[Federal Register Volume 64, Number 233 (Monday, December 6, 1999)]
[Proposed Rules]
[Pages 68062-68065]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-31477]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-74-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 727-100, -100C, and -200 
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 727-100, -
100C, and -200 series airplanes. For certain airplanes, this proposal 
would require a one-time inspection of certain fuselage circumferential 
skin joints to determine the type of fasteners installed, and 
replacement of any aluminum fasteners with steel fasteners, if 
necessary; or modification of certain fuselage circumferential skin 
joints; as applicable. For certain other airplanes, this proposal would 
also require repetitive inspections to detect corrosion, sealant 
deterioration, cracking, or disbonding; repair, if necessary; and 
modification of certain fuselage circumferential skin joints. This 
proposal is prompted by reports of corrosion between the body skins and 
cold-bonded doublers at the fuselage circumferential skin joints. The 
actions specified by the proposed AD are intended to prevent 
delamination of the cold-bonded doublers, which could result in 
corrosion of the body skins and doublers, and consequent reduced 
structural capability of the fuselage circumferential skin joints.

DATES: Comments must be received by January 20, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-74-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: Walt 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-74-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-74-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    In 1990, the FAA issued AD 90-06-09, amendment 39-6488 (55 FR 8370, 
March 7, 1990), which required incorporation of certain structural 
modifications on certain Boeing Model 727 series airplanes, in 
accordance with Boeing Document No. D6-54860, Revision C, dated 
December 11, 1989, ``Aging Airplane Service Bulletin Structural 
Modification Program--Model 727.'' One of those modifications was 
replacement of countersunk fasteners installed at cold-bonded doublers 
of fuselage circumferential skin joints at body stations (BS) 259, 360, 
441, 481, and 681 with oversize, protruding-head fasteners. That AD was 
prompted in part by reports of corrosion between the body skins and 
cold-bonded doublers at the fuselage circumferential skin joints. 
Delamination of the cold-bonded doublers allows moisture to enter voids 
caused by the bond separation, which could result in corrosion of the 
body skins and doublers, and consequent reduced structural capability 
of the fuselage circumferential skin joints.
    Since the issuance of AD 90-06-09, the airplane manufacturer has 
notified the FAA that the incorrect fastener type was used in the 
modification of the fuselage circumferential skin joints required by 
that AD. Aluminum fasteners were used for that modification; the 
airplane manufacturer now knows that aluminum fasteners reduce the 
structural capability of the fuselage circumferential skin joints.
    In 1990, the FAA also issued AD 90-26-09, amendment 39-6835 (55 FR 
51403, December 14, 1990), which required repetitive inspections of 
certain fuselage circumferential skin joints, and repair, if necessary, 
in accordance with Boeing Service Bulletin 727-53-0084, Revision 4, 
dated August 2, 1990. The modification of the fuselage circumferential 
skin joints required by AD 90-06-09 was considered terminating action 
for certain repetitive inspections required by AD 90-26-09.
    Since the issuance of AD 90-26-09, the airplane manufacturer has 
notified the FAA that certain airplanes were inadvertently not included 
in the effectivity listing in paragraph I.A.1. of Boeing Service 
Bulletin 727-53-0084, Revision 4, although they were included in the 
effectivity statement in the summary of the service bulletin. The FAA 
has determined that operators of those airplanes may not realize that 
those airplanes are subject to AD 90-26-09. In addition, the airplane 
manufacturer has notified the FAA that

[[Page 68063]]

