AD 2000-04-02

[Federal Register Volume 65, Number 36 (Wednesday, February 23, 2000)]
[Rules and Regulations]
[Pages 8845-8848]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 00-3886]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-150-AD; Amendment 39-11584; AD 2000-04-02]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 737-100, -200, -300, -400, and -500 
series airplanes, that requires repetitive testing of certain main tank 
fuel boost pumps to identify those with degraded performance, and 
replacement of degraded pumps with new or serviceable pumps. This AD 
also requires eventual replacement of the existing low pressure 
switches for boost pumps located in the main fuel tanks with higher 
threshold low pressure switches, which, when accomplished, terminates 
the repetitive testing. This amendment is prompted by reports of engine 
power loss caused by unsatisfactory performance of the fuel boost 
pumps. The actions specified by this AD are intended to prevent fuel 
suction feed operation on both engines without flight crew indication, 
and possible consequent multiple engine power loss.

DATES: Effective March 29, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 29, 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),

[[Page 8846]]

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 was published as a 
supplemental notice of proposed rulemaking (NPRM) in the Federal 
Register on June 2, 1999 (64 FR 29602). That action proposed to require 
repetitive testing of certain main tank fuel boost pumps to identify 
those with degraded performance, and replacement of degraded pumps with 
new or serviceable pumps. That action also proposed to require eventual 
replacement of the existing low pressure switches for boost pumps 
located in the main fuel tanks with higher threshold low pressure 
switches, which, when accomplished, terminates the repetitive testing.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Requests To Extend Compliance Time

    Two commenters request that the proposed compliance time for 
replacement of the low pressure switches with higher low pressure 
switches be extended.
    One commenter, the manufacturer, requests that the compliance time 
for installation of higher threshold switches on Model 737-200 series 
airplanes be extended from 2 to 3 years. The commenter states the 
vendor for the low pressure switches for Model 737-200 series airplanes 
had not committed to providing the required parts within the proposed 
2-year compliance time. The commenter states that the pressure switch, 
unlike the one used on Model 737-300, -400, and -500 series airplanes, 
was previously used only on auxiliary fuel tank installations, and that 
production was in very low quantities. There are approximately 1,000 
Model 737-200 series airplanes that would require the subject switch. 
The commenter also states that the vendor for the low pressure switches 
for Model 737-300, -400, and -500 is able to provide the needed 
hardware within the proposed compliance time.
    Another commenter requests that airplanes with Argo-Tech/TRW boost 
pumps installed in the main tanks be allowed up to 4 years to install 
the higher threshold low pressure switches to accommodate parts 
replacement at heavy maintenance visits.
    The FAA does not concur with the commenters' requests. In 
developing an appropriate compliance time for this action, the FAA 
considered not only the degree of urgency associated with addressing 
the subject unsafe condition, but the availability of required parts 
and the practical aspect of accomplishing the required replacement 
within an interval of time that parallels normal scheduled maintenance 
for the majority of affected operators. Subsequent to closure of the 
comment period of the proposed AD, the FAA has confirmed with the 
manufacturer that an ample number of required parts will be available 
for accomplishment of the replacement within the proposed 2-year 
compliance time. However, under the provisions of paragraph (c) of the 
final rule, the FAA may approve requests for adjustments to the 
compliance time if data are submitted to substantiate that such an 
adjustment would provide an acceptable level of safety.

Request To Follow Service Bulletin Threshold Time

    One commenter, an operator, recommends that the compliance time for 
accomplishing the pump output pressure test follow the 180-day 
threshold recommended in Boeing Alert Service Bulletin 737-28A1114, 
Revision 1, dated April 2, 1998. The commenter states that the 180-day 
compliance time will not compromise safe operation of the airplane fuel 
feed system based upon results of their testing and the redundancy 
associated with the fuel system on Model 737 series airplanes.
    The FAA does not concur with the commenter's request. As discussed 
in the preamble of the original NPRM (63 FR 42596, August 10, 1998), 
the FAA has determined that an interval of 180 days would not address 
the identified unsafe condition in a timely manner, as degraded fuel 
boost pump performance may go undetected. Degraded fuel boost pump 
performance that is not detected by the low pressure switch and 
annunciated on the flight deck could result in multi-engine suction 
feed operation without flight crew indication, and possible consequent 
multiple engine failure. Redundancy in the fuel system has not 
prevented a number of in-service engine failures associated with pumps 
operating in a degraded manner. Therefore, no change to the final rule 
is necessary.

