[Federal Register Volume 61, Number 111 (Friday, June 7, 1996)]
[Proposed Rules]
[Pages 29038-29039]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-14384]



 ========================================================================
 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 61, No. 111 / Friday, June 7, 1996 / Proposed 
Rules  

[[Page 29038]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-06-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100 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 737-100 and -
200 series airplanes. This proposal would require replacement of the 
250 volt-ampere (VA) rated static inverters with 410 or 500 VA rated 
static inverters, and an operational test of the standby electrical 
power system. This proposal is prompted by a report that accomplishment 
of a certain modification could result in overload of the static 
inverter on these airplanes. The actions specified by the proposed AD 
are intended to prevent overload of the static inverter, which could 
result in the loss of the 115 volt alternating current standby bus and 
the associated flight instruments when the airplane is operating on 
standby electrical power.

DATES: Comments must be received by July 19, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-06-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: Stephen Oshiro, 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 (206) 227-2793; fax (206) 
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 96-NM-06-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-103, Attention: Rules 
Docket No. 96-NM-06-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received a report indicating that, during an 
engineering review of Revision 4 to Boeing Service Bulletin 737-24-1051 
by the manufacturer, it was found that the effectivity listing of the 
original issue through Revision 4 of this service bulletin included 
some Boeing Model 737-100 and -200 series airplanes equipped with 250 
volt-ampere (VA)-rated static inverters. That particular static 
inverter may overload on these airplanes if the modification described 
in these particular revisions of the service bulletin has been 
accomplished. The modification entails revising the power connections 
to the captain's instrument panel. Such an overload on the static 
inverters could result in the loss of the 115 VAC standby bus and the 
associated flight instruments when the airplane is operating on standby 
electric power. Loss of use of these components may adversely affect 
the handling characteristics of the airplane.

FAA's Conclusions

    Based on the information obtained from the manufacturer's review, 
the FAA finds that static inverters rated at 410 VA or 500 VA can 
safely handle the increase in electrical loading of the 115 VAC standby 
bus when the modification specified in Service Bulletin 737-24-1051 
(the original issue through Revision 4) is accomplished. Therefore, the 
FAA has determined that replacement of 250 VA-rated static inverters 
with 410 VA or 500 VA-rated static inverters will positively 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 replacement of the 250 VA-rated static 
inverters with certain 410 or 500 VA-rated static inverters. This 
replacement would be required only on those airplanes on which the 
modification specified in the various revisions of Boeing Service 
Bulletin 737-24-1051 has been accomplished.
    After accomplishment of the replacement, the proposed AD would also 
require performing an operational test of the standby electrical power 
system.

[[Page 29039]]

    The proposed actions would be required to be accomplished in 
accordance with the Boeing 737 Airplane Maintenance Manual.

Cost Impact

    There are approximately 51 Boeing Model 737-100 and -200 series 
airplanes of the affected design in the worldwide fleet. The FAA 
estimates that 1 airplane of U.S. registry would be affected by this 
proposed AD, that it would take approximately 2 work hours per airplane 
to accomplish the proposed actions, and that the average labor rate is 
$60 per work hour. Required parts would cost approximately $10,500 per 
airplane. Based on these figures, the cost impact of the proposed AD on 
U.S. operators is estimated to be $10,620.
    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 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 96-NM-06-AD.

    Applicability: Model 737-100 and -200 series airplanes; equipped 
with 250 volt-ampere (VA) rated static inverters; on which the 
modification specified in Boeing Service Bulletin 737-24-1051 
(original issue, dated October 20, 1988; Revision 1, dated October 
5, 1989; Revision 2, dated June 28, 1990; Revision 3, dated May 7, 
1992; or Revision 4, dated December 21, 1995) has been accomplished; 
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 (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 overload of the static inverter, which could result 
in the loss of the 115 VAC standby power and the associated flight 
instruments, accomplish the following:
    (a) Within 10 months after the effective date of this AD, 
replace the 250 VA rated static inverters either with 500 VA-rated 
static inverters having Boeing part number (P/N) 60B40023-2, or with 
410 VA-rated static inverters having Jet Electronics and Technology 
P/N 3S2060DV109B1, in accordance with Section 20-10-111 of the 
Boeing 737 Airplane Maintenance Manual. Prior to further flight 
following the replacement, perform an operational test of the 
standby electrical power system in accordance with Section 24-54-0 
of the Boeing 737 Airplane Maintenance Manual.

    Note 2: Replacements and operational tests accomplished prior to 
the effective date of this amendment in accordance with Boeing Alert 
Service Bulletin 737-24A2113, dated February 29, 1996, are 
considered acceptable for compliance with this AD.
    (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. 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.
    (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 June 3, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-14384 Filed 6-6-96; 8:45 am]
BILLING CODE 4910-13-U