[Federal Register Volume 60, Number 64 (Tuesday, April 4, 1995)]
[Proposed Rules]
[Pages 17030-17032]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-8174]



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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.

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Federal Register / Vol. 60, No. 64 / Tuesday, April 4, 1995 / 
Proposed Rules
[[Page 17030]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-255-AD]


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 repetitive inspections for 
cracking in the inboard strut-to-diagonal brace attach fittings and 
repair or replacement, if necessary. This action would require an 
additional inspection of those attach fittings, and additional 
inspections in an area beyond that specified in the existing AD. This 
action also would provide an optional terminating action for the 
required inspections, and would expand the applicability of the 
existing AD to include additional airplanes. This proposal is prompted 
by reports of cracking and severing of the attach fittings. The actions 
specified by the proposed AD are intended to prevent failure of the 
strut and separation of an engine from the airplane due to cracking of 
the inboard strut-to-diagonal brace attach fittings.

DATES: Comments must be received by May 30, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-255-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: Tim Backman, Aerospace Engineer, 
Airframe Branch, ANM-120S, Seattle Aircraft Certification Office, FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2776; fax (206) 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 94-NM-255-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-103, Attention: Rules 
Docket No. 94-AD-255-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On August 13, 1979, the FAA issued AD 79-17-07, amendment 39-3533 
(44 FR 50033, August 27, 1979), applicable to certain Boeing Model 747 
series airplanes, to require repetitive visual inspections for cracking 
in the inboard strut-to-diagonal brace attach fittings, and repair or 
replacement, if necessary. That action was prompted by reports of 
cracking in the inboard strut-to-diagonal brace attach fittings. The 
requirements of that AD are intended to prevent structural failure of 
these attach fittings, and the consequent separation of an engine from 
the airplane.
    Since the issuance of that AD, the FAA has received additional 
reports of cracking of inboard strut-to-diagonal brace attach fittings. 
On one airplane that had accumulated 14,151 landings, a 12-inch long 
crack was detected and, in another case, a severed fitting was reported 
on an airplane that had accumulated 15,323 landings. Investigation has 
revealed that the cracking was caused by fatigue. These airplanes had 
been inspected in accordance with AD 79-17-07. Cracking of the attach 
fittings, if not detected and corrected in a timely manner, could 
result in failure of the strut and separation of an engine from the 
airplane.
    The FAA has reviewed and approved Boeing Service Bulletin 747-54-
2062, Revision 7, dated December 21, 1994, which describes the 
following:
    1. Procedures for repetitive visual and high frequency eddy current 
(HFEC) inspections for cracking of the inboard strut-to-diagonal brace 
attach fittings;
    2. Procedures for reinspections of certain attach fittings at 
decreased intervals; and
    3. Procedures for replacement of certain attach fittings with 
serviceable fittings.
    This service bulletin also describes procedures for accomplishment 
of a modification that entails removing the aluminum attach fittings 
and replacing them with steel fittings. Accomplishment of this 
modification eliminates the need for inspections of the subject area. 
(This modification is part of the ``Boeing Model 747 Strut and Wing 
Structural Modification Program,'' described in Boeing Service Bulletin 
747-54A2159, dated November 3, 1994.)
    Revision 7 of this service bulletin also describes additional 
action to be [[Page 17031]] accomplished on airplanes on which the 
``terminating modification,'' as provided by AD 79-17-07, was 
previously installed. This additional action involves sealing a gap 
between the fitting and the existing closure web, which can be 
accomplished by either installing a new closure web, or fabricating and 
installing a new seal plate.
    The manufacturer also has identified additional Model 747 series 
airplanes that are subject to the same cracking conditions addressed by 
AD 79-17-07; therefore, those additional airplanes are included in the 
effectivity listing of Revision 7 of the service bulletin.
    Based on these data, the FAA has determined that, in addition to 
adding airplanes to the applicability of this AD, additional actions 
also are necessary on airplanes that have been inspected in accordance 
with AD 79-17-07. The FAA finds that repetitive visual inspections and 
repetitive surface HFEC inspections must be accomplished on the attach 
fittings. Additionally, the FAA finds that certain attach fittings with 
known cracking must be inspected at a decreased interval and the attach 
fitting must be replaced, if necessary.
    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 79-17-07 to continue to require 
repetitive visual inspections to detect cracking of the inboard strut-
to-diagonal brace attach fittings, and replacement or repair of the 
cracking, if necessary. This proposal would add repetitive HFEC 
inspections to detect cracks of the attach fittings. This proposal also 
would require that certain attach fittings with cracks be reinspected 
at decreased intervals, and would require subsequent replacement of the 
attach fittings of airplanes with certain known cracking. The actions 
would be required to be accomplished in accordance with the service 
bulletin described previously.
    Additionally, this proposal also would expand the applicability of 
the rule to include additional affected airplanes.
    This proposal also provides for an optional terminating 
modification for the requirements of the proposed AD. This optional 
modification entails removing the aluminum attach fittings and 
replacing them with steel fittings. By a separate rulemaking action 
[refer to Notice of Proposed Rulemaking, Docket 94-NM-187-AD, (59 FR 
65733, December 21, 1994)], the FAA is proposing to require the 
mandatory accomplishment of this modification (described in Boeing 
Alert Service Bulletin 747-54A2159, dated November 3, 1994) as part of 
a ``Strut and Wing Structural Modification Program'' developed by 
Boeing. The intent of that program is to address the cracking condition 
and other items associated with the engine struts on Boeing Model 747 
series airplanes.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. The FAA 
points out that all airplanes identified in the applicability provision 
of an AD are legally subject to the AD. If an airplane has been altered 
or repaired in the affected area in such a way as to affect compliance 
with the AD, the owner or operator is required to obtain FAA approval 
for an alternative method of compliance with the AD, in accordance with 
the paragraph of each AD that provides for such approvals. A note has 
been included in this notice to clarify this requirement.
    There are approximately 367 Model 747 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 152 
airplanes of U.S. registry would be affected by this proposed AD, that 
it would take approximately 11 work hours per airplane to accomplish 
the proposed actions, and that the average labor rate is $60 per work 
hour. Based on these figures, the total cost impact of the proposed AD 
on U.S. operators is estimated to be $100,320, or $660 per airplane, 
per inspection cycle. -
    The total 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. -
    Should an operator elect to accomplish the terminating modification 
that would be provided by this AD action, it would take approximately 
176 work hours to accomplish it, at an average rate of $60 per work 
hour. The cost of required parts would be $4,752. Based on these 
figures, the total cost impact of the terminating modification would be 
$15,312 per airplane. -
    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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended] -

