[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
