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. 98-NM-253-AD]

RIN 2120-AA64

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

and -500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain Boeing Model 737-100, -

200, -300, -400, and -500 series airplanes. This proposal would require

repetitive inspections to detect damage of certain taxi light

assemblies, and replacement with a new or serviceable part, if

necessary. This proposal also would require eventual replacement of

certain taxi light assemblies with improved parts, which would

constitute terminating action for the repetitive inspections. This

proposal is prompted by a report that a damaged taxi light detached

from an airplane and was ingested into the airplane engines. The

actions specified by the proposed AD are intended to prevent damage to

the taxi light assembly, which could result in detachment of the taxi

light assembly from the airplane, ingestion of taxi light debris into

an engine, and consequent loss of thrust from one or both engines.

DATES: Comments must be received by June 24, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 98-NM-253-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.

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-253-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-253-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The FAA has received reports indicating that certain taxi light

assemblies mounted on the nose landing gear assemblies of certain

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

been found to be damaged. That damage has been attributed to contact

between the light assembly and the tow bar during towing operations.

Such contact occurs due to the proximity of the taxi lights to the

fitting for towing operations. In one incident, a damaged taxi light

assembly detached from the airplane, and debris from the taxi light

assembly was ingested into both engines of a Boeing Model 737 series

airplane during takeoff. That ingestion resulted in a loss of thrust,

which forced the flightcrew to make an emergency landing. A damaged

taxi light assembly, if not corrected, could result in detachment of

the taxi light from the airplane, ingestion of taxi light debris into

an engine, and consequent loss of thrust from one or both engines. Such

loss of thrust could result in reduced controllability of the airplane.

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 require repetitive detailed visual inspections to

detect damage (including cracking, corrosion, deformation, or evidence

of impact) of certain taxi light assemblies, and replacement with a new

or serviceable part, if necessary. The proposed AD also would require

eventual replacement of certain taxi light assemblies with improved

parts, which would constitute terminating action for the repetitive

inspections. The actions are required to be accomplished in accordance

with the applicable maintenance manual.

Cost Impact

There are approximately 2,857 airplanes of the affected design in

the worldwide fleet. The FAA estimates that 1,159 airplanes of U.S.

registry would be affected by this proposed AD.

It would take approximately 1 work hour per airplane to accomplish

the proposed inspection, at an average labor rate of $60 per work hour.

Based on these figures, the cost impact of the proposed inspection on

U.S. operators is estimated to be $69,540, or $60 per airplane, per

inspection cycle.

It would take approximately 2 work hours per airplane to accomplish

the proposed replacement, at an average

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

approximately $549 per airplane. Based on these figures, the cost

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

$775,371, or $669 per airplane.

The cost impact figures discussed above are based on assumptions

that no operator has yet accomplished any of the proposed 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 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 adding the following new

airworthiness directive:

Boeing: Docket 98-NM-253-AD.

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

airplanes; that are not equipped with a Grimes Aerospace taxi light

assembly having part number (P/N) 50-0199-9, 50-0199-11, 50-0128-1A,

50-0128-1MA, 50-0128-3A, or 50-0128-3MA; 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 (d) 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 damage to the taxi light assembly, which could result

in detachment of the taxi light from the airplane, ingestion of taxi

light debris into an engine, and consequent loss of thrust from one

or both engines; accomplish the following:

Initial and Repetitive Inspections

(a) Within 60 days after the effective date of this AD, perform

a detailed visual inspection to detect damage (including cracking,

corrosion, deformation, or evidence of impact) of the taxi light

assembly mounted on the nose landing gear of the airplane. Repeat

the inspection thereafter at intervals not to exceed 1 day, until

the requirements of paragraph (c) have been accomplished.

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

inspection is defined as an intensive visual inspection 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 lighting at an

intensity deemed appropriate by the inspector. Inspection aids such

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

and elaborate access procedures may be necessary.

Replacement

(b) If any damage of the taxi light assembly is detected during

any inspection performed in accordance with paragraph (a) of this

AD, prior to further flight, replace the existing taxi light

assembly with a new or serviceable taxi light assembly in accordance

with the applicable maintenance manual. If the existing taxi light

assembly is replaced with a Grimes Aerospace taxi light assembly

having P/N 50-0199-9, 50-0199-11, 50-0128-1A, 50-0128-1MA, 50-0128-

3A, or 50-0128-3MA: no further action is required by this AD.

Terminating Action

(c) Within 2 years after the effective date of this AD: Replace

the existing taxi light assembly with a Grimes Aerospace taxi light

assembly having P/N 50-0199-9, 50-0199-11, 50-0128-1A, 50-0128-1MA,

50-0128-3A, or 50-0128-3MA; in accordance with the applicable

maintenance manual. Such replacement constitutes terminating action

for the repetitive inspection requirement of paragraph (a) of this

AD.

Alternative Methods of Compliance

(d) 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

(e) 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.

Issued in Renton, Washington, on May 3, 1999.

D.L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-11617 Filed 5-7-99; 8:45 am]

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