[Federal Register Volume 69, Number 47 (Wednesday, March 10, 2004)]
[Rules and Regulations]
[Pages 11299-11303]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-5069]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NM-258-AD; Amendment 39-13516; AD 2004-05-21]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-8-102, -103, -106, 
-201, -202, -301, -311, and -315 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Bombardier airplanes as listed above. This 
action requires lubrication of the flap actuators, repetitive 
measurements (``checks'') of the backlash of the flap actuators, 
determination of the next backlash measurement interval, and 
replacement of discrepant actuators with new or overhauled actuators if 
necessary. This action is necessary to prevent the mechanical 
disconnection of a flap actuator, which, if followed by failure of the 
flap panel's second actuator due to increased loading, could result in 
flap asymmetry and consequent loss of controllability of the airplane. 
This action is intended to address the identified unsafe condition.

DATES: Effective March 25, 2004.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 25, 2004.
    Comments for inclusion in the Rules Docket must be received on or 
before April 9, 2004.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2003-NM-258-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 the Internet must contain 
``Docket No. 2003-NM-258-AD'' in the subject line and need not be 
submitted in triplicate. Comments sent via fax or the Internet as 
attached electronic files must be formatted in Microsoft Word 97 or 
2000 or ASCII text.
    The service information referenced in this AD may be obtained from 
Bombardier, Inc., Bombardier Regional Aircraft Division, 123 Garratt 
Boulevard, Downsview, Ontario M3K 1Y5, Canada. This information may be 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, 
SW., Renton, Washington; or at the FAA, New York Aircraft Certification 
Office, FAA, 1600 Stewart Avenue, suite 410, Westbury, New York; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Ezra Sasson, Aerospace Engineer, 
Systems and Flight Test Branch, ANE-172, New York Aircraft 
Certification Office, FAA, 1600 Stewart Avenue, suite 410, Westbury, 
New York 11590; telephone (516) 228-7320; fax (516) 794-5531.

SUPPLEMENTARY INFORMATION: Transport Canada Civil Aviation (TCCA), 
which is the airworthiness authority for Canada, notified the FAA that 
an unsafe condition may exist on certain Bombardier Model DHC-8-102, -
103,

[[Page 11300]]

-106, -201, -202, -301, -311, and -315 airplanes. TCCA advises that 
field reports indicate that the ballscrew and nut assembly of the flap 
drive actuators may wear to the extent that the ballscrew mechanically 
disconnects from the ballnut. There have been four known incidents that 
involved actuator disconnect. The mechanical disconnection of the 
ballscrew from the ballnut can lead to binding of the flap system. If 
both actuators of an extended flap panel disconnect, the affected panel 
may be aerodynamically backdriven, resulting in asymmetric flaps. This 
condition, if not corrected, could result in loss of controllability of 
the airplane.

Maintenance Schedule

    Analysis of new data indicates the need to reduce the current 
interval specified in the Bombardier Model DHC-8 maintenance program 
for measuring the backlash of the flap ballscrew actuators. Based on 
the new data, the FAA and TCCA have determined that this interval must 
be reduced from a ``2C'' check (currently a maximum of 10,000 flight 
hours) to a variable interval (a maximum of 3,000 flight cycles) that 
is based on each previous backlash measurement and actuator wear rate.

Explanation of Relevant Service Information

    Bombardier has issued Alert Service Bulletin A8-27-98, dated 
February 20, 2003, which describes procedures for measuring the 
backlash of the flap actuators. The service bulletin also provides the 
means to calculate each subsequent interval for repeating the backlash 
measurement, based on the wear rate and previous backlash measurement. 
If a certain backlash length is exceeded, the service bulletin 
recommends replacing the actuator with a serviceable actuator before 
further flight.
    Bombardier has revised certain procedures for lubricating the flap 
actuators, which are described in the temporary revisions (TRs) to the 
de Havilland Dash-8 Maintenance Program Manual listed in the following 
table:

                                   de Havilland Maintenance Program Manual TRs
----------------------------------------------------------------------------------------------------------------
                  Model                       PSM No.               de Havilland TR No.              Task No.
----------------------------------------------------------------------------------------------------------------
DHC-8-102, -103, and -106 airplanes.....           1-8-7  MRB-143...............................         2750/04
DHC-8-201 and -202 airplanes............          1-82-7  MRB 2-21..............................         2750/04
DHC-8-301, -311, and -315 airplanes.....          1-83-7  MRB 3-152.............................         2750/04
----------------------------------------------------------------------------------------------------------------

These TRs introduce procedures that incorporate use of new lubrication 
tools and a particular grease that will improve lubrication of the flap 
actuators and consequently reduce component wear.
    Accomplishment of the actions specified in the service information 
is intended to adequately address the identified unsafe condition. TCCA 
mandated accomplishment of this service information and issued Canadian 
airworthiness directive CF-2002-26R1, dated October 6, 2003, to ensure 
the continued airworthiness of these airplanes in Canada.

