
[Federal Register: August 29, 2008 (Volume 73, Number 169)]
[Proposed Rules]               
[Page 50896-50899]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr29au08-16]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0933; Directorate Identifier 2007-NM-261-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 777 Airplanes

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

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede an existing airworthiness 
directive (AD) that applies to all Boeing Model 777 airplanes. The 
existing AD requires, for the drive mechanism of the horizontal 
stabilizer, repetitive detailed inspections for discrepancies, 
repetitive lubrication of the ballnut and ballscrew, repetitive 
measurements of the freeplay between the ballnut and the ballscrew, and 
corrective action if necessary. This proposed AD would revise the 
compliance times of the existing AD. This proposed AD results from a 
report of extensive corrosion of a ballscrew in the drive mechanism of 
the horizontal stabilizer on a Boeing Model 757 airplane, which is 
similar in design to the ballscrew on Model 777 airplanes. We are 
proposing this AD to prevent an undetected failure of the primary load 
path for the ballscrew in the drive mechanism of the horizontal 
stabilizer and subsequent wear and failure of the secondary load path, 
which could lead to loss of control of the horizontal stabilizer and 
consequent loss of control of the airplane.

DATES: We must receive comments on this proposed AD by October 14, 
2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this AD, contact Boeing 
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: Kelly McGuckin, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 917-6490; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about

[[Page 50897]]

this proposed AD. Send your comments to an address listed under the 
ADDRESSES section. Include ``Docket No. 2008-0933; Directorate 
Identifier 2007-NM-261-AD'' at the beginning of your comments. We 
specifically invite comments on the overall regulatory, economic, 
environmental, and energy aspects of this proposed AD. We will consider 
all comments received by the closing date and may amend this proposed 
AD because of those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    On August 14, 2007, we issued AD 2007-17-12, amendment 39-15170 (72 
FR 49158, August 28, 2007), for all Boeing Model 777 airplanes. That AD 
requires, for the drive mechanism of the horizontal stabilizer, 
repetitive detailed inspections for discrepancies, repetitive 
lubrication of the ballnut and ballscrew, repetitive measurements of 
the freeplay between the ballnut and the ballscrew, and corrective 
action if necessary. That AD resulted from a report of extensive 
corrosion of a ballscrew in the drive mechanism of the horizontal 
stabilizer on a Boeing Model 757 airplane, which is similar in design 
to the ballscrew on Model 777 airplanes. We issued that AD to prevent 
an undetected failure of the primary load path for the ballscrew in the 
drive mechanism of the horizontal stabilizer and subsequent wear and 
failure of the secondary load path, which could lead to loss of control 
of the horizontal stabilizer and consequent loss of control of the 
airplane.

Actions Since Existing AD Was Issued

    Since we issued AD 2007-17-12, Boeing submitted a letter asking 
that we clarify the compliance times specified in that AD. In this 
letter Boeing states that the wording in the existing AD has resulted 
in some confusion and may not adequately account for airplanes that 
have replacement actuators that are new or have been overhauled. Boeing 
proposes that the AD use the following three different categories for 
the horizontal stabilizer trim actuator (HSTA):
     HSTA not replaced;
     HSTA replaced with a new or overhauled HSTA; and
     HSTA replaced with a HSTA that was not new or overhauled.
    Boeing further states that the existing AD does not account for 
airplanes receiving a certificate of airworthiness after the effective 
date of the AD. Boeing suggests that the following changes be made to 
the existing AD to address the three different categories and revise 
the compliance times.
    Boeing proposes that we make changes to paragraph (g) of AD 2007-
17-12 to include subparagraphs (g)(1), (g)(2), and (g)(3) as follows:

    (g) For airplanes that have received a certificate of 
airworthiness prior to the effective date of this AD: Within 180 
days or 3,500 [flight hours] after the effective date of this AD, 
whichever occurs first, perform a maintenance records check or 
inspect to determine the status of the horizontal stabilizer trim 
actuator as follows:
    (1) Original horizontal stabilizer trim actuator still 
installed;
    (2) Original horizontal stabilizer trim actuator replaced with a 
new or overhauled horizontal stabilizer trim actuator;
    (3) Original horizontal stabilizer trim actuator replaced with a 
serviceable horizontal stabilizer trim actuator that was not new or 
overhauled, and has not received a detailed inspection and freeplay 
measurement since the replacement conducted per the Service Bulletin 
identified in paragraph (f) of this AD.

