[Federal Register Volume 64, Number 122 (Friday, June 25, 1999)]
[Proposed Rules]
[Pages 34168-34170]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-16158]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-53-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 adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 727 series 
airplanes. This proposal would require repetitive structural 
inspections of certain aging airplanes, and repair, if necessary. This 
proposal also provides for optional terminating action for the 
repetitive inspections. This proposal is prompted by reports of 
incidents involving fatigue cracking and corrosion in transport 
category airplanes that are approaching or have exceeded their economic 
design service goal. The actions specified by the proposed AD are 
intended to prevent degradation of the structural capabilities of the 
affected airplanes. This proposal relates to the recommendations of the 
Airworthiness Assurance Task Force assigned to review Model 727 series 
airplanes, which indicate that, to assure long term continued 
operational safety, various structural inspections should be 
accomplished.

DATES: Comments must be received by August 9, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-53-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 99-NM-53-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. 99-NM-53-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    In April 1988, a high-cycle Boeing Model 737 suffered major 
structural damage in flight. Investigation revealed that the airplane 
had numerous fatigue cracks and a great deal of corrosion. This 
incident prompted the FAA to sponsor a conference on aging airplanes, 
which was attended by members of the aviation industry, other 
regulatory authorities, and the general public. The conferees agreed 
that, because of the huge increase in air travel, the relatively slow 
pace of new airplane production, and the apparent economic feasibility 
of operating older technology airplanes, operators will continue to fly 
aging airplanes rather than retire them. Because of the problems 
revealed by the accident described above, the consensus was that this 
aging fleet needed more attention and maintenance to ensure its 
continued operational safety.
    The Air Transport Association (ATA) of America and the Aerospace 
Industries Association (AIA) of America committed to identifying and 
implementing procedures to ensure continuing structural airworthiness 
of aging transport category airplanes. An Airworthiness Assurance Task 
Force, with representatives from the aircraft operators, manufacturers, 
regulatory authorities, and other aviation representatives, was 
established in August 1988. The objective of the Task Force was to 
sponsor ``Working Groups'' to:
    1. Select service bulletins, applicable to each airplane model in 
the transport fleet, to be recommended for mandatory modification of 
aging airplanes,
    2. Develop corrosion-directed inspections and prevention programs,
    3. Review the adequacy of each operator's structural maintenance 
program,
    4. Review and update the Supplemental Structural Inspection 
Documents (SSID), and
    5. Assess repair quality.

[[Page 34169]]

    The Working Group assigned to review the Boeing Model 727 series 
airplanes completed its work on Item (2) in July 1989 and developed a 
baseline program for controlling corrosion problems that may jeopardize 
the continued airworthiness of the Boeing Model 727 fleet. This program 
is contained in Boeing Document Number D6-54929, ``Aging Airplane 
Corrosion Prevention and Control Program--Model 727,'' dated July 28, 
1989. The FAA issued AD 90-25-03, Amendment 39-6787 (55 FR 49258, 
November 27, 1990), which requires implementation of a corrosion 
prevention and control program.
    The Working Group completed a portion of its work on Item (1), 
above, in March 1989. The Working Group's proposal is contained in 
Boeing Document Number D6-54860, ``Aging Airplane Service Bulletin 
Structural Modification Program--Model 727,'' Revision C, dated 
December 11, 1989. The FAA issued AD 90-06-09, Amendment 39-6488 (55 FR 
8370, March 7, 1990), which requires the installation of the structural 
modifications identified in that document.
    The action being proposed herein follows from the ongoing 
activities of the Working Group relative to Item (1). The Working Group 
has identified certain service difficulties that warrant mandatory 
inspections of the airplane. The Working Group considers that these 
service difficulties can be controlled safely in aging airplanes by 
inspections and that because of the safety implications, the 
inspections should be mandatory to assure that all operators perform 
them. Typically, the addressed unsafe conditions have occurred 
infrequently on aging airplanes, and the Working Group has a very high 
degree of confidence in the ability of an inspection program to detect 
the damage before it adversely affects safety.
    The Working Group reviewed 286 service bulletins related to the 
long term operation of the Model 727 series airplanes. Twelve of these 
service bulletins were recommended to the FAA for mandatory inspection 
action to ensure the successful long term operation of Model 727 series 
airplanes. The conditions addressed by these service bulletins, if not 
corrected, could result in degradation of the structural capabilities 
of the affected airplanes. The FAA has concurred with the Working 
Group's recommendations and has determined that AD action to mandate 
the inspections is warranted to assure the continued airworthiness of 
the Model 727 fleet.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 727-57-
0127, Revision 3, dated August 24, 1989, which describes procedures for 
repetitive dye penetrant inspections of certain wing ribs at the rib-
to-stringer attachment, and repair, if necessary. The service bulletin 
also describes procedures for the accomplishment of a preventative 
modification, which would eliminate the need for the repetitive 
inspections.
    Boeing Standard Overhaul Practices Manual D6-51702, Chapter 20-20-
02, Revision 79, dated March 1, 1999, also describes procedures for the 
accomplishment of the dye penetrant inspections.
    Boeing Commercial Jet Nondestructive Test Manual, Chapter 51-00-00, 
Part 6, dated August 5, 1997, describes procedures for a high frequency 
eddy current inspection to detect cracking of certain wing ribs at the 
rib-to-stringer attachment.
    Accomplishment of the actions specified in the service bulletin, 
the overhaul manual, and the NDT Manual is intended to adequately 
address the identified unsafe condition.

