[Federal Register Volume 67, Number 169 (Friday, August 30, 2002)]
[Proposed Rules]
[Pages 55737-55739]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-22131]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-64-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 777 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Boeing Model 777 series 
airplanes. This proposal would require either a one-time inspection or 
a review of the airplane maintenance records for both stabilizer trim 
control modules (STCM) of the trim system of the horizontal stabilizer 
to determine if STCMs having certain serial numbers are installed; and 
follow-on corrective actions, if necessary. This proposal also would 
require eventual replacement of affected STCMs with new or reworked 
STCMs, which would terminate the follow-on actions. This action is 
necessary to prevent an uncommanded stabilizer trim due to simultaneous 
failure of two static seals on one STCM, combined with failure of the 
automatic shutdown function of the stabilizer trim system. Such 
failures could result in loss of pitch control and consequent loss of 
control of the airplane. This action is intended to address the 
identified unsafe condition.

DATES: Comments must be received by October 15, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2002-NM-64-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 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-64-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 for Windows 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: Technical Information: Kenneth J. 
Fairhurst, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, 
FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056; telephone (425) 227-1118; fax (425) 227-
1181.
    Other Information: Sandy Carli, Airworthiness Directive Technical 
Editor/Writer; telephone (425) 687-4243, fax (425) 227-1232. Questions 
or comments may also be sent via the Internet using the following 
address: [email protected]. Questions or comments sent via the 
Internet as attached electronic files must be formatted in Microsoft 
Word 97 for Windows or ASCII text.

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:
     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.
     For each issue, state what specific change to the proposed 
AD is being requested.
     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-64-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.

[[Page 55738]]

2002-NM-64-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

    The FAA has received a report of an uncommanded stabilizer trim on 
a Boeing Model 777 series airplane that occurred on the ground. The 
leading edge of the horizontal stabilizer moved fully up, which would 
have resulted in a pitch command in the nose-down direction during 
flight. Investigation revealed that two seals on one stabilizer trim 
control module (STCM) of the trim system of the horizontal stabilizer 
had failed. An error in manufacturing the metal adjacent to the seals 
in the STCM caused the failures.
    The STCM has a dual-valve design that requires simultaneous arm and 
control valve motion to create a stabilizer trim command. A single STCM 
seal failure can cause a single uncommanded valve motion, resulting in 
inoperative stabilizer trim in the airplane nose-up direction. Two STCM 
seal failures can cause two valves to move, resulting in an uncommanded 
stabilizer trim in the airplane nose-down direction. The stabilizer 
trim system includes a protective monitoring-and-shutdown function to 
detect and stop uncommanded stabilizer motion using a motor-operated 
shutoff valve to block hydraulic pressure supplied to the STCM. An 
uncommanded stabilizer trim due to simultaneous failure of two STCM 
seals and the automatic shutdown function of the stabilizer trim system 
could result in loss of pitch control and consequent loss of control of 
the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 777-
27A0047, Revision 2, dated October 11, 2001, which describes procedures 
for examination of both STCMs of the trim system of the horizontal 
stabilizer to identify affected serial numbers (S/N) and follow-on 
corrective actions, if necessary.
    If any affected serial number is found, Part 1 of the Work 
Instructions describes procedures for repetitive functional tests to 
verify proper functioning of the stabilizer trim system of the 
horizontal stabilizer, including the automatic shutdown function of the 
stabilizer trim system. Part 1 also includes expanded instructions on 
how to conduct the test and interpret the results, as follows:
     If the functional test results indicate a test condition 
of ``FAILED'' or if the stabilizer does not move, the service bulletin 
specifies correcting the fault or cause of the condition, and repeating 
the functional test.
     Before returning the airplane to service, the functional 
test must have passed per Part 1.A.1. of the service bulletin, or the 
stabilizer trim system must be serviceable per Part 1.A.5.a. of the 
service bulletin.
    Part 2 of the Work Instructions describes procedures for 
identification and removal of STCMs having S/N 6 through 549 inclusive, 
and replacement with new or reworked STCMs. Accomplishment of the 
actions specified in the service bulletin is intended to adequately 
address the identified unsafe condition.
    Boeing Service Bulletin 777-27A0047, Revision 2, references MOOG 
Aircraft Group Service Bulletin 160300-27-124, Revision 1, dated August 
24, 2000, as the source of service information for changing and marking 
(reworking) the removed STCM units for installation on an airplane. The 
service bulletin also references certain chapters of the Boeing 777 
Airplane Maintenance Manual for procedures for certain corrective 
actions.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require accomplishment of the actions specified in 
the Boeing service bulletin described previously, except as discussed 
below.