    Boeing further suggests that we change paragraphs (h)(1), (h)(2), 
(i)(1), (i)(2), (j)(1), and (j)(2) of AD 2007-17-12, as follows:

    (1) For airplanes identified in sub-paragraph (g)(1) of this AD 
and those receiving a certificate of airworthiness on or after the 
effective date of this AD: Before the accumulation of 15,000 total 
flight hours or within 18 months after the effective date of this 
AD, whichever occurs later.
    (2) For airplanes identified in sub-paragraph (g)(2) of this AD: 
Before the accumulation of 15,000 flight hours since replacement of 
the horizontal stabilizer trim actuator, or within 18 months after 
the effective date of this AD, whichever occurs later.

Boeing further suggests that we add a new subparagraph (3) to 
paragraphs (h), (i), and (j) of AD 2007-17-12, as shown:

    (3) For airplanes identified in sub-paragraph (g)(3) of this AD: 
Before the accumulation of 3,500 flight hours or within 12 months 
after the effective date of this AD, whichever occurs later.

    We agree with Boeing that the compliance times need to be 
clarified. Therefore, we are proposing this AD, which would supersede 
AD 2007-17-12, and retain the actions specified in the existing AD but 
with revisions to paragraphs (g), (h), (i), and (j) to reflect Boeing's 
suggestions and to clarify the compliance times. This proposed AD also 
contains new paragraphs (h)(4), (i)(4), and (j)(4) to address airplanes 
that received an original airworthiness certificate or original export 
certificate of airworthiness on or after the effective date of this AD.
    We have also determined that an additional category is needed to 
account for airplanes on which the HSTA has been replaced with an 
actuator that is not new or not overhauled but that has received a 
detailed inspection and freeplay measurement as described in paragraphs 
(h) and (i) of this proposed AD since that replacement. Accordingly, we 
have added paragraph (g)(4) to this proposed AD.
    We have also clarified the wording in paragraph (l) of this 
proposed AD to specify that the credit is for replacement of the HSTA.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to develop on other airplanes of the 
same type design. For this reason, we are proposing this AD, which 
would supersede AD 2007-17-12, to retain the actions specified in the 
existing AD but with new initial inspection compliance times.

Costs of Compliance

    There are about 596 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 203 airplanes of 
U.S. registry. The new requirements of this proposed AD add no 
additional economic burden. The current costs of the existing AD are 
repeated for the convenience of affected operators, as follows.
    The maintenance records check would take about 1 work hour per 
airplane, at an average labor rate of $80 per work hour. Based on these 
figures, the estimated cost of the maintenance records check for U.S. 
operators is $16,240, or $80 per airplane.
    The proposed detailed inspection would take about 1 work hour per 
airplane, at an average labor rate of $80 per work hour. Based on these 
figures, the estimated cost of the inspection for U.S. operators is 
$16,240, or $80 per airplane, per inspection cycle.
    The proposed freeplay measurement would take about 5 work hours per 
airplane, at an average labor rate of $80 per work hour. Based on these 
figures, the estimated cost of the freeplay measurement for U.S. 
operators is $81,200, or $400 per airplane, per measurement cycle.
    The proposed required lubrication would take about 1 work hour per 
airplane, at an average labor rate of $80 per work hour. Based on these 
figures, the estimated cost of the lubrication for U.S. operators is 
$16,240, or $80 per airplane, per lubrication cycle.

[[Page 50898]]

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. 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.
    We are issuing this rulemaking 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 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify that the 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. 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
removing amendment 39-15170 (72 FR 49158, August 28, 2007) and adding 
the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2008-0933; Directorate Identifier 2007-NM-
261-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by October 
14, 2008.

Affected ADs

    (b) This AD supersedes AD 2007-17-12.

Applicability

    (c) This AD applies to all Boeing Model 777 airplanes, 
certificated in any category.

