AD 2005-12-18

[Federal Register Volume 70, Number 116 (Friday, June 17, 2005)]
[Rules and Regulations]
[Pages 35166-35172]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 05-11793]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NM-89-AD; Amendment 39-14134; AD 2005-12-18]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 757 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to all Boeing Model 757 series airplanes. For certain 
affected airplanes, this action requires repetitive testing of the 
secondary brakes of the horizontal stabilizer trim actuator (HSTA). For 
all affected airplanes, this action requires repetitive overhauls of 
the primary brake and differential assembly of the HSTA, which would 
constitute terminating action for the repetitive testing of the 
secondary brake. This action is necessary to prevent grease 
contamination on the primary HSTA brake and consequent loss of the 
primary brake function, which, in combination with the loss of the 
secondary HSTA brake function, could result in loss of control of the 
airplane. This action is intended to address the identified unsafe 
condition.

DATES: Effective July 22, 2005.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 22, 2005.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplanes, 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 National 
Archives and Records Administration (NARA). For information on the 
availability of this material at NARA, call (202) 741-6030, or go to: 
<a href="http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html">http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html</a>.

FOR FURTHER INFORMATION CONTACT: Kenneth W. Frey, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington; 
telephone (425) 917-6468; fax (425) 917-6590.

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 all Boeing Model 757 series 
airplanes was published in the Federal Register on December 22, 2003 
(68 FR 71047). For certain affected airplanes, that action proposed to 
require repetitive testing of the secondary brakes of the horizontal 
stabilizer trim actuator (HSTA). For all affected airplanes, that 
action proposed to require repetitive overhauls of the primary brake, 
ballscrew assembly, and

[[Page 35167]]

differential assembly of the HSTA, which would constitute terminating 
action for the repetitive testing of the secondary brake.

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.

Request for Alternative Actions to the Overhaul of the HSTA Ballscrew 
Assembly

    Two commenters request that alternative actions be accomplished 
instead of the overhaul of the HSTA ballscrew assembly specified in the 
proposed AD.
    One commenter requests that the actions specified in Boeing Alert 
Service Bulletin 757-27A0144, dated August 7, 2003, be required to 
address corrosion findings in the ballscrew assemblies. The commenter 
notes that this service bulletin provides a detailed inspection of the 
ballscrew primary load path for damage, cracking, corrosion, and wear. 
In addition, the commenter states the service bulletin provides a 
freeplay check and an increased lubrication interval for the HSTA. The 
commenter notes that all of these service bulletin actions are included 
in the Boeing maintenance planning document (MPD). The commenter 
contends that these procedures further the airworthiness of the HSTA 
assembly specific to concerns presented by the proposed AD. The 
commenter notes that these procedures have not been referenced in the 
proposed AD. The commenter adds that the initial compliance times of 
the proposed AD, the availability of spares, and the costs of the 
initial requirements of the proposed AD pose an industrywide concern 
over the ability to meet compliance with the proposed AD. The commenter 
concludes that consideration of the actions provided by the service 
bulletin would increase the level of safety of the HSTA assembly, 
lessen impact on component maintenance and spares availability, and 
help spread the cost associated with the initial requirements of the 
proposed AD over time.
    The other commenter states that the proposed AD specifies that, ``* 
* * all ballscrew assemblies on HSTAs that have been recently 
overhauled showed corrosion or wear.'' The commenter notes that this is 
not consistent with its findings. The commenter believes the lack of 
data regarding the severity or consequences of corrosion or wear is 
significant. The commenter suggests that, since the reason for the 
proposed AD is to address contamination of the primary brake, the 
corrosion on the ballscrew could be identified and corrected during on-
wing detailed inspections and freeplay checks. The commenter states 
that overhaul of the ballscrew should be based on the condition of the 
part or at the discretion of the operator since an unsafe condition has 
not been established.
    We agree that alternative actions should be accomplished instead of 
the requirement to overhaul the ballscrew assembly specified in the 
proposed AD. The identified unsafe condition in the final rule involves 
grease contamination on the primary HSTA brake. The corrosion findings 
in the ballscrew assemblies referenced in Boeing Alert Service Bulletin 
757-27A0142, Revision 2, dated October 23, 2003; and Boeing Alert 
Service Bulletin 757-27A0143, Revision 1, dated October 23, 2003; which 
are referenced in the final rule; are not related to the identified 
unsafe condition addressed in this final rule. Thus, we have determined 
that it is not necessary to mandate the periodic overhaul of the 
ballscrew assembly. The corrosion findings are addressed in Boeing 
Alert Service Bulletin 757-27A0144, dated August 7, 2003; and Boeing 
Alert Service Bulletin 757-27A0145, dated August 7, 2003. The service 
bulletins provide instructions to perform a freeplay and a detailed 
inspection/lubrication of the HSTA ballscrew assembly. These service 
bulletins are intended to prevent the loss the HSTA primary and 
secondary load paths. We are planning to review these service bulletins 
and may consider further rulemaking action. We have removed the 
requirement to overhaul the ballscrew assembly from paragraphs (a), 
(b), and (f) of the final rule.

