[Federal Register Volume 64, Number 227 (Friday, November 26, 1999)]
[Rules and Regulations]
[Pages 66361-66364]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-30517]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-18-AD; Amendment 39-11430; AD 99-24-06]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, 
and -500 Series Airplanes; and Model 727-100 and -200 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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[[Page 66362]]

SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 737-100, -200, -300, -400, and -500 
series airplanes; and Model 727-100 and -200 series airplanes. This 
amendment requires a one-time inspection to determine the presence and 
condition of the breather plug in each fuel tank boost pump; and either 
installation of a new plug or replacement of the boost pump with a new 
or serviceable pump, if necessary. This amendment is prompted by a 
report that breather plugs were missing from fuel tank boost pumps. The 
actions specified by this AD are intended to prevent possible ignition 
of fuel vapor in the fuel tank boost pump, which could result in a fuel 
tank explosion in the event of a boost pump internal failure.

DATES: Effective January 3, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of January 3, 2000.

ADDRESSES: 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 Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 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: 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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 737-100, -
200, -300, -400, and -500 series airplanes; and all Model 727-100 and -
200 series airplanes; was published in the Federal Register on May 10, 
1999 (64 FR 24964). That action proposed to require a one-time 
inspection to determine the presence and condition of the breather plug 
in each fuel tank boost pump; and either installation of a new plug or 
replacement of the boost pump with a new pump, if necessary.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposal

    One commenter supports the proposed rule.

Request To Clarify Part Numbers of Affected Fuel Pump

    Two commenters request that Argo-Tech/TRW fuel tank boost pumps 
subject to the unsafe condition be identified by part number in the 
proposed rule. The commenters state that there are Argo-Tech/TRW fuel 
tank boost pumps with certain part numbers that are not subject to the 
identified unsafe condition. The FAA concurs and has revised the 
applicability section and paragraph (b) of the final rule accordingly.

Request To Allow Replacement With Serviceable Pumps

    One commenter requests that the proposed rule be revised to allow 
replacement of any discrepant fuel tank boost pump with a serviceable 
pump. The proposed rule specifies that discrepant fuel tank boost pumps 
be replaced with new pumps. The commenter states that boost pumps may 
be overhauled and re-installed on airplanes. The FAA concurs with the 
commenter that either overhauled or new pumps are acceptable for 
compliance with this AD. Therefore, paragraph (a) of the final rule has 
been revised to allow replacement of any discrepant boost pump with a 
new or serviceable pump.

Request To Reference Additional Service Information

    Three commenters request that the proposed rule be revised to 
reference Boeing Alert Service Bulletin 737-28A1134, dated February 23, 
1999, and Revision 1, dated June 10, 1999 (for Model 737 series 
airplanes); and Boeing Alert Service Bulletin 727-28A0125, dated 
February 23, 1999, and Revision 1, dated June 10, 1999 (for Model 727 
series airplanes); as additional sources of service information. The 
commenters state that these alert service bulletins provide 
instructions equivalent to those contained in Boeing Telex M7200-98-
03173, dated October 21, 1998 (which is cited in the proposed rule as 
the appropriate source of service information for accomplishment of the 
inspection requirements of the proposed AD).
    The FAA partially concurs and has revised paragraph (a) of the 
final rule to cite Boeing Alert Service Bulletin 737-28A1134, Revision 
1, and Boeing Alert Service Bulletin 727-28A0125, Revision 1, as 
additional sources of service information. However, the original issues 
of the alert service bulletins incorrectly identify the part numbers of 
affected fuel tank boost pumps, though the procedures needed to 
accomplish the required actions of this AD are correctly described. 
Therefore, a note has been added to the final rule stating that, for 
the applicable boost pumps, accomplishment of the actions in accordance 
with the original issues of the alert service bulletins, prior to the 
effective date of this AD, is acceptable.

Request for Change in Applicability

    One commenter requests that the Model 737-500 series airplane be 
excluded from the applicability of the proposed rule. The commenter 
states that, to its knowledge, Argo-Tech/TRW fuel tank boost pumps 
subject to the identified unsafe condition are not approved for 
installation on the Model 737-500 series airplane. The commenter also 
requests that boost pumps installed in the main or center fuel tanks of 
the Model 737-400 series airplane be excluded from the applicability of 
the proposed rule because, to its knowledge, Argo-Tech/TRW boost pumps 
subject to the identified unsafe condition are not approved for 
installation in those fuel tanks on the Model 737-400 series airplane.
    The FAA does not concur. The FAA recognizes that Argo-Tech/TRW fuel 
tank boost pumps subject to the identified unsafe condition were not 
installed during production in any fuel tank on Model 737-500 series 
airplanes or in the main or center fuel tanks of Model 737-400 series 
airplanes. However, the FAA cannot confirm that these boost pumps were 
not installed as part of a post-production modification to an airplane. 
Therefore, the FAA continues to require that each operator confirm 
whether Argo-Tech/TRW boost pumps subject to the identified unsafe 
condition are installed on its airplanes. No change to the final rule 
is necessary in this regard.