Differences Between Service Information and This Proposed AD

    The effectivity of Boeing Service Bulletin 777-27A0047 identifies 
only Model 777-200 and 300 series airplanes having line numbers 2 
through 266 and 273, excluding line numbers 256, 258, and 260 through 
263 inclusive, as being subject to the service bulletin, but we have 
determined that the proposed AD applies to all Model 777 series 
airplanes. The subject STCMs are line-replaceable units and may have 
been installed on other airplanes not included in the effectivity in 
the service bulletin. This proposed AD requires that all Model 777 
series airplanes be inspected for STCMs having the serial numbers 
specified in the service bulletin.
    Although the service bulletin does not specify a records review, 
this proposed AD requires, as the initial action, doing a one-time 
general visual inspection or reviewing the airplane maintenance records 
to determine if STCMs having the serial numbers specified in Part 2 of 
the Work Instructions of the service bulletin are installed (Part 2 
identifies the serial numbers of the STCMs that are to be removed) 
within 30 days after the effective date of this AD. The functional test 
and follow-on corrective actions specified in the service bulletin, 
would be required on airplanes with the affected STCMs installed within 
150 flight hours after doing the inspection or review. Note 2 of this 
proposed AD defines a general visual inspection.

Cost Impact

    There are approximately 404 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 131 airplanes of U.S. registry 
would be affected by this proposed AD.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed inspection/review, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the inspection/
review proposed by this AD on U.S. operators is estimated to be $7,860, 
or $60 per airplane.
    The cost impact figure discussed above is 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 proposed 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.
    Should an operator be required to do the functional test, it would 
take approximately 1 work hour per airplane to accomplish, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of the functional test proposed by this AD on U.S. 
operators is estimated to be $60 per airplane, per test cycle.
    Should an operator be required to do the replacement, it would take 
approximately 3 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts would be provided by 
the vendor at no cost to operators. Based on these figures, the cost 
impact of the replacement proposed by this AD on U.S. operators is 
estimated to be $180 per airplane.

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

[[Page 55739]]

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 adding the following new 
airworthiness directive:

Boeing: Docket 2002-NM-64-AD.

    Applicability: All Model 777 series airplanes, certificated in 
any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (e) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent an uncommanded stabilizer trim due to simultaneous 
failure of two static seals on one stabilizer trim control module 
(STCM) combined with failure of the automatic shutdown function of 
the stabilizer trim system, which could result in loss of pitch 
control and consequent loss of control of the airplane, accomplish 
the following:

One-Time Inspection/Review of Maintenance Records

    (a) Within 30 days after the effective date of this AD: Do 
either a one-time general visual inspection or a review of the 
airplane maintenance records of both STCMs of the trim system of the 
horizontal stabilizer to determine the serial numbers (S/N), per 
Part 2 of the Work Instructions of Boeing Service Bulletin 777-
27A0047, Revision 2, dated October 11, 2001. If any affected S/N (6 
through 556 inclusive) is found on either STCM, within 150 flight 
hours after doing the inspection or review, do the actions specified 
in either paragraph (a)(1) or (a)(2) of this AD. If no affected 
serial number is found, no further action is required by this AD.

    Note 2: 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.''

Follow-On Corrective Actions

    (1) Do a functional test of the trim system of the horizontal 
stabilizer per Part 1 of the Work Instructions of the service 
bulletin.
    (i) If a test condition of PASSED is reported per Part 1.A.1. of 
the service bulletin, or considered serviceable per Part 1.A.5.a. of 
the service bulletin, repeat the test at least every 150 flight 
hours until the terminating action required by paragraph (b) of this 
AD is done.
    (ii) If a test condition of FAILED is reported, or if the 
stabilizer does not move, correct the condition as specified in the 
Boeing 777 Airplane Maintenance Manual, and repeat the functional 
test at least every 150 flight hours until the terminating action 
specified in paragraph (b) of this AD is done. If failure of either 
STCM is found during the test, before further flight, replace the 
affected STCM with a new or reworked STCM as required by paragraph 
(b) of this AD.
    (2) Replace any affected STCM with a new or reworked STCM as 
required by paragraph (b) of this AD.

Terminating Action

    (b) Except as provided by paragraphs (a)(1)(ii) and (a)(2) of 
this AD: Within 2 years after the effective date of this AD, replace 
any STCM having an affected serial number identified in paragraph 
(a) of this AD with a new or reworked (modified and marked with an 
``R'' suffix) STCM per Part 2 of the Work Instructions of Boeing 
Service Bulletin 777-27A0047, Revision 2, dated October 11, 2001. 
Such replacement ends the repetitive functional tests required by 
paragraph (a)(1) of this AD.

Credit for Actions Accomplished per Previous Revisions of Service 
Bulletin

    (c) Replacement of affected STCMs before the effective date of 
this AD per Boeing Service Bulletin 777-27A0047, dated September 21, 
2000; or Revision 1, dated November 2, 2000; is considered 
acceptable for compliance with paragraph (b) of this AD.

Spares

    (d) As of the effective date of this AD, no person may install 
on any airplane a STCM having S/N 6 through 556 inclusive.

Alternative Methods of Compliance

    (e) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle Aircraft Certification 
Office (ACO). Operators shall submit their requests through an 
appropriate FAA Principal Maintenance Inspector, who may add 
comments and then send it to the Manager, Seattle ACO.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permit

    (f) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished, provided there has 
been no known failure of any STCM during any functional test 
required by paragraph (a)(1) of this AD.


    Issued in Renton, Washington, on August 22, 2002.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-22131 Filed 8-29-02; 8:45 am]
BILLING CODE 4910-13-P