[Federal Register Volume 68, Number 213 (Tuesday, November 4, 2003)]
[Proposed Rules]
[Pages 62409-62415]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-27672]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-219-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

-----------------------------------------------------------------------

SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), applicable to all Boeing Model 737-100, -200, -200C, -
300, -400, and -500 series airplanes, that would have superseded an 
existing AD that currently requires repetitive inspections to find 
cracks, fractures, or corrosion of each carriage spindle of the left 
and

[[Page 62410]]

right outboard mid-flaps; and corrective action, if necessary. The 
proposed AD would also have mandated the previously optional overhaul 
or replacement of the carriage spindles, which would have ended the 
repetitive inspections required by the existing AD. This new action 
revises the proposed rule by adding a new requirement to the nickel 
plating procedures and extending the compliance time for the overhaul 
or replacement. The actions specified by this new proposed AD are 
intended to prevent severe flap asymmetry due to fractures of the 
carriage spindles on an outboard mid-flap, which could result in 
reduced control or loss of controllability of the airplane. This action 
is intended to address the identified unsafe condition.

DATES: Comments must be received by December 1, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2002-NM-219-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. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2002-NM-219-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 or 2000 or 
ASCII text.
    The service information referenced in the proposed rule 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.

FOR FURTHER INFORMATION CONTACT: Robert Hardwick, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6457; fax (425) 917-6590.

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 action may be changed in 
light of the comments received.
    Submit comments using the following format:
    [sbull] Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] Include justification (e.g., reasons or data) for each 
request.
    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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2002-NM-219-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. 2002-NM-219-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to all 
Boeing Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes, was published as a notice of proposed rulemaking (NPRM) in 
the Federal Register on March 4, 2003 (68 FR 10188). That NPRM (the 
``original NPRM'') proposed to supersede AD 2002-22-05, amendment 39-
12929 (67 FR 66316, October 31, 2002), which is applicable to all 
Boeing Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes. That proposal would have continued to require repetitive 
inspections to find cracks, fractures, or corrosion of each carriage 
spindle of the left and right outboard mid-flaps; and corrective 
action, if necessary. That NPRM also proposed to mandate the previously 
optional overhaul or replacement of the carriage spindles, which would 
end the repetitive inspections required by the existing AD. Fractures 
of the carriage spindles on an outboard mid-flap could result in severe 
flap asymmetry and consequent reduced control or loss of 
controllability of the airplane.

Actions Since Issuance of Previous Proposal

    Due consideration has been given to the comments received in 
response to the original NPRM. Some of the comments have resulted in 
changes to the original NPRM.

Request To Change Maximum Thickness of Nickel Plating

    One commenter, the manufacturer, asks that the maximum thickness of 
the nickel plating, as specified in paragraph (d)(2) of the original 
NPRM, be changed. The commenter provides substantiating data which show 
that, since the rate of plating is directly related to the rate of 
hydrogen generation in the plating process, limiting the deposition 
rate more efficiently minimizes hydrogen generation during plating and 
reduces the potential for hydrogen embrittlement of the part. The 
commenter asks that paragraph (d)(2) be changed to read, ``After 
initial application of the plating current and during the plating 
process, the rate of plating deposit must be maintained between .001-
inch-per-hour and a maximum of .002-inch-per-hour.''
    The FAA partially agrees with the commenter. The material and 
configuration of the outboard flap carriage are such that there is 
increased concern for hydrogen embrittlement in the large diameter of 
the spindle region. After reviewing the service experience and finding 
no other existing related requirements, the FAA finds it necessary to 
include the plating requirements in this AD. Controlling the deposition 
rate is a direct method of controlling the quality of the plate and 
generation of hydrogen during the plating process. The absorption and 
diffusion of hydrogen into the metal during the plating process leads 
to a condition known as ``hydrogen embrittlement.'' Metals affected by 
hydrogen embrittlement have reduced ductility and may prematurely fail 
during normal usage due to this condition. The original requirement of 
0.020-inch-per-plating/baking cycle did not control the deposition 
rate, and

