[Federal Register Volume 60, Number 34 (Tuesday, February 21, 1995)]
[Proposed Rules]
[Pages 9645-9647]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-4122]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-120-AD]


Airworthiness Directives; Boeing Model 747SP Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), applicable to certain Boeing Model 747SP series 
airplanes, that would have superseded an existing AD to require 
inspections to detect cracks in the web of the wing front spar, and 
modification, if necessary. That proposal was prompted by a report of 
cracking in the web in an area outside the inspection zone specified in 
the existing AD. A crack in the web that is not detected before it 
extends outside the chord footprints can allow fuel leakage. This 
action revises the proposed rule by reducing the compliance time for 
inspections of certain airplanes. The actions specified by this 
proposed AD are intended to prevent fuel leakage onto an engine and a 
resultant fire due to cracking in the web of the wing front spar.

DATES: Comments must be received by March 7, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-120-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-120-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-120-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
certain Boeing Model 747SP series airplanes, was published as a notice 
of proposed rulemaking (NPRM) in the Federal Register on October 28, 
1994 (59 FR 54134). That NPRM would have superseded an existing AD to 
require repetitive inspections to detect cracks in the web of the wing 
front spar over engine numbers 2 and 3, and repair, if necessary. That 
NPRM was prompted by a report of cracking in the web in an area outside 
the inspection zone specified in the existing AD. That condition, if 
not corrected, could result in fuel leakage onto an engine and a 
resultant fire. [[Page 9646]] 
    Two commenters support the proposed rule.
    One commenter to the NPRM, Boeing, requests that the proposed 
compliance time of 1,000 landings, specified in paragraph (b) of the 
NPRM for airplanes on which the terminating modification has not been 
accomplished, be shortened to 6 months, as recommended in the 
manufacturer's service bulletin. The FAA concurs with the commenter's 
request. Due to an error during publication of the NPRM, an incorrect 
compliance time was specified in paragraph (b). The FAA's intent was 
that this compliance time coincide with the recommendation of the 
manufacturer's service bulletin. Paragraph (b) of this supplemental 
NPRM has been revised to specify a compliance time of ``prior to the 
accumulation of 4,000 total landings on the airplane, or within 6 
months after the effective date of the AD, whichever occurs later.''
    Since this change expands the scope of the originally proposed 
rule, the FAA has determined that it is necessary to reopen the comment 
period to provide additional opportunity for public comment.
    The FAA has recently reviewed the figures it has used over the past 
several years in calculating the economic impact of AD activity. In 
order to account for various inflationary costs in the airline 
industry, the FAA has determined that it is necessary to increase the 
labor rate used in these calculations from $55 per work hour to $60 per 
work hour. The economic impact information, below, has been revised to 
reflect this increase in the specified hourly labor rate.
    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 supplemental NPRM to clarify this requirement.
    The manufacturer has advised that it is currently developing a 
modification program for the engine struts on these airplanes that will 
positively address the fatigue cracking condition and other items 
associated with the engine struts. Once this modification program is 
developed and approved, the FAA may consider additional rulemaking.
    There are approximately 35 Model 747SP series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 11 
airplanes of U.S. registry would be affected by this proposed AD.
    The FAA estimates that it would take approximately 22 work hours 
per airplane to accomplish the proposed inspections (between front spar 
stations 628 and 675) specified in this AD, 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 $14,520, 
or $1,320 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 terminating modification 
that would be provided by this AD action, it would take approximately 
644 work hours to accomplish it, at an average labor rate of $60 per 
work hour. The cost of required parts would be $21,800. Based on these 
figures, the total cost impact of the terminating modification would be 
$60,440 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 39-6702 (55 FR 
33279, August 15, 1990), and by adding a new airworthiness directive 
(AD) to read as follows:

Boeing: Docket 94-NM-120-AD.