    2. Section 39.13 is amended by removing amendment 39-3533 (44 FR 
50033, August 27, 1979), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 94-NM-255-AD. Supersedes AD 79-17-07, Amendment 39-
3533.

     -Applicability: Model 747 series airplanes; as listed in Boeing 
Service Bulletin 747-54-2062, Revision 7, dated December 21, 1994; 
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 use the authority 
provided in paragraph (g) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition; or different actions necessary to 
address the unsafe [[Page 17032]] condition described in this AD. 
Such a request should include an assessment of the effect of the 
changed configuration on the unsafe condition addressed by this AD. 
In no case does the presence of any modification, alteration, or 
repair remove any airplane from the applicability of this AD.

     -Compliance: Required as indicated, unless accomplished 
previously. -
    To prevent failure of the strut and subsequent loss of an 
engine, accomplish the following:

     -Note 2: Paragraph (a) of this AD restates the requirements for 
initial and repetitive visual inspections contained in paragraphs 
A., and C., respectively, of AD 79-17-07, amendment 39-3583. 
Therefore, for operators who have previously accomplished at least 
the initial inspection in accordance with AD 79-17-07, paragraph (a) 
of this AD requires that the next scheduled inspection be performed 
within the intervals specified in (a)(1) or (a)(2), as applicable, 
after the last inspection performed in accordance with paragraph A. 
or C. of AD 79-17-07. -
    (a) For airplanes listed in Boeing Service Bulletin 747-54-2062, 
dated August 17, 1979: Prior to the accumulation of 5,000 total 
landings on the airplane, or within 500 hours time-in-service after 
September 4, 1979 (the effective date of AD 79-17-07, Amendment 39-
3533), whichever occurs later, perform a visual inspection of the 
forward lower diagonal brace fittings of the inboard pylon to detect 
cracking, in accordance with Boeing Service Bulletin 747-54-2062, 
dated August 17, 1979, or Revision 7, dated December 21, 1994; or in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office, FAA, Transport Airplane Directorate. After the 
effective date of this AD, only Revision 7 of the service bulletin 
shall be used.


     -Note 3: Inspections performed prior to the effective date of 
this AD are considered in compliance with this paragraph if 
performed in accordance with Boeing Service Bulletin 747-54-2062, 
Revision 1, dated November 13, 1980; Revision 2, dated March 19, 
1981; Revision 3, dated August 28, 1981; Revision 4, dated June 30, 
1982; Revision 5, dated June 1, 1984; or Revision 6, dated October 
2, 1986.

