Airworthiness Directives; Boeing Model 737-100 and -200 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-72-AD]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 737-100 and -200 Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to certain Boeing Model 737-

100 and -200 series airplanes, that currently requires replacement of

certain outboard and inboard wheel halves with improved wheel halves;

cleaning and inspecting certain outboard and inboard wheel halves for

corrosion, missing paint in large areas, and cracks; and repair or

replacement of the wheel halves with serviceable wheel halves, if

necessary. That AD was prompted by a review of the design of the flight

control systems on Model 737 series airplanes. This action would

require that the actions be accomplished in accordance with revised

service information. The actions specified by the proposed AD are

intended to prevent failure of the wheel flanges, which could result in

damage to the hydraulics systems, jammed flight controls, loss of

electrical power, or other combinations of failures; and consequent

reduced controllability of the airplane.

DATES: Comments must be received by August 24, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 98-NM-72-AD, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056. Comments may be inspected at this location

between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal

holidays.

The service information referenced in the proposed rule may be

obtained from Allied Signal Aerospace Company, Bendix Wheels and Brakes

Division, South Bend, Indiana 46624; and Bendix, Aircraft Brake and

Strut Division, 3520 Westmoor Street, South Bend, Indiana 46628-1373.

This information may be examined at the FAA, Transport Airplane

Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: David Herron, 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) 227-2672; 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 98-NM-72-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. 98-NM-72-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

On August 4, 1997, the FAA issued AD 97-17-01, amendment 39-10102

(62 FR 43067, August 12, 1997), applicable to certain Boeing Model 737-

100 and -200 series airplanes, to require replacement of certain

outboard and inboard wheel halves with improved wheel halves; cleaning

and inspecting certain outboard and inboard wheel halves for corrosion,

missing paint in large areas, and cracks; and repair or replacement of

the wheel halves with serviceable wheel halves, if necessary. That

action was prompted by a review of the design of the flight control

systems on Model 737 series airplanes. The requirements of that AD are

intended to prevent failure of the wheel flanges, which could result in

damage to the hydraulics systems, jammed flight controls, loss of

electrical power, or other combinations of failures; and consequent

reduced controllability of the airplane.

Explanation of Revised Service Information

Since the issuance of that AD, the FAA has been advised that Allied

Signal Service Bulletin No. 737-32-026, dated April 26, 1988, which was

referenced as the appropriate source of service information for

accomplishment of the actions specified in that original AD, was

incorrect. Subsequently, the FAA has reviewed and approved Allied

Signal Service Bulletin No. 737-32-026, dated June 27, 1988. The

procedures described in that revision are similar to those described in

the earlier version of the service bulletin. However, among other

things, this new version of the service bulletin differs from the

original version in the following respects:

1. The effectivity listing in the revised service bulletin includes

a new part number for inboard wheel halves.

2. The revised service bulletin provides a new option for

repainting the wheels.

3. The revised service bulletin identifies specific serial numbers

of wheel halves on which ``beef-ups'' were

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accomplished, but inspections are still necessary.

Accomplishment of the actions specified in the service bulletin 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 supersede AD 97-17-01 to continue to require

replacement of certain outboard and inboard wheel halves with improved

wheel halves; cleaning and inspecting certain outboard and inboard

wheel halves for corrosion, missing paint in large areas, and cracks;

and repair or replacement of the wheel halves with serviceable wheel

halves, if necessary. The actions would be required to be accomplished

in accordance with the revised service bulletin described previously.

Cost Impact

There are approximately 634 Boeing Model 737-100 and -200 series

airplanes of the affected design in the worldwide fleet. The FAA

estimates that 241 airplanes of U.S. registry would be affected by this

proposed AD.

Because this proposed AD would merely require that the actions

currently required by AD 97-17-01 be accomplished in accordance with

revised service information, the proposed AD would add no additional

costs, and would require no additional work to be performed by affected

operators. The current costs associated with this amendment are

reiterated in their entirety (as follows) for the convenience of

affected operators.

