[Federal Register Volume 64, Number 234 (Tuesday, December 7, 1999)]
[Proposed Rules]
[Pages 68297-68300]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-31680]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-73-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 all Boeing Model 727 series 
airplanes. This proposal would require a one-time

[[Page 68298]]

detailed visual inspection of the fuselage skin and bonded doubler area 
above the forward entry doorway to detect fatigue cracking or the 
existence of certain repairs, and follow-on corrective actions, if 
necessary. This action also would require a preventive modification or 
full-sized repair doubler, as applicable. This proposal is prompted by 
reports of fatigue cracking in the fuselage skin and bonded doublers in 
the forward and aft corners above the forward entry doorway. The 
actions specified by the proposed AD are intended to prevent such 
fatigue cracking of the fuselage skin and bonded doubler, which could 
result in reduced structural integrity and consequent loss of cabin 
pressurization.

DATES: Comments must be received by January 21, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-73-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-73-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-73-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On February 18, 1994, the FAA issued AD 94-05-04, amendment 39-8842 
(59 FR 13442, March 22, 1994), applicable to certain Boeing Model 727 
series airplanes, to require incorporation of certain structural 
modifications. That action was prompted by an evaluation by the Model 
727 Structures Working Group, comprised of aircraft operators, 
manufacturers, and the FAA. This Working Group evaluated Boeing service 
bulletins that must be included as part of the ``Aging Airplane 
Structural Modification Program.'' The actions specified by that AD are 
intended to prevent degradation in the structural capabilities of the 
affected airplanes. Those actions also reflect the FAA's decision that 
long-term continued operational safety should be assured by actual 
modification of the airframe rather than repetitive inspections.
    Since the issuance of AD 94-05-04, the FAA has determined that 
additional action (specified by Boeing Service Bulletin 727-53-0186, 
Revision 1, dated May 21, 1992) is required to include certain 
airplanes that are excluded in the applicability of that AD. Because AD 
94-05-04 only requires modification of the airplane structure if no 
cracking is detected in the fuselage skin and bonded doubler area above 
the forward entry doorway, some airplanes do not have the full-sized 
repair doubler installed. In addition, there is no mandatory 
requirement to inspect airplanes on which the half- or full-sized 
repair doubler has been installed to repair any crack that exceeds 2.5 
inches or is located in the bear strap. Such conditions, if not 
corrected, could result in a degradation in the structural capabilities 
of the affected airplanes. In light of this, the FAA has determined 
that corrective action is required for airplanes on which only a half-
sized repair doubler has been accomplished, or on which either a half- 
or full-size repair doubler is found and any crack exceeds 2.5 inches 
or is located in the bear strap. Accomplishment of the inspection and 
corrective actions required by this AD is intended to ensure the 
structural integrity of such airplanes, and to reduce the extent of 
crack propagation (i.e., not to exceed 2.5 inches) in the fuselage skin 
and bonded doublers above the upper area of the doorway. Such action 
also reflects the FAA's decision that long-term continued operational 
safety would be better assured by modification of the airframe, rather 
than by repetitive inspections.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 727-53-
0186, Revision 1, dated May 21, 1992, which describes procedures for 
repetitive close (detailed) visual inspections to detect cracking of 
the fuselage skin and bonded doubler area above the forward entry 
doorway. Among other things, this service bulletin also describes 
procedures for the accomplishment of either a preventive modification 
(fabricating and installing a preventive modification doubler) or a 
full-sized repair doubler of the upper area of the doorway skin.

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 the Service Information and the Proposed AD

    Operators should note that the service bulletin recommends a visual 
inspection for cracks ``at 40,000 cycles'' for airplanes that have not 
yet accumulated 40,000 total flight cycles, and an inspection ``within 
3,000 flight cycles'' for airplanes that have accumulated more than 
40,000 total flight cycles. The service bulletin also recommends a 
repetitive inspection interval of 3,000 flight cycles, and 
accomplishment of either a preventive

[[Page 68299]]

modification or a full-sized repair doubler prior to the accumulation 
of 60,000 total flight cycles. However, paragraph (a) of this proposed 
AD requires accomplishment of a one-time detailed visual inspection and 
either the preventive modification or full-sized repair doubler ``prior 
to the accumulation of 60,000 total flight cycles.'' This proposed AD 
does not require repetitive inspections prior to modification or 
repair. The FAA points out that cracks in the fuselage skin and bonded 
doubler area above the forward entry doorway have not been found to be 
a safety factor prior to the accumulation of 60,000 total flight 
cycles. Therefore, the FAA considers that accomplishment of the actions 
required by paragraph (a) of this proposed AD would provide an adequate 
level of operational safety.
    Operators also should note that the service bulletin specifies 
three repair options, which include a procedure for installing a half-
sized repair doubler in the forward corner or aft area of the doorway 
skin. However, this proposed AD requires installing a full-sized repair 
doubler rather than a half-sized repair doubler.
    Operators also should note that the service bulletin specifies 
contacting the manufacturer if any repair was previously accomplished 
for cracking that exceeded 2.5 inches, or if a crack was repaired in 
the bear strap. However, this proposed AD requires that such repairs 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 also should note that, although the service bulletin 
specifies a ``close visual inspection,'' this proposed AD requires a 
``detailed visual inspection.''

