[Federal Register Volume 64, Number 153 (Tuesday, August 10, 1999)]
[Proposed Rules]
[Pages 43318-43321]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-20504]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-323-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 727 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 727 
series airplanes, that currently requires repetitive inspections of the 
front spar web between the upper and lower seals of the center section 
of the wings, and repair, if necessary. That AD also provides for an 
optional terminating modification for the repetitive inspections. This 
action would require a new terminating modification for the repetitive 
inspections. For certain airplanes, this action would require new 
repetitive inspections to detect discrepancies of the front spar web. 
This proposal is prompted by a report indicating that the optional 
terminating modification in the existing AD does not address the 
identified unsafe condition. The actions specified by the proposed AD 
are intended to prevent fatigue cracks in the front spar web, which 
could lead to fuel leakage into the air-conditioning distribution bay 
and/or depressurization of the cabin, and to prevent fuel fumes in the 
cabin of the airplane.

DATES: Comments must be received by September 24, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-323-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: Walter Sippel, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2774; 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 97-NM-323-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. 97-NM-323-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On December 21, 1989, the FAA issued AD 90-02-16, amendment 39-6452 
(55 FR 602, January 8, 1980), applicable to certain Boeing Model 727 
series airplanes, to require inspection of the front spar web of the 
center section of the wings, and repair, if necessary. That action was 
prompted by reports of cracks in the front spar web. The requirements 
of that AD are intended to detect and correct such cracking, which 
could lead to fuel leakage and/or depressurization of the cabin.

Actions Since Issuance of Previous Rule

    Since issuance of AD 90-02-16, the FAA has received a report 
indicating that modification procedures specified in Boeing Service 
Bulletin 727-57-0177, dated December 22, 1988; Revision 1, dated 
November 21, 1991; and Revision 2, dated September 16, 1993; do not 
adequately address airplanes equipped with internal fuel tanks in the 
center section of the wings. Specifically, the service bulletin does 
not include procedures for application of the secondary fuel seal on 
the forward side of the front spar and on the fillet seals on the aft 
side of the front spar. The service bulletin also describes procedures 
for the application of sealant Boeing material specification (BMS) 5-95 
inside the fuel tank instead of the fuel-proof sealant BMS 5-26, and 
the installation of non-fluid tight fasteners instead of fluid tight 
fasteners.
    Boeing Service Bulletin 727-57-0177, dated December 22, 1988, was 
referenced in AD 90-02-16 as the appropriate source of service 
information for accomplishment of the required modification and close 
visual and high frequency eddy current (HFEC) inspections. Revisions 1 
and 2 of that service bulletin were approved by the FAA as alternative 
methods of compliance for accomplishment of those actions.

[[Page 43319]]

    In light of this information, the FAA has determined that the 
optional modification specified in AD 90-02-16 does not adequately 
preclude fuel leakage into the air-conditioning distribution bay, which 
could result in fuel fumes in the cabin of the airplane.
    In addition, the FAA finds that the subject service bulletin does 
not contain procedures for accomplishing an HFEC inspection as an 
option to the close visual inspection, as required by paragraph A. of 
AD 90-02-16. The actual procedures used to accomplish that HFEC 
inspection and the effectiveness of those procedures are unknown to the 
FAA. The FAA has determined that performing an HFEC inspection in 
accordance with an unknown procedure does not ensure that cracks will 
be detected in a timely manner. Therefore, the FAA has determined that 
all affected airplanes must accomplish repetitive detailed visual 
inspections to ensure that cracks are detected in a timely manner.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 727-57-
0177, Revision 3, dated February 15, 1996, which describes procedures 
for repetitive detailed visual inspections to detect cracks of the 
front spar web between the upper and lower seals of the center section 
of the wings, and repair, if necessary. The service bulletin also 
describes procedures for modification of the front spar web between the 
upper and lower seals of the center section of the wings, which would 
eliminate the need for the repetitive inspections. For certain 
airplanes, the service bulletin describes procedures for repetitive 
visual inspections of the front spar web to detect fuel leakage and 
penetrations in the secondary fuel barrier, and to verify the 
installation of the secondary fuel barrier. Accomplishment of the 
actions specified in the service bulletin are 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 90-02-16, amendment 39-6452 (55 FR 602, 
January 8, 1980), to continue to require repetitive detailed visual 
inspections of the front spar web between the upper and lower seals of 
the center section of the wings, and repair, if necessary. The proposed 
AD also would require modification of the subject front spar web, which 
would constitute terminating action for the repetitive inspections. For 
certain airplanes, the proposed AD would require repetitive visual 
inspections of the front spar web to detect fuel leakage and 
penetrations in the secondary fuel barrier, and to verify the 
installation of the secondary fuel barrier. The actions would be 
required to be accomplished in accordance with the service bulletin 
described previously; except as discussed below.
    The FAA has determined that, for airplanes equipped with integral 
fuel tanks in the center section of the wings, the repairs and 
modifications specified in Figure 2 and Figure 3 of Boeing Service 
Bulletin 727-57-0177, dated December 22, 1988; Revision 1, dated 
November 21, 1991; and Revision 2, dated September 16, 1993; do not 
describe procedures for installation of a fuel proof sealant in these 
tanks, which could lead to identified unsafe condition of this AD. The 
procedures specified in the original version, Revision 1, and Revision 
2 of the service bulletin are acceptable for airplanes without integral 
fuel tanks in the center section of the wings. However, the FAA finds 
that Revision 3 of the subject service bulletin does provide procedures 
for installation of a fuel proof sealant for integral fuel tanks.