those same airplanes were also inadvertently not included in the 
effectivity listing of Boeing Document No. D6-54860, Revision C, and 
hence, were also omitted from the applicability of AD 90-06-09. Those 
airplanes are subject to the same unsafe condition as the airplanes 
that are included in the applicability statements of those two AD's. 
Therefore, the FAA finds that additional rulemaking is necessary to 
ensure that the unsafe condition is addressed on all affected 
airplanes.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 727-53-
0084, Revision 4, dated August 2, 1990, which describes procedures for 
repetitive inspections of the cold-bonded doublers of the fuselage 
circumferential skin joints at BS 259, 360, 441, 481, and 681; and 
repair, if necessary. The inspections include an external detailed 
visual inspection to detect corrosion and sealant deterioration, a low 
frequency eddy current (LFEC) inspection to detect corrosion, a high 
frequency eddy current (HFEC) inspection to detect cracking, and an 
internal detailed visual inspection to detect cracking, sealant 
deterioration, or disbonding. The service bulletin also describes 
procedures for modification of the cold-bonded doublers in those areas. 
In addition, the service bulletin describes procedures for a one-time 
inspection of the fuselage circumferential skin joints at BS 259, 360, 
441, 481, and 681 to determine the type of fasteners installed, and 
replacement of any aluminum fasteners with steel fasteners, if 
necessary. Accomplishment of the actions specified in the service 
bulletin is 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 require accomplishment of the actions specified in 
the service bulletin described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that, although the service bulletin specifies 
that the manufacturer may be contacted for disposition of certain 
repair conditions, this AD requires the repair of those conditions to 
be accomplished in accordance with a method approved by the FAA, or in 
accordance with data meeting the type certification basis of the 
airplane approved by a Boeing Company Designated Engineering 
Representative who has been authorized by the FAA to make such 
findings.
    Operators should also note that, for those airplanes on which 
modification of cold-bonded doublers of certain fuselage 
circumferential skin joints has already been accomplished, this AD 
proposes only to mandate the one-time inspection of the joints to 
determine the type of fastener installed, and replacement of any 
aluminum fasteners with steel fasteners, if necessary; or modification 
of certain fuselage circumferential skin joints; as applicable.
    Operators should also note that this proposed AD would require the 
repetitive inspections and modification of the cold-bonded doublers of 
certain fuselage circumferential skin joints for only certain 
airplanes. These airplanes were inadvertently omitted from the 
applicability of AD 90-26-09.
    The service bulletin recommends accomplishing the repetitive 
internal visual inspections every 30 months if the repetitive HFEC 
inspection is accomplished every 48 months, or accomplishing the 
repetitive internal visual inspections every 48 months if the 
repetitive HFEC inspection is accomplished every 15 months. In 
developing an appropriate compliance time for this AD, the FAA 
considered not only the manufacturer's recommendation, but the degree 
of urgency associated with addressing the subject unsafe condition, the 
average utilization of the affected fleet, and the time necessary to 
perform the inspections. In light of all of these factors, the FAA 
finds a 48-month compliance time for both the internal visual 
inspection and the HFEC inspection to be warranted, in that it 
represents an appropriate interval of time allowable for affected 
airplanes to continue to operate without compromising safety. This 
compliance time is consistent with that specified in AD 90-26-09.

Cost Impact

    There are approximately 549 airplanes of the affected design in the 
worldwide fleet. Based on a records review, the FAA estimates that only 
374 of those airplanes are still in service. The FAA estimates that 280 
airplanes of U.S. registry still in service would be affected by this 
proposed AD.
    The number of airplanes that would be subject to the proposed one-
time inspection to determine the type of fasteners installed is 
unknown. For affected airplanes, it would take approximately 45 work 
hours per airplane to accomplish the proposed one-time inspection, at 
an average labor rate of $60 per work hour. Based on these figures, the 
cost impact of this proposed inspection on U.S. operators is estimated 
to be $2,700 per airplane.
    The FAA estimates that 3 airplanes of U.S. registry would be 
required to perform the external detailed visual inspection of certain 
fuselage circumferential skin joints that is proposed in this AD 
action. It would take approximately 8 work hours per airplane to 
accomplish this proposed inspection, at an average labor rate of $60 
per work hour. Based on these figures, the cost impact of this proposed 
inspection on U.S. operators is estimated to be $1,440, or $480 per 
airplane, per inspection cycle.
    The FAA estimates that 3 airplanes of U.S. registry would be 
required to perform the internal detailed visual inspection of certain 
fuselage circumferential skin joints that is proposed in this AD 
action. It would take approximately 12 work hours per airplane to 
accomplish this proposed inspection, at an average labor rate of $60 
per work hour. Based on these figures, the cost impact of this proposed 
inspection on U.S. operators is estimated to be $2,160, or $720 per 
airplane, per inspection cycle.
    The FAA estimates that 3 airplanes of U.S. registry would be 
required to perform the LFEC inspection of certain fuselage 
circumferential skin joints that is proposed in this AD action. It 
would take approximately 100 work hours per airplane to accomplish this 
proposed inspection, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of this proposed inspection on 
U.S. operators is estimated to be $18,000, or $6,000 per airplane, per 
inspection cycle.
    The FAA estimates that 3 airplanes of U.S. registry would be 
required to perform the HFEC inspection of certain fuselage 
circumferential skin joints that is proposed in this AD action. It 
would take approximately 24 work hours per airplane to accomplish this 
proposed inspection, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of this proposed inspection on 
U.S. operators is estimated to be $4,320, or $1,440 per airplane, per 
inspection cycle.
    For affected airplanes, it would take approximately 192 work hours 
per airplane to accomplish the proposed modification of the cold-bonded 
doublers of certain fuselage circumferential skin joints, at an average 
labor rate of $60 per work hour. Required parts would cost

