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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-332-AD; Amendment 39-11445; AD 99-25-02]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 737-100, -200, -300, -400,

and -500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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

is applicable to all Boeing Model 737-100, -200, -300, -400, and -500

series airplanes. This action requires a one-time inspection to verify

correct installation of the fastener that connects the input rod of the

spoiler mixer mechanism to the torque tube crank, and corrective

actions, if necessary. For certain airplanes, this action requires

replacement of the nut, bolt, and cotter pin that connects the input

rod of the spoiler mixer mechanism to the torque tube crank with a new

or serviceable nut, bolt, and cotter pin. This amendment is prompted by

reports indicating numerous discrepancies in the installation of the

fastener that connects the input rod of the spoiler mixer mechanism to

the torque tube crank. The actions specified in this AD are intended to

prevent the linkage between the ratio changer input rod and the aft

aileron control quadrant from becoming disconnected, which could result

in reduced controllability of the airplane.

DATES: Effective December 15, 1999.

The incorporation by reference of certain publications listed in

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

of December 15, 1999.

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

before January 31, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 99-NM-332-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: Robert C. Jones, 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) 227-1118; fax (425)

227-1181.

SUPPLEMENTARY INFORMATION: The FAA has received reports indicating

numerous discrepancies in the installation of the fastener that

connects the input rod of the spoiler mixer mechanism to the torque

tube crank on Boeing Model 737-100, -200, -300, -400, and -500 series

airplanes. These discrepancies include the use of incorrect hardware,

the lack of secondary means of retention, and the incorrect (inverted)

installation of the bolt. Additionally, the airplane manufacturer has

indicated that the torque values specified, in a previously issued

service bulletin, for the nut and bolt of the fastener in the spoiler

mixer mechanism were too high. The previously specified torque values

could cause the nut and bolt to fail, which could result in a

disconnection of the linkage between the ratio changer input rod and

the aft aileron control quadrant. This condition, if not corrected,

could result in reduced controllability of the airplane.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin

737-27A1213, Revision 1, dated May 21, 1998, which describes procedures

for a one-time visual inspection to verify

[[Page 66766]]

correct installation of the fastener that connects the input rod of the

spoiler mixer mechanism to the torque tube crank, and corrective

actions, if necessary. The corrective actions involve either re-

installation of the existing fastener, or replacement of the fastener

with a new or serviceable fastener.

For certain airplanes on which the initial issue of the alert

service bulletin has been accomplished, the alert service bulletin

describes procedures for replacement of the nut, bolt, and cotter pin

that connects the input rod of the spoiler mixer mechanism to the

torque tube crank with a new or serviceable nut, bolt, and cotter pin.

Accomplishment of the actions specified in the alert service

bulletin is intended to adequately address the identified unsafe

condition.

Explanation of the Requirements of the Rule

Since an unsafe condition has been identified that is likely to

exist or develop on other airplanes of the same type design, this AD is

being issued to prevent the linkage between the ratio changer input rod

and the aft aileron control quadrant from becoming disconnected, which

could result in reduced controllability of the airplane. The actions

are required to be accomplished in accordance with the alert service

bulletin described previously, except as discussed below. This AD also

requires that operators report certain results of the one-time

inspections to the FAA.

Differences Between AD and Alert Service Bulletin

Operators should note that the Boeing alert service bulletin

recommends that the inspection to verify correct installation of the

fastener that connects the input rod of the spoiler mixer mechanism to

the torque tube crank be performed at the operator's earliest

maintenance opportunity. However, the FAA has determined that such an

interpretive compliance time may not address the identified unsafe

condition in a timely manner. In developing appropriate compliance

times 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, the accessibility of the area to be inspected, the time

necessary to accomplish the inspection (approximately 1 hour), and the

time necessary to accomplish the replacement (approximately 1 hour). In

light of all these factors, the FAA finds that inspecting to verify

correct installation of the fastener in the spoiler mixer mechanism

within a 90-day compliance time is warranted, in that it represents an

appropriate interval of time allowable for affected airplanes to

continue to operate without compromising safety.

Operators also should note that the Boeing alert service bulletin

specifies the effectivity to be Boeing Model 737-100, -200, -300, -400,

and -500 series airplanes having line numbers 1 through 2681. However,

the FAA has determined that this effectivity would not address all the

affected airplanes on which the identified unsafe condition is likely

to exist or develop. Therefore, the applicability of this AD includes

all Boeing Model 737-100, -200, -300, -400, and -500 series airplanes.

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-332-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.

[[Page 66767]]

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

99-25-02 Boeing: Amendment 39-11445. Docket 99-NM-332-AD.

Applicability: All Model 737-100, -200, -300, -400, and -500

series airplanes, 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 the linkage between the ratio changer input rod and

the aft aileron control quadrant from becoming disconnected, which

could result in reduced controllability of the airplane; accomplish

the following:

Detailed Visual Inspection

(a) Within 90 days after the effective date of this AD,

accomplish the actions required by paragraph (a)(1) or (a)(2) of

this AD, as applicable, in accordance with Boeing Alert Service

Bulletin 737-27A1213, Revision 1, dated May 21, 1998.

(1) For airplanes on which Boeing Alert Service Bulletin 737-

27A1213, dated April 23, 1998, has not been accomplished: Perform a

one-time detailed visual inspection to verify correct installation

of the fastener that connects the input rod of the spoiler mixer

mechanism to the torque tube crank, in accordance with Revision 1 of

the alert service bulletin.

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.''

(i) If the fastener that connects the input rod of the spoiler

mixer mechanism to the torque tube crank is installed correctly, no

further action is required by this AD.

(ii) If the fastener that connects the input rod of the spoiler

mixer mechanism to the torque tube crank is not installed correctly,

prior to further flight, either re-install the existing fastener, or

install a new or serviceable fastener, in accordance with Revision 1

of the alert service bulletin.

(2) For airplanes on which Boeing Alert Service Bulletin 737-

27A1213, dated April 23, 1998, has been accomplished: Replace the

nut, bolt, and cotter pin that connects the input rod of the spoiler

mixer mechanism to the torque tube crank with a new or serviceable

nut, bolt, and cotter pin in accordance with Revision 1 of the alert

service bulletin.

Reporting Requirement

(b) Within 10 days after accomplishing the actions required by

paragraph (a)(1) of this AD, submit a report of any findings of

fasteners that connect the input rod of the spoiler mixer mechanism

to the torque tube crank that require corrective action to the

Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport

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

98055-4056; fax (425) 227-1181. Information collection requirements

contained in this regulation have been approved by the Office of

Management and Budget (OMB) under the provisions of the Paperwork

Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been

assigned OMB Control Number 2120-0056.

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, ACO. 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

(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 actions shall be done in accordance with Boeing Alert

Service Bulletin 737-27A1213, Revision, 1, dated May 21, 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 December 15, 1999.

Issued in Renton, Washington, on November 22, 1999.

D.L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-30946 Filed 11-29-99; 8:45 am]

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