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

[Federal Register Volume 65, Number 81 (Wednesday, April 26, 2000)]
[Rules and Regulations]
[Pages 24384-24387]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-10289]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-253-AD; Amendment 39-11703; AD 2000-08-17]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 737-100, -200, -300, -400, and -500 
series airplanes, that requires repetitive inspections to detect damage 
of certain taxi light assemblies, and replacement with a new or 
serviceable part, if necessary. This AD also requires eventual 
replacement of certain taxi light assemblies with improved parts, which 
constitutes terminating action for the repetitive inspections. This 
amendment 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 this 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.

EFFECTIVE DATE: May 31, 2000.

ADDRESSES: Information pertaining to this amendment may be examined at 
the Federal Aviation Administration (FAA), Transport Airplane 
Directorate, Rules Docket, 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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to

[[Page 24385]]

include an airworthiness directive (AD) that is applicable to certain 
Boeing Model 737-100, -200, -300, -400, and -500 series airplanes was 
published in the Federal Register on May 10, 1999 (64 FR 24963). That 
action proposed to 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. That action also proposed to require 
eventual replacement of certain taxi light assemblies with improved 
parts, which constitutes terminating action for the repetitive 
inspections.

Comments Received

    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. Another commenter 
considers the daily repetitive inspection interval to be unnecessarily 
restrictive, but has no objections to the proposed rule.

Requests To Extend Repetitive Inspection Interval

    Two commenters request that the FAA extend the repetitive daily 
inspection interval for the visual inspection to detect damage of the 
taxi light assembly mounted on the nose landing gear of the airplane.
    One commenter states that the daily inspection is redundant and the 
interval should be extended to every five days. The commenter states 
that, during the pre-flight walk-around, the flight crew checks the 
nose taxi light bracket prior to each flight. If damage is found, the 
flight crew notifies maintenance to correct the discrepancy.
    Therefore, the commenter states that its suggested change would 
provide an equivalent level of safety to the daily inspections.
    Another commenter states that a daily repetitive inspection is 
excessive and suggests a weekly inspection interval. The commenter 
justifies its request by stating that it has recently placed additional 
focus on proper towing procedures, which will ``dramatically'' reduce 
the potential for impact damage.
    The FAA does not concur with the commenters' request. Inspections 
at a frequency of every five or seven days, instead of daily, reduce 
the opportunity for discovering damage and are not adequate to ensure 
that any damage is detected in a timely manner.
    With regard to the first commenter's reference to the pre-flight 
walk-around performed by the flight crew, the FAA does not consider 
flight crews to be trained in the same manner as maintenance personnel 
to carry out the detailed visual inspections required by this AD. These 
expectations and definitions are contained within Parts 1 and 43 of the 
Federal Aviation Regulations (FAR) (14 CFR parts 1 and 43).
    With regard to the second commenter's justification of additional 
focus on proper towing procedures, the FAA finds that there is no 
meaningful way to gauge the effectiveness of training procedures in 
mitigating the unsafe condition addressed in this AD. The FAA expects 
that the individuals who have been performing towing operations were 
properly trained; however, there have still been numerous incidents of 
damage to the taxi light assemblies.
    In developing an appropriate repetitive interval for this action, 
the FAA considered the average utilization of the affected fleet 
(average of 7 flight cycles per day), the numerous reports of damaged 
taxi light assemblies, and the degree of urgency associated with 
addressing the subject unsafe condition. In consideration of all of 
these factors, the FAA has determined that daily inspections are 
appropriate to ensure that an acceptable level of safety can be 
maintained. No change to the final rule is necessary.

Request To Include Approved Repair

    One commenter requests that an approved repair be included as a 
terminating action for the repetitive inspections. The commenter 
promotes repair as a cost effective means of compliance, but does not 
provide any reason why a repair would provide a level of safety 
equivalent to that achieved by accomplishment of the proposed AD.
    The FAA does not concur with the commenter's request. The new taxi 
light assemblies listed in paragraph (c) of this AD as acceptable 
replacement parts differ from the taxi light assemblies that are the 
subject of this AD in both the dimensions of the part and the material 
from which the part is made. These design changes address the inherent 
failure mode associated with the unsafe condition (i.e., damaged taxi 
light assemblies due to towing operation practices and design 
deficiencies). However, repair of the taxi light assemblies subject to 
this AD would not affect the failure mode. No change to the final rule 
is necessary.