Request To Revise the Cost Impact

    Many commenters request that the Cost Impact paragraph of the 
proposed AD be revised. The commenters state that the estimate in the 
proposed AD is too low. Several commenters mention that the costs of 
materials/components are not included in the estimate. One commenter 
also states that testing is not included in the estimate. The 
commenters estimate the cost of the overhaul to be between $40,000 and 
$80,000. One commenter also notes there is a high cost impact on 
operators due to the combination of material costs for the overhaul and 
performing the overhaul within the initial compliance time. Another 
commenter also believes that the estimated labor hours in the proposed 
AD is 20 percent too low.
    We partially agree to revise the Cost Impact paragraph in the final 
rule. We included only an estimate of labor hours for the overhaul and 
an estimate of the labor hours for the brake test in the proposed AD. 
We did not include the cost of parts associated with the overhaul. 
Based on the manufacturer's and operators' estimates, we now estimate 
the cost to overhaul the primary brake and differential assembly to be 
$60,000 per airplane, per overhaul. The cost of overhauling the 
ballscrew assembly is not included in the estimate, as the final rule 
does not contain a requirement to overhaul the ballscrew assembly. We 
have revised the Cost Impact paragraph of the final rule to include an 
estimate of $60,000 per airplane for the overhaul.
    However, we do not agree with the one commenter that the labor 
hours specified in the final rule are too low. The labor hours are 
based on manufacturer estimates and represent only the time necessary 
to perform the specific actions actually required by the AD. Labor 
hours 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. No change is made to the 
final rule in this regard.
    We also acknowledge there is a high cost impact on operators during 
the initial compliance time. However, the actions required by the final 
rule must be done within the compliance times specified in the final 
rule to ensure continued operational safety. In developing an 
appropriate compliance time for this AD, we considered the safety 
issues as well as the recommendations of the manufacturer, the 
availability of necessary repair parts, and the practical aspect of 
accomplishing the required inspection within an interval of time that 
corresponds to the normal maintenance schedules of most affected 
operators.

Request To Limit Actions to the Inspection of the Differential Assembly

    One commenter requests that the requirements of the proposed AD for 
the differential shaft be limited to inspecting the differential 
assembly for signs of corrosion every 30,000 flight hours as specified 
in the proposed AD. The commenter notes that the proposed AD specifies 
that the FAA received reports that `` * * * corrosion or cracking was 
found during HSTA overhaul in some differential assemblies.'' The 
commenter believes that the corrosion and cracking discussed in Boeing 
All Operator Letter M-7200-03-01358, dated September 30, 2003, is the 
report mentioned in the proposed AD. The commenter states the

[[Page 35168]]

all operator letter discusses the finding of a single cracked 
differential shaft. The commenter believes that requiring an overhaul 
of the differential assembly goes beyond the actions necessary to 
ensure safety. The commenter states that doing an overhaul is an 
economic decision that should be based upon the condition of the parts.
    While we agree with the commenter that the differential assembly 
should be inspected for corrosion every 30,000 flight hours as required 
in the final rule, we do not agree that the inspection should be the 
only action required. A detailed inspection is not sufficient to detect 
subsurface cracks in the differential shafts that could propagate and 
cause the differential shaft to fail. The overhaul required by the 
final rule includes a magnetic particle check of the differential 
assembly for cracking and is necessary to address the identified unsafe 
condition. No change is made to the final rule in this regard.

