[Federal Register Volume 64, Number 89 (Monday, May 10, 1999)]
[Proposed Rules]
[Pages 24964-24967]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-11615]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-18-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Models 737-100, -200, -300, -
400, and -500 Series Airplanes; and Model 727-100 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 Models 737-100, -
200, -300, -400, and -500 series airplanes, and all Models 727-100 and 
-200 series airplanes. This proposal would require a one-time 
inspection to determine the presence and condition of the breather plug 
in each fuel tank boost pump; and

[[Page 24965]]

either installation of a new plug or replacement of the boost pump with 
a new pump, if necessary. This proposal is prompted by a report that 
breather plugs were missing from fuel tank boost pumps. The actions 
specified by the proposed AD are intended to prevent possible ignition 
of fuel vapor in the fuel boost pump, which could result in a fuel tank 
explosion in the event of a boost pump internal failure.

DATES: Comments must be received by June 24, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-18-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056. Comments may be inspected at this location 
between 9 a.m. and 3 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: Dorr Anderson, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2684; 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-18-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-18-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that breather plugs were 
missing from the Argo-Tech/TRW fuel tank boost pumps of two Boeing 
Model 727 series airplanes. One fuel pump on each airplane was missing 
its associated breather plug. At another facility, an operator reported 
finding 2 breather plugs in a test stand filter, which suggests that 
those plugs may have been removed from boost pumps but not reinstalled.
    A breather plug serves as a flame arrestor in the return line from 
the boost pump to the fuel tank. The purpose of the flame arrestor is 
to quench a flame front initiated inside the fuel pump and prevent it 
from propagating back to the fuel tank.
    The breather plug on an Argo-Tech/TRW boost pump is retained within 
the boost pump return line by an adhesive bond. When a boost pump is 
installed in an airplane, the breather plug is also mechanically 
retained within the pump return line by a mating surface on the 
airplane side of the installation. If the pump is removed from the 
airplane, the plug is secured within the pump by only the adhesive 
bond. Any failure of that adhesive could result in loss of the breather 
plug. A loose, damaged, or missing breather plug, if not detected and 
corrected, could result in possible ignition of fuel vapor in the fuel 
boost pump and a consequent fuel tank explosion in the event of a boost 
pump internal failure.

Other Affected Models

    Certain Boeing Model 737 series airplanes also are equipped with 
Argo-Tech/TRW boost pumps, which incorporate the breather plugs; 
therefore, those airplanes also may be subject to the unsafe condition 
identified in this proposed AD.

Explanation of Relevant Service Information

    The FAA has reviewed Boeing Telex M-7200-98-03173, dated October 
21, 1998, which describes procedures for a one-time inspection of each 
fuel tank boost pump to determine the presence and condition of its 
breather plug. For any plug that is loose, damaged, or missing, the 
telex provides procedures for either installation of a new breather 
plug or replacement of the boost pump with a new pump.
    Temporary Revision (TR) No. 28-1 to the Argo Overhaul Manual 
(``Plug-in Booster Pump''), dated November 13, 1998, provides 
procedures for the installation of breather plugs into fuel tank boost 
pumps.
    Accomplishment of the actions specified in the telex and the TR 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 telex and the TR described previously, except as discussed below.

Differences Between Proposed AD and Telex: Compliance Times

    The compliance times recommended in the telex differ from those 
proposed by this AD. The telex recommends a longer compliance time for 
inspection of the boost pumps of the main fuel tanks, and the proposed 
AD would allow a longer compliance time for inspection of the boost 
pumps of the center and auxiliary fuel tanks.
    For the inspections of the boost pumps in the main fuel tanks, the 
proposed AD would require a 12-month compliance time, whereas the telex 
recommends accomplishment at the next ``C'' check or within 6,000 
flight hours for Model 737 series airplanes. (The telex does not 
specify a compliance time for inspection of affected Model 727 series 
airplanes.) The FAA has determined that 12 months would allow operators 
sufficient time to complete the required inspections of all affected 
airplanes during regular maintenance, without compromising safety. 
Further, the FAA has determined that an adequate supply of parts is 
expected to be available within this compliance time.
    For the inspections of the boost pumps of Model 737 center fuel 
tanks and Model 727 center and auxiliary fuel

