[Federal Register Volume 66, Number 162 (Tuesday, August 21, 2001)]
[Rules and Regulations]
[Pages 43763-43766]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-20803]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-401-AD; Amendment 39-12380; AD 2001-16-11]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, and -200C 
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, and -200C series 
airplanes; that requires a one-time inspection of the carriage spindles 
on the outboard midflap for circumferential score marks; and rework of 
the carriage spindles or replacement with new or serviceable spindles, 
if necessary. This action is necessary to prevent severe flap asymmetry 
due to fractures of both carriage spindles at an outboard midflap, 
which could result in loss of controllability of the airplane. This 
action is intended to address the identified unsafe condition.

DATES: Effective September 25, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of September 25, 2001.

ADDRESSES: 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 Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 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: James Blilie, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2131; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 737-100, -
200, and -200C series airplanes was published in the Federal Register 
on April 12, 2001 (66 FR 18878). That action proposed to require a one-
time detailed visual inspection of the carriage spindles on the 
outboard midflap for circumferential score marks; and rework of the 
carriage spindles or replacement with new or serviceable spindles, if 
necessary.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Inspection Methods

    All of the commenters expressed concern about the proposed 
inspection methods.
    Regarding the detailed visual inspection that is included as one 
acceptable method of inspection in Boeing Alert Service Bulletin 737-
57A1256, dated September 30, 1999,

[[Page 43764]]

one of the commenters states that the proposed detailed visual 
inspection of the carriage spindle cannot be accomplished. The 
commenter states that surrounding airplane structure and a certain seal 
make it difficult to gain access to and properly clean the carriage 
spindle when the flap carriage assembly is installed on the airplane.
    Regarding the borescopic inspection that is included in the service 
bulletin as another acceptable method of inspection, two of the 
commenters stated that the borescopic inspection specified in the 
service bulletin is not sufficient to detect circumferential score 
marks on the carriage spindles on the outboard midflap. The commenters 
state that routine applications of protective coatings such as primer 
or paint on the carriage spindles may obscure score marks.
    One of the commenters, the airplane manufacturer, submitted this 
comment:

    The Boeing Company is of the opinion that the minimum acceptable 
inspection method to look for score marks on the carriage spindles 
(which the flap is attached to the flap t[r]acks) is the use of a 
borescope or equivalent method[;] otherwise[,] close visual 
inspection is acceptable provided the flaps are removed from the 
airplane for the purpose of inspecting the spindles for 
circumferential score marks.

    The FAA infers that the commenters are requesting that we clarify 
what inspection methods are acceptable for compliance with this AD and 
what other actions must be accomplished on the airplane for these 
inspection methods to be used. We concur that some clarification is 
necessary. Our intent is that either the detailed visual or borescopic 
inspection methods described in the service bulletin are acceptable for 
compliance with this AD. For clarification, we have revised the summary 
of this final rule to remove the words ``detailed visual.''
    With regard to the suitability of the borescopic inspection for 
finding score marks on the carriage spindle, we note that data in the 
Operator's Equipment Manual indicate that an inspection with a 
borescope is adequate to detect the score marks that are the subject of 
this AD. Accordingly, we have revised paragraph (a) of this AD to 
require either a detailed visual or borescopic inspection per the 
service bulletin.
    With regard to accomplishing the detailed visual inspection without 
using a borescope, we note that the service bulletin clearly specifies 
that it is necessary to remove the outboard trailing edge flaps from 
the airplane before the detailed visual inspection of the carriage 
spindles can be carried out. However, to clarify this matter, and per 
the airplane manufacturer's comment stated above, we have added a new 
note, Note 3, to this final rule (and reordered subsequent notes 
accordingly). Note 3 states that removal of the outboard trailing edge 
flaps from the airplane is necessary for the detailed visual 
inspection, but an inspection using a borescope is acceptable if the 
flap carriages are not removed from the airplane.

Compliance Time

    On behalf of one of its members, the Air Transport Association of 
America requests extension of the compliance time from 18 months to 36 
months for accomplishment of the requirements of the proposed AD. The 
commenter states that this compliance time will allow accomplishment of 
the proposed actions during normal scheduled heavy maintenance visits 
and would provide ``a level of safety commensurate with the intent of 
the proposal.''
    The FAA does not concur. 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, and the average utilization of the 
affected fleet. In light of these factors, the FAA finds an 18-month 
compliance time for completing the required actions is warranted, in 
that it represents an appropriate interval of time allowable for 
affected airplanes to continue to operate without compromising safety. 
No change to the final rule is necessary in this regard. However, as 
noted in paragraph (c) of this AD, we will consider requests for 
approval of an alternative method of compliance or adjustment of the 
compliance time, provided that data are submitted which show that an 
acceptable level of safety will be maintained.

