[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
