Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, and -800 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-342-AD; Amendment 39-11480; AD 99-26-21]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 737-300, -400, -500, -600,

-700, and -800 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: This amendment adopts a new airworthiness directive (AD) that

is applicable to certain Boeing Model 737-300, -400, -500, -600, -700,

and -800 series airplanes. This action requires a one-time detailed

visual inspection of certain wire bundles and hydraulic hoses for the

electric motor driven pump (EMDP) for hydraulic system ``B'' located in

the right main wheel well to detect discrepancies; and corrective

actions, if necessary. This amendment is prompted by a report that the

wire bundle to the EMDP had been chafed by the pressure hose for

hydraulic system ``B'' on a Model 737-700 series airplane, and reports

of failed or damaged case drain or pressure hoses on the EMDP for

hydraulic system ``B'' on Model 737-400 series airplanes. The actions

specified in this AD are intended to prevent electrical arcing due to

chafing between certain hydraulic hoses and adjacent wire bundles,

which could result in a consequent increased risk of fire.

DATES: Effective January 31, 2000.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of January 31, 2000.

Comments for inclusion in the Rules Docket must be received on or

before March 14, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 99-NM-342-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056.

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 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.

FOR FURTHER INFORMATION CONTACT: Stephen S. Oshiro, Aerospace Engineer,

Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane

Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,

SW., Renton, Washington 98055-4056; telephone (425) 227-2793; fax (425)

227-1181.

SUPPLEMENTARY INFORMATION: The FAA has received one report from an

operator of a Boeing Model 737-700 series airplane describing how one

of the three electrical wires in the wire bundle to the electric motor

driven pump (EMDP) had chafed the pressure hose for hydraulic system

``B.'' The FAA also has received several reports of failed or damaged

case drain or pressure hoses on the EMDP for hydraulic system ``B'' for

Boeing Model 737-300, -400, and -500 series airplanes. Chafing between

the hydraulic case drain and pressure hoses could damage the hoses, and

cause a hydraulic leak and failure of the pressure hose. Chafing

between the wire bundle and hydraulic hoses could damage those

components, and lead to electrical arcing between the components and a

consequent hydraulic leak, which could result in an increased risk of

fire.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin

737-29A1076, Revision 1 (for Model 737-300, -400, and -500 series

airplanes), and Boeing Alert Service Bulletin 737-29A1077, Revision 1

(for Model 737-600, -700, and -800 series airplanes); both dated

October 21, 1999; which describe procedures for an inspection of wire

bundles W0334 and W5230, and the hydraulic case drain and pressure

hoses for the EMDP for hydraulic system ``B'' to detect any

discrepancies; and corrective actions, if necessary. Corrective actions

include repair of the wire bundles if any damage is found; replacement

of any hose that is damaged outside specified limits, and any

incorrectly sized or loose components; and certain modifications.

Modifications include adjusting or changing certain support clamps,

fittings, and check valves; and installing additional clamps and

spacers in the hydraulic hoses to obtain specified separation between

the wire bundle and the hoses. For certain EMDP's, modifications also

include ensuring that certain components are attached correctly.

The alert service bulletins also specify a test of the EMDP if wire

bundles W0334 or W5230 were repaired, or a leak test if the hydraulic

case drain or pressure hoses were replaced in accordance with either

Part 1 or Part 2 of the Accomplishment Instructions of the Boeing alert

service bulletins, as applicable.

Explanation of Requirements of the Rule

Since an unsafe condition has been identified that is likely to

exist or develop on other Boeing Model 737-300, -400, -500, -600, -700,

and -800 series airplanes of the same type design, this AD is being

issued to prevent electrical arcing due to chafing between certain

hydraulic hoses and adjacent wire bundles, which could result in a

consequent increased risk of fire. This AD requires a one-time detailed

visual inspection of wire bundles W0334 and W5230 and the hydraulic

case drain and pressure hoses for the EMDP for hydraulic system ``B''

located in the right main wheel well to detect discrepancies; and

corrective actions, if necessary. The actions are required to be

accomplished in accordance with the alert service bulletins described

previously, except as described below.

[[Page 2286]]

Differences Between This AD and the Alert Service Bulletins

Operators should note that the alert service bulletins recommend

accomplishment of the inspection and corrective actions as soon as

manpower and equipment are available. However, the FAA has determined

that the compliance time proposed by the manufacturer would not address

the identified unsafe condition in a timely manner. In developing an

appropriate compliance time for this AD, the FAA considered not only

the manufacturer's recommendation, but the degree of urgency associated

with addressing the subject unsafe condition, the average utilization

of the affected fleet, and the time necessary to perform the inspection

(less than two hours). In light of all these factors, the FAA finds a

90-day compliance time for accomplishing the required actions to be

warranted, in that it represents an appropriate interval of time

allowable for affected airplanes to continue to operate without

compromising safety.

Determination of Rule's Effective Date

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All

communications received on or before the closing date for comments will

be considered, and this rule may be amended in light of the comments

received. Factual information that supports the commenter's ideas and

suggestions is extremely helpful in evaluating the effectiveness of the

AD action and determining whether additional rulemaking action would be

needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this rule must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 99-NM-342-AD.'' The postcard will be date stamped and

returned to the commenter.

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.

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and that it is not a ``significant regulatory

action'' under Executive Order 12866. It has been determined further

that this action involves an emergency regulation under DOT Regulatory

Policies and Procedures (44 FR 11034, February 26, 1979). If it is

determined that this emergency regulation otherwise would be

significant under DOT Regulatory Policies and Procedures, a final

regulatory evaluation will be prepared and placed in the Rules Docket.