The FAA estimates that it will take approximately 4 work hours per

airplane to accomplish the required replacement of wheel halves at an

average labor rate of $60 per work hour. Required parts will cost

approximately $20,212 per airplane. Based on these figures, the cost

impact of the required replacement on U.S. operators is estimated to be

$4,928,932, or $20,452 per airplane.

The FAA also estimates that it will take approximately 2 work hours

per airplane to accomplish the required cleaning and inspection at an

average labor rate of $60 per work hour. Based on these figures, the

cost impact of the required cleaning and inspection on U.S. operators

is estimated to be $28,920, or $120 per airplane.

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 removing amendment 39-10102 (62 FR

43067, August 12, 1997), and by adding a new airworthiness directive

(AD), to read as follows:

Boeing: Docket 98-NM-72-AD. Supersedes AD 97-17-01, amendment 39-

10102.

Applicability: Model 737-100 and -200 series airplanes equipped

with Bendix main wheel assemblies having part number (P/N) 2601571-

1, 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 failure of the wheel flanges, which could result in

damage to the hydraulics systems, jammed flight controls, loss of

electrical power, or other combinations of failures; and consequent

reduced controllability of the airplane; accomplish the following:

Note 2: Allied Signal, Aircraft Landing Systems, Service

Information Letter (SIL) #619, dated February 26, 1997, is an

additional source of service information for appropriate wheel half

serial numbers.

(a) For airplanes equipped with a Bendix main wheel assembly

having P/N 2601571-1 with an inboard wheel half with serial number

(S/N) B-5898 or lower, or S/N H-1721 or lower; or with an outboard

wheel half with S/N B-5898 or lower, or S/N H-0863 or lower;

accomplish the following:

(1) Within 180 days after September 16, 1997 (the effective date

of AD 97-17-01, amendment 39-10102, 62 FR 43067), and thereafter at

each tire change until the replacement required by paragraph (b) of

this AD is accomplished: Accomplish the actions specified in

paragraphs (a)(1)(i), (a)(1)(ii), and (a)(1)(iii) of this AD, in

accordance with the Accomplishment Instructions of Allied Signal

Service Bulletin No. 737-32-026, dated June 27, 1988.

(i) Clean any inboard and outboard wheel half specified in

paragraph (a) of this AD. And

(ii) Inspect the wheel halves for corrosion or missing paint. If

any corrosion is found, or if any paint is missing in large areas,

prior to further flight, strip or remove paint, and remove any

corrosion. And

(iii) Perform an eddy current inspection to detect cracks of the

bead seat area.

(2) If any cracking is found during the inspections required by

this paragraph, prior to further flight, repair or replace the wheel

halves with serviceable wheel halves in accordance with procedures

specified in the Component Maintenance Manual.

(b) For airplanes equipped with a Bendix main wheel assembly

having P/N 2601571-1 with an inboard wheel half with S/N B-5898 or

lower, or S/N H-1721 or lower; or with an outboard wheel half with

S/N B-5898 or lower, or S/N H-0863 or lower; accomplish the

following: Within 2 years after September 16, 1997, accomplish the

actions specified in paragraphs (b)(1) and (b)(2) of this AD, in

accordance with Bendix SIL 392, Revision 1, dated November 15, 1979.

Accomplishment of the replacement constitutes terminating action for

the repetitive inspections required by paragraph (a) of this AD.

(1) Remove any inboard wheel half specified in paragraph (b) of

this AD, and

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replace it with an inboard wheel half having P/N 2607046, S/N 5899

or greater, or S/N H-1722 or greater. And

(2) Remove any outboard wheel half specified in paragraph (b) of

this AD, and replace it with an outboard wheel half having P/N

2607047, S/N B-5899 or greater, or S/N H-0864 or greater.

(c)(1) 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.

(c)(2) Alternative methods of compliance, approved previously in

accordance with AD 97-17-01, amendment 39-10102, are approved as

alternative methods of compliance with this AD.

Note 3: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Seattle ACO.

(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.

Issued in Renton, Washington, on July 1, 1998.

Stewart R. Miller,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 98-18159 Filed 7-8-98; 8:45 am]

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