[Federal Register Volume 69, Number 40 (Monday, March 1, 2004)]
[Rules and Regulations]
[Pages 9523-9526]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-4373]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-CE-73-AD; Amendment 39-13493; AD 2004-05-01]
RIN 2120-AA64


Airworthiness Directives; Bombardier Inc. Model Otter DHC-3 
Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA adopts a new airworthiness directive (AD) for certain 
Bombardier Inc. (formerly deHavilland Inc.) Model Otter DHC-3 airplanes 
that have turbine engines installed per one of three supplemental type 
certificates (STC). This AD prohibits you from operating any affected 
airplane with these engine and propeller configurations unless a new 
STC for an elevator servo-tab with a redundant control linkage is 
installed. This AD is the result of reports of the control rod to the 
elevator servo-tab system detaching from the elevator servo-tab, which 
caused the elevator servo-tab to flutter on airplanes with a turbine 
engine installed. We are issuing this AD to prevent a single failure of 
the elevator servo-tab system, which could cause severe tab flutter. 
This failure could lead to possible loss of control of the airplane.

DATES: This AD becomes effective on April 20, 2004.
    As of April 20, 2004, the Director of the Federal Register approved 
the incorporation by reference of certain publications listed in the 
regulation.

ADDRESSES: You may get the service information identified in this AD 
from:
     For STC No. SA3777NM: A.M. Luton 3025 Eldridge 
Avenue, Bellingham, Washington 98225; telephone (360) 671-7817; 
facsimile (360) 671-7820.
     For STC No. SA09866SC: Texas Turbine 
Conversions, Inc., 8955 CR 135, Celina, Texas 75009; telephone: (972) 
382-4402; facsimile: (972) 382-4402.
     For STC No. SA09857SC: Canada Turbine 
Conversions, Inc., Lot 16, 105081 Highway 11, Pine Falls MB ROE 1MO, 
Canada.
     For STC No. SA01059SE: American Aeromotives, 
Inc. (American Aeromotives), 3025 Eldridge Avenue, Bellingham, 
Washington 98225, telephone: (360) 671-7817; facsimile: (360) 671-7820.
    You may view the AD docket at FAA, Central Region, Office of the 
Regional Counsel, Attention: Rules Docket No. 2000-CE-73-AD, 901 
Locust, Room 506, Kansas City, Missouri 64106. Office hours are 8 a.m. 
to 4 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:
     For STC No. SA3777NM or STC No. SA01059SE: 
Richard Simonson, Aerospace Engineer, FAA, Seattle Aircraft 
Certification Office (ACO), 1601 Lind Avenue, SW., Renton, Washington 
98055; telephone: (425) 917-6507; facsimile: (425) 917-6590.
     For STC No. SA09866SC: Richard Karanian, 
Aerospace Engineer, Special Certification Office, FAA, Rotorcraft 
Directorