[Federal Register Volume 63, Number 236 (Wednesday, December 9, 1998)]
[Rules and Regulations]
[Pages 67771-67775]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-32472]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-319-AD; Amendment 39-10932; AD 98-23-51]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 727 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment 
adopting Airworthiness Directive (AD) T98-23-51 that was sent 
previously to all known U.S. owners and operators of certain Boeing 
Model 727 series airplanes by individual telegrams. This AD requires 
modification of certain fuselage skin lap joints and, on certain 
airplanes, modification of the lap joint(s) in the door structure. This 
AD also requires repetitive internal detailed visual inspections to 
detect cracking, corrosion, or delamination of the fuselage skin lap 
joints, and repair, if necessary. This action is prompted by 
information that a modification required by an existing AD may not have 
been accomplished completely on as many as 160 airplanes. The actions 
specified by this AD are intended to prevent corrosion and subsequent 
fatigue cracking of the fuselage skin lap joints, which could result in 
rapid decompression of the airplane.

DATES: Effective December 14, 1998, to all persons except those persons 
to whom it was made immediately effective by telegraphic AD T98-23-51, 
issued on November 27, 1998, which contained the requirements of this 
amendment.
    The incorporation by reference of Boeing Service Bulletin 727-53-
0072, Revision 5, dated June 1, 1989, as listed in the regulations, is 
approved by the Director of the Federal Register as of December 14, 
1998.
    The incorporation by reference of Boeing Document D6-54929, ``Aging 
Airplane Corrosion Prevention and Control Program, Model 727,'' 
Revision A, dated July 28, 1989, as listed in the regulations, was 
approved previously by the Director of the Federal Register as of 
December 31, 1990 (55 FR 49258, November 27, 1990).
    Comments for inclusion in the Rules Docket must be received on or 
before February 8, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-319-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    The applicable service information 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; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.


[[Page 67772]]


FOR FURTHER INFORMATION CONTACT: Steven R. Edgar, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2025; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: On February 21, 1991, the FAA issued AD 91-
06-06, amendment 39-6921 (56 FR 9612, March 7, 1991), which is 
applicable to certain Boeing Model 727 series airplanes. [The airplanes 
affected by that AD are those on which the body skin longitudinal lap 
joints were bonded together with a room temperature curing epoxy 
adhesive (``cold-bonded'') in conjunction with flush riveting.] That AD 
superseded two existing AD's to require inspections to detect cracks, 
corrosion, and delamination of the fuselage skin lap joints, and 
repair, if necessary. That AD also requires modifications of certain 
lap joints. That action was prompted by reports of cracking in the lap 
joints. The actions required by that AD are intended to prevent rapid 
decompression of the airplane.
    The compliance times for accomplishment of the modifications 
required by AD 91-06-06 were specified in that AD as follows:
     For airplanes that had accumulated 45,000 or more landings 
as of August 21, 1989 [the effective date of AD 89-15-06, amendment 39-
6262 (54 FR 29530, July 13, 1989)]: Within 4 years after August 21, 
1989.
     For airplanes that had accumulated less than 45,000 
landings as of August 21, 1989: Within 6 years after August 21, 1989, 
or prior to the accumulation of 28,000 landings, whichever occurs 
later.

Actions Since Issuance of Previous Rule

    The FAA recently received information that the modification 
required by AD 91-06-06 may not have been accomplished completely on as 
many as 160 airplanes that are included in the applicability of that AD 
and that are subject to the unsafe condition addressed in that AD. 
These airplanes were converted from a passenger-carrying to a cargo-
carrying (``freighter'') configuration, or to a passenger-and cargo-
carrying (``combi'') configuration. These conversions included 
installation of a main deck cargo door. Although these conversions were 
accomplished in accordance with several different Supplemental Type 
Certificates (STC), in each case, as part of the modification, a 
doubler (approximately 20 feet long) was installed over lap joints S-
4L, S-10L, S-19L, and (sometimes) S-26L.
    FAA personnel have recently examined five of these airplanes, 
operated by three operators, and determined that the lap joints had not 
been modified, as required, in the area covered by the doublers on any 
of the five airplanes. Preliminary inquiries indicate a substantial 
likelihood that very few of the freighters or combi airplanes have been 
so modified.