[[Page 24966]]

tanks, the proposed AD would allow a compliance time longer than that 
recommended by the telex. (The telex does not specify a compliance time 
for inspection of Model 727 center fuel tanks.) While the FAA 
recognizes the unsafe condition identified in this proposed AD, the FAA 
also finds that the burden that would be imposed on operators by 
specifying a 30-day compliance time is unjustified. The 6-month 
compliance time proposed by this AD was determined to be appropriate in 
consideration of the safety implications, the average utilization rate 
of the affected fleet, and the practical aspects of an orderly 
inspection of the fleet during regular maintenance periods.
    In consideration of all of these factors, the FAA has determined 
that the proposed compliance times would represent an appropriate 
interval in which the proposed actions could be accomplished within the 
fleet in a timely manner, and still maintain an adequate level of 
safety.

Difference Between Proposed AD and Telex: Approved Installation 
Method

    In addition, operators should note that, although the telex 
recommends that the manufacturer be contacted for instructions 
regarding installation of breather plugs, if necessary, this proposal 
would require such installation to be accomplished in accordance with 
Argo Overhaul Manual TR 28-1. (The proposed AD would optionally require 
replacement of the pump with a new pump, in accordance with Boeing 
maintenance manual procedures.)

Cost Impact

    There are approximately 2,477 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 1,345 airplanes of U.S. 
registry would be affected by this proposed AD. It would take 
approximately 2 work hours per boost pump to accomplish the proposed 
inspection at an average labor rate of $60 per work hour. (There are 6 
boost pumps in the center and main fuel tanks on Model 737 series 
airplanes, 8 boost pumps in the center and main fuel tanks on Model 727 
series airplanes, and 2 boost pumps in each auxiliary fuel tank, which 
may be installed on some affected airplanes of both models.) Based on 
these figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $120 per boost pump.
    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 99-NM-18-AD.

    Applicability: Model 737-100, -200, -300, -400, and -500 series 
airplanes that are equipped with Argo-Tech/TRW fuel boost pumps; and 
all Model 727-100 and -200 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 possible ignition of fuel tank vapor in the fuel 
boost pump, which could result in a fuel tank explosion, accomplish 
the following:

Inspection and Corrective Actions

    (a) Perform a one-time detailed inspection to detect discrepant 
breather plugs (including loose, damaged, and missing plugs) in the 
fuel tank boost pumps, at the time specified in paragraph (a)(1) or 
(a)(2), as applicable, of this AD; in accordance with Boeing Telex 
M-7200-98-03173, dated October 21, 1998. If any discrepancy is 
detected, prior to further flight, either install a new breather 
plug in accordance with Temporary Revision (TR) No. 28-1 of the Argo 
Overhaul Component Maintenance Manual, dated November 13, 1998; or 
replace the boost pump with a new pump, in accordance with 
procedures specified in section 28-22-41 of the Boeing 737 Airplane 
Maintenance Manual (AMM) or Section 28-22-21 of the Boeing 727 AMM, 
as applicable.
    (1) For center fuel tanks installed on Model 737 series 
airplanes, and for auxiliary fuel tanks installed on Model 727 and 
737 series airplanes: Inspect within 6 months after the effective 
date of this AD.
    (2) For main fuel tanks installed on Model 737 series airplanes, 
and for center and main fuel tanks installed on Model 727 series 
airplanes: Inspect within 12 months after the effective date of this 
AD.

Spares

    (b) As of the effective date of this AD, no person shall install 
on any airplane an Argo-Tech/TRW fuel boost pump, unless that pump 
has been inspected and applicable corrective actions have been 
performed in accordance with the requirements of this AD.

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

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and 21.199) to operate the airplane to a location where the 
requirements of this AD can be accomplished.

    Issued in Renton, Washington, on May 3, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-11615 Filed 5-7-99; 8:45 am]
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DEPARTMENT OF TRANSPORTATION
BILLING CODE 4910-13-P