[Federal Register Volume 65, Number 3 (Wednesday, January 5, 2000)]
[Proposed Rules]
[Pages 401-402]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-135]



[[Page 401]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-335-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 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 747 series 
airplanes. This proposal would require replacement of any brake system 
accumulator that has aluminum end caps with an accumulator that has 
stainless steel end caps. This proposal is prompted by reports of 
fractures of aluminum end caps on brake system accumulators. The 
actions specified by the proposed AD are intended to prevent high-
velocity separation of a brake system accumulator barrel, piston, or 
end cap, which could result in injury to personnel in the wheel well 
area, loss of cabin pressurization, loss of certain hydraulic systems, 
or damage to the fuel line of the auxiliary power unit.

DATES: Comments must be received by February 22, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-335-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: Barbara Mudrovich, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; telephone (425) 227-2983; 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-335-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-335-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that fracture of aluminum 
end caps has occurred on brake system accumulators installed on Boeing 
Model 747 series airplanes. One event resulted in an injury to a 
maintenance worker. Fracture of the aluminum end caps has been 
attributed to fatigue cracking caused by stress corrosion or tooling 
marks. Fracture of an end cap could lead to a rupture of a brake system 
accumulator, which could result in high velocity separation of the 
accumulator barrel, piston, or end cap. Such separation could result in 
injury to personnel in the wheel well area, loss of cabin 
pressurization, loss of certain hydraulic systems, or damage to the 
fuel line of the auxiliary power unit.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 747-32-
2461, dated August 19, 1999, which describes procedures for replacement 
of any brake system accumulator that has aluminum end caps with an 
accumulator that has stainless steel end caps. Stainless steel end caps 
provide added strength and corrosion resistance over aluminum end caps, 
thereby reducing the potential for separation of the end caps. 
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.

Cost Impact

    There are approximately 1,217 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 324 airplanes of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 1 work hour per accumulator (airplanes may have three, 
four, or five accumulators of various types) to accomplish the proposed 
replacement, and that the average labor rate is $60 per work hour. 
Required parts would cost approximately between $7,650 and $13,418 per 
airplane (depending on the number and type of affected accumulators). 
Based on these figures, the cost impact of the proposed AD on U.S. 
operators is estimated to be between $7,830 and $13,718 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

[[Page 402]]

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-335-AD.
    Applicability: Model 747 series airplanes; as listed in Boeing 
Service Bulletin 747-32-2461, dated August 19, 1999; 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 high velocity separation of a brake system 
accumulator barrel, piston, or end cap; which could result in injury 
to personnel in the wheel well area, loss of cabin pressurization, 
loss of certain hydraulic systems, or damage to the fuel line of the 
auxiliary power unit; accomplish the following:

Replacement

    (a) Within 3,000 flight hours after the effective date of this 
AD, replace any brake system accumulator that has aluminum end caps 
with an accumulator that has stainless steel end caps in accordance 
with Boeing Service Bulletin 747-32-2461, dated August 19, 1999.

Spares

    (b) As of the effective date of this AD, no person shall install 
a brake system accumulator having part number BACA11E1 or BACA11E5 
on any airplane.

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 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

    (d) 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 December 29, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-135 Filed 1-4-00; 8:45 am]
BILLING CODE 4910-13-U