FAA's Determinations

    The installation of doublers over the lap joints during the 
freighter or combi conversions did not correct the unsafe condition 
addressed by AD 91-06-06 because it is not effective in preventing 
delamination, corrosion, and cracking in the lap joint. In fact, in 
some cases, the unsafe condition may be aggravated because of load 
redistribution due to the installation of a main deck cargo door. This 
may accelerate crack growth along the lap joint under the doubler.
    Because it is possible that these lap joints have been neither 
inspected nor modified as required by AD 91-06-06, the FAA considers 
that there is a significant risk that such cracking may have occurred 
on these airplanes. Because without special inspections such cracking 
cannot be detected until the crack emerges from under the doubler, such 
cracks could remain undetected until they approach or reach a length at 
which the fuselage can no longer sustain pressure loads sufficiently to 
prevent catastrophic rapid decompression.
    Ordinarily, failure to comply with an AD may result in immediate 
grounding of the affected airplane(s) until compliance is achieved. 
However, given the size of the fleet affected by this AD, the length of 
time that will be necessary to modify the fleet using existing 
available maintenance facilities, and the interim inspections required 
by this AD, the FAA considers that immediate grounding would be 
unwarranted.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 727-53-
0072, Revision 5, dated June 1, 1989, which describes procedures for 
modification of the fuselage skin lap joints. Those procedures include 
separating and reworking the joint; performing a high frequency eddy 
current inspection of the holes to detect cracking; and oversizing the 
fastener holes; and installing certain fasteners.

Explanation of Requirements of the Rule

    Since the unsafe condition described is likely to exist or develop 
on other airplanes of the same type design, the FAA issued Telegraphic 
AD T98-23-51 to prevent corrosion and subsequent fatigue cracking of 
the fuselage skin lap joints, which could result in rapid decompression 
of the airplane. The AD requires modification of certain fuselage skin 
lap joints. On certain airplanes, the fuselage structure that was 
removed to make the opening for the door is used to fabricate the door 
itself. For those airplanes, this AD also requires modification of the 
lap joint(s) in the door structure. This AD allows continued operation 
of these airplanes for a limited period to permit the required 
modification to be accomplished without undue disruption. The 
modification is required to be accomplished in accordance with the 
service bulletin described previously.
    This AD also requires repetitive internal detailed visual 
inspections to detect cracking, corrosion, or delamination of the 
fuselage skin lap joints, and repair, if necessary. The AD requires 
that those inspections be accomplished repetitively at intervals not to 
exceed 60 landings until the modification is accomplished. The 
inspection is required to be accomplished in accordance with certain 
tasks specified in Boeing Document D6-54929, ``Aging Airplane Corrosion 
Prevention and Control Program, Model 727,'' Revision A, dated July 28, 
1989. Repair, if necessary, is required to be accomplished in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office, FAA, Transport Airplane Directorate.
    The FAA investigated several different non-destructive inspection 
methods that could be used to detect cracking in the upper row of the 
lap joints that have been covered by the doublers. The FAA (including 
representatives of the FAA Technical Center and a national resource 
specialist for non-destructive evaluation), in conjunction with Sandia 
Laboratories, The Boeing Company, and several designated engineering 
representatives, considered various inspection methods. Those methods 
included low frequency eddy current, high frequency eddy current, x-
ray, sliding probe eddy current, and ultrasonic techniques. Some of 
these techniques hold potential for detecting cracking in the hidden 
upper row of the lap joint. However, those methods tend to be sensitive 
to configurational differences and require good accessibility to the 
joint. Due to variability of configurations within the fleet, a single 
procedure and standard could not be developed in sufficient