[[Page 62411]]

there were wide variations. High deposition rates produce high rates of 
hydrogen and poor-quality grain structure. The key parameter of 0.002-
inch-per-hour maximum deposition rate (which is a more stringent 
requirement) provides a safeguard against high deposition rates. There 
is no significant detrimental effect from low deposition rates, so the 
minimum requirement requested will not be included. Therefore, we have 
changed paragraph (d)(2) of this supplemental NPRM to read, ``The 
maximum thickness of the nickel plating that is deposited in any one 
plating/baking cycle must not exceed 0.002-inch-per-hour.''

Request To Remove Nickel Plating Requirement

    One commenter asks that the nickel plating requirement specified in 
paragraph (d)(2) of the original NPRM be removed. The commenter states 
that if it performs the nickel plating per the new requirement, it must 
perform a minimum of three plating/baking cycles, which would extend 
the time necessary for overhaul of the carriage spindle by 15 days. The 
commenter suggests two alternative methods to use in place of the 
current proposed requirement, and provides documentation showing those 
methods.
    We do not concur that the nickel plating requirement should be 
removed. However, as explained under ``Request to Change Maximum 
Thickness of Nickel Plating,'' we have changed paragraph (d)(2) of this 
supplemental NPRM to read, ``The maximum deposition rate of the nickel 
plating that is deposited in any one plating/baking cycle must not 
exceed 0.002-inch-per-hour.'' No other change to the supplemental NPRM 
is necessary in this regard.

