[Federal Register Volume 64, Number 136 (Friday, July 16, 1999)]
[Proposed Rules]
[Pages 38379-38382]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18202]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-277-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 supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 747 
series airplanes, that currently requires inspections of the lower 
engine mount to determine if the tangential link upper bolt and nut are 
oriented properly, and if the tangential link upper bolt nut is torqued 
within certain limits. Additionally, that AD requires replacement of 
the bolt and nut with serviceable parts, if necessary, and requires 
certain follow-on actions for airplanes on which the upper bolt is 
missing. That AD also provides for replacement of the safety links with 
modified links as an optional terminating action for the repetitive 
inspections. This action would require accomplishment of either the 
previously optional terminating action or a new, alternative 
terminating action. This proposal is prompted by development of a new 
terminating action by the manufacturer. The actions specified by the 
proposed AD are intended to prevent separation of the engine from the 
airplane due to migration of the tangential link upper bolt.

DATES: Comments must be received by August 30, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-277-AD, 1601 Lind Avenue, SW.,

[[Page 38380]]

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-277-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-277-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On January 22, 1996, the FAA issued AD 96-03-01, amendment 39-9496 
(61 FR 3550, February 1, 1996), applicable to certain Boeing Model 747 
series airplanes. That AD requires inspections of the lower engine 
mount to determine if the tangential link upper bolt and nut are 
oriented properly, and if the tangential link upper bolt nut is torqued 
within certain limits. Additionally, that AD requires replacement of 
the bolt and nut with serviceable parts, if necessary, and certain 
follow-on actions for airplanes on which the upper bolt is missing. 
Terminating action is also provided by that AD. That action was 
prompted by reports of migration of bolts completely from the 
tangential link of the aft engine mount, a condition which would reduce 
the capability of the retention system for the engine. The requirements 
of that AD are intended to prevent separation of the engine from the 
airplane due to migration of the tangential link upper bolt.
    Subsequently, on March 6, 1996, the FAA issued a correction to that 
AD, AD 96-03-01 R1, amendment 39-9538 (61 FR 10270, March 13, 1996), to 
clarify an incorrect description of a part.

Actions Since Issuance of Previous Rule

    In the preamble to AD 96-03-01, the FAA indicated that the actions 
required by that AD were considered ``interim action'' and that further 
rulemaking action was being considered. The FAA now has determined that 
further rulemaking action is indeed necessary, and this proposed AD 
follows from that determination.

Explanation of Relevant Service Information

    Since the issuance of AD 96-03-01 R1, the FAA has reviewed and 
approved Boeing Service Bulletin 747-71A2277, Revision 1, dated May 21, 
1998, and Revision 2, dated January 14, 1999. That service bulletin 
describes procedures for an alternative modification that would 
eliminate the need for the repetitive inspections required by AD 96-03-
01 R1. That modification involves replacement of the tangential link 
upper bolt on the aft engine mount with a reworked bolt and a new nut 
retainer. The service bulletin also describes procedures for reworking 
the tangential link upper bolt and fabricating the nut retainer. 
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 supersede AD 96-03-01 R1 to continue to require 
inspections of the lower engine mount to determine if the tangential 
link upper bolt and nut are oriented properly, and if the tangential 
link upper bolt nut is torqued within certain limits; replacement of 
the bolt and nut with serviceable parts, if necessary; and certain 
follow-on actions for airplanes on which the upper bolt is missing. 
This proposed AD also would require either replacement of the safety 
links with modified safety links, or replacement of the tangential link 
upper bolt on the aft engine mount with a reworked bolt and a new nut 
retainer. Accomplishment of either such replacement would constitute 
terminating action for the repetitive inspection requirement.
    The inspections would be required to be accomplished in accordance 
with Boeing Alert Service Bulletin 747-71A2277, dated November 29, 
1995, or the service bulletins described previously. The replacement of 
the safety links, if accomplished, would be required to be accomplished 
in accordance with Boeing Service Bulletin 747-71-2206, dated April 16, 
1987; or Boeing Service Bulletin 747-71-2206, Revision 1, dated 
November 12, 1987, as revised by Boeing Notice of Status Change No. 
747-71-2206 NSC 1, dated December 4, 1987, and Boeing Notice of Status 
Change No. 747-71-2206 NSC 2, dated March 17, 1988. The replacement of 
the tangential link bolt, if accomplished, would be required to be 
accomplished in accordance with the service bulletins described 
previously.

Cost Impact

    There are approximately 421 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 185 airplanes of U.S. registry 
would be affected by this proposed AD.
    The inspections that are currently required by AD 96-03-01 R1 take 
approximately 16 work hours 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 actions on U.S. operators is estimated 
to be $177,600, or $960 per airplane, per inspection cycle.
    The replacement of the safety link that is proposed as one option 
for compliance with this AD action would take approximately 18 work 
hours per airplane to accomplish, at an average