[[Page 67773]]

time to accomplish the necessary inspections.
    As a result of these discussions, the FAA deemed a detailed 
internal visual inspection the most useful short-term inspection. The 
FAA expects that this inspection is not likely to detect cracking 
unless the cracking has turned and run circumferentially. However, this 
inspection can be accomplished quickly and easily in the field, and is 
expected to yield some measure of security in the short term.
    While these inspections will be effective in detecting some types 
of cracking, the FAA is not confident that all potentially catastrophic 
cracking can be detected by these inspections. Therefore, this AD 
requires accomplishment of the modification within 120 days or 250 
landings after the effective date of the AD, whichever occurs later. In 
addition, paragraph (f) specifies that no airplane shall be returned to 
service following modification from a passenger-carrying to a 
``freighter'' or a ``combi'' configuration, unless the modification 
required by paragraph (b) of this AD has been accomplished on that 
airplane.
    It should be noted that, although this AD has the effect of staying 
the requirement of AD 91-06-06 to accomplish the modifications in the 
area of the main deck cargo door, for the period specified in this AD, 
this stay applies only once the AD becomes effective. For the period 
between the compliance deadline imposed by AD 91-06-06 and the 
effective date of this AD, the FAA has initiated investigations to 
determine the causes of the operators' failures to comply, and may 
initiate appropriate legal enforcement action to address those 
failures.
    In most AD's, the compliance provision includes the phrase, 
``compliance required as indicated, unless accomplished previously.'' 
In this AD, the phrase ``unless accomplished previously'' is omitted 
because it is possible that operators' maintenance records may indicate 
that the requirements of AD 91-06-06, including the modification, have 
been accomplished. As indicated, however, these records are likely to 
be inaccurate for the subject airplanes. Therefore, this AD requires 
that the modification be accomplished regardless of the information 
contained in the maintenance records. If an operator can verify that 
the modification required by this AD has, in fact, been accomplished, 
it may request approval of an alternative method of compliance (AMOC), 
in accordance with the provisions of paragraph (g) of this AD, based on 
submission of data verifying such accomplishment.
    Since the issuance of AD 91-06-06, the FAA has approved several 
AMOC's for that AD for freighter and combi airplanes. These AMOC's 
allow internal and external visual inspections in lieu of the 
repetitive visual and high frequency eddy current inspections. However, 
the approval of these alternative inspection methods did not affect the 
modification requirement of paragraph F. of AD 91-06-06, and were based 
on an assumption that the modification either had been or would be 
accomplished. In addition, these inspections are unreliable to detect 
cracking in the upper row of fasteners under the doubler.
    The FAA also approved one AMOC, applicable to Supplemental Type 
Certificate (STC) SA1368SO, which approved the modification in 
accordance with the STC to be an acceptable alternative to the 
modification required by paragraph F. of AD 91-06-06. Preliminary 
information indicates that as many as 30 airplanes may have been 
modified in accordance with STC SA1368SO.
    As explained previously, installation of the doubler in accordance 
with this STC is not likely to stop propagation of cracking that was 
present at the time the main deck cargo door was installed, nor will it 
prevent new cracks from initiating. Further, once initiated, such 
cracking is likely to grow undetected because it is hidden between the 
doubler and the inner skin. AMOC's approved previously in accordance 
with AD 91-06-06 are not considered to be valid as alternative methods 
of compliance with this AD unless those AMOC's are approved separately 
under the provisions of paragraph (g) of this AD.
    Normally, the compliance time specified for the required 
modification would be sufficient for the FAA to provide notice and a 
brief public comment period before adopting such a requirement. 
However, in this case, because of the significant time required to 
accomplish the modification, the full compliance time is necessary to 
prevent unnecessarily disrupting operations. This compliance period 
will enable operators either to comply or to develop sufficient data to 
substantiate extension of the compliance time or approval of an AMOC. 
This compliance time does not reflect a lack of urgency for adopting 
the requirement.
    On November 19, 1998, the FAA met with affected operators and STC 
holders to discuss the issues addressed in this AD. A joint FAA/
industry team was formed to address the relevant technical issues and 
to develop data necessary to address the identified unsafe condition. 
It was agreed that the team's objective is either to provide means for 
operators to comply within the specified compliance time or to 
substantiate that an acceptable level of safety can be maintained for 
some longer period before the required modification is accomplished.
    At this meeting, the FAA emphasized the necessity of correcting the 
unsafe condition by modifying the lap joints under the doublers. The 
FAA also emphasized the risk that AMOC requests would not be approvable 
if, as some suggested, industry focuses its efforts during the 120-day 
compliance time on attempting to develop alternatives to modifying the 
lap joints. For airplanes that are already scheduled to undergo heavy 
maintenance during the 120-day compliance time, operators have the 
opportunity to comply with this AD with the least possible disruption. 
Accomplishment of the modification on these airplanes also will provide 
important data on the condition of the lap joints under the doubler 
that will be very useful in assessing the appropriateness of AMOC 
requests for other airplanes. Therefore, if operators fail to avail 
themselves of this opportunity, the FAA will not be receptive to 
requests for AMOC's or compliance time extensions for those airplanes.
    Since it was found that immediate corrective action was required, 
notice and opportunity for prior public comment thereon were 
impracticable and contrary to the public interest, and good cause 
existed to make the AD effective immediately by individual telegrams 
issued on November 27, 1998, to all known U.S. owners and operators of 
certain Boeing Model 727 series airplanes. These conditions still 
exist, and the AD is hereby published in the Federal Register as an 
amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 
39.13) to make it effective to all persons.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before