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approximately $1,250. Based on these figures, the cost impact of this 
proposed modification on U.S. operators is estimated to be $12,770 per 
airplane.
    The cost impact figures discussed above are 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.

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-74-AD.

    Applicability: Model 727-100, -100C, and -200 series airplanes; 
line numbers 1 through 549 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 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 delamination of the cold-bonded doublers, which could 
result in corrosion of the body skins and doublers, and consequent 
reduced structural capability of the fuselage circumferential skin 
joints, accomplish the following:

    Note 2: For the purposes of this AD, a detailed visual 
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.''

One-Time Inspection/Replacement

    (a) For airplanes on which the modification specified in Boeing 
Service Bulletin 727-53-0084, Revision 2, dated June 5, 1972, and 
the additional actions (including additional fastener replacement 
locations) specified in Boeing Document No. D6-54860, Revision C, 
dated December 11, 1989, ``Aging Airplane Service Bulletin 
Structural Modification Program--Model 727''; or the modification 
specified in Boeing Service Bulletin 727-53-0084, Revision 3, dated 
September 28, 1989; HAS been accomplished: Within 36 months after 
the effective date of this AD, perform a one-time inspection of the 
fuselage circumferential skin joints to determine the type of 
fastener installed, in accordance with Figure 7 of the Boeing 
Service Bulletin 727-53-0084, Revision 4, dated August 2, 1990.
    (1) If no aluminum fasteners are found, no further action is 
required by this AD.
    (2) If any aluminum fastener is found, prior to further flight, 
replace with a steel fastener, in accordance with Boeing Service 
Bulletin 727-53-0084, Revision 4, dated August 2, 1990.

Modification

    (b) For airplanes listed in Boeing Document No. D6-54860, 
Revision C, dated December 11, 1989, ``Aging Airplane Service 
Bulletin Structural Modification Program--Model 727'' on which the 
modification specified in Boeing Service Bulletin 727-53-0084, 
Revision 2, dated June 5, 1972, and the additional actions specified 
in Boeing Document No. D6-54860, Revision C, dated December 11, 
1989; or the modification specified in Boeing Service Bulletin 727-
53-0084, Revision 3, dated September 28, 1989; has not been 
accomplished prior to the effective date of this AD: Prior to the 
accumulation of 60,000 total flight cycles, modify the fuselage 
circumferential skin joints in accordance with Part IV of the 
Accomplishment Instructions of Boeing Service Bulletin 727-53-0084, 
Revision 4, dated August 2, 1990. Such action constitutes 
terminating action for the modification in that area required by AD 
90-06-09.