[[Page 38381]]

labor rate of $60 per work hour. Required parts would cost 
approximately $30,228 per airplane. Based on these figures, the cost 
impact of this replacement proposed by this AD on U.S. operators is 
estimated to be $31,308 per airplane.
    In lieu of replacement of the safety link, this proposed AD 
provides for replacement of the tangential link upper bolt on the aft 
engine mount with a reworked bolt and a new nut retainer. Such 
replacement, which is proposed as an additional option for compliance 
with this AD action, would take approximately 20 work hours per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
Required parts would cost approximately $1,888 per airplane. Based on 
these figures, the cost impact of this replacement proposed by this AD 
on U.S. operators is estimated to be $3,088 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 39-9538 (61 FR 
10270, March 13, 1996), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 98-NM-277-AD. Supersedes AD 96-03-01 R1, amendment 
39-9538.
    Applicability: Model 747 series airplanes, as listed in Boeing 
Alert Service
    Bulletin 747-71A2277, dated November 29, 1995; or Boeing Service 
Bulletin 747-71A2277, Revision 1, dated May 21, 1998, or Revision 2, 
dated January 14, 1999; 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 (c)(1) 
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 separation of the engine from the airplane, 
accomplish the following:

Restatement of Requirements of AD 96-03-01 R1, Amendment 39-9538

Inspections and Corrective Actions

    (a) Within 90 days after February 16, 1996 (the effective date 
of AD 96-03-01 R1, amendment 39-9538), accomplish the requirements 
of paragraphs (a)(1) and (a)(2) of this AD in accordance with Boeing 
Alert Service Bulletin 747-71A2277, dated November 29, 1995, or 
Boeing Service Bulletin 747-71A2277, Revision 1, dated May 21, 1998, 
or Revision 2, dated January 14, 1999.
    (1) Perform a visual inspection to ensure that installation of 
the tangential link upper bolt nut is on the forward side of the 
engine mount fitting.
    (i) If the tangential link upper bolt nut is installed on the 
forward side of the engine mount fitting, repeat the visual 
inspection at intervals not to exceed 18 months.
    (ii) If the tangential link upper bolt nut is not installed on 
the forward side of the engine mount fitting, prior to further 
flight, remove the nut, bolt, and washers, and reinstall the nut, 
bolt, and washers in accordance with the service bulletin. 
Thereafter, repeat the visual inspection at intervals not to exceed 
18 months.
    (iii) If the tangential link upper bolt is missing from the 
engine mount fitting, prior to further flight, perform the various 
follow-on actions in accordance with the service bulletin. (The 
follow-on actions include visual inspections, magnetic particle 
inspections, replacement of the lower engine mount fitting with a 
serviceable part, if necessary; installation of new safety links, 
bolts, and nuts; and installation of a new tangential link upper 
bolt.) Thereafter, repeat the visual inspection at intervals not to 
exceed 18 months.
    (2) Perform an inspection to verify that the torque value of the 
tangential link upper bolt (on both sides of the mount) is within 
the limits specified in the service bulletin.
    (i) If the torque value of the tangential link upper bolt nut is 
within the limits specified in the service bulletin, repeat the 
inspection (verification) at intervals not to exceed 18 months.
    (ii) If the torque value of the tangential link upper bolt nut 
is outside the limits specified in the service bulletin, prior to 
further flight, perform a visual inspection of the tangential link 
upper bolt and washer for any damage or discrepancy, in accordance 
with the service bulletin.
    (A) If no damage or discrepancy of the tangential link upper 
bolt and washers is found, prior to further flight, replace the bolt 
nut with a new or serviceable part in accordance with the service 
bulletin. Thereafter, repeat the inspection (verification) specified 
in paragraph (a)(2) of this AD at intervals not to exceed 18 months.
    (B) If any damage or discrepancy of the tangential link upper 
bolt and washers is found, prior to further flight, replace the 
damaged or discrepant part with a new or serviceable part, and 
replace the bolt nut with a new or serviceable part, in accordance 
with the service bulletin. Thereafter, repeat the inspection 
(verification) specified in paragraph (a)(2) of this AD at intervals 
not to exceed 18 months.

New Requirements of This AD

Replacement

    (b) Within 18 months after the effective date of this AD, 
accomplish the requirements of either paragraph (b)(1) or (b)(2) of 
this AD. Accomplishment of either paragraph (b)(1) or (b)(2) of this 
AD constitutes terminating action for the repetitive inspection 
requirements of this AD.
    (1) Replace the safety links on the aft engine mount with 
modified safety links in accordance with Boeing Service Bulletin 
747-71-2206, dated April 16, 1987; or Boeing Service Bulletin 747-
71-2206, Revision 1, dated November 12, 1987, as revised by Boeing 
Notice of Status Change No. 747-71-2206 NSC 1, dated December 4, 
1987, and Boeing Notice of Status Change

[[Page 38382]]

No. 747-71-2206 NSC 2, dated March 17, 1988.
    (2) Replace the tangential link upper bolt on the aft engine 
mount with a reworked bolt and a new nut retainer, in accordance 
with Parts 2 and 3 of Boeing Service Bulletin 747-71A2277, Revision 
1, dated May 21, 1998, or Revision 2, dated January 14, 1999.

Alternative Methods of Compliance

    (c)(1) 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.
    (2) Alternative methods of compliance, approved previously in 
accordance with AD 96-03-01 R1, amendment 39-9538, are approved as 
alternative methods of compliance with this AD.

    Note 2: 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

    (d) 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 July 12, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-18202 Filed 7-15-99; 8:45 am]
BILLING CODE 4910-13-P