Request To Extend Compliance Time

    One commenter requests that the proposal rule be revised to extend 
the compliance time from the proposed 6 months to 12 months for the 
inspection of the fuel tank boost pumps in the center fuel tanks on 
Model 737 series airplanes and in the auxiliary fuel tanks on Model 737 
and 727 series airplanes. The commenter requests this extension so that 
affected operators will be able to perform the inspection during a 
regularly scheduled maintenance interval. The commenter states that the

[[Page 66363]]

adoption of the proposed compliance time of 6 months would require 
operators to schedule special times for the accomplishment of the 
inspection, at additional expense and downtime.
    The FAA does not concur. The operator provided no technical 
justification for revising this interval as requested. The FAA 
specifically selected a shorter compliance time for fuel tank boost 
pumps in the center fuel tanks on Model 737 series airplanes and in the 
auxiliary fuel tanks on Model 737 and 727 series airplanes because 
these fuel tanks have a higher flammability exposure than the other 
fuel tanks. This is due to the fact that these fuel tanks are warmer 
than the main fuel tanks and because they are routinely operated until 
they are dry, exposing the pump return lines directly to flammable fuel 
vapors. The FAA considered not only those safety issues in developing 
an appropriate compliance time for this action, but the recommendations 
of the manufacturer, the availability of any necessary replacement 
parts, and the practical aspect of accomplishing the required 
inspection within an interval of time that parallels normal scheduled 
maintenance for the majority of affected operators. In light of these 
factors, the FAA has determined that the 6-month compliance time for 
inspection of fuel tank boost pumps in the center fuel tanks on Model 
737 series airplanes and in the auxiliary fuel tanks on Model 737 and 
727 series airplanes, as proposed, is appropriate. No change to the 
final rule is necessary in this regard.

Request To Reduce Compliance Time

    One commenter requests that the proposed 6-month compliance time 
for the inspection of fuel tank boost pumps in the center fuel tanks on 
Model 737 series airplanes and in the auxiliary fuel tanks on Model 737 
and 727 series airplanes be shortened to 3 months, and that the 
proposed 12-month compliance time for the inspection of boost pumps in 
the main fuel tanks on Model 737 series airplanes and in center and 
main fuel tanks on Model 727 series airplanes be shortened to 6 months. 
This commenter suggests that the proposed compliance time may be too 
long to allow an airplane to fly with a potential failure that could 
result in a fuel tank explosion. The commenter notes that the time 
required to carry out the inspections will have minimal impact on 
airplane operations.
    The FAA does not concur with the request for a shorter compliance 
time. In developing the proposed compliance time, the FAA considered 
the probability of a fuel tank explosion occurring on any of these 
airplanes due to a missing breather plug. The FAA determined that the 
occurrence of a fuel tank ignition event is improbable; therefore, more 
urgent action is not necessary. In making this determination, the FAA 
has taken into account the conditions that are required for a missing 
breather plug to cause a fuel tank explosion. Specifically, the FAA 
considered the probability of an in-service fuel tank boost pump 
missing a breather plug (based on inspections that had been conducted 
on over 1,050 fuel pumps), the probability of a boost pump failure that 
would cause an internal ignition inside the pump, and the probability 
of fuel vapors in the fuel tank being flammable. The proposed 
compliance times were determined to be appropriate in consideration of 
the safety implications, the average utilization rate of the affected 
fleet, the practical aspects of an orderly inspection of the fleet 
during regular maintenance periods, and the availability of required 
replacement parts. No change to the final rule is necessary in this 
regard.