Requests To Extend Compliance Time

    Several commenters request that the compliance time for the 
overhaul or replacement specified in paragraphs (c), (c)(1), and (c)(2) 
of the original NPRM be extended as follows:
    [sbull] One commenter states that the proposed compliance time of 1 
year after the effective date of the AD to replace the carriage 
spindles on Model 737-200C series airplanes is restrictive. The 
commenter asks that it be changed, due to inspection results, from ``1 
year after the effective date of this AD'' to 24 to 36 months after the 
effective date, to allow time for procurement/overhaul of the spindles 
and to schedule the airplane during a heavy maintenance check. The 
commenter also states that the proposed compliance time of 2 years 
after the effective date of the AD to replace the spindles on Model 
737-400 series airplanes is also restrictive. The commenter asks that 
the compliance time be changed, due to inspection results, to 36 to 48 
months after the effective date, to allow time for procurement/overhaul 
of spindles and to schedule the airplane during a heavy maintenance 
check.
    [sbull] One commenter asks that carriage spindles that were 
overhauled per Boeing 737 Component Maintenance Manual 57-53-36 before 
the effective date of AD 2002-22-05, and have not had all finishes and 
plating removed, be allowed to remain in service on the airplane for 8 
years or 12,000 flight cycles, whichever comes later. The commenter 
adds that it has found no fractured carriage spindles to date. The 
commenter also asks that we allow 30 months instead of 24 months to 
overhaul or replace with new, any in-service carriage spindles that 
have not been overhauled per the referenced service bulletin. The 
commenter states that this would allow scheduling of the replacement of 
the carriage spindle during the current maintenance program without 
undue burden to its in-service operations.
    [sbull] One commenter states that it currently has 52 Model 737-200 
and 26 Model 737-300 series airplanes that would be affected by the 
original NPRM and has insufficient data for identifying the date each 
carriage spindle was overhauled or replaced during heavy maintenance 
visits. The commenter adds that, due to this fact, it would be forced 
to overhaul/replace the carriage spindles at the earliest time allowed, 
which is within 1 year for Model 737-200 series airplanes and 2 years 
for Model 737-300 series airplanes. The commenter notes that the 
manufacturer is unable to supply new carriage spindles to operators at 
a rate that would allow the replacement to be done within the time 
allotted. For Model 737-300 series airplanes, the manufacturer is 
producing about two carriage spindles per month, and overhaul of the 
part using an outside vendor takes approximately 3-4 weeks per 
airplane. With this turnaround time, the commenter would be unable to 
overhaul the parts in the timeframe required by the original NPRM. The 
commenter makes no specific request. We infer that the commenter is 
requesting that the compliance time be extended.
    [sbull] One commenter asks that the compliance time for the initial 
overhaul specified in paragraph (c) of the original NPRM be extended to 
2.5 years. The commenter states that, in order to install overhauled 
carriages on an aircraft, the flaps must be removed and reinstalled. 
The commenter adds that it performs a one-quarter D-check every 2.5 
years, and this structural visit is the opportune time to perform such 
extensive maintenance.
    [sbull] One commenter asks that the initial compliance times for 
the overhaul on Model 737-100/200 series airplanes and 737-300/400/500 
series airplanes be extended to at least 3 years and 4 years, 
respectively, for the following reasons:
    First, the compliance time for the initial inspection does not 
appear to account for the nondestructive test (NDT) inspection 
referenced in both the service bulletin and the existing AD. The 
commenter adds that the inspection in the referenced service bulletin 
is effective as an interim action in maintaining airplane safety, which 
indicates there are no urgent reasons to adhere to the short compliance 
time specified in the service bulletin for the spindle overhaul/
replacement.
    Second, the carriage spindle overhaul requirement means, in the 
commenter's case, that the spindle will have to be shipped off-site, 
which would require additional spares support. The short initial 
compliance timeframe creates a surge in demand for spares during the 
first 1 to 2 years. After that time, all additional spares acquired by 
the operators would sit on the shelf because that demand would go away 
for the remainder of the 8-year period until the next overhaul.
    Third, due to the short initial compliance time, operators will 
have to remove the flaps outside the regularly scheduled maintenance 
visits to gain access. According to the procedures in the Boeing 737-
300/-400/-500 Maintenance Planning Document D6-38278, the commenter 
estimates that the initial compliance time should be between 6 and 8 
years for Model 737-300, -400, and -500 series airplanes, and between 6 
and 10 years for Model 737-100 and -200 series airplanes.
    In conclusion, the commenter states that, with immediate safety 
concerns already addressed in paragraph (a) of the original NPRM, 
increasing the compliance time specified in paragraph (c) of the 
original NPRM would allow accomplishment of the actions at regular 
maintenance intervals and would avoid a sudden demand for spares.
    [sbull] One commenter asks that the compliance time specified in 
paragraph (c)(2)(ii) of the original NPRM (for the spindle overhaul/
replacement) be changed to read, ``Not later than the next major 
maintenance (D-check), and, until that time, repeat the NDT inspection 
of the spindles per the existing AD.'' The commenter states that

[[Page 62412]]