Other Relevant Rulemaking

    AD 94-07-08, amendment 39-8866 (59 FR 14545, March 29, 1994) 
currently requires initial structural inspections only of certain wing 
ribs at the rib-to-stringer attachment, as specified in the Boeing 
Document Number D6-54860, ``Aging Airplane Service Bulletin Structural 
Modification and Inspection Program--Model 727,'' Revision G, dated 
March 5, 1993. That AD inadvertently omitted the requirement to mandate 
repetitive inspections of certain wing ribs at the rib-to-stringer 
attachment. This proposed AD would mandate those repetitive inspections 
to detect cracks of certain structural components. In addition, the 
repetitive inspection requirement in this proposal would be terminated 
following accomplishment of the modification required by AD 94-05-04, 
amendment 39-8842 (59 FR 13442, March 22, 1994) as specified in Boeing 
Service Bulletin 727-57-0127, Revision 3, dated August 24, 1989. That 
AD requires incorporation of certain structural modifications. This 
proposed AD would not affect the current requirements of the AD's 
described previously.

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 require accomplishment of the repetitive inspections, 
and repair, if necessary, as specified in the overhaul manual, NDT 
manual, and service bulletin described previously, except as discussed 
below. The proposed AD also provides for optional terminating action, 
which would terminate the repetitive inspections.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that, unlike the procedures described in the 
service bulletin, this proposed AD would require the applicable 
inspection to be repeated at intervals not to exceed 14,000 flight 
cycles, regardless of detection of cracking. The FAA has determined 
that, because of the safety implications and consequences associated 
with fatigue cracking, repetitive inspections are necessary until 
accomplishment of the modification required by AD 94-05-04, in order to 
adequately ensure the safety of the transport airplane fleet.
    Operators also should note that, although the service bulletin 
describes procedures for accomplishment of a dye penetrant inspection 
only, this proposed AD would include the option of accomplishment of a 
either a dye penetrant inspection or a high frequency eddy current 
inspection to detect cracking of certain wing ribs at the rib-to-
stringer attachment. This option gives operators greater flexibility 
for detecting cracking in a timely manner.

Cost Impact

    There are approximately 975 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 538 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
300 work hours per airplane to accomplish the proposed inspection, and 
that the average labor rate is $60 per work hour. Based on these 
figures, the cost impact of the inspection proposed by this AD on U.S. 
operators is estimated to be $9,684,000, or $18,000 per airplane, per 
inspection cycle.
    The 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 rather than continue the repetitive inspections, it would take 
approximately 900 work hours per

[[Page 34170]]

airplane to accomplish the modification, at an average labor rate of 
$60 per work hour. Required parts will cost approximately $31,144 per 
airplane. Based on these figures, the cost impact of this optional 
terminating action is estimated to be $85,144 per airplane.

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 adding the following new 
airworthiness directive:

Boeing: Docket 99-NM-53-AD.
    Applicability: Model 727-100, -100C, and -200 series airplanes, 
line numbers 1 through 1214 inclusive; certificated in any category; 
on which the modification required by AD 94-05-04, amendment 39-
8842, as specified in Boeing Service Bulletin 727-57-0127, Revision 
3, dated August 24, 1989, has not been accomplished.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (e) 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 degradation of the structural capabilities of the 
affected airplanes, accomplish the following:

Initial Inspection

    (a) Within 2,000 flight cycles after the effective date of this 
AD, unless accomplished within the last 12,000 flight cycles in 
accordance with AD 94-07-08, amendment 39-8866; accomplish paragraph 
(a)(1) or (a)(2) of this AD, as applicable.
    (1) Perform a dye penetrant inspection to detect cracking of 
certain wing ribs at the rib-to-stringer attachment, in accordance 
with Boeing Service Bulletin 727-57-0127, Revision 3, dated August 
24, 1989; and Boeing Standard Overhaul Practices Manual D6-51702, 
Chapter 20-20-02, Revision 79, dated March 1, 1999.
    (2) Perform a high frequency eddy current inspection to detect 
cracking of certain wing ribs at the rib-to-stringer attachment, as 
specified in Boeing Service Bulletin 727-57-0127, Revision 3, dated 
August 24, 1989; in accordance with the procedures specified in 
Boeing Commercial Jet Nondestructive Test Manual, Chapter 51-00-00, 
Part 6, dated August 5, 1997.

Repetitive Inspections and Corrective Action

    (b) If no crack is detected during any inspection required by 
paragraph (a) of this AD, repeat the applicable inspection 
thereafter at intervals not to exceed 14,000 flight cycles.
    (c) If any crack is detected during any inspection required by 
paragraph (a) of this AD, prior to further flight, repair in 
accordance with Boeing Service Bulletin 727-57-0127, Revision 3, 
dated August 24, 1989. Repeat the applicable inspection thereafter 
at intervals not to exceed 14,000 flight cycles, following 
accomplishment of the repair.

Terminating Action

    (d) Accomplishment of the structural modification required by 
paragraph (a) of AD 94-05-04, amendment 39-8842, as specified in 
Boeing Service Bulletin 727-57-0127, Revision 3, dated August 24, 
1989, constitutes terminating action for the requirements of this 
AD.

Alternative Methods of Compliance

    (e) 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.

    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

    (f) 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 June 18, 1999.
Dorenda D. Baker,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-16158 Filed 6-24-99; 8:45 am]
BILLING CODE 4910-13-U