Request To Revise Compliance Time

    One commenter requests that the proposed rule be revised to provide 
an extension of the compliance time for any airplane that is out of 
service for heavy maintenance for a long period of time. The commenter 
suggests the compliance time should be within 6 months (or 12 months) 
after the effective date of this AD, or prior to further flight, 
whichever occurs later.
    The FAA does not concur with the commenter's request; however, the 
FAA agrees with the commenter's intent. Part 39 of the Federal Aviation 
Regulations (14 CFR part 39) states that, ``No person may operate a 
product to which an airworthiness directive applies except in 
accordance with the requirements of that airworthiness directive.'' 
This regulation provides compliance relief for airplanes that are not 
being operated, because affected airplanes need only be in compliance 
prior to return to operation. No change to the final rule is necessary 
in this regard.

Request for Credit for Previously Accomplished Actions

    Two commenters request that a statement be added to the proposed 
rule to clarify that no further action is required for airplanes that 
have already accomplished the actions specified in the proposed rule. 
The FAA agrees that no further action is required for these airplanes. 
Operators are always given credit for previously accomplished actions 
by means of the phrase in the compliance section of the AD that states, 
``Required . . . unless accomplished previously.'' Therefore, no change 
to the final rule is necessary in this regard.

Explanation of Change Made to Proposal

    The airplane manufacturer has revised the instructions in the 
airplane maintenance manual (AMM) sections specified in paragraph (a) 
of the proposed rule to include, prior to installation of a new fuel 
tank boost pump, a check of the vent port to ensure that a breather 
plug is installed. The FAA finds that this check is appropriate. 
Therefore, the FAA has revised paragraph (a) of the final rule to 
specify that, after the effective date of the final rule, only Section 
28-22-41 of the Boeing 737 AMM, dated May 1, 1999, or Section 28-22-21 
of the Boeing 727 AMM, dated January 20, 1999, as applicable, shall be 
used.
    The FAA also has added a note to the final rule to clarify the 
definition of a detailed visual inspection.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

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 will be affected by this AD. It will take approximately 2 work 
hours per fuel tank boost pump to accomplish the required actions 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 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 requirements of this AD 
action, and that no operator would accomplish those actions in the 
future if this AD were not adopted.

[[Page 66364]]

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.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it 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:

99-24-06 Boeing: Amendment 39-11430. Docket 99-NM-18-AD.

    Applicability: Model 737-100, -200, -300, -400, and -500 series 
airplanes; and Model 727-100 and -200 series airplanes; certificated 
in any category; equipped with Argo-Tech/TRW fuel tank boost pumps 
having part numbers 258000-2, -3, and -5, or 382300-1, -2, and -3.

    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 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 visual 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; or Boeing 
Alert Service Bulletin 737-28A1134, Revision 1, dated June 10, 1999 
(for Model 737 series airplanes); or Boeing Alert Service Bulletin 
727-28A0125, Revision 1, dated June 10, 1999 (for Model 727 series 
airplanes). 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-Tech Overhaul Manual, dated 
November 13, 1998, or the alert service bulletins; or replace the 
boost pump with a new or serviceable 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. After the effective date of this AD, only Section 28-
22-41 of the Boeing 737 Airplane Maintenance Manual (AMM), dated May 
1, 1999, or Section 28-22-21 of the Boeing 727 AMM, dated January 
20, 1999, as applicable, shall be used for replacement of the boost 
pump.
    (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.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''
    Note 3: For Argo-Tech/TRW fuel tank boost pumps, part numbers 
258000-2, -3, and -5, and 382300-1, -2, and -3: Accomplishment of 
the actions specified in paragraph (a) of this AD, prior to the 
effective date of this AD, in accordance with Boeing Alert Service 
Bulletin 737-28A1134, dated February 23, 1999 (for Model 737 series 
airplanes), or Boeing Alert Service Bulletin 727-28A0125, dated 
February 23, 1999 (for Model 727 series airplanes), is acceptable 
for compliance with this AD.

Spares

    (b) As of the effective date of this AD, no person shall install 
on any airplane an Argo-Tech/TRW fuel tank boost pump having the 
part number 258000-2, -3, or -5; or 382300-1, -2, or -3; 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 4: 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.

Incorporation by Reference

    (e) The inspection and installation shall be done in accordance 
with Boeing Telex M-7200-98-03173, dated October 21, 1998; Boeing 
Alert Service Bulletin 737-28A1134, Revision 1, dated June 10, 1999; 
Boeing Alert Service Bulletin 727-28A0125, Revision 1, dated June 
10, 1999; or Temporary Revision No. 28-1 of the Argo-Tech Overhaul 
Manual, dated November 13, 1998; as applicable. 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 January 3, 2000.

    Issued in Renton, Washington, on November 17, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-30517 Filed 11-24-99; 8:45 am]
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