    Applicability: Model 747SP series airplanes; variable numbers 
RG001 through RG142 inclusive, and RG171 through RG222 inclusive; 
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 (f) 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 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 fuel leakage onto an engine and a resultant fire, 
accomplish the following:
    (a) For airplanes on which the ``terminating modification'' 
[between front spar station (FSS) 640 and FSS 670] specified in 
Boeing Alert Service Bulletin 747-57A2259, dated February 15, 1990; 
or Revision 1, dated September 6, 1990; has not been accomplished: 
Within the next six months after September 21, 1990 (the effective 
date of AD 90-17-18, amendment 39-6702), perform a visual and an 
ultrasonic inspection of the front spar web between front spar 
station (FSS) 636 and FSS 675 in accordance with Boeing Alert 
Service Bulletin 747- [[Page 9647]] 57A2259, dated February 15, 
1990, or Revision 1, dated September 6, 1990. If no crack is found, 
repeat these inspections at intervals not to exceed 1,000 landings 
until the inspections required by paragraph (b) of this AD are 
accomplished.
    (b) For airplanes on which the ``terminating modification'' 
[between front spar station (FSS) 640 and FSS 670] specified in 
Boeing Alert Service Bulletin 747-57A2259, dated February 15, 1990; 
or Revision 1, dated September 6, 1990; has not been accomplished: 
Prior to the accumulation of 4,000 total landings on the airplane, 
or within 6 months after the effective date of this AD, whichever 
occurs later, perform the inspections specified in paragraphs 
(b)(1), (b)(2), and (b)(3) of this AD to detect cracks in the web 
between FSS 628 and FSS 675, in accordance with Boeing Alert Service 
Bulletin 747-57A2259, Revision 2, dated June 9, 1994. Accomplishment 
of these inspections terminates the repetitive inspection 
requirement of paragraph (a) of this AD. If no crack is found, 
repeat these inspections thereafter at intervals not to exceed 1,000 
landings.
    (1) Perform an ultrasonic inspection in the web under the upper 
and lower chord footprints; and
    (2) Perform a high frequency eddy current inspection in the web 
in an area one inch below the upper chord and one inch above the 
lower chord footprints; and
    (3) Perform a detailed visual inspection in the forward face of 
the web of the wing front spar at fastener locations in the web-to-
stiffeners and web-to-rib posts.
    (c) For airplanes on which the ``terminating modification'' 
specified in Boeing Alert Service Bulletin 747-57A2259, dated 
February 15, 1990; or Revision 1, dated September 6, 1990; has been 
accomplished: Prior to the accumulation of 4,000 total landings on 
the airplane, or within 6 months after the effective date of this 
AD, whichever occurs later, perform the inspections specified in 
paragraphs (c)(1), (c)(2), and (c)(3) of this AD to detect cracks in 
the web between FSS 628 and FSS 636, in accordance with Boeing Alert 
Service Bulletin 747-57A2259, Revision 2, dated June 9, 1994. If no 
crack is found, repeat these inspections thereafter at intervals not 
to exceed 1,000 landings.
    (1) Perform an ultrasonic inspection of the web under the upper 
and lower chord footprints; and
    (2) Perform a high frequency eddy current inspection of the web 
in an area one inch below the upper chord and one inch above the 
lower chord footprints; and
    (3) Perform a detailed visual inspection of the forward face of 
the web of the wing front spar at fastener locations in the web-to-
stiffeners and web-to-rib posts.
    (d) If any crack is found during any inspection required by this 
AD, prior to further flight, accomplish a terminating modification 
(between FSS 623 and FSS 670) in accordance with Boeing Alert 
Service Bulletin 747-57A2259, Revision 2, dated June 9, 1994; or in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate.
    (e) Installation of a terminating modification (between FSS 623 
and FSS 670) in accordance with Boeing Alert Service Bulletin 747-
57A2259, Revision 2, dated June 9, 1994; or in accordance with a 
method approved by the Manager, Seattle ACO; constitutes terminating 
action for the requirements 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 2: 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 February 14, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-4122 Filed 2-17-95; 8:45 am]
BILLING CODE 4910-13-U