FAA's Conclusions

    These airplane models are manufactured in Canada and are type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, TCCA has kept the FAA informed of 
the situation described above. The FAA has examined the findings of 
TCCA, reviewed all available information, and determined that AD action 
is necessary for products of this type design that are certificated for 
operation in the United States.

Explanation of Requirements of Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, this AD is being issued to prevent the mechanical 
disconnection of a flap actuator, which, if followed by failure of the 
panel's second actuator due to increased loading, could result in flap 
asymmetry and consequent loss of controllability of the airplane. This 
AD requires a one-time actuator lubrication, repetitive measurements 
(``checks'') of the backlash of the flap actuators, determination of 
each subsequent backlash check interval, and replacement of discrepant 
actuators with new or overhauled actuators if necessary. The actions 
are required to be accomplished in accordance with the service 
information described previously. The compliance times for the initial 
measurement range from 30 days to 3,000 total accumulated flight cycles 
on the actuator, with each subsequent interval ranging from 45 to 3,000 
flight cycles, depending on each previous measurement and the wear 
rate. The FAA and TCCA agree on the following minor variations between 
the airworthiness directives:
    1. Part A., paragraph 1., of the TCCA airworthiness directive 
mandates revising the TCCA-approved maintenance schedule by 
incorporating the applicable flap actuator lubrication task specified 
in the maintenance program manual TRs described previously. This (FAA) 
AD requires a one-time lubrication, but the lubrication maintenance 
schedule is not expressly required by this AD, because the lubrication 
schedule itself does not address the unsafe condition identified in 
this (FAA) AD. Rather, the lubrication schedule was established to 
reduce wear and tear on the flap actuators (thereby extending actuator 
life and decreasing costs).
    2. Part A., paragraph 3., of the TCCA airworthiness directive 
mandates a specific compliance time, task card, and lubrication tools 
and grease for the lubrication. This (FAA) AD does not include these 
requirements, which are specified in the task card as part of the 
maintenance manual TRs (and specified in part A., paragraph 2., of the 
TCCA airworthiness directive); operators are expected to comply with 
the current, MRB-required task card. If an operator cannot comply with 
this AD because the specific grease or tools are unavailable within the 
required compliance time, the FAA may consider requests to extend the 
compliance time, as provided by paragraph (f) of this AD, if data are 
presented to justify such an extension.
    3. The TCCA airworthiness directive mandates sending an inspection 
report to Bombardier or the actuator manufacturer (Hamilton 
Sundstrand). This (FAA) AD does not require such a report.
    4. The TCAA airworthiness directive requires that certain actions 
be done ``not later than during the next A-check.'' Paragraph (a)(2) of 
this (FAA) AD identifies that interval as 500 flight

[[Page 11301]]

hours, which for all affected operators is the same as the A-check.
    5. In this (FAA) AD, Notes 1 through 12 of the TCCA airworthiness 
directive have been either excluded as redundant or incorporated as 
guidance into the requirements.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    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 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 rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2003-NM-258-AD.'' The postcard will be date stamped 
and returned to the commenter.

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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, 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:

2004-05-21 Bombardier, Inc. (Formerly de Havilland, Inc.): Amendment 
39-13516. Docket 2003-NM-258-AD.

    Applicability: Model DHC-8-102, -103, -106, -201, -202, -301, -
311, and -315 airplanes; certificated in any category; serial 
numbers 003 and subsequent; equipped with any flap actuator having 
part number 734181, 734374, or 755216.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent the mechanical disconnection of a flap actuator, 
which, if followed by failure of the flap panel's second actuator 
due to increased loading, could result in flap asymmetry and 
consequent loss of controllability of the airplane, accomplish the 
following:

Actuator Lubrication

    (a) Lubricate the flap actuators at the later of the times 
specified in paragraphs (a)(1) and (a)(2) of this AD, in accordance 
with the product support manuals (PSMs) and temporary revisions 
(TRs) to the maintenance program manual listed in Table 1 of this 
AD.
    (1) Within 2,500 flight hours or 18 months after the most recent 
flap actuator lubrication, whichever occurs first.
    (2) Within 500 flight hours after the effective date of this AD.