Request To Test Primary Brake Instead of Doing Overhaul

    One commenter requests that the proposed AD be revised to allow 
testing of the primary brake every 2 years instead of doing an 
overhaul. The commenter notes that the proposed AD addresses concerns 
about grease contamination on the primary HSTA brake. The commenter 
believes that requiring the overhaul of the primary brake goes beyond 
addressing the stated safety concern. The commenter states that 
although Boeing indicated that an effective on-airplane primary brake 
test is not available, the HSTA could be removed to conduct the brake 
test. The commenter concludes that the replacement of bearings, etc., 
should be based on the condition of the parts or on the operator's 
discretion.
    We do not agree with the request to allow a primary brake test 
every 2 years instead of the overhaul required by the final rule. Even 
with the grease contamination on the primary brake, a primary brake 
test may indicate that the primary brake is functioning to its full 
capacity. It has been shown that grease contamination on the primary 
brake did not produce repeatable results when the brake test was 
conducted. Brake test results can change due to environmental 
conditions of the test setup. The only way to ensure that the primary 
brake will function to its full capacity is to overhaul the brake 
assembly using the procedures in the applicable component maintenance 
manual (CMM) (referenced in Boeing Alert Service Bulletin 757-27A0142, 
Revision 2, dated October 23, 2003; and Boeing Alert Service Bulletin 
757-27A0143, Revision 1, dated October 23, 2003; which are the 
appropriate sources of service information for accomplishing the 
required actions). During the overhaul, the HSTA thrust bearings and 
seal will be replaced. Replacing the thrust bearings and seal at the 
overhaul intervals specified in the Boeing Alert Service Bulletins 
should reduce the chance of grease contamination on the primary brake. 
If the thrust bearings are not changed during the overhaul, it is 
likely that grease will eventually leak from the thrust bearing and 
contaminate the primary brake. No change is made to the final rule in 
this regard.

Request To Extend Compliance Time

    One commenter requests that several of the compliance times in the 
proposed AD be extended. The commenter suggests making the following 
changes to the compliance times specified in paragraph (a) of the 
proposed AD:
    <bullet> Where paragraph A of the table referenced in paragraph (a) 
of the proposed AD says ``Overhaul the primary brake, ballscrew 
assembly and differential assembly of the HSTA within 2 years,'' revise 
it to say ``overhaul the primary brake, ballscrew assembly and 
differential assembly of the HSTA within 3 years after the effective 
date of this AD.''
    <bullet> Where paragraphs B, C, and D of the table referenced in 
paragraph (a) of the proposed AD say ``Overhaul the primary brake, 
ballscrew assembly and differential assembly of the HSTA within 5 years 
or within 2 years after the HSTA reaches 42,000 hours, whichever comes 
first,'' revise it to say ``overhaul the primary brake, ballscrew 
assembly and differential assembly of the HSTA within 6 years or within 
3 years after the HSTA reaches 42,000 hours, whichever comes first.''
    <bullet> Where paragraph D of the table referenced in paragraph (a) 
of the proposed AD says ``If the HSTA has less than 30,000 hours within 
five years, overhaul the primary brake, ballscrew assembly and 
differential assembly of the HSTA when or before the HSTA reaches 
30,000 hours,'' revise it to say ``if the HSTA has less than 30,000 
hours within 6 years, overhaul the primary brake, ballscrew assembly 
and differential assembly of the HSTA when or before the HSTA reaches 
30,000 hours.''
    The commenter states that the unsafe condition with the primary 
brake specified in the proposed AD is overcome by the secondary brakes 
and would not affect the operation of the HSTA assembly. The commenter 
also notes that the manufacturer has not reported any Model 757 
airplane events associated with the findings referenced by Boeing Alert 
Service Bulletin 757-27A0142, Revision 2, dated October 23, 2003; and 
Boeing Alert Service Bulletin 757-27A0143, Revision 1, dated October 
23, 2003. The commenter believes that any in-service difficulty related 
to the finding on one differential assembly would not result in a 
``run-away'' stabilizer and would be adequately managed by the 
flightcrew. The commenter concludes that, by revising the proposed AD 
to require 3-year and 6-year initial compliance times, along with 
proposed secondary brake checks, the intent of the proposed AD will be 
accomplished within a timeframe better aligned with scheduled 
maintenance, and the continued safety of the aircraft will be ensured.
    Furthermore, the commenter proposes that more frequent secondary 
brake checks or consideration of actions specified in Boeing Alert 
Service Bulletin 757-27A0144, dated August 7, 2003, and the 
corresponding MPD changes would further increase the level of safety of 
the HSTA assembly to support the extended initial compliance times. The 
commenter believes that the extended compliance times and more 
efficient alignment with scheduled maintenance will reduce the impact 
of removing airplanes from scheduled service and will help spread the 
tremendous financial burden associated with the material and initial 
overhaul cost over time while maintaining a safe Model 757 fleet.
    We do not agree with the request to extend the compliance times in 
the final rule. While we agree the manufacturer has not reported any 
Model 757 airplane events, the intent of the final rule is to perform 
the required actions before an airplane event occurs due to the 
identified unsafe condition. We also do not agree with the commenter 
that more frequent secondary brake checks or actions specified in 
Boeing Alert Service Bulletin 757-27A0144, dated August 7, 2003, and 
the corresponding MPD changes would increase the level of safety of the 
HSTA assembly. A contaminated primary brake is a latent failure until 
the HSTA is overhauled. Also, a cracked differential shaft is a latent 
failure until the HSTA is overhauled. A secondary brake test shows only 
whether the secondary brake and one of two differential shafts are 
functioning. Even after passing the secondary brake test, the HSTA 
assembly may be one failure from the identified unsafe condition. No 
change is made to the final rule in this regard.
    We acknowledge the commenter's statement that the compliance times 
in the final rule may not align with