Removal and Destruction of Seal

    One commenter expresses concern about cutting and removing a 
certain seal, which is necessary for accomplishing the inspection using 
a borescope, as specified in Figure 1 of the referenced service 
bulletin. The commenter is concerned that cutting the seal could allow 
fluids or debris to enter the area, resulting in long-term deleterious 
effects in the area previously protected by the seal. The commenter 
states that the airplane manufacturer responded to this concern by 
indicating that it is adequate to remove the seal to facilitate the 
proposed inspection and replace the seal only when the airplane is next 
overhauled after the inspection. The airplane manufacturer also 
indicated that replacement of a previously installed Teflon bearing 
with a new spherical bearing would result in no damage if small debris 
enters the area.
    The FAA acknowledges that it is necessary to cut and remove the 
identified seal to perform the inspection with a borescope. For those 
operators who choose to use the borescope method of inspection, we find 
that the risk of damage associated with the missing segment of seal is 
low, as long as the seal is replaced at the next maintenance interval. 
We note, however, that it is not necessary to cut the seal in order to 
do the detailed visual inspection described in the service bulletin 
because the service bulletin provides an alternative method of gaining 
access to do this inspection. If the commenter is sufficiently 
concerned with the risk associated with the missing seal, the 
alternative method may be used, as specified in the service bulletin. 
No change to the final rule is necessary in this regard.

Cost Estimate

    One commenter states that the FAA's estimate of 12 work hours does 
not reflect the true number of work hours necessary for the proposed 
inspection. The commenter states that the compliance time will 
necessitate that the proposed work be accomplished on the vast majority 
of airplanes at maintenance visits other than overhauls, which is the 
only maintenance visit in which access to the subject area would be 
readily available. The commenter notes that the referenced service 
bulletin estimates that 21 work hours would be necessary for the 
borescopic inspection or 68 work hours would be necessary for the 
detailed visual inspection. The commenter asks that the FAA revise the 
proposed rule to provide a more accurate cost estimate.
    The FAA does not concur. The estimates of 21 and 68 work hours 
provided in the referenced service bulletin include time for gaining 
access, closing up, and testing. The cost impact analysis in AD 
rulemaking actions typically includes only the ``direct'' costs of the 
specific actions required by the AD, and does not include incidental 
costs, such as the time required to gain access and close up, planning 
time, or time necessitated by other administrative actions. Because 
incidental costs may vary significantly from operator to operator, they 
are almost impossible to calculate. No change to the final rule is 
necessary in this regard.

[[Page 43765]]

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 changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 870 Model 737-100, -200, and -200C series 
airplanes of the affected design in the worldwide fleet. The FAA 
estimates that 320 airplanes of U.S. registry will be affected by this 
AD, that it will take approximately 12 work hours per airplane to 
accomplish the required actions, and that the average labor rate is $60 
per work hour. Based on these figures, the cost impact of this AD on 
U.S. operators is estimated to be $230,400, or $720 per airplane.
    The cost impact figure discussed above is 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. The cost impact figures discussed 
in AD rulemaking actions represent only the time necessary to perform 
the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.

Regulatory Impact

    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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, 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:

32001-16-11  Boeing: Amendment 39-12380. Docket 2000-NM-401-AD.

    Applicability: Model 737-100, -200, and -200C airplanes without 
high gross weight flaps installed; 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 severe flap asymmetry due to fractures of both 
carriage spindles at an outboard midflap, which could result in loss 
of controllability of the airplane, accomplish the following:

One-Time Detailed Visual Inspection

    (a) Within 18 months after the effective date of this AD, do a 
one-time detailed visual or borescopic inspection of the outboard 
midflap carriage spindles for circumferential score marks per Boeing 
Alert Service Bulletin 737-57A1256, dated September 30, 1999.

    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.''


    Note 3: As specified in Boeing Alert Service Bulletin 737-
57A1256, dated September 30, 1999, removal of the outboard trailing 
edge flaps from the airplane is necessary for the detailed visual 
inspection method to be used. A borescopic inspection according to 
the service bulletin is acceptable if the flap carriages are not 
removed from the airplane.

    (1) If no scoring is found on any carriage spindle, no further 
action is required by this paragraph.
    (2) If any scoring is found on any carriage spindle, before 
further flight, rework the carriage spindle, or replace it with a 
new or serviceable spindle per the service bulletin.

Spares

    (b) As of the effective date of this AD, no person shall install 
any outboard midflap carriage spindle having a part number 
identified in paragraph 2.E. of Boeing Alert Service Bulletin 737-
57A1256, dated September 30, 1999, on any airplane, unless the 
spindle has been inspected for score marks and reworked, as 
necessary, per the service bulletin.

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, Seattle Aircraft Certification 
Office (ACO), FAA. 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 4: 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 737-57A1256, dated September 30, 1999. 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.

Effective Date

    (f) This amendment becomes effective on September 25, 2001.


[[Page 43766]]


    Issued in Renton, Washington, on August 13, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-20803 Filed 8-20-01; 8:45 am]
BILLING CODE 4910-13-P