[[Page 67774]]

the closing date for comments will be considered, and this rule may be 
amended in light of the comments received. Factual information that 
supports the commenter's ideas and suggestions is extremely helpful in 
evaluating the effectiveness of the AD action and determining whether 
additional rulemaking action would be needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 98-NM-319-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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:

98-23-51  Boeing: Amendment 39-10932. Docket 98-NM-319-AD.

    Applicability: Model 727 series airplanes, line positions 1 
through 849 inclusive; that have been converted from a passenger-
carrying to a cargo-carrying (``freighter'') configuration, or to a 
passenger- and cargo-carrying (``combi'') configuration; 
certificated in any category.

    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 (g) 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.
    To prevent corrosion and subsequent fatigue cracking of the 
fuselage skin lap joints, which could result in rapid decompression 
of the airplane, accomplish the following:
    (a) Within 60 landings after the effective date of this AD, 
perform a detailed internal visual inspection to detect cracking, 
corrosion, or delamination of the fuselage skin lap joints where 
those lap joints are covered by external doublers at stringers S-4L, 
S-10L, S-19L, and S-26L from body station 360 to 740; in accordance 
with task numbers C53-224-01 and C53-111-01 of Boeing Document D6-
54929, ``Aging Airplane Corrosion Prevention and Control Program, 
Model 727,'' Revision A, dated July 28, 1989. The lap joints must be 
completely exposed to perform the inspection.
    (1) If no cracking, corrosion, or delamination is found, repeat 
the inspection required by paragraph (a) of this AD thereafter at 
intervals not to exceed 60 landings until the modification required 
by paragraph (b) of this AD is accomplished.
    (2) If any crack, corrosion, or delamination is found, prior to 
further flight, repair damaged structure in accordance with a method 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA, Transport Airplane Directorate. Thereafter, repeat the 
inspection required by paragraph (a) of this AD at intervals not to 
exceed 60 landings until the modification required by paragraph (b) 
of this AD is accomplished.
    (b) Modify the fuselage skin lap joints where those lap joints 
are covered by external doublers at stringers S-4L, S-10L, S-19L, 
and S-26L from body station 360 to 740 by removing the external 
doublers; and by separating and reworking the joint in accordance 
with Part IV, Figure 4, of the Accomplishment Instructions of Boeing 
Service Bulletin 727-53-0072, Revision 5, dated June 1, 1989, except 
that blind fasteners shall not be installed. Before oversizing the 
fastener holes as part of the modification, perform a high frequency 
eddy current inspection of the holes to detect cracking, in 
accordance with the service bulletin; and, prior to further flight, 
repair any cracking in accordance with a method approved by the 
Manager, Seattle ACO. When reassembling the lap joint, all three 
rows of fasteners must penetrate all layers of the lap joint, 
including the upper skin, lower skin, and the doublers; and the 
stringers and tripler, as applicable. Accomplish the modification at 
the latest of the times specified in paragraphs (b)(1), (b)(2), and 
(b)(3) of this AD.
    (1) Prior to the accumulation of 28,000 total landings.
    (2) Within 250 landings after the effective date of this AD.
    (3) Within 120 days after the effective date of this AD.