A copy of it, if filed, 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:

99-26-21 Boeing: Amendment 39-11480. Docket 99-NM-342-AD.

Applicability: Model 737-300, -400, and -500 series airplanes,

as listed in Boeing Alert Service Bulletin 737-29A1076, Revision 1,

dated October 21, 1999; and Model 737-600, -700, and -800 series

airplanes, as listed in Boeing Alert Service Bulletin 737-29A1077,

Revision 1, dated October 21, 1999; 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 (e) 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 electrical arcing due to chafing between certain

hydraulic hoses and adjacent wire bundles, which could result in a

consequent increased risk of fire; accomplish the following:

Actions for Model 737-300, -400, and -500 Series Airplanes

(a) For certain Model 737-300, -400, and -500 series airplanes

on which the actions specified by Boeing Alert Service Bulletin 737-

29A1076, dated April 2, 1998, have not been accomplished: Within 90

days after the effective date of this AD, perform a one-time

detailed visual inspection of wire bundle W0334 and the hydraulic

case drain and pressure hoses for the electric motor driven pump

(EMDP) for hydraulic system ``B'' to detect any discrepancy (e.g.,

damage or chafing of wire bundle W0334 and the hydraulic case drain

and pressure hoses, and incorrect separation between those

components), in accordance with Part 1 of the Accomplishment

Instructions of Boeing Alert Service Bulletin 737-29A1076, Revision

1, dated October 21, 1999.

(1) If no discrepancy is found, no further action is required by

this paragraph.

(2) If any discrepancy is found, prior to further flight,

perform corrective actions in accordance with Part 1 of the

Accomplishment Instructions of the alert service bulletin.

Note 2: For the purposes of this AD, a detailed visual

inspection is defined as: ``An intensive 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 an

[[Page 2287]]

intensity deemed appropriate by the inspector. Inspection aids such

as mirrors, magnifying lenses, etc. may be used. Surface cleaning

and elaborate access procedures may be required.''

(b) For certain Model 737-300, -400, and -500 series airplanes

on which the actions specified by Boeing Alert Service Bulletin 737-

29A1076, dated April 2, 1998, have been accomplished: Within 90 days

after the effective date of this AD, perform a one-time detailed

visual inspection of wire bundle W0334 and the hydraulic case drain

and pressure hoses for the EMDP for hydraulic system ``B'' to detect

any discrepancy (e.g., damage or chafing of wire bundle W0334 and

the hydraulic case drain and pressure hoses; and incorrect

separation between those components), in accordance with Part 2 of

the Accomplishment Instructions of Boeing Alert Service Bulletin

737-29A1076, Revision 1, dated October 21, 1999.

(1) If no discrepancy is found, no further action is required by

this paragraph.

(2) If any discrepancy is found, prior to further flight,

perform corrective actions in accordance with Part 2 of the

Accomplishment Instructions of the alert service bulletin.

Actions for Model 737-600, -700, and -800 Series Airplanes

(c) For certain Model 737-600, -700, and -800 series airplanes

on which the actions specified by Boeing Alert Service Bulletin 737-

29A1077, dated March 4, 1999, have not been accomplished: Within 90

days after the effective date of this AD, perform a one-time

detailed visual inspection of wire bundle W5230 and the hydraulic

case drain and pressure hoses for the EMDP for hydraulic system

``B'' to detect any discrepancy (e.g., damage or chafing of the

W5230 wire bundle and the hydraulic case drain and pressure hoses;

and incorrect separation between those components) in accordance

with Part 1 of the Accomplishment Instructions of Boeing Alert

Service Bulletin 737-29A1077, Revision 1, dated October 21, 1999.

(1) If no discrepancy is found, no further action is required by

this paragraph.

(2) If any discrepancy is found, prior to further flight,

perform corrective actions in accordance with Part 1 of the

Accomplishment Instructions of the alert service bulletin.

(d) For certain Model 737-600, -700, and -800 series airplanes

on which the actions specified by Boeing Alert Service Bulletin 737-

29A1077, dated March 4, 1999, have been accomplished: Within 90 days

after the effective date of this AD, perform a one-time detailed

visual inspection of wire bundle W5230 and the case drain and

pressure hoses for the EMDP for hydraulic system ``B'' to detect any

discrepancy (e.g., damage or chafing of the W5230 wire bundles and

the hydraulic case drain and pressure hoses; and incorrect

separation between those components), in accordance with Part 2 of

Boeing Alert Service Bulletin 737-29A1077, Revision 1, dated October

21, 1999.

(1) If no discrepancy is found, no further action is required by

this paragraph.

(2) If any discrepancy is found, prior to further flight,

perform corrective actions in accordance with Part 2 of the

Accomplishment Instructions of the alert service bulletin.

Alternative Methods of Compliance

(e) 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 3: 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

(f) 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

(g) The inspection and corrective actions shall be done in

accordance with Boeing Alert Service Bulletin 737-29A1076, Revision

1, dated October 21, 1999; or Boeing Alert Service Bulletin 737-

29A1077, Revision 1, dated October 21, 1999; 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.

(h) This amendment becomes effective on January 31, 2000.

Issued in Renton, Washington, on January 7, 2000.

Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 00-876 Filed 1-13-00; 8:45 am]

BILLING CODE 4910-13-U