[[Page 35169]]

scheduled maintenance. Generally, we make every effort to establish 
compliance times that align with operators' scheduled maintenance. In 
this case, the compliance times in the final rule are based on Boeing 
airplane-level risk assessment, service history, and input from the 
lead airline. However, according to the provisions of paragraph (h) of 
the final rule, we may approve requests to adjust the compliance time 
if the request includes data that prove that the new compliance time 
would provide an acceptable level of safety.

Request To Reduce Repetitive Inspection Interval

    One commenter requests the repetitive secondary brake test interval 
required by the proposed AD be revised. The commenter recommends the 
repetitive interval to be the closest scheduled maintenance (letter) 
check within every 500 flight hour interval. The commenter states that 
the test requires two engineers and the use of ground equipment for 
access, which are not always readily available during normal 
operational visits. The commenter suggests that its proposed repetitive 
interval would allow flexibility for operators that have an approved 
escalated schedule to perform tests at regularly scheduled maintenance 
intervals.
    We do not agree to revise the repetitive secondary brake test 
interval. Compliance times have to be based on defined intervals to 
ensure that the required action in a final rule will be done within an 
appropriate timeframe for safe operation of the airplane. Since 
maintenance schedules vary among operators, it is not possible to align 
the compliance time to fit all operators' scheduled maintenance 
(letter) checks. The repetitive interval of 600 flight hours required 
in the final rule is based on a Boeing airplane-level risk assessment 
and input from the lead airline. No change is made to the final rule in 
this regard. However, according to the provisions of paragraph (h) of 
the final rule, we may approve requests to adjust the compliance time 
if the request includes data that prove that the new compliance time 
would provide an acceptable level of safety.