Unsafe Condition

    (d) This AD results from a report of extensive corrosion of a 
ballscrew in the drive mechanism of the horizontal stabilizer on a 
Boeing Model 757 airplane, which is similar in design to the 
ballscrew on Model 777 airplanes. We are issuing this AD to prevent 
an undetected failure of the primary load path for the ballscrew in 
the drive mechanism of the horizontal stabilizer and subsequent wear 
and failure of the secondary load path, which could lead to loss of 
control of the horizontal stabilizer and consequent loss of control 
of the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Restatement of Requirements of AD 2007-17-12 With Revised Compliance 
Times

Service Bulletin Reference

    (f) The term ``service bulletin,'' as used in this AD, means 
Boeing Alert Service Bulletin 777-27A0059, Revision 1, dated August 
18, 2005.

    Note 1: The service bulletin refers to the Boeing 777 Aircraft 
Maintenance Manual (AMM), Subjects 12-21-05, 27-41-13, and 29-11-00, 
as additional sources of service information for accomplishing the 
actions required by this AD.

Maintenance Records Check

    (g) For airplanes that have received an original airworthiness 
certificate or original export certificate of airworthiness prior to 
the effective date of this AD: Within 180 days or 3,500 flight hours 
after the effective date of this AD, whichever occurs first, perform 
a maintenance records check or inspect to determine the status of 
the horizontal stabilizer trim actuator (HSTA) as specified in 
paragraph (g)(1), (g)(2), (g)(3), or (g)(4) of this AD, as 
applicable:
    (1) The original HSTA has been neither replaced nor overhauled;
    (2) The original HSTA has been replaced with a new or overhauled 
HSTA;
    (3) The original HSTA has been replaced with a serviceable HSTA 
that was not new or not overhauled, and which has not received a 
detailed inspection and freeplay measurement as described in 
paragraphs (h) and (i) of this AD since that replacement; or
    (4) The original HSTA has been replaced with a serviceable HSTA 
that was not new or not overhauled, and which has received a 
detailed inspection and freeplay measurement as described in 
paragraphs (h) and (i) of this AD since that replacement.

Detailed Inspection

    (h) Within the compliance time specified in paragraph (h)(1), 
(h)(2), (h)(3), or (h)(4) of this AD, as applicable: Perform a 
detailed inspection for discrepancies of the horizontal stabilizer 
trim actuator ballnut and ballscrew in accordance with Part 1 of the 
Accomplishment Instructions of the service bulletin. Repeat the 
detailed inspection thereafter at intervals not to exceed 3,500 
flight hours or 12 months, whichever occurs first. If any 
discrepancy is found during any inspection required by this AD, 
before further flight, replace the actuator with a new or 
serviceable actuator, in accordance with the Accomplishment 
Instructions of the service bulletin.
    (1) For airplanes identified in paragraph (g)(1) of this AD: 
Before the accumulation of 15,000 total flight hours, or within 18 
months after the effective date of this AD, whichever occurs later.
    (2) For airplanes identified in paragraph (g)(2) or (g)(4) of 
this AD: Before the accumulation of 15,000 flight hours since the 
replacement of the HSTA, or within 18 months after the effective 
date of this AD, whichever occurs later.
    (3) For airplanes identified in paragraph (g)(3) of this AD: 
Before the accumulation of 3,500 flight hours since the replacement 
of the HSTA, or within 12 months after the effective date of this 
AD, whichever occurs later.
    (4) For airplanes that have received an original airworthiness 
certificate or original export certificate of airworthiness on or 
after the effective date of this AD: Before the accumulation of 
15,000 total flight hours, or within 18 months after the issuance of 
the original airworthiness certificate or original export 
certificate of airworthiness, whichever occurs later.

Freeplay Measurement (Inspection)

    (i) Within the compliance times specified in paragraphs (i)(1), 
(i)(2), (i)(3), and (i)(4) of this AD, as applicable: Perform a 
freeplay measurement of the ballnut and ballscrew in accordance with 
Part 2 of the Accomplishment Instructions of the service bulletin. 
Repeat the freeplay measurement thereafter at intervals not to 
exceed 18,000 flight hours or 60 months, whichever occurs first. If 
the freeplay is found to exceed the limits specified in the service 
bulletin during any measurement required by this AD, before further 
flight, replace the actuator with a new or serviceable actuator in 
accordance with the Accomplishment Instructions of the service 
bulletin.
    (1) For airplanes identified in paragraph (g)(1) of this AD: 
Before the accumulation of