airplanes that have accumulated more than 12,000 total flight cycles, 
and exceeded the 8-year limitation, will be subject to the proposed 2-
year compliance time. The commenter adds that, since no seed units have 
been provided by Boeing, procurement of the spindle is expensive, and 
the turnaround time is expected to be 20 days, there is no reason to 
ground the airplane and send the spindle for overhaul without having 
any spares.
    [sbull] One commenter states that it will take about a year to 
obtain parts after ordering them, and the overhaul cannot be completed 
until the parts are received. The commenter states that it will be 
impossible to overhaul/replace the flap carriage within the proposed 2-
year compliance time.
    [sbull] One commenter asks for a change in the compliance time 
specified in paragraph (c) of the original NPRM from 12,000 flight 
cycles or 8 years, whichever occurs first, to 20,000 flight cycles or 8 
years in-service, whichever occurs first. The commenter states that the 
additional flight-cycle allowance would allow the work to be done at 
every other D-check where time and resources to overhaul/replace the 
spindles are available. The commenter requests that this change apply 
to both the original inspection and the overhaul/replacement 
requirements.
    [sbull] One commenter asks that we evaluate the requirement to 
overhaul or replace the spindles every 12,000 flight cycles or 8 years, 
based on inspection results and parts replacement costs. The commenter 
adds that the repetitive inspection intervals required by paragraph (a) 
of the proposed AD should be extended from 180 days to 18 months, so 
the airplane can be scheduled for inspection during heavy maintenance 
check intervals.
    [sbull] One commenter states that mandating the overhaul of the 
carriage spindles every 8 years or 12,000 flight cycles, whichever is 
sooner, will have a significant cost impact on its fleet. The commenter 
adds that, under the current maintenance program, the carriage spindles 
are overhauled every 8 years, which, at current flying rates, equates 
to about 18,000 flight cycles. Therefore, a 12,000-flight-cycle 
compliance time would require overhaul at every heavy maintenance 
check, thereby doubling the overhaul cost. The commenter proposes that 
the carriage spindles remain in service until the 8-year limit is 
reached, provided the 180-day repetitive inspections are reinstated 
once the airplane reaches 12,000 flight cycles. The commenter states 
that this would provide an equivalent level of safety and give 
operators a significant cost benefit.
    We agree to extend the initial compliance time somewhat. In 
revising this compliance time, we considered the safety implications, 
parts availability, and typical maintenance schedules of affected 
operators. In addition, the repetitive NDT inspections required by the 
existing AD, and restated in paragraph (a) of this supplemental NPRM, 
will allow operators more time to schedule maintenance and ensure 
safety in the interim until accomplishment of the overhaul or 
replacement. We have extended the compliance time specified in 
paragraphs (c)(1)(i) and (c)(1)(ii) of this supplemental NPRM to the 
later of the following: ``Before the accumulation of 20,000 total 
flight cycles on the carriage spindle, or within 8 years since overhaul 
of the spindle or installation of a new spindle, whichever is first,'' 
or ``Within 2 years after the effective date of this AD.'' We have 
extended the compliance time specified in paragraphs (c)(2)(i) and 
(c)(2)(ii) of this supplemental NPRM to the later of the following: 
``Before the accumulation of 20,000 total flight cycles on the carriage 
spindle, or within 8 years since overhaul of the spindle or 
installation of a new spindle, whichever is first,'' or ``Within 4 
years after the effective date of this AD.'' We have also extended the 
compliance time in paragraph (c) of this supplemental NPRM for the 
repetitive overhaul or replacement to every 20,000 flight cycles or 8 
years, whichever is first. Extending the compliance time will not 
adversely affect safety but will accommodate the time necessary for the 
operators to obtain replacement parts and schedule the work.
    We do not agree to extend the repetitive inspection intervals 
required by paragraph (a) of the supplemental NPRM; those inspections 
end when the overhaul or replacement specified in paragraph (c) of this 
supplemental NPRM is done. In developing an appropriate compliance time 
for the repetitive inspections, we considered not only the degree of 
urgency associated with addressing the subject unsafe condition, but 
the manufacturer's recommendation as to an appropriate compliance time, 
and the practical aspect of accomplishing the repetitive inspections 
within an interval of time that parallels normal scheduled maintenance 
for the majority of affected operators. No change to the supplemental 
NPRM is necessary in this regard.

Request To Change Compliance Time to Calendar Time

    One commenter contends that corrosion associated with the 
identified unsafe condition is a function of time rather than flight 
cycles. We infer that the commenter requests that the original NPRM be 
revised to reflect a compliance time for the spindle overhaul/
replacement in terms of calendar time rather than flight cycles. We do 
not agree to use a calendar date in the AD because the compliance time 
in this case is a function of fleet utilization, which is unrelated to 
calendar dates. No change to the supplemental NPRM is necessary in this 
regard.