          Table 1.--de Havilland Maintenance Program Manual TRs
------------------------------------------------------------------------
                   TR                           PSM          Task No.
------------------------------------------------------------------------
MRB-143.................................           1-8-7         2750/04
MRB 2-21................................          1-82-7         2750/04
MRB 3-152...............................          1-83-7         2750/04
------------------------------------------------------------------------

Initial Backlash Measurement

    (b) Table 2 of this AD identifies service information references 
for the backlash measurement. Operators may have previously used one 
of these references to measure the actuator backlash.

[[Page 11302]]



                Table 2.--Backlash Measurement References
------------------------------------------------------------------------
             Reference                               Date
------------------------------------------------------------------------
Bombardier Alert Service Bulletin    October 31, 2001.
 A8-27-95.
Bombardier Alert Service Bulletin    April 17, 2002.
 A8-27-95, Revision A.
Bombardier Alert Service Bulletin    February 20, 2003.
 A8-27-98.
DHC-8 Maintenance Task Card Manual,  November 23, 2001, or later
 Task No. 2750/18.                    revisions issued before the
                                      effective date of this AD.
Transport Canada Airworthiness       May 2, 2002.
 Directive CF-2002-26.
------------------------------------------------------------------------

    Measure the backlash of each actuator at the applicable time 
specified in paragraph (b)(1) or (b)(2) of this AD, in accordance 
with the Accomplishment Instructions of the applicable Hamilton 
Sundstrand Service Bulletin 734181-27-A5 or 734374-27-A5, both of 
which form part of Bombardier Alert Service Bulletin A8-27-98, dated 
February 20, 2003.
    (1) If the most recent backlash measurement has been done before 
the effective date of this AD in accordance with a reference listed 
in Table 2 of this AD: Do the applicable action specified in Table 3 
of this AD.

        Table 3.--Intervals: Backlash Measurement Done Previously
------------------------------------------------------------------------
   If the measurement was--                      Then--
------------------------------------------------------------------------
                               Do the initial measurement within the
                                later of:
(i) <= 0.027 inch............  3,000 flight cycles since the most recent
                                measurement, or 90 days after the
                                effective date of this AD.
(ii)  0.027 inch    The applicable interval specified in
 and < 0.060 inch, and the      Service Bulletin A8-27-98, or 90 days
 wear rate is recorded or can   after the effective date of this AD.
 be calculated.
(iii)  0.027 inch   The applicable interval, based on a wear
 and < 0.060 inch, but the      rate of 0.010 inch per 1,000 flight
 wear rate is unknown or        cycles, as specified in Service Bulletin
 cannot be calculated due to    A8-27-98, or 90 days after the effective
 lack of data.                  date of this AD.
(iv) = 0.060 inch   The applicable interval specified in
 and < 0.070 inch, and the      Service Bulletin A8-27-98, or 30 days
 wear rate is recorded or can   after the effective date of this AD.
 be calculated.
(v) = 0.060 inch    The applicable interval, based on a wear
 and < 0.070 inch, but the      rate of 0.010 inch per 1,000 flight
 wear rate is unknown or        cycles, as specified in Service Bulletin
 cannot be calculated due to    A8-27-98, or 30 days after the effective
 lack of data.                  date of this AD.
(vi) < 0.050 inch, but not     1,000 flight cycles since the most recent
 recorded.                      measurement, or 90 days after the
                                effective date of this AD.
(vii) = 0.070 inch  Replace the flap actuator with a new or
                                overhauled part: Before further flight.
------------------------------------------------------------------------

    (2) If no backlash measurement has been done as of the effective 
date of this AD in accordance with a reference listed in Table 2 of 
this AD: Do the next measurement at the applicable time specified in 
Table 4 of this AD.