[[Page 50899]]

15,000 total flight hours, or within 18 months after the effective 
date of this AD, whichever occurs later.
    (2) For airplanes identified in paragraph (g)(2) or (g)(4) of 
this AD: Before the accumulation of 15,000 flight hours since the 
replacement of the HSTA, or within 18 months after the effective 
date of this AD, whichever occurs later.
    (3) For airplanes identified in paragraph (g)(3) of this AD: 
Before the accumulation of 3,500 flight hours since the replacement 
of the HSTA, or within 12 months after the effective date of this 
AD, whichever occurs later.
    (4) For airplanes that have received an original airworthiness 
certificate or original export certificate of airworthiness on or 
after the effective date of this AD: Before the accumulation of 
15,000 total flight hours, or within 18 months after the issuance of 
the original airworthiness certificate or original export 
certificate of airworthiness, whichever occurs later.

Lubrication

    (j) Within the compliance times specified in paragraphs (j)(1), 
(j)(2), (j)(3), and (j)(4) of this AD, as applicable: Lubricate the 
ballnut and ballscrew in accordance with Part 3 of the 
Accomplishment Instructions of the service bulletin. Repeat the 
lubrication thereafter at intervals not to exceed 2,000 flight hours 
or 12 months, whichever occurs first.
    (1) For airplanes identified in paragraph (g)(1) of this AD: 
Before the accumulation of 15,000 total flight hours, or within 18 
months after the effective date of this AD, whichever occurs later.
    (2) For airplanes identified in paragraph (g)(2) or (g)(4) of 
this AD: Before the accumulation of 15,000 flight hours since the 
replacement of the HSTA, or within 18 months after the effective 
date of this AD, whichever occurs later.
    (3) For airplanes identified in paragraph (g)(3) of this AD: 
Before the accumulation of 3,500 flight hours since the replacement 
of the HSTA, or within 12 months after the effective date of this 
AD, whichever occurs later.
    (4) For airplanes that have received an original airworthiness 
certificate or original export certificate of airworthiness on or 
after the effective date of this AD: Before the accumulation of 
15,000 total flight hours, or within 18 months after the issuance of 
the original airworthiness certificate or original export 
certificate of airworthiness, whichever occurs later.

Credit for Using Original Issue of Service Bulletin

    (k) Actions performed prior to the effective date of this AD, in 
accordance with Boeing Alert Service Bulletin 777-27A0059, dated 
September 18, 2003, are considered acceptable for compliance with 
the corresponding actions specified in paragraphs (h), (i), and (j) 
of this AD.

Credit for Hard-Time Replacement of HSTA

    (l) Any HSTA overhauled within the compliance times specified in 
paragraphs (h), (i), and (j) of this AD or before the effective date 
of this AD--as part of a ``hard-time'' replacement program that 
includes removal of the HSTA from the airplane and overhaul of the 
stabilizer ballscrew in accordance with original equipment 
manufacturer component maintenance manual instructions--meets the 
intent of one detailed inspection, one freeplay inspection, and one 
lubrication of the HSTA. Therefore, any such HSTA is considered 
acceptable for compliance with the initial accomplishment of the 
actions specified in paragraphs (h), (i), and (j) of this AD, and 
repetitions of those actions may be determined from the performance 
date of that overhaul.

Parts Installation

    (m) As of the effective date of this AD, no person may install, 
on any airplane, a horizontal stabilizer trim actuator that is not 
new or overhauled, unless a detailed inspection, freeplay 
measurement, and lubrication of that actuator are performed in 
accordance with paragraphs (h), (i), and (j) of this AD, as 
applicable.

Alternative Methods of Compliance (AMOCs)

    (n)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, ATTN: Kelly McGuckin, Aerospace Engineer, Systems and Equipment 
Branch, ANM-130S, FAA, Seattle ACO, 1601 Lind Avenue SW., Renton, 
Washington 98057-3356; telephone (425) 917-6490; fax (425) 917-6590; 
has the authority to approve AMOCs for this AD, if requested using 
the procedures found in 14 CFR 39.19.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.

    Issued in Renton, Washington, on August 21, 2008.
Kevin Hull,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-20087 Filed 8-28-08; 8:45 am]

BILLING CODE 4910-13-P