    Note 2: Installation of protruding head fasteners in the upper 
row of fasteners of the lap joint in itself does not constitute 
accomplishment of the modification.
    (c) For airplanes on which the cargo door itself was 
manufactured using the original fuselage skin, paragraphs (a) and 
(b) of this AD also apply to the lap joint(s) in the door structure.
    (d) Accomplishment of the modification required by paragraph (b) 
of this AD constitutes terminating action for the inspections 
required by paragraph (a) of this AD, and constitutes an acceptable 
alternative method of compliance with paragraph F. of AD 91-06-06 
for the affected area.
    (e) Contrary provisions of AD 91-06-06 notwithstanding, this AD 
allows continued operation of the subject airplanes following the 
effective date of this AD in accordance with the terms of this AD, 
provided that the modification required by AD 91-06-06 has been 
accomplished on all lap joints other than those in the area of the 
main deck cargo door.
    (f) For any airplane that, as of the effective date of this AD, 
is being, or will be converted from a passenger-carrying to a cargo-
carrying (``freighter'') configuration, or to a passenger-and cargo-
carrying (``combi'') configuration: After the effective date of this 
AD, no such

[[Page 67775]]

airplane shall be returned to service following such conversion 
unless the modification required by paragraph (b) of this AD has 
been accomplished on that airplane.
    (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 3: Alternative methods of compliance, approved previously 
in accordance with AD 91-06-06, amendment 39-6921, are not 
considered to be approved as alternative methods of compliance with 
this AD.

    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 
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.
    (i) The actions shall be done in accordance with Boeing Service 
Bulletin 727-53-0072, Revision 5, dated June 1, 1989; and Boeing 
Document D6-54929, ``Aging Airplane Corrosion Prevention and Control 
Program, Model 727,'' Revision A, dated July 28, 1989.
    (1) The incorporation by reference of Boeing Service Bulletin 
727-53-0072, Revision 5, dated June 1, 1989, is approved by the 
Director of the Federal Register, in accordance with 5 U.S.C. 552(a) 
and 1 CFR part 51.
    (2) The incorporation by reference of Boeing Document D6-54929, 
``Aging Airplane Corrosion Prevention and Control Program, Model 
727,'' Revision A, dated July 28, 1989, was approved previously by 
the Director of the Federal Register as of December 31, 1990 (55 FR 
49258, November 27, 1990).
    (3) Copies may be obtained from Boeing Commercial Airplane 
Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be 
inspected at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (j) This amendment becomes effective on December 14, 1998, to 
all persons except those persons to whom it was made immediately 
effective by telegraphic AD T98-23-51, issued on November 27, 1998, 
which contained the requirements of this amendment.

    Issued in Renton, Washington, on December 1, 1998.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-32472 Filed 12-8-98; 8:45 am]
BILLING CODE 4910-13-P