Request To Revise Initial Compliance Time

    One commenter states the compliance times in Boeing Alert Service 
Bulletin 757-27A0142, dated February 13, 2003, ``range from 2 years for 
aircraft with 42,000 flight hours or more, to 5 years for aircraft with 
30,000 but less than 42,000 flight hours.'' The commenter notes that 
its data for the overhaul of HSTAs show that the 2-year compliance time 
specified in the service bulletin for aircraft with 42,000 flight hours 
or more is not being complied with. The commenter also points out that 
the initial compliance time for the same aircraft in the proposed AD 
(which is 2 years after the effective date of the AD) may result in 
overhauls not being required to be done until close to 4 years after 
February 13, 2003, (the issue date of Boeing Alert Service Bulletin 
757-27A0142). The commenter is concerned that this compliance time in 
the proposed AD may result in an unacceptable exposure to the 
identified unsafe condition.
    We infer that the commenter is requesting that the initial 
compliance time specified in paragraph (c) of the proposed AD be 
revised from ``after the effective date of this AD'' to a time closer 
to or matching after the date of the ``initial release of the service 
bulletin.'' We do not agree to revise the initial compliance time in 
the final rule. In developing the compliance time for this AD, we 
considered not only the safety implications of the identified unsafe 
condition, but the average utilization rate of the affected fleet, the 
practical aspects of doing the overhauls of the fleet during regular 
maintenance periods, and the time necessary for the rulemaking process. 
We determined that using an initial compliance time following the 
effective date of the final rule is appropriate. Further, we arrived at 
the proposed compliance time with manufacturer concurrence.
    In addition, reducing the compliance time would necessitate (under 
the provisions of the Administrative Procedure Act) reissuing the 
notice, reopening the period for public comment, considering additional 
comments subsequently received, and eventually issuing a final rule. We 
have determined that further delay of this final rule is not 
appropriate. However, if additional data are presented that would 
justify a shorter compliance time, we may consider further rulemaking 
on this issue. No change is made to the final rule in this regard.

Request To Include Overhaul of Secondary Brake

    Two commenters request that the overhaul of the secondary brake be 
included in the proposed AD.
    One commenter requests the same compliance time for the overhaul of 
the secondary brake as time specified in the proposed AD for the 
overhaul of the primary brake, differential, and ballscrew. The 
commenter notes that the proposed AD does not mandate the overhaul of 
the secondary brake or hydraulic motor, which are integral parts of the 
HSTA. The commenter points out that hydraulic fluid leakage from 
secondary brakes and hydraulic motors into the differential washes the 
grease off of the differential and leads to corrosion and, therefore, 
necessitates the overhaul of the differential. The commenter states, 
``Brakes or motors, which are not overhauled, would likely start 
leaking as soon as the HSTA is put back into service after overhaul. 
When the brakes and motors were new (or fully overhauled) such 
corrosion causing leakage would not likely have begun for several 
years.''
    The other commenter requests that the overhaul of the secondary 
brake be recommended in the proposed AD. The commenter recommends 
adding notes like the ones specified in Boeing Alert Service Bulletin 
757-27A0142, Revision 2, dated October 23, 2003; and Boeing Alert 
Service Bulletin 757-27A0143, Revision 1, dated October 23, 2003; to 
paragraphs (a) and (b) of the proposed AD, as follows: ``It is 
recommended that you also do an overhaul of the secondary hydraulic 
brakes and hydraulic motors of the HSTA. Hydraulic fluid can leak from 
these components and wash the grease out of the differential 
assembly.'' The commenter suggests adding the following note to 
paragraph (d) of the proposed AD: ``It is recommended that you also do 
an overhaul of the secondary hydraulic brakes and hydraulic motors of 
the HSTA. Hydraulic fluid can leak from these components and wash the 
grease out of the differential assembly. Boeing also recommends that 
you do an operational test of the HSTA secondary brakes (refer to MPD 
27-41-00-5D) when the HSTA reaches 24,000 flight hours.'' The commenter 
notes that the proposed AD does not address that the secondary brakes 
should be overhauled as specified in the service bulletins. The 
commenter states that the secondary brake was never designed to perform 
the operation of the primary brake in repetitive circumstances. The 
commenter indicates that if the secondary brake is subject to the 
braking requirements of the primary brake, there may be wear to the 
internal parts in the secondary brake that would not be identified 
during the limited testing required by the proposed AD. The commenter 
proposes that the only way to identify any potential premature wear to 
the rotors or stators in the secondary brake is to disassemble and 
inspect internal components within the secondary brake.