Other Relevant Rulemaking

    The FAA has previously issued AD 94-05-04, amendment 39-8842 (59 FR 
13442, March 22, 1994), which requires incorporation of certain 
structural modification on certain Boeing Model 747 series airplanes. 
Accomplishment of certain actions required by this proposed AD would 
constitute terminating action for the requirements specified in 
paragraph (a) of AD 94-05-04 with respect to the modification specified 
in Boeing Service Bulletin 727-57-0177, dated December 22, 1998. This 
service bulletin is one of many service bulletins referenced in Boeing 
Document D6-54860, Revision G, Appendix A.3, dated March 5, 1993. All 
other service bulletins referenced in that document still apply.

Cost Impact

    There are approximately 1,524 Model 727 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 1,098 
airplanes of U.S. registry would be affected by this proposed AD.
    The detailed visual inspection that is currently required by AD 90-
02-16, and retained in this AD, takes approximately 3 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 
detailed visual inspection on U.S. operators is estimated to be 
$197,640, or $180 per airplane, per inspection cycle.
    The modification that is proposed in this new AD action would take 
approximately 360 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts would cost 
approximately $1,430 per airplane. Based on these figures, the cost 
impact of the proposed modification required by this AD on U.S. 
operators is estimated to be $25,286,940, or $23,030 per airplane.
    For certain airplanes, the visual inspection that is proposed in 
this new AD action would take approximately 1 work hour per airplane to 
accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of the proposed modification required by 
this AD on U.S. operators is estimated to be $60 per airplane, per 
inspection cycle.
    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.

[[Page 43320]]

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 39-6452 (55 FR 
602, January 8, 1990), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 97-NM-323-AD. Supersedes AD 90-02-16, Amendment 39-
6452.

    Applicability: Model 727 series airplanes, as listed in Boeing 
Service Bulletin 727-57-0177, dated December 22, 1988; 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 (g)(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 fatigue cracks of the front spar web of the center 
section of the wings, which could lead to fuel leakage and/or 
depressurization of the cabin, or to prevent fuel fumes in the cabin 
of the airplane, accomplish the following:

Repetitive Detailed Visual Inspections

    (a) For areas on which the front spar web between the upper and 
lower seals of the center section of the wings has not been repaired 
or modified in accordance with Figure 2 or 3 of Boeing Service 
Bulletin 727-57-0177, dated December 22, 1988; Revision 1, dated 
November 21, 1991; or Revision 2, dated September 16, 1993: Prior to 
the accumulation of 40,000 total flight cycles, or with the next 
2,300 flight cycles after February 12, 1990 (effective date of AD 
90-02-16, amendment 39-6452), whichever occurs later, unless 
accomplished with the last 700 flight cycles, perform a detailed 
visual inspection to detect cracks in the front spar web, in 
accordance with Figure 1 of Boeing Service Bulletin 727-57-0177, 
dated December 22, 1988; Revision 1, dated November 21, 1991; 
Revision 2, dated September 16, 1993; or Revision 3, dated February 
15, 1996. Repeat the detailed visual inspection thereafter at 
intervals not to exceed 3,000 flight cycles, until accomplishment of 
the requirements specified in either paragraph (b) or (c) of this 
AD.

    Note 2: For the purposes of this AD, a detailed inspection is 
defined as: ``An intensive visual examination of a specific 
structural area, system, installation, or assembly to detect damage, 
failure, or irregularity. Available lighting is normally 
supplemented with a direct source of good lighting at intensity 
deemed appropriate by the inspector. Inspection aids such as mirror, 
magnifying lenses, etc., may be used. Surface cleaning and elaborate 
access procedures may be required.''
    Note 3: Accomplishment of the high frequency eddy current (HFEC) 
inspection required by AD 90-02-16, is considered acceptable for 
compliance with the initial detailed visual inspection required by 
paragraph (a) of this AD.

Repair of Cracks

    (b) If any crack is detected during any inspection required by 
paragraph (a) of this AD, prior to further flight, accomplish the 
actions specified in either paragraph (b)(1) or (b)(2) of this AD, 
as applicable. Accomplishment of the repair action constitutes 
terminating action for the repetitive inspection requirements of 
paragraph (a) of this AD for that repaired area.
    (1) For airplanes equipped with integral fuel tanks in the 
center section of the wings: Repair in accordance with Figure 2 of 
Boeing Service Bulletin 727-57-0177, Revision 3, dated February 15, 
1996.
    (2) For airplanes not equipped with integral fuel tanks in the 
center section of the wings: Repair in accordance with Figure 2 of 
Boeing Service Bulletin 727-57-0177, dated December 22, 1988, 
Revision 1, dated November 21, 1991; Revision 2, dated September 16, 
1993; or Revision 3, dated February 15, 1996.

