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

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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