[[Page 35170]]

    We do not agree to include the overhaul of the secondary brake in 
the final rule. The intent of the final rule is to require actions that 
address the identified unsafe condition, which is the loss of primary 
and secondary braking function. The overhaul of the secondary brake is 
a recommended maintenance practice, which does not address the 
identified unsafe condition. Also, the service history of the secondary 
brakes shows the brakes are functioning normally, and testing shows 
that the HSTA secondary brakes could last one airplane life under 
normal operations with no assistance from any other braking system. No 
change is made to the final rule in this regard.
    In regard to the commenter's statement about hydraulic fluid 
leakage from the secondary brakes and hydraulic motor, we recognize 
that hydraulic fluid can leak from the secondary brake or hydraulic 
motor, washing away grease and leading to corrosion or damage to the 
differential bearings. The leakage of hydraulic fluid from the 
secondary brake and hydraulic motor may infrequently cause loss of trim 
capability in one or both directions and does not affect braking 
function. Infrequent inability to move the horizontal stabilizer is not 
related to the identified unsafe condition of the final rule. However, 
we may consider further rulemaking on this issue of hydraulic fluid 
leakage if additional data are presented that would justify additional 
rulemaking.

Request To Clarify Scope of the Proposed AD

    One commenter requests that paragraphs (a)(2) and (b) of the 
proposed AD be revised to clarify the intended scope of the overhaul of 
the primary brake, ballscrew assembly, and differential assembly in 
order to differentiate this overhaul from an overhaul of the HSTA 
assembly. The commenter also recommends that the related service 
bulletins and CMMs be revised to provide specific work instructions 
before issuance of the final rule. The commenter notes that CMM 27-41-
05 does not define an overhaul of the HSTA assembly nor does it itemize 
requirements for an overhaul of the primary brake, ballscrew assembly, 
or differential assembly.
    The commenter also points out that the use of the terms ``restore'' 
and ``overhaul'' in various Boeing documents has generated much 
confusion and discussion throughout the industry regarding the 
definition of the work scope that will be needed to accomplish the full 
intent of this HTSA effort and the requirements of the proposed AD. The 
commenter notes that restoration versus overhaul significantly affects 
the extent to which part disassembly and inspection are accomplished on 
the HSTA assembly.
    We do not agree that clarification of the scope of the work in the 
final rule is needed. The final rule requires overhaul of the primary 
brake and differential assembly of the HSTA. The overhaul of the 
primary brake and differential assembly consists of inspection, testing 
and troubleshooting, disassembly, cleaning, check, repair, and assembly 
as described in the applicable CMM referenced in Boeing Alert Service 
Bulletin 757-27A0142, Revision 2, dated October 23, 2003; and Boeing 
Alert Service Bulletin 757-27A0143, Revision 1, dated October 23, 2003. 
We consider the CMM reference to be of sufficient detail to correct the 
identified unsafe condition. No change is made to the final rule in 
this regard.

Request To Add Statement To Allow Credit for Secondary Brake Tests

    One commenter requests adding a statement to the ``Difference 
Between the Proposed Rule and Service Bulletin 757-27A0142'' paragraph 
of the proposed AD that allows operators to take credit for secondary 
brake tests performed according to their scheduled maintenance program 
at the 4C interval. No specific reason was given for the request.
    We do not agree to add a statement allowing credit for secondary 
brake tests to the ``Difference Between the Proposed Rule and Service 
Bulletin 757-27A0142'' paragraph as the ``Difference Between the 
Proposed Rule and Service Bulletin 757-27A0142'' paragraph is not 
restated in the final rule. We also have verified the paragraph and 
find that no changes are necessary. For actions performed according to 
methods other than those specified in the final rule or at different 
compliance times, operators may request an alternative method of 
compliance (AMOC) according to the provisions of paragraph (h) of the 
final rule, if sufficient data are included to justify that the AMOC 
would provide an acceptable level of safety. Because operators' 
schedules vary substantially, we cannot accommodate every operator's 
optimal scheduling in the compliance times of each AD. We have not 
changed the final rule regarding this issue.