    Note 4: Where there are differences between the referenced 
service bulletins and this AD, the AD prevails.

Modification

    (c) Except as provided by paragraph (d) of this AD, prior to the 
accumulation of 60,000 total flight cycles, or within 48 months 
after the effective date of this AD, whichever occurs later, 
accomplish the actions specified in either paragraph (c)(1) or 
(c)(2) of this AD, as applicable. Accomplishment of this action 
constitutes terminating action for the repetitive inspection 
requirements of paragraph (a) of this AD.
    (1) For airplanes equipped with integral fuel tanks in the 
center section of the wings: Modify the front spar web, between the 
upper and lower seals, of the center section of the wings, in 
accordance with Part I of the Accomplishment Instructions of Boeing 
Service Bulletin 727-57-0177, Revision 3, dated February 15, 1996.
    (2) For airplanes not equipped with integral fuel tanks in the 
center section of the wings: Modify the front spar web, between the 
upper and lower seals, of the center section of the wings, in 
accordance with Boeing Service Bulletin 727-57-0177, dated December 
22, 1988, Revision 1, dated November 21, 1991; Revision 2, dated 
September 16, 1993; or Revision 3, dated February 15, 1996.

Repetitive Visual Inspections and Repair/Modification of the Front Spar 
Web

    (d) For areas on which the front spar web between the upper and 
lower seals of the center section of the wings has been repaired or 
modified in accordance with Figure 2 or 3 of Boeing Service Bulletin 
727-57-0177, dated December 22, 1988; Revision 1, dated November 21, 
1991; or Revision 2, dated September 16, 1993: Accomplish the 
actions required by either paragraph (d)(1) or (d)(2) of this AD, as 
applicable.
    (1) For airplanes not equipped with integral fuel tanks in the 
center section of the wings: No further action is required by this 
AD for those areas repaired or modified.
    (2) For airplanes equipped with integral fuel tanks in the 
center section of the wings: Accomplish the actions required by both 
paragraphs (d)(2)(i) and (d)(2)(ii) of this AD.
    (i) Within 500 flight cycles after the effective date of this 
AD, perform a detailed visual inspection of the front spar web to 
detect fuel leakage and penetrations in the secondary fuel barrier, 
and to verify the installation of the secondary fuel barrier; in 
accordance with Boeing Service Bulletin 727-57-0177, Revision 3, 
dated February 15, 1996. Repeat the visual inspection thereafter at 
intervals not to exceed 1,500 flight cycles, until accomplishment of 
the actions required by paragraph (d)(2)(ii) of this AD.
    (ii) Prior to the accumulation of 14,000 flight cycles, or 
within 96 months after the effective date of this AD, whichever 
occurs later, repair/modify the front spar web in accordance with 
Part II of the Accomplishment Instructions of Boeing Service 
Bulletin 727-57-0177, Revision 3, dated February 15, 1996. 
Accomplishment of this action constitutes terminating action for the 
repetitive inspection requirements of paragraph (d)(2)(i) of this AD 
for that repaired/modified area.

Follow-On Corrective Action

    (e) During any inspection required by paragraph (d)(2)(i) of 
this AD, if any fuel leakage or penetration in the secondary fuel 
barrier is detected, or if any secondary fuel barrier is verified as 
not being installed, prior to further flight, repair in accordance 
with Part II of the Accomplishment Instructions of Boeing Service 
Bulletin 727-57-0177, Revision 3, dated February 15, 1996. 
Accomplishment of this action constitutes terminating action for the 
repetitive inspection requirements of paragraph (d)(2)(i) of this AD 
for that repaired area.

Terminating Action for AD 94-05-04

    (f) Accomplishment of the actions required by paragraph (b), 
(c), (d)(2)(ii), or (e) of this AD constitutes terminating action 
for the requirements specified in paragraph (a) of AD 94-05-04, 
amendment 39-8842 (59 FR 13442

[[Page 43321]]

dated March 22, 1994), with respect to the modification specified in 
Boeing Service Bulletin 727-57-0177, dated December 22, 1988. This 
service bulletin is one of many service bulletins referenced in 
Boeing Document D6-54860, Revision G, Appendix A.3, dated March 5, 
1993. All other service bulletins referenced in that document still 
apply.

Alternative Method of Compliance

    (g)(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 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 5: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (g)(2) For airplanes not equipped with integral fuel tanks in 
the center section of the wings: Alternative methods of compliance, 
approved previously in accordance with AD 90-02-16, amendment 39-
6452, are approved as alternative methods of compliance with this 
AD. For airplanes equipped with integral fuel tank in the center 
section of the wings: Alternative methods of compliance, approved 
previously in accordance with AD 90-02-15, are NOT approved as 
alternative methods of compliance with this AD.

Special Flight Permits

    (h) 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 4, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-20504 Filed 8-9-99; 8:45 am]
BILLING CODE 4910-13-P