Request for Credit for Previously Overhauled Carriage Spindles

    One commenter asks that the carriage spindles overhauled before 
issuance of AD 2002-22-05 (no finish/plating required) remain in 
service for 8 years or 12,000 flight cycles, whichever comes first. The 
commenter has been proactive on this issue, and started carriage 
spindle overhauls prior to the effective date of the original NPRM. The 
commenter adds that no fractured carriage spindles have been found to 
date.
    We do not agree with the commenter. Although we acknowledge the 
fact that the commenter has not had any carriage spindle failures and 
maintains a good track record for diligent completion of AD 
requirements, many operators have been working to overhaul their fleets 
before the release of the AD in order to minimize the impact on the 
fleet. In light of the fact that the finish/plating removal was not 
required before issuance of AD 2002-22-05, carriage spindles that were 
overhauled before issuance of that AD may not have had the finishes/
platings removed, and would not be compliant with that AD. Therefore, 
no change to the supplemental NPRM is necessary in this regard.

Request To Accept Alternative Methods of Compliance (AMOCs) Approved 
for AD 2002-22-05

    Two commenters ask that the original NPRM be revised to accept 
certain AMOCs previously approved for AD 2002-22-05. One commenter 
states that the original NPRM does not have a provision for such AMOCs, 
and asks that a paragraph be added for previously approved AMOCs for 
paragraphs (a) and (b) of the original NPRM. The commenter recognizes 
that it would not be able to use previously approved AMOCs after 
paragraph (c) of the supplemental NPRM is accomplished.

[[Page 62413]]

Another commenter asks that we allow for optional tracking of the 
carriage part and serial number instead of the aircraft serial number 
to demonstrate compliance. The commenter states that it currently has 
an AMOC approved for AD 2002-22-05 that addresses this situation.
    We agree with the commenters' requests to accept certain AMOCs 
approved previously for AD 2002-22-05. We have added a new paragraph 
(f)(2) to this supplemental NPRM to include AMOCs previously approved 
for AD 2002-22-05. Regarding optional tracking of the carriage part and 
serial number instead of the airplane serial number, the commenter may 
submit substantiating data that support a request for an AMOC for this 
proposed AD per paragraph (f)(1) of this proposed AD.

Request To Require Additional AD for Carriage Spindle Only

    One commenter states that paragraph (d) of the original NPRM 
describes two constraints on the overhaul process. The commenter notes 
that paragraph (d)(1) of the original NPRM specifies the maximum time 
allowed before carrying out the hydrogen embrittlement procedure, and 
paragraph (d)(2) of the original NPRM defines the maximum thickness of 
nickel plating that can be done at any one plating/baking cycle. The 
commenter adds that the Boeing Standard Operating Procedures Manual for 
nickel plating includes the requirements specified in paragraph (d)(1), 
but the maximum plating requirements specified in paragraph (d)(2) are 
not included in the Boeing Component Maintenance Manual (CMM) 57-53-56, 
so compliance cannot be assumed by following the procedures in the CMM. 
The commenter is concerned that if these elements are required in an 
AD, there is a possibility that a flap carriage may be overhauled 
without reference to the AD, and subsequently, since there is no 
mechanism to prevent it, passed back to the operator without evidence 
of compliance with requirements. The commenter suggests that, if the 
relevant amendments are not placed in the CMM (against which the 
overhaul is to be performed before the effective date of the AD), a 
component AD against the flap carriage assemblies should be issued to 
ensure that the overhaul requirements are both complied with and 
certified as such before the assemblies are passed on to an operator. 
The commenter adds that the magnetic particle inspection addresses only 
the carriage, not the carriage spindle.
    We do not agree with the commenter. Overhaul manuals are not FAA-
approved documents. Updating these manuals is done by the original 
equipment manufacturer for the benefit of the operators. When an unsafe 
condition exists, we issue an AD to correct that condition, and, if 
additional safeguards are required as part of the mandated action, 
those safeguards are included in the text of the AD, unless mandated in 
other rulemaking actions. Ultimately, it is the responsibility of the 
operator to ensure compliance with any ADs that affect the operator's 
fleet. No change to the supplemental NPRM is necessary in this regard.