Request To Clarify Paragraph (g) of the Proposed AD

    Two commenters request clarification of paragraph (g) of the 
proposed AD, which gives operators credit for overhauls accomplished 
according to previous issues of the service bulletin. One commenter 
wants the proposed AD to indicate that the accomplishment of previous 
issues of the service bulletins constitutes only partial compliance 
with the proposed AD. The other commenter believes that the overhauls 
of the ballscrew assembly and differential assembly accomplished 
according to applicable Thomson Saginaw service bulletins, Boeing 
service bulletins, or operator's equivalent CMMs (during primary brake 
overhaul done according to Boeing Alert Service Bulletin 757-27A0142, 
dated February 13, 2003; or Revision 1, dated April 10, 2003) should be 
acceptable for compliance with the proposed AD.
    We do not find it necessary to change paragraph (g) of the final 
rule. The paragraph indicates that certain previous overhauls of the 
primary brakes and tests of the secondary brakes are acceptable for 
compliance with the corresponding action in the final rule. We do not 
find it necessary to indicate that this is only partial compliance with 
the final rule. The remaining actions in the final rule such as the 
overhaul of the differential assembly are still required. However, for 
clarity, we have revised the header above paragraph (g) of the final 
rule from ``overhauls accomplished * * *'' to ``actions accomplished * 
* *'' since paragraph (g) of the final rule describes both overhauls 
and tests.
    Overhaul of the ballscrew assembly is not a requirement of this 
final rule for the reasons discussed above in the paragraph titled 
``Request for Alternative Actions to the Overhaul of the HSTA Ballscrew 
Assembly.'' We also cannot give credit for overhauls of the 
differential assembly accomplished according to Boeing service 
bulletins or operator's equivalent CMMs. The commenter did not provide 
sufficient data to indicate that previous overhauls of the differential 
assembly according to these methods would provide an acceptable level 
of safety. Also, Boeing Alert Service Bulletin 757-27A0142, dated 
February 13, 2003; and Boeing Alert Service Bulletin 757-27A0142, 
Revision 1, dated April 10, 2003; do not provide procedures to overhaul 
the differential assembly. We have not changed the final rule in this 
regard. However, according to the provisions of paragraph (h) of the 
final rule, operators may request an AMOC if sufficient data are 
included to justify that the AMOC would provide an acceptable level of 
safety.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air

[[Page 35171]]

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 1,085 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 754 airplanes of U.S. 
registry will be affected by this AD; 722 of the affected airplanes of 
U.S. registry are Model 757-200, -200PF, and -200CB series airplanes, 
and 32 are Model 757-300 series airplanes.
    For the affected Model 757-200 and Model 757-300 series airplanes, 
we estimate the cost impact of the overhaul on U.S. operators to be 
$45,240,000, or $60,000 per airplane, per overhaul cycle.
    For the affected Model 757-200 series airplanes, the FAA estimates 
that it will take approximately 1 work hour per airplane to accomplish 
the test of the HSTA secondary brake, and that the average labor rate 
is $65 per work hour. Based on these figures, the cost impact of the 
secondary brake test on U.S. operators is estimated to be $46,930, or 
$65 per airplane, per test.
    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. 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.

Authority for This Rulemaking

    The FAA's authority to issue rules regarding aviation safety is 
found in Title 49 of the United States Code. Subtitle I, Section 106 
describes the authority of the FAA Administrator. Subtitle VII, 
Aviation Programs, describes in more detail the scope of the agency's 
authority.
    This rulemaking is promulgated under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this AD.

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

0
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

0
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]

0
2. Section 39.13 is amended by adding the following new airworthiness 
directive:

2005-12-18 Boeing: Amendment 39-14134. Docket 2003-NM-89-AD.

    Applicability: All Model 757-200, -200PF, -200CB, and -300 
series airplanes, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent grease contamination on the primary horizontal 
stabilizer trim actuator (HSTA) brake and consequent loss of the 
primary brake function, which, in combination with the loss of the 
secondary HSTA brake function, could result in loss of control of 
the airplane, accomplish the following:

For Model 757-200, -200CB, and -200PF Series Airplanes: Repetitive 
Overhauls and Tests