    -(1) If no cracking is detected, repeat the inspections at 
intervals not to exceed 1,000 landings until all affected fittings 
are replaced with steel fittings in accordance with Revision 7 of 
the service bulletin. -
    (2) If any cracking is detected, prior to further flight, 
accomplish either paragraph (a)(2)(i) or (a)(2)(ii) of this AD until 
the inspections required by paragraph (b) of this AD are 
accomplished. -
    (i) Repair or replace the cracked fitting in accordance with the 
service bulletin; or -
    (ii) Rework the cracked fitting in accordance with the service 
bulletin as required by paragraph (b) of this AD. Thereafter, repeat 
the inspections at intervals not to exceed 250 landings until the 
reworked fitting is replaced with a serviceable fitting, or until 
the inspections required by paragraph (b) of this AD are 
accomplished. -
    (b) For airplanes as listed in Boeing Service Bulletin 747-54-
2062, Revision 7, dated December 21, 1994: Perform a detailed visual 
inspection and a surface high frequency eddy current (HFEC) 
inspection to detect cracking of the inboard strut-to-diagonal brace 
attach fittings, in accordance with the service bulletin at the time 
specified in either paragraph (b)(1) or (b)(2) of this AD, as 
applicable. -
    (1) For airplanes on which a cracked fitting has been reworked 
in accordance with Boeing Service Bulletin 747-54-2062, dated August 
17, 1979: Perform the inspections within 250 landings since the last 
inspection performed in accordance with paragraph (a)(2)(ii) of this 
AD. -
    (2) For airplanes other than those identified in paragraph 
(b)(1) of this AD: Perform the inspections at the earlier of the 
times specified in paragraph (b)(2)(i) or (b)(2)(ii) of this AD. -
    (i) Prior to the accumulation of 5,000 total landings on the 
airplane, or within 1,000 landings after the effective date of this 
AD, whichever occurs later; or -
    (ii) Within 1,000 landings since the last inspection performed 
in accordance with paragraph (a) of this AD. -
    (c) If no cracking is detected during the inspections required 
by paragraph (b) of this AD, repeat the inspections thereafter at 
intervals not to exceed 1,000 landings. -
    (d) If more than one crack is found during any inspection 
required by this AD, or if any crack is detected that is beyond the 
limits specified in Boeing Service Bulletin 747-54-2062, Revision 7, 
dated December 21, 1994, prior to further flight, replace the attach 
fitting with a steel fitting in accordance with the service 
bulletin. -
    (e) If any transverse or longitudinal crack is found during the 
inspection required by paragraph (b) of this AD, and that crack is 
within the limits specified by Boeing Service Bulletin 747-54-2062, 
Revision 7, dated December 21, 1994: Prior to further flight, stop 
drill the crack in accordance with the service bulletin, and 
accomplish the requirements of either paragraph (e)(1) or (e)(2) of 
this AD, as applicable. -
    (1) For any transverse crack that is found, accomplish the 
following: -
    (i) Prior to further flight, remove the affected fastener and 
perform an open-hole HFEC inspection to detect cracking of the 
fastener hole, in accordance with the service bulletin. Thereafter, 
repeat this inspection within 125 landings. -
    (ii) Repeat the inspections required by paragraph (b) of this AD 
within 125 landings after performing them initially. -
    (iii) If any crack is found during the inspections required by 
this paragraph and the crack is beyond the limits specified in the 
service bulletin, prior to further flight, replace the attach 
fitting with a steel fitting in accordance with the service 
bulletin. -
    (iv) Prior to the accumulation of 250 landings following the 
detection of the transverse cracking, unless previously 
accomplished, replace the attach fitting with a steel fitting in 
accordance with the service bulletin. -
    (2) For any longitudinal crack that is found, accomplish the 
following: -
    (i) Repeat the inspection required by paragraph (b) of this AD 
at intervals not to exceed 250 landings. -
    (ii) Prior to the accumulation of 1,000 landings following 
detection of the longitudinal cracking, replace the attach fitting 
with a steel fitting in accordance with the service bulletin. -
    (f) Replacement of the attach fittings of the strut-to-diagonal 
brace with steel fittings, in accordance with Boeing Service 
Bulletin 747-54-2062, Revision 7, dated December 21, 1994, 
constitutes terminating action for the requirements of this AD. -
    (g) 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 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    -(h) 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 March 29, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-8174 Filed 4-3-95; 8:45 am]
BILLING CODE 4910-13-U