Request To Remove or Change Paragraph (a)

    One commenter asks that the current inspections that would be 
required by paragraph (a) of the original NPRM be removed or changed as 
they are ineffective for finding cracks. The commenter states that it 
performed the inspections and, approximately 10 days later, a carriage 
spindle severed during flight. The commenter does not see any benefit 
in performing the current inspections.
    We do not agree with the commenter. The inspections mandated by AD 
2002-22-05 are designed to find a fully failed spindle before the 
second spindle fails due to load redistribution from the failed 
spindle. AD 2002-22-05 is required to safeguard against a dual-spindle 
failure. Further, the carriage spindle is manufactured from high 
strength steel, which is a material not generally conducive to damage 
tolerance methods. No change to the supplemental NPRM is necessary in 
this regard.

Request To Add the Repetitive Overhaul in Paragraph (c) to the 
Operator's Time Limit Index

    One commenter asks that paragraph (c) of the original NPRM, which 
requires repetitive overhaul of the carriage spindles every 12,000 
flight cycles or 8 years, whichever is first, be incorporated into an 
Operator's Time Limit Index (Hard Time Component Program). The 
commenter states that this can be done by adding the following 
statement to paragraph (c): ``Operators may incorporate the overhaul 
requirement into the FAA-approved maintenance program if the Principal 
Maintenance Inspector (PMI) approves that action.'' The commenter adds 
that this would allow the PMI to approve the action, when appropriate, 
without a concern that it violates the Code of Federal Regulations.
    We do not agree with the commenter. To include the overhaul of this 
part in a particular overhaul program would be an operations-dependent 
procedure and cannot be done as a general option. The commenter 
provides no data to substantiate that its request would provide an 
acceptable level of safety. However, an affected operator may request 
approval of an AMOC, as provided by paragraph (f)(1) of this AD, if 
data are submitted to support that an alternative method would provide 
an acceptable level of safety. No change to the supplemental NPRM is 
necessary in this regard.

Request To Change Cost Impact Section

    Two commenters ask the Cost Impact section of the original NPRM be 
changed, as follows:
    [sbull] One commenter states that the estimated cost of the 
replacement of the carriage spindle ($45,000 per spindle, and $10,000 
per spindle for the overhaul) does not include the out-of-service time 
and work hours necessary.
    [sbull] One commenter states that the ``short'' initial compliance 
time would require operators to remove flaps outside their routine 
maintenance program, which would take an additional 192 work hours per 
airplane. The commenter estimates the additional labor cost at over 
$500,000. The commenter adds that the overhaul of the carriage spindle 
will require additional spare carriage spindles over the short initial 
compliance timeframe. Based on an overhaul turnaround time of 30 days, 
the commenter estimates it would need up to six shipments of spare 
carriage spindles at a cost of approximately $1.2 million. All these 
spares would then not be used for the remainder of the 8-year period 
until the next overhaul. In addition, the commenter notes that the cost 
for overhauling the carriage spindle is almost $100,000, based on the 
cost estimate per airplane provided in the original NPRM.
    We do not agree with the commenters. The cost impact information 
describes only the costs of the specific actions required by this AD. 
The number of work hours necessary to accomplish the overhaul or 
replacement, as specified in the cost impact information, is consistent 
with the service bulletin. This number represents the time necessary to 
perform only the actions actually required by this AD. We recognize 
that, in accomplishing the requirements of any AD, operators may incur 
additional costs due to special circumstances when scheduling 
maintenance visits. However, because maintenance schedules vary 
significantly from operator to operator,

[[Page 62414]]

the hours necessary for access and close-up time, including out-of-
service time, are almost impossible to calculate. No change to the 
supplemental NPRM is necessary in this regard.

Conclusion

    Since certain changes described previously expand the scope of the 
original NPRM, the FAA has determined that it is necessary to reopen 
the comment period to provide additional opportunity for public 
comment.

