[Federal Register Volume 59, Number 162 (Tuesday, August 23, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-20593]


[[Page Unknown]]

[Federal Register: August 23, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-27-AD]

 

Airworthiness Directives; Boeing Model 747-100 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-
100 series airplanes, that currently requires repetitive inspections to 
detect cracking of the wing front spar web above engine numbers 2 and 
3, and repair, if necessary. This action would require repetitive 
inspections to detect cracks in the web and cracked or broken fasteners 
in an area beyond that specified in the existing AD. This action also 
would provide an optional terminating action for the repetitive 
inspections. This proposal is prompted by reports of broken fasteners 
and cracking of the web common to the upper and lower chords in an area 
outside the inspection zone specified in the existing AD. The actions 
specified by the proposed AD are intended to prevent fuel leakage onto 
an engine and a resultant fire due to cracking or broken fasteners in 
the wing front spar.

DATES: Comments must be received by October 17, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-27-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, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 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-27-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-NM-27-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On March 10, 1992, the FAA issued AD 92-07-11, amendment 39-8207 
(57 FR 10415, March 26, 1992), applicable to certain Boeing Model 747-
100 series airplanes, to require inspections to detect cracking of the 
wing front spar web above engine numbers 2 and 3, and repair, if 
necessary. That action was prompted by a report of an 18-inch crack in 
the front spar web at the attach fitting of the number 3 engine. The 
requirements of that AD are intended to prevent fuel leakage onto an 
engine and a resultant fire.
    Since the issuance of that AD, the FAA has received reports of 
broken fasteners and cracking in the fastener holes of the web common 
to the upper and lower chords in areas outside the inspection zone 
specified in AD 92-07-11. The airplanes on which these cracks and 
broken fasteners were found had accumulated between 13,700 and 22,000 
flight cycles. Based on these findings, the FAA has determined that 
inspections to detect cracks and broken fasteners in an area beyond 
that specified in AD 92-07-11 are necessary.
    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-57A2266, Revision 3, dated March 31, 1994, which describes 
procedures for repetitive detailed visual inspections of the chords, 
stiffeners, and rib posts between the fastener heads and ultrasonic 
inspections to detect cracks of the wing front spar web between front 
spar stations (FSS) 570 and 684. The alert service bulletin also 
describes procedures for repetitive ultrasonic inspections of the 
fasteners in the web-to-chords, web-to-stiffeners, and web-to-rib posts 
to detect cracked or broken fasteners between FSS 570 and 684. For 
those airplanes on which cracks or broken fasteners are found, the 
alert service bulletin also describes procedures for oversizing 
fastener holes, performing an eddy current inspection to detect 
cracking of the fastener holes, and replacing cracked fasteners with 
oversized fasteners. The alert service bulletin also describes 
procedures for replacement of certain fasteners with oversized 
fasteners, which, if accomplished, would eliminate the need for the 
repetitive inspections.
    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 92-07-11 to require repetitive detailed 
visual and ultrasonic inspections to detect cracks in an area beyond 
that specified in the existing AD; and repetitive ultrasonic 
inspections of the fasteners in the web-to-chords, web-to-stiffeners, 
and web-to-rib posts to detect cracked or broken fasteners between FSS 
570 and 684. If any cracked or broken fastener is found, this proposed 
AD would require oversizing the fastener holes, performing an eddy 
current inspection to detect cracking of the fastener holes, and 
replacing cracked fasteners with oversized fasteners. This proposed AD 
also would provide an optional terminating action for the repetitive 
inspections. The actions would be required to be accomplished in 
accordance with the alert service bulletin described previously.
    There are approximately 190 Model 747-100 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 95 
airplanes of U.S. registry would be affected by this proposed AD.
    The inspections that were required previously by AD 92-07-11, and 
retained in this AD, take approximately 16 work hours per airplane to 
accomplish, at an average labor rate of $55 per work hour. Based on 
these figures, the total cost impact of that inspection requirement on 
U.S. operators is estimated to be $83,600, or $880 per airplane, per 
inspection cycle.
    The FAA estimates that it would take approximately 54 work hours 
per airplane to accomplish the proposed inspections of the expanded 
area specified in this AD, and that the average labor rate is $55 per 
work hour. Based on these figures, the future total cost impact of the 
inspection requirement of the expanded zone on U.S. operators is 
estimated to be $282,150, or $2,970 per airplane.
    Based on these figures, the total cost impact of the proposed AD on 
U.S. operators is estimated to be $365,750, or $3,850 per airplane.
    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 optional terminating 
action (fastener replacement between FSS 570 and FSS 684) that would be 
provided by this AD action, it would take approximately 306 work hours 
to accomplish it, at an average labor rate of $55 per work hour. The 
cost of required parts would be provided by the manufacturer at no cost 
to operators. Based on these figures, the total cost impact of the 
optional terminating action would be $16,830 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 39-8207 (57 FR 
10415, March 26, 1992), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 94-NM-27-AD. Supersedes AD 92-07-11, Amendment 39-
8207.