           Table 4.--Intervals: No Prior Backlash Measurement
------------------------------------------------------------------------
     If the actuator, since new or       Then do the initial measurement
     overhauled, has accumulated--                   within--
------------------------------------------------------------------------
(i) <= 3,000 total flight cycles.......  3,000 total flight cycles since
                                          new or overhauled, or within
                                          180 days after the effective
                                          date of this AD, whichever
                                          occurs later.
(ii)  3,000 total flight      60 days after the effective
 cycles.                                  date of this AD.
------------------------------------------------------------------------

Determination of Subsequent Intervals

    (c) After each actuator backlash measurement required by this 
AD, determine (calculate) the next measurement interval by the 
applicable time specified in Table 5 of this AD. To determine each 
interval, use paragraph 2.A.(4)(b) and Figure 4 of the applicable 
Hamilton Sundstrand Service Bulletin 734181-27-A5 or 734374-27-A5, 
both of which form part of Bombardier Alert Service Bulletin A8-27-
98, dated February 20, 2003. Alternatively, the Bombardier 
spreadsheet ``Dash 8 Q100/200/300 Flap Ballscrew Backlash Data, Data 
Recording and Charting Utility,'' document number BM--DHI--RM--
APP01, may be used.

          Table 5.--Timeframe To Determine Subsequent Intervals
------------------------------------------------------------------------
                                          Determine (calculate) the next
  For any recorded backlash that was--              interval--
------------------------------------------------------------------------
(1) = 0.060 inch and < 0.070  Within 45 flight cycles after
 inch.                                    the recorded completion of
                                          backlash measurement.
(2)  0.027 inch and < 0.060   Within 30 days after the
 inch.                                    recorded completion of
                                          backlash measurement.
(3) <= 0.027 inch......................  Within 3,000 flight cycles
                                          after the recorded completion
                                          of backlash measurement.
(4) Not done because the actuator was    Before the accumulation of
 new or newly overhauled.                 3,000 total flight cycles on
                                          the actuator.
------------------------------------------------------------------------


[[Page 11303]]

Subsequent Repetitive Measurements

    (d) After the initial backlash measurement required by paragraph 
(b) of this AD, repeat each subsequent measurement within the 
applicable interval specified in paragraph (c) of this AD, in 
accordance with paragraph 2.A.(1) of the applicable Hamilton 
Sundstrand Service Bulletin 734181-27-A5 or 734374-27-A5, both of 
which form part of Bombardier Alert Service Bulletin A8-27-98, dated 
February 20, 2003.

Follow-on and Corrective Actions

    (e) After each backlash measurement required by paragraph (b) or 
(d) of this AD, do the actions required by paragraph (e)(1) or 
(e)(2), as applicable, of this AD. Do the actions in accordance with 
the Accomplishment Instructions of Bombardier Alert Service Bulletin 
A8-27-98, dated February 20, 2003.
    (1) For any measured backlash of less than 0.070 inch: Repeat 
the measurement within the interval specified in paragraph (c) of 
this AD.
    (2) For any measured backlash of 0.070 inch or more: Replace the 
actuator with a new or overhauled actuator before further flight.

Alternative Methods of Compliance

    (f) In accordance with 14 CFR 39.19, the Manager, New York 
Aircraft Certification Office (ACO), FAA, is authorized to approve 
alternative methods of compliance for this AD.

Incorporation by Reference

    (g) Unless otherwise specified in this AD, the actions must be 
done in accordance with Bombardier Alert Service Bulletin A8-27-98, 
dated February 20, 2003; and the de Havilland temporary revisions to 
the applicable de Havilland Dash-8 Program Support Manuals listed in 
Table 6 of this AD:

                                   Table 6.--de Havilland Temporary Revisions
----------------------------------------------------------------------------------------------------------------
              Service information                     PSM                   Task No.                   Date
----------------------------------------------------------------------------------------------------------------
Temporary Revision MRB-143....................           1-8-7  2750/04.........................   May 18, 2001.
Temporary Revision MRB 2-21...................          1-82-7  2750/04.........................   May 18, 2001.
Temporary Revision MRB 3-152..................          1-83-7  2750/04.........................   May 18, 2001.
----------------------------------------------------------------------------------------------------------------

    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 Bombardier, Inc., Bombardier 
Regional Aircraft Division, 123 Garratt Boulevard, Downsview, 
Ontario M3K 1Y5, Canada. Copies may be inspected at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the FAA, New York Aircraft Certification Office, 
FAA, 1600 Stewart Avenue, suite 410, Westbury, New York; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.

    Note 1: The subject of this AD is addressed in Canadian 
airworthiness directive CF-2002-26R1, dated October 6, 2003.

Effective Date

    (h) This amendment becomes effective on March 25, 2004.

    Issued in Renton, Washington, on March 1, 2004.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-5069 Filed 3-9-04; 8:45 am]
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