Request To Limit the Applicability to Certain Fuel Pumps

    One commenter requests that the applicability of the proposed AD be 
revised to only affect airplanes which are fitted with General Electric 
Company (GEC) boost pumps. The commenter points out that the Boeing 
Alert Service Bulletin 737-28A1114, Revision 1, dated April 2, 1998, 
reveals that the unsafe condition or flameout occurred on Model 737-
300, -400, and -500 series airplanes equipped with GEC pumps. No case 
of flameout was reported on Model 737-100, or -200 series airplanes 
equipped with Pratt and Whitney Model JT8D engines. The commenter 
states that its request will in no way affect the safety of the 
airplane.
    The FAA does not concur with the commenter's request. As discussed 
in the supplemental NPRM, the FAA has determined that all pump 
configurations on affected Boeing Model 737 series airplanes may be 
subject to the identified unsafe condition.

Explanation of Changes to Proposal

    The FAA has revised paragraph (a)(4) of the final rule to clarify 
that accomplishment of the required replacement constitutes terminating 
action for paragraphs (a)(1), (a)(2), and (a)(3) of this AD.

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 change previously 
described. The FAA has determined that this change will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 2,772 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 1,140 airplanes of U.S. 
registry will be affected by this AD.
    It will take approximately 2-8 work hours per airplane to 
accomplish the required testing for airplanes equipped with GEC pumps, 
at an average labor rate of $60 per work hour. Based on these figures, 
the cost impact of the testing required by this AD on U.S. operators is 
estimated to be $120-$480 per airplane, per testing cycle.
    It will take approximately 4-6 work hours per airplane to 
accomplish the

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required modification, at an average labor rate of $60 per work hour. 
Required parts will cost $1,900 [for airplanes equipped with part 
number (P/N) 60B92400-3 low pressure switches] or $2,700 (for airplanes 
equipped with P/N 10-3067-3 low pressure switches). Based on these 
figures, the cost impact of the modification required by this AD on 
U.S. operators is estimated to be $273,600-$410,400, or $2,140-$3,060 
per airplane.
    The cost impact figures discussed above are 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.

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:
2000-04-02  Boeing: Amendment 39-11584. Docket 98-NM-150-AD.
    Applicability: Model 737-100, -200, -300, -400, and -500 series 
airplanes; line numbers 1 through 3002 inclusive; 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 fuel suction feed operation on both engines without 
flight crew indication, and possible consequent multiple engine 
power loss, accomplish the following:

Requirements for Airplanes Equipped With GEC Boost Pumps:

    (a) For airplanes equipped with one or more main tank fuel boost 
pumps manufactured by the General Electric Company (GEC), of the 
United Kingdom: Accomplish paragraphs (a)(1), (a)(2), (a)(3), and 
(a)(4) of this AD.
    (1) As of the effective date of this AD, no airplane shall be 
dispatched with any main tank fuel boost pump inoperative unless the 
initial testing and any follow-on corrective actions required by 
paragraph (a)(2) of this AD have been accomplished on the operative 
pump in that main tank.
    (2) Test each GEC-manufactured main tank fuel boost pump to 
determine the output pressure, in accordance with Boeing Alert 
Service Bulletin 737-28A1114, Revision 1, dated April 2, 1998; at 
the later of the times specified in paragraphs (a)(2)(i) and 
(a)(2)(ii) of this AD. If the fuel boost pump output pressure 
measured during the testing required by this paragraph is less than 
23 pounds per square inch gauge (psig), as measured at the input to 
the engine fuel pump; or less than 36 psig, as measured at the fuel 
boost pump low pressure switch; prior to further flight, replace the 
fuel boost pump with a new or serviceable fuel pump, in accordance 
with the alert service bulletin.
    (i) Prior to the accumulation of 3,000 total flight hours, or 
within 1 year since date of manufacture of the airplane, whichever 
occurs first; or
    (ii) Within 90 days after the effective date of this AD.
    (3) Repeat the testing required by paragraph (a)(2) of this AD 
thereafter at intervals not to exceed 6 months, until accomplishment 
of the requirements of paragraph (a)(4) of this AD.
    (4) Within 2 years after the effective date of this AD, replace 
all four low pressure switches installed downstream of the main tank 
fuel boost pumps with higher threshold low pressure switches, in 
accordance with Boeing Alert Service Bulletin 737-28A1114, Revision 
1, dated April 2, 1998. Accomplishment of this replacement 
constitutes terminating action for the requirements of paragraphs 
(a)(1), (a)(2), and (a)(3) of this AD.

Requirements for Airplanes Equipped With Non-GEC boost pumps:

    (b) For airplanes other than those identified in paragraph (a) 
of this AD: Within 2 years after the effective date of this AD, 
replace all four low pressure switches installed downstream of the 
main tank fuel boost pumps with higher threshold low pressure 
switches, in accordance with Boeing Alert Service Bulletin 737-
28A1114, Revision 1, dated April 2, 1998.

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) The tests and replacements shall be done in accordance with 
Boeing Alert Service Bulletin 737-28A1114, Revision 1, dated April 
2, 1998. 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 March 29, 2000.


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    Issued in Renton, Washington, on February 14, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-3886 Filed 2-22-00; 8:45 am]
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