Request To Clarify Degree of Damage That Warrants Replacement

    One commenter requests that the FAA clarify the degree of damage 
that warrants replacement of the light assembly, because minor 
superficial damage would not reduce the airworthiness of the assembly. 
The commenter provides no data or analysis beyond the statement made.
    The FAA does not concur with the commenter's request. The FAA has 
defined the type of damage and level of inspection necessary in 
paragraph (a) of the AD. The FAA has determined that any damage found 
at this inspection level would decrease the safety of the aircraft to 
the point where replacement is necessary. No change to the final rule 
is necessary.

Clarification of the Term ``Inspector''

    One commenter requests clarification of the term ``inspector'' 
referenced in Note 2 of the NPRM. The commenter wants to know if this 
term refers to a job title or the person conducting the inspection.
    The FAA concurs that clarification should be provided in this case. 
The term ``inspector,'' as used in the note, refers to the person 
performing the inspection. It is not intended as a job title and does 
not refer to a person with any special technical qualifications. The 
FAA notes that Part 43 of the FAR (14 CFR part 43) specifies who may 
perform maintenance. Note 2 of this final rule has been revised 
accordingly to clarify the term ``inspector'' as ``the person 
performing the inspection.''

Request to Include Additional Instructions for Identification of 
Parts

    One commenter recommends that the proposed AD include additional 
instructions or reference a Boeing or original equipment manufacturer 
document to assist in identification and reidentification of parts. The 
commenter states that many of the light assemblies will be difficult to 
identify due to part numbers ``wearing off.'' The commenter states that 
an alternative method of identifying parts would preclude unnecessary 
removals and inspections.
    The FAA does not concur with the commenter's request. The FAA 
understands the difficulty the commenter may have in identifying which 
airplanes are configured with what parts. However, to develop 
procedures for identifying a part by a means other than part number 
would take time and would delay the issuance of this final rule. In 
consideration of the safety implications of the unsafe condition 
identified in this rule, the

[[Page 24386]]

FAA finds that it would be inappropriate to delay the issuance of this 
rule in this way. The economic benefit that would be gained (by 
minimizing unnecessary inspections and replacements) does not outweigh 
the safety benefits that will be gained by implementing the 
requirements of this rule in a timely manner. In addition, considering 
the estimated time necessary for replacement of the taxi light assembly 
(2 hours), it may cost more in time and effort for operators to 
properly identify a part as needing replacement than to replace the 
part. Therefore, the FAA finds that it would be more efficient and cost 
effective to accomplish the requirements of the AD as proposed. No 
change to the final rule is necessary.

Comment on Use of Lights Identified in Parts Catalog

    One commenter states that it has only authorized the use of light 
assemblies that are identified within the airplane manufacturer's 
illustrated parts catalog. However, the commenter makes no request for 
a specific change to the proposed rule and provides no justification 
for a change. Therefore, no change to the final rule is necessary in 
this regard.

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 change described 
previously.

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 will be affected by this AD.
    It will take approximately 1 work hour per airplane to accomplish 
the required inspection, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the inspection required by 
this AD on U.S. operators is estimated to be $69,540, or $60 per 
airplane, per inspection cycle.
    It will take approximately 2 work hours per airplane to accomplish 
the required replacement, at an average labor rate of $60 per work 
hour. Required parts will cost approximately $549 per airplane. Based 
on these figures, the cost impact of the replacement required by this 
AD 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 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 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, 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:

2000-08-17  Boeing: Amendment 39-11703. 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 (i.e., the person 
performing the inspection). 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.

[[Page 24387]]

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 nager, 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 
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.

Effective Date

    (f) This amendment becomes effective on May 31, 2000.

    Issued in Renton, Washington, on April 19, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-10289 Filed 4-25-00; 8:45 am]
BILLING CODE 4910-13-P

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