Changes to 14 CFR Part 39/Effect on the Proposed AD

    On July 10, 2002, the FAA issued a new version of 14 CFR part 39 
(67 FR 47997, July 22, 2002), which governs the FAA's airworthiness 
directives system. This regulation now includes material that relates 
to altered products, special flight permits, and alternative methods of 
compliance (AMOCs). Because we have now included this material in part 
39, only the office authorized to approve AMOCs is identified in each 
individual AD.

Change in Labor Rate

    We have reviewed the figures we have used over the past several 
years to calculate AD costs to operators. To account for various 
inflationary costs in the airline industry, we find it necessary to 
increase the labor rate used in these calculations from $60 per work 
hour to $65 per work hour. The cost impact information, below, reflects 
this increase in the specified hourly labor rate.

Cost Impact

    There are approximately 3,132 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 1,384 airplanes of U.S. 
registry would be affected by this proposed AD.
    The inspections that are currently required by AD 2002-22-05 take 
approximately 10 work hours per airplane to accomplish, at an average 
labor rate of $65 per work hour. Based on these figures, the cost 
impact of the currently required inspections on U.S. operators is 
estimated to be $899,600, or $650 per airplane.
    It would take approximately 2 work hours per airplane to accomplish 
the new detailed inspection, at an average labor rate of $65 per work 
hour. Based on these figures, the cost impact of the inspection 
proposed by this AD on U.S. operators is estimated to be $179,920, or 
$130 per airplane, per inspection cycle.
    Should an operator be required to accomplish the overhaul, it would 
take approximately 32 work hours per airplane to accomplish, at an 
average labor rate of $65 per work hour. Based on these figures, the 
cost impact of the overhaul proposed by this AD is estimated to be 
$2,080 per airplane.
    Should an operator be required to accomplish the replacement, it 
would take approximately 32 work hours per airplane to accomplish, at 
an average labor rate of $65 per work hour. Required parts would cost 
approximately $45,000 per carriage spindle. Based on these figures, the 
cost impact of the replacement proposed by this AD is estimated to be 
$47,080 per spindle, 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. 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 proposed herein would 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 proposal would not have federalism implications 
under Executive Order 13132.
    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 39-12929 (67 FR 
66316, October 31, 2002), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 2002-NM-219-AD. Supersedes AD 2002-22-05, Amendment 
39-12929.

    Applicability: All Model 737-100, -200, -200C, -300, -400, and -
500 series airplanes, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent severe flap asymmetry due to fractures of the 
carriage spindles on an outboard mid-flap, which could result in 
reduced control or loss of controllability of the airplane, 
accomplish the following:

Restatement of Requirements of AD 2002-22-05

Repetitive Inspections

    (a) Do general visual and nondestructive test (NDT) inspections 
of each carriage spindle (two on each flap) of the left and right 
outboard mid-flaps to find cracks, fractures, or corrosion at the 
later of the times specified in paragraphs (a)(1) and (a)(2) of this 
AD, as applicable, per the Work Instructions of Boeing Alert Service 
Bulletin 737-57A1277, dated July 25, 2002. Thereafter, repeat the 
inspections at intervals not to exceed 180 days until paragraph (b) 
or (c) of this AD is done, as applicable.
    (1) Before the accumulation of 12,000 total flight cycles or 8-
years-in-service on new or overhauled carriage spindles, whichever 
is first.
    (2) Within 90 days after November 15, 2002 (the effective date 
of AD 2002-22-05, amendment 39-12929).

    Note 1: For the purposes of this AD, a general visual inspection 
is defined as: ``A visual examination of an interior or exterior 
area, installation, or assembly to detect obvious damage, failure, 
or irregularity. This level of inspection is made from within 
touching distance unless otherwise specified. A mirror may be 
necessary to enhance visual access to all exposed surfaces in the 
inspection area. This level of inspection is made under normally 
available lighting conditions such as daylight, hangar lighting, 
flashlight, or droplight and may require removal or opening of 
access panels or doors. Stands, ladders, or platforms may be 
required to gain proximity to the area being checked.''