Repetitive Inspections

    (c) For airplanes having line numbers 153, 339, 416, and 540: 
Accomplish the requirements of paragraphs (c)(1), (c)(2), and (c)(3) 
of this AD at the compliance time specified in those paragraphs.
    (1) Within 15 months after the effective date of this AD, 
perform an external detailed visual inspection and a low frequency 
eddy current (LFEC) inspection of the fuselage circumferential skin 
joints to detect corrosion or sealant deterioration, in accordance 
with Parts II.A. and II.B. of the Accomplishment Instructions of 
Boeing Service Bulletin 727-53-0084, Revision 4, dated August 2, 
1990. Repeat the external detailed visual inspection thereafter at 
intervals not to exceed 15 months, and repeat the LFEC inspection 
thereafter at intervals not to exceed 30 months.
    (2) Within 3,000 flight cycles or 30 months after the effective 
date of this AD, whichever occurs first, perform a high frequency 
eddy current (HFEC) inspection of the fuselage circumferential skin 
joints to detect cracking, in accordance with Part II.D. of the 
Accomplishment Instructions of Boeing Service Bulletin 727-53-0084, 
Revision 4, dated August 2, 1990. Repeat the HFEC inspection 
thereafter at intervals not to exceed 4,000 flight cycles or 48 
months, whichever occurs first, until accomplishment of paragraph 
(f) of this AD.
    (3) Within 48 months after the effective date of this AD, 
perform an internal detailed visual inspection of the fuselage 
circumferential skin joints to detect cracking, disbonding, or 
sealant deterioration; in accordance with Part II.C. of the 
Accomplishment Instructions of Boeing Service Bulletin 727-53-0084, 
Revision 4, dated August 2, 1990. Repeat the internal detailed 
visual inspection thereafter at intervals not to exceed 48 months.

Repair

    (d) For airplanes having line numbers 153, 339, 416, and 540: If 
any discrepancy is detected during any inspection required by 
paragraph (c) of this AD, accomplish paragraph (d)(1) or (d)(2) of 
this AD, as applicable.
    (1) If any corrosion, cracking, or disbonding is detected during 
any inspection required by paragraph (c) of this AD, prior to 
further flight, repair in accordance with Part III of the 
Accomplishment Instructions of Boeing Service Bulletin 727-53-0084, 
Revision 4, dated August 2, 1990, except as provided by paragraph 
(e) of this AD. No

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further action is required by this AD for that area.
    (2) If the sealant has deteriorated but no corrosion, cracking, 
or disbonding is detected during any inspection required by 
paragraph (c) of this AD, prior to further flight, reseal in 
accordance with Figure 5 or 6, as applicable, of Boeing Service 
Bulletin 727-53-0084, Revision 4, dated August 2, 1990.
    (e) Where the service bulletin specifies that the manufacturer 
may be contacted for disposition of certain repair conditions, prior 
to further flight, repair in accordance with a method approved by 
the Manager, Seattle Aircraft Certification Office (ACO), FAA, 
Transport Airplane Directorate; or in accordance with data meeting 
the type certification basis of the airplane approved by a Boeing 
Company Designated Engineering Representative (DER) who has been 
authorized by the Manager, Seattle ACO, to make such findings. For a 
repair method to be approved by the Manager, Seattle ACO, or a 
Boeing DER, as required by this paragraph, the approval letter must 
specifically reference this AD.

Modification

    (f) For airplanes having line numbers 153, 339, 416, and 540: 
Prior to the accumulation of 60,000 total flight cycles, or within 
3,000 flight cycles after the effective date of this AD, whichever 
occurs later, modify the fuselage circumferential skin joints in 
accordance with Part IV of the Accomplishment Instructions of Boeing 
Service Bulletin 727-53-0084, Revision 4, dated August 2, 1990. Such 
action constitutes terminating action for the requirements of 
paragraph (c)(2) of this AD.

Alternative Methods 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 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.
    (2) An alternative method of compliance for paragraph (f) of 
this AD that provides an acceptable level of safety may be used in 
accordance with data meeting the type certification basis of the 
airplane approved by a Boeing Company Designated Engineering 
Representative who has been authorized by the Manager, Seattle ACO, 
to make such findings.

    Note 3: 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

(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 November 30, 1999.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-31477 Filed 12-3-99; 8:45 am]
BILLING CODE 4910-13-P