    (a) For Model 757-200, -200CB, and -200PF series airplanes: 
Except as provided by paragraphs (c), (d), and (e) of this AD, at 
the applicable time specified in paragraph 1.E., ``Compliance,'' of 
Boeing Alert Service Bulletin 757-27A0142, Revision 2, dated October 
23, 2003; including the compliance time ``since the most recent 
overhaul of the primary brake, the ballscrew assembly, and the 
differential assembly''; do the actions specified in paragraphs 
(a)(1) and (a)(2) of this AD.
    (1) Test the secondary brakes of the HSTA in accordance with 
Part 2 of the Accomplishment Instructions of the service bulletin. 
If any secondary brake fails, before further flight, replace with a 
serviceable brake or overhaul in accordance with Part 2 of the 
Accomplishment Instructions of the service bulletin.
    (2) Overhaul the primary brake and differential assembly of the 
HSTA in accordance with Part 1 of the Accomplishment Instructions of 
the service bulletin. Accomplishment of the overhaul constitutes 
terminating action for the repetitive tests of the secondary brake 
required by paragraph (a)(1) of this AD.
    (b) Repeat the overhaul of the primary brake and differential 
assembly of the HSTA at intervals not to exceed 30,000 flight hours, 
in accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 757-27A0142, Revision 2, dated October 23, 2003.
    (c) Where the service bulletin specified in paragraph (a) of 
this AD specifies a date from which the initial compliance time 
interval starts as being the date of the initial release of the 
service bulletin, this AD requires compliance within the applicable 
initial compliance time after the effective date of this AD.
    (d) Where the service bulletin specified in paragraph (a) of 
this AD states ``total hours since delivery,'' this AD requires 
compliance prior to the accumulation of the applicable number of 
flight hours since the date of issuance of the original 
Airworthiness Certificate or the date of issuance of the original 
Export Certificate of Airworthiness.
    (e) Where paragraph D. of the table in paragraph 1.E., 
``Compliance,'' of the service bulletin specified in paragraph (a) 
of this AD states: ``Test the HSTA secondary brake when the HSTA 
reaches 24,000 hours (4C) (this is currently a scheduled maintenance 
task)'; this AD requires testing secondary brakes that have 
accumulated between 15,000 and 23,999 flight hours when the HSTA 
reaches 24,000 flight hours or within 500 flight hours after the 
effective date of this AD, whichever occurs later. For HSTAs that 
have accumulated between 24,000 and 29,999 flight hours, this AD 
requires testing the secondary brake within 500 flight hours after 
the effective date of this AD. All testing

[[Page 35172]]

should be done in accordance with the service bulletin.

For Model 757-300 Series Airplanes: Repetitive Overhauls

    (f) For Model 757-300 series airplanes: Prior to the 
accumulation of 30,000 total flight hours, overhaul the primary 
brake and differential assembly of the HSTA in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 757-
27A0143, Revision 1, dated October 23, 2003. Repeat the overhaul 
thereafter at intervals not to exceed 30,000 flight hours.

Actions Accomplished Per Previous Issues of Service Bulletins

    (g) Overhauls of the primary brake and tests of the secondary 
brakes accomplished before the effective date of this AD in 
accordance with Boeing Alert Service Bulletin 757-27A0142, dated 
February 13, 2003; or Revision 1, dated April 10, 2003; and 
overhauls of the primary brake accomplished before the effective 
date of this AD in accordance with Boeing Alert Service Bulletin 
757-27A0143, dated February 13, 2003; are considered acceptable for 
compliance with the overhaul of the primary brake only and tests of 
the secondary brakes specified in this AD.

Alternative Methods of Compliance (AMOCs)

    (h) In accordance with 14 CFR 39.19, the Manager, Seattle 
Aircraft Certification Office (ACO), FAA, is authorized to approve 
AMOCs for this AD.

Incorporation by Reference

    (i) Unless otherwise specified in this AD, the actions shall be 
done in accordance with Boeing Alert Service Bulletin 757-27A0142, 
Revision 2, dated October 23, 2003; or Boeing Alert Service Bulletin 
757-27A0143, Revision 1, dated October 23, 2003; as applicable. 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 Airplanes, 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 National Archives and Records 
Administration (NARA). For information on the availability of this 
material at NARA, call (202) 741-6030, or go to: <a href="http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html">http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html</a>.

Effective Date

    (j) This amendment becomes effective on July 22, 2005.

    Issued in Renton, Washington, on June 3, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-11793 Filed 6-16-05; 8:45 am]
BILLING CODE 4910-13-P