Corrective Action

    (b) If any crack, fracture, or corrosion is found during any 
inspection required by

[[Page 62415]]

paragraph (a) of this AD: Before further flight, do the applicable 
actions for that spindle, as specified in paragraph (b)(1) or (b)(2) 
of this AD, per the Work Instructions of Boeing Alert Service 
Bulletin 737-57A1277, dated July 25, 2002. Thereafter, repeat the 
inspections required by paragraph (a) of this AD at intervals not to 
exceed 12,000 flight cycles or 8 years, whichever is first, on the 
overhauled or replaced spindle only.
    (1) If any corrosion is found in the carriage spindle, overhaul 
the spindle.
    (2) If any crack or fracture is found in the carriage spindle, 
replace with a new or overhauled carriage spindle.

    Note 2: Although Boeing Alert Service Bulletin 737-57A1277, 
dated July 25, 2002, recommends that operators report inspection 
findings of any crack or fracture in the carriage spindle to the 
manufacturer, this AD does not contain such a reporting requirement.

New Requirements of This AD

Overhaul or Replacement

    (c) Overhaul or replace, as applicable, all four carriage 
spindles (two on each flap) of the left and right outboard mid-flaps 
at the applicable time specified in paragraph (c)(1) or (c)(2) of 
this AD, per the Work Instructions of Boeing Alert Service Bulletin 
737-57A1218, Revision 3, dated July 25, 2002. Thereafter, repeat the 
applicable overhaul or replacement at intervals not to exceed 20,000 
flight cycles or 8 years, whichever is first. Accomplishment of this 
paragraph ends the repetitive inspections required by paragraphs (a) 
and (b) of this AD.
    (1) For Model 737-100, -200, and -200C series airplanes, 
overhaul or replace at the later of the times specified in 
paragraphs (c)(1)(i) and (c)(1)(ii) of this AD.
    (i) Before the accumulation of 20,000 total flight cycles on the 
carriage spindle, or within 8 years since overhaul of the spindle or 
installation of a new spindle, whichever is first.
    (ii) Within 2 years after the effective date of this AD.
    (2) For Model 737-300, -400, and -500 series airplanes, overhaul 
or replace at the later of the times specified in paragraphs 
(c)(2)(i) and (c)(2)(ii) of this AD.
    (i) Before the accumulation of 20,000 total flight cycles on the 
carriage spindle, or within 8 years since overhaul of the spindle or 
installation of a new spindle, whichever is first.
    (ii) Within 4 years after the effective date of this AD.
    (d) During accomplishment of any overhaul required by paragraph 
(c) of this AD, use the procedures specified in paragraphs (d)(1) 
and (d)(2) of this AD during application of the nickel plating of 
the carriage spindle in addition to those specified in Boeing 737 
Standard Overhaul Practices Manual, Chapter 20-42-09.
    (1) Begin the hydrogen embrittlement relief bake within 10 hours 
after application of the plating, or less than 24 hours after the 
current was first applied to the part, whichever is first.
    (2) The maximum deposition rate of the nickel plating that is 
deposited in any one plating/baking cycle must not exceed 0.002-
inch-per-hour.
    (e) Overhauling or replacing the carriage spindles before the 
effective date of this AD, in accordance with Boeing Alert Service 
Bulletin 737-57A1277, dated July 25, 2002, is considered acceptable 
for compliance with the overhaul or replacement specified in 
paragraph (c) of this AD.

Alternative Methods of Compliance

    (f)(1) In accordance with 14 CFR 39.19, the Manager, Seattle 
Aircraft Certification Office, FAA, is authorized to approve 
alternative methods of compliance for this AD.
    (2) Alternative methods of compliance, approved previously per 
AD 2002-22-05, amendment 39-12929, are approved as alternative 
methods of compliance with paragraphs (a) and (b) of this AD.

    Issued in Renton, Washington, on October 29, 2003.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-27672 Filed 11-3-03; 8:45 am]
BILLING CODE 4910-13-P