1 of the Accomplishment Instructions 
of Boeing Alert Service Bulletin 747-57A2312, dated June 15, 2000.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

    (1) If no alloy-steel fasteners are found and no fasteners are 
missing, no further action is required by this AD.
    (2) If any alloy-steel fasteners are found or any fasteners are 
missing, before further flight, do an ultrasonic inspection of the 
alloy-steel fasteners to find damage per Part 2 of the 
Accomplishment Instructions of the service bulletin.
    (i) If no damaged alloy-steel fasteners are found, and no 
fasteners are missing: Repeat the ultrasonic inspection thereafter 
at intervals not to exceed 18 months until accomplishment of the 
terminating action required by paragraph (b) of this AD.
    (ii) If any damaged alloy-steel fasteners are found, or any 
fasteners are missing: Before further flight, do an ultrasonic 
inspection of all 10 aft fasteners (including non-alloy steel) per 
Part 2 of the Accomplishment Instructions of the service bulletin. 
Before further flight, replace damaged and missing fasteners with 
new fasteners per Part 3 of the Accomplishment Instructions of the 
service bulletin, except as provided by paragraph (c) of this AD. 
Thereafter, repeat the inspection of the remaining alloy-steel 
fasteners at intervals not to exceed 18 months until accomplishment 
of the terminating action required by paragraph (b) of this AD.

Terminating Action

    (b) Within 48 months after the effective date of this AD: Do the 
actions required by paragraphs (b)(1) and (b)(2), or (b)(3) of this 
AD, per Boeing Alert Service Bulletin 747-57A2312, dated June 15, 
2000. Accomplishment of the actions specified in this paragraph 
constitutes terminating action for the repetitive inspection 
requirements of this AD.
    (1) Perform an open-hole high frequency eddy current (HFEC) 
inspection to detect cracks at the bolt hole locations of the aft 10 
taperlock fasteners in the diagonal brace underwing fitting at the 
Number 1 and Number 4 engine pylons per Part 3 of the Accomplishment 
Instructions of the service bulletin. If any cracking is detected, 
before further flight, perform applicable corrective actions per the 
service bulletin, except as provided by paragraph (c) of this AD.
    (2) Before further flight: Replace all 10 aft taperlock 
fasteners with new, improved fasteners per Part 3 of the 
Accomplishment Instructions of the service bulletin.
    (3) Do an ultrasonic inspection to find damaged fasteners per 
Part 2 of the Accomplishment Instructions of the service bulletin. 
Before further flight, replace all damaged non-alloy steel and all 
alloy-steel fasteners with new fasteners per Part 3 of the 
Accomplishment Instructions of the service bulletin. Do an open-hole 
HFEC inspection before installation of the new fasteners, if any 
cracking is found, before further flight, perform applicable 
corrective actions per the service bulletin, except as provided by 
paragraph (c) of this AD.

Corrective Actions

    (c) If any cracking of the bolt hole that exceeds the limits 
specified in the service bulletin is found, or if any non-alloy 
steel bolt is found to be damaged, during any inspection required by 
this AD, and the bulletin specifies to contact Boeing for 
appropriate action: Before further flight, repair per a method 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA; or per 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.

Spares

    (d) As of the effective date of this AD, no person shall install 
on any airplane, a fastener, part number BACB30PE( ) * ( ); or any 
other fastener made of 4340, 8740, PH13-8 Mo or H-11 steel, in the 
locations specified in this AD.

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 Permit

    (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 January 16, 2001.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-1890 Filed 1-22-01; 8:45 am]
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