[Federal Register Volume 64, Number 152 (Monday, August 9, 1999)]
[Rules and Regulations]
[Pages 43056-43058]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-20058]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-188-AD; Amendment 39-11246; AD 99-16-11]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, and -800 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Boeing Model 737-600, -700, and -800 series 
airplanes. This action requires a test of the squib circuit ground 
studs of the engine fire extinguisher bottles to measure the 
resistance, and repair or replacement of the ground stud with a new 
ground stud, if necessary. This amendment is prompted by reports of 
improper grounding of the squib circuit. Such a condition would prevent 
the engine fire extinguisher bottle from discharging when commanded, 
which could result in the inability to extinguish an engine fire.

DATES: Effective August 24, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 24, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before October 8, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-188-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    The service information referenced in this AD 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; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Bernie Gonzalez, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2682; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: The FAA has received a report indicating 
that the flight crew of a Boeing Model 737-800 series airplane pulled 
the engine fire handle in response to an elevated exhaust gas 
temperature indication on the right engine. Maintenance personnel found 
the fire handle turned to the right, indicating that the flight crew 
had attempted to discharge the right engine fire extinguisher bottle. 
Flight crew reports state that the pilot did not intend to discharge 
the bottle. It is not known if the fire handle was held in position 
long enough to discharge the bottle; however, ground resistance 
measurements revealed an open circuit from the right bottle squib and 
the ground stud to structure. Subsequent investigation determined that 
the open circuit was caused by an improperly installed ground stud 
during production. The engine fire extinguisher bottle installations on 
certain Model 737-600 and -700 series airplanes are identical to those 
installed on the affected Model 737-800 series airplanes. Since the 
initial event, the FAA has received reports indicating that 
approximately 25 percent of the squib ground studs installed on these 
Model 737-600, -700, and -800 series airplanes have improper grounding 
of the squib circuit. Such a condition would prevent the engine fire 
extinguisher bottle from discharging when commanded, which could result 
in the inability to extinguish an engine fire.

Explanation of Relevant Service Information

    The FAA has reviewed Boeing Telex M-7200-99-01098, dated February 
5, 1999, which describes procedures for a test of the squib circuit 
ground studs of the engine fire extinguisher bottles to measure the 
resistance, and repair or replacement of the ground stud with a new 
ground stud, if necessary. Accomplishment of the actions specified in 
the telex is intended to adequately address the identified unsafe 
condition.

[[Page 43057]]

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, this AD is 
being issued to detect and correct improper grounding of the squib 
circuit. Such a condition would prevent the engine fire extinguisher 
bottle from discharging when commanded, which could result in inability 
to extinguish an engine fire. This AD requires accomplishment of the 
actions specified in the telex described previously, except as 
discussed below.

Differences Between This AD and the Telex

    The telex recommends accomplishing the test at the earliest 
opportunity where manpower and facilities are available, not to exceed 
two weeks from February 5, 1999, and specifies that operators should 
report the findings of the test to the airplane manufacturer. 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 
extent of the problem in the fleet based on findings from operators' 
reports, and the time necessary to perform the test (less than one 
hour). In light of all of these factors, the FAA finds a 90-day 
compliance time for initiating the required actions to be warranted, in 
that it represents an appropriate interval of time allowable for 
affected airplanes to continue to operate without compromising safety. 
Operators should also note that this AD does not require reporting of 
test findings.
    Operators should note that, although the telex only describes 
procedures for replacement of the squib circuit ground stud with a new 
squib circuit ground stud, the airplane manufacturer has advised the 
FAA that replacement with a standard built-up ground stud (nut and bolt 
type) is an acceptable alternative to replacement with a squib circuit 
ground stud. Therefore, the FAA has included the option of replacing 
the squib circuit ground stud with a standard built-up ground stud as 
an acceptable method of compliance with the requirements of this AD.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 99-NM-188-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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:

99-16-11  Boeing: Amendment 39-11246. Docket 99-NM-188-AD.

    Applicability: Model 737-600, -700, and -800 series airplanes; 
line numbers 1 through 110 inclusive, 112 through 183 inclusive, 
185, 186, 188, 189, 191, 193, and 195; 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 detect and correct improper grounding of the squib circuit, 
which would prevent the engine fire extinguisher bottle from 
discharging when commanded and could result in inability to 
extinguish an engine fire, accomplish the following:

[[Page 43058]]

Test

    (a) Within 90 days after the effective date of this AD, perform 
a test of the squib circuit ground studs of the engine fire 
extinguisher bottles to measure the resistance, in accordance with 
Boeing Telex M-7200-99-01098, dated February 5, 1999.

Repair/Replacement

    (b) If the resistance is greater than 0.5 milliohms, prior to 
further flight, repair in accordance with Boeing Telex M-7200-99-
01098, dated February 5, 1999; or replace the ground stud with a new 
ground stud, in accordance with either paragraph (b)(1) or (b)(2) of 
this AD.
    (1) Install a ground stud having Boeing part number BACS53B, in 
accordance with Boeing Telex M-7200-99-01098, dated February 5, 
1999; or
    (2) Install a standard built-up ground stud (nut and bolt type), 
in accordance with Subject 20-20-00 of Boeing Document No. D6-54446, 
``Standard Wiring Practices Manual.''

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 
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.

Incorporation by Reference

    (e) Except as provided by paragraph (b)(2) of this AD, the 
actions shall be done in accordance with Boeing Telex M-7200-99-
01098, dated February 5, 1999. This incorporation by reference was 
approved by the Director of the Federal Register in accordance with 
5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from 
Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 
98124-2207. Copies may be inspected at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.
    (f) This amendment becomes effective on August 24, 1999.

    Issued in Renton, Washington, on July 29, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-20058 Filed 8-6-99; 8:45 am]
BILLING CODE 4910-13-U