    Applicability: Model 747-100 series airplanes; as listed in 
Boeing Alert Service Bulletin 747-57A2266, Revision 3, dated March 
31, 1994; certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent fuel leakage onto an engine and a resultant fire, 
accomplish the following:
    Restatement of Actions Required by AD 92-07-11, Amendment 39-
8207:
    (a) For airplanes listed in Boeing Alert Service Bulletin 747-
57A2266, dated June 6, 1991, on which the optional terminating 
action (fastener replacement) specified in the original issue, dated 
June 6, 1991; Revision 1, dated May 21, 1992; or Revision 2, dated 
June 10, 1993; of the alert service bulletin has not been 
accomplished: Perform a visual inspection and an ultrasonic 
inspection to detect cracks of the wing front spar web between front 
spar station (FSS) 636 and FSS 675 in accordance with Boeing Alert 
Service Bulletin 747-57A2266, dated June 6, 1991; Revision 1, dated 
May 21, 1992; Revision 2, dated June 10, 1993; or Revision 3, dated 
March 31, 1994; at the time specified in paragraph (a)(1), (a)(2), 
or (a)(3) of this AD, as applicable. Repeat these inspections 
thereafter at intervals not to exceed 2,000 flight cycles until the 
inspections required by paragraph (b) of this AD are accomplished.
    (1) For airplanes that have accumulated more than 20,000 total 
flight cycles as of May 4, 1992 (the effective date of AD 92-07-11, 
amendment 39-8207): Inspect within 6 months after May 4, 1992.
    (2) For airplanes that have accumulated between 15,000 and 
20,000 total flight cycles as of May 4, 1992: Inspect within 15 
months after May 4, 1992.
    (3) For airplanes that have accumulated less than 15,000 total 
flight cycles as of May 4, 1992: Inspect within 15 months after 
accumulating 15,000 total flight cycles.
    New Actions Required by This AD:
    (b) For airplanes on which the terminating action (fastener 
replacement) specified in Boeing Alert Service Bulletin 747-57A2266, 
dated June 6, 1991; Revision 1, dated May 21, 1992; or Revision 2, 
dated June 10, 1993; has not been accomplished: Prior to the 
accumulation of 13,000 total flight cycles, or within 6 months after 
the effective date of this AD, or within 1,000 flight cycles after 
the immediately preceding inspection accomplished in accordance with 
paragraph (a) of this AD, whichever occurs later, accomplish the 
inspections specified in paragraphs (b)(1), (b)(2), and (b)(3) of 
this AD in accordance with Boeing Alert Service Bulletin 747-
57A2266, Revision 3, dated March 31, 1994. Repeat these inspections 
thereafter at intervals not to exceed 2,000 flight cycles. 
Accomplishment of these inspections terminates the inspections 
required by paragraph (a) of this AD. After the effective date of 
this AD, the inspections required by this paragraph shall be 
accomplished only in accordance with Revision 3 of the alert service 
bulletin.
    (1) Perform a detailed visual inspection of the chords, 
stiffeners, and rib posts between the fastener heads; and
    (2) Perform an ultrasonic inspection of the web under the upper 
and lower chord footprints to detect cracking of the wing front spar 
web between FSS 570 and FSS 684; and
    (3) Perform an ultrasonic inspection of the fasteners in the 
web-to-chords, web-to-stiffeners, and web-to-rib posts to detect 
cracked or broken fasteners between FSS 570 and FSS 684. -
    (c) For airplanes on which the terminating action (fastener 
replacement) specified in Boeing Alert Service Bulletin 747-57A2266, 
dated June 6, 1991; Revision 1, dated May 21, 1992; or Revision 2, 
dated June 10, 1993; has been accomplished: Within 18 months after 
accomplishing the terminating action specified in the original 
issue, Revision 1, or Revision 2 of the alert service bulletin, or 
within 9 months after the effective date of this AD, whichever 
occurs later, accomplish the inspections specified in paragraphs 
(c)(1), (c)(2), and (c)(3) of this AD in accordance with Boeing 
Alert Service Bulletin 747-57A2266, Revision 3, dated March 31, 
1994. Repeat these inspections thereafter at intervals not to exceed 
2,000 flight cycles. After the effective date of this AD, the 
inspections required by this paragraph shall be accomplished only in 
accordance with Revision 3 of the alert service bulletin.
    (1) Perform a detailed visual inspection of the chords, 
stiffeners, and rib posts between the fastener heads; and -
    (2) Perform an ultrasonic inspection of the web under the upper 
and lower chord footprints to detect cracking of the wing front spar 
web between FSS 570 and FSS 636 and between FSS 675 and FSS 684; and
    (3) Perform an ultrasonic inspection of the fasteners in the 
web-to-chords, web-to-stiffeners, and web-to-rib posts to detect 
cracked or broken fasteners between FSS 570 and FSS 636 and between 
FSS 675 and 684. -
    (d) If any crack in the web or any cracked or broken fastener is 
found during any inspection required by this AD, prior to further 
flight, oversize the fastener hole, perform an eddy current 
inspection to detect cracks in the fastener hole, and replace the 
fastener with an oversized fastener, in accordance with Boeing Alert 
Service Bulletin 747-57A2266, Revision 3, dated March 31, 1994. 
Thereafter, continue to inspect the remaining fasteners in 
accordance with paragraph (b) or (c) of this AD, as applicable, 
until the terminating action specified in paragraph (e) of this AD 
is accomplished. If any crack is found that cannot be removed by 
oversizing the fastener hole, prior to further flight, repair in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate.
    (e) Replacement of the fasteners in the web-to-chords and of the 
fasteners in the web-to-stiffeners and web-to-rib posts, as 
specified in Boeing Alert Service Bulletin 747-57A2266, Revision 3, 
dated March 31, 1994, with oversized fasteners on each wing spar in 
accordance with the alert service bulletin constitutes terminating 
action for the repetitive inspections required by paragraph (b) and 
(c) of this AD.
    (f) 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: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (g) 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 August 17, 1994.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-20593 Filed 8-22-94; 8:45 am]
BILLING CODE 4910-13-U