[Federal Register Volume 64, Number 137 (Monday, July 19, 1999)]
[Proposed Rules]
[Pages 38603-38605]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18368]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-378-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 modification of the pressure web 
of the nose landing gear wheel well. This proposal is prompted by 
reports of fatigue cracks in the pressure web of the nose landing gear 
wheel well. The actions specified by the proposed AD are intended to 
prevent cracking of the pressure web of the nose landing gear wheel 
well, which could result in loss of airplane pressurization.

DATES: Comments must be received by September 2, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-378-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

[[Page 38604]]

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 98-NM-378-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. 98-NM-378-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 
installation of reinforcement straps and stiffeners on the sidewall, 
top, and forward bulkhead panels of the pressure web of the nose 
landing gear wheel well. That AD was prompted in part by reports of 
fatigue cracks in the pressure web of the nose landing gear wheel well.
    Since the issuance of AD 90-06-09, the airplane manufacturer has 
notified the FAA that certain Model 727 series airplanes were 
inadvertently not included in the effectivity listing of Boeing 
Document No. D6-54860, Revision C, and hence, were also omitted from 
the applicability of that AD. Because such cracking has been attributed 
to fatigue, those airplanes may also be subject to the same unsafe 
condition. Cracking in the pressure web of the nose landing gear wheel 
well could result in loss of airplane pressurization.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 727-53-
0145, Revision 1, dated December 7, 1989, which describes procedures 
for repetitive inspections of the sidewall, top, and forward bulkhead 
panels of the pressure web of the nose landing gear wheel well, and 
repair, if necessary. The service bulletin also describes procedures 
for a modification that involves installation of reinforcement straps 
and stiffeners on the sidewall, top, and forward bulkhead panels of the 
pressure web of the nose landing gear wheel well. Such installation 
would eliminate the need for the repetitive inspections in that area. 
Accomplishment of the modification 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 describes 
procedures for repetitive inspections of the pressure web of the nose 
landing gear wheel well, and repair, if necessary, this AD proposes to 
mandate only the modification of the pressure web of the nose landing 
gear wheel well. The FAA has determined that long-term continued 
operational safety will be better assured by design changes to prevent 
cracks, rather than repetitive inspections. Long-term inspections may 
not provide the degree of safety assurance necessary for the transport 
airplane fleet. This, coupled with a better understanding of the human 
factors associated with numerous continual inspections, has led the FAA 
to consider placing less emphasis on inspections and more emphasis on 
design improvements. The decision to propose mandating only the 
modification and not the repetitive inspections described previously is 
in consonance with these conditions.
    Operators should also note that this proposed AD would be 
applicable to airplanes not included in the effectivity listing of the 
service bulletin. AD 90-06-09 mandated the modification of the pressure 
web of the nose landing gear wheel well for airplanes listed in Boeing 
Document No. D6-54860, Revision C, dated December 11, 1989, ``Aging 
Airplane Service Bulletin Structural Modification Program--Model 727.'' 
The airplanes to which this proposed AD would be applicable are 
included in the effectivity listing of Revision H, dated May 9, 1996, 
of that document.

Cost Impact

    There are approximately 24 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 13 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
82 work hours per airplane to accomplish the proposed modification, and 
that the average labor rate is $60 per work hour. Required parts would 
cost approximately $701 per airplane. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be $73,073, 
or $5,621 per airplane.
    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.

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

[[Page 38605]]

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 98-NM-378-AD.

    Applicability: Model 727 series airplanes; line numbers 124, 
126, 130, 146, 221, 287, 331, 339, 345, 355, 416, 439, 516, 532, 
540, 608, 631, 650, 717, 777, 788, 791, 837, and 1087; 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 (b) 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 cracking of the pressure web of the nose landing gear 
wheel well, which could result in loss of airplane pressurization, 
accomplish the following:

Modification

    (a) Prior to the accumulation of 60,000 total flight cycles, or 
within 4 years after the effective date of this AD, whichever occurs 
later, install reinforcement straps and stiffeners on the sidewall, 
top, and forward bulkhead panels of the pressure web of the nose 
landing gear wheel well, in accordance with Part II of the 
Accomplishment Instructions of Boeing Service Bulletin 727-53-0145, 
Revision 1, dated December 7, 1989.

Alternative Methods of Compliance

    (b) 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; 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 Manager, Seattle ACO, to make such 
findings. 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

    (c) 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 July 13, 1999.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-18368 Filed 7-16-99; 8:45 am]
BILLING CODE 4910-13-P