Other Relevant Rulemaking

    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 727-53-0186, dated April 27, 1989. 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 1,429 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 887 airplanes of U.S. 
registry would be affected by this proposed AD.
    The FAA estimates that it would take approximately 1 work hour per 
airplane to accomplish the inspection of the fuselage skin and bonded 
doubler area, and that the average labor rate is $60 per work hour. 
Based on these figures, the cost impact of the proposed AD on U.S. 
operators is estimated to be $53,220, or $60 per airplane.
    The FAA estimates that it would take approximately 27 work hours 
per airplane to accomplish the preventive modification or full-sized 
repair doubler, and that the average labor rate is $60 per work hour. 
Required parts would cost approximately $979 per airplane. Based on 
these figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $2,305,313, or $2,599 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-73-AD.

    Applicability: All Model 727 series airplanes, 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 (c) 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 cracking of the fuselage skin and bonded 
doubler area above the forward entry doorway, which could result in 
reduced structural integrity and consequent loss of cabin 
pressurization, accomplish the following:

Detailed Visual Inspection

    (a) 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: Perform a one-time detailed visual 
inspection of the fuselage skin and bonded doubler area above the 
forward entry doorway to detect fatigue cracking or the existence of 
a previous repair, in accordance with Boeing Service Bulletin 727-
53-0186, Revision 1, dated May 21, 1992.

Corrective Action

    (1) If no crack or repair is detected, prior to further flight, 
perform the preventive modification in accordance with the service 
bulletin. No further action is required by this AD.
    (2) If any crack but no repair is detected, prior to further 
flight, accomplish the actions required by paragraph (a)(2)(i), 
(a)(2)(ii), or (a)(2)(iii), as applicable.
    (i) If any crack is less than or equal to 2.5 inches, perform 
the full-sized repair doubler in accordance with Boeing Service 
Bulletin

[[Page 68300]]

727-53-0186, Revision 1, dated May 21, 1992. Accomplishment of this 
action constitutes terminating action for the requirements of this 
AD.
    (ii) If any crack exceeds 2.5 inches, 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 the Boeing DER, as required by this paragraph, the 
approval letter must specifically reference this AD.
    (iii) If any crack in the bear strap is detected, 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 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 the Boeing DER, as 
required by this paragraph, the approval letter must specifically 
reference this AD.
    (3) If any repair is found, accomplish paragraph (a)(3)(i), 
(a)(3)(ii), or (a)(3)(iii), of this AD, as applicable.
    (i) If a full-sized repair doubler is found, as specified by 
Boeing Service Bulletin 727-53-0186, dated April 27, 1989, or 
Revision 1, dated May 21, 1992, and any crack is less than or equal 
to 2.5 inches, no further action is required by this AD.
    (ii) If a half-sized repair doubler is found, as specified by 
Boeing Service Bulletin 727-53-0186, dated April 27, 1989, or 
Revision 1, dated May 21, 1992, and any crack is less than or equal 
to 2.5 inches and is not in the bear strap: Prior to further flight, 
perform the full-sized repair doubler in accordance with Boeing 
Service Bulletin 727-53-0186, Revision 1, dated May 21, 1992. No 
further action is required by this AD.
    (iii) If a half-sized or full-sized repair doubler is found, as 
specified by the service bulletin, and any crack exceeds 2.5 inches 
or is located in the bear strap: 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 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 the Boeing DER, as 
required by this paragraph, the approval letter must specifically 
reference this AD.

    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 an 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirrors, magnifying lenses, etc. may be used. Surface cleaning 
and elaborate access procedures may be required.''

Terminating Action for AD 94-05-04

    (b) Accomplishment of the requirements of this AD constitutes 
terminating action for the requirements of paragraph (a) of AD 94-
05-04, amendment 39-8842 (which are required to be accomplished in 
accordance with Appendices A.3, B.3, and C.3 of Boeing Document 
Number D6-54860, ``Aging Airplane Service Bulletin Structural 
Modification and Inspection Program--Model 727,'' Revision G, dated 
March 5, 1993), with respect to the modification specified in Boeing 
Service Bulletin 727-53-0186, dated April 27, 1989. All other 
service bulletins referenced in Boeing Document Number D6-54860 
still apply.

Alternative Methods of Compliance

    (c) 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, 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 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

    (d) Special flight permits may be issued in accordance with 
Secs. 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.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-31680 Filed 12-6-99; 8:45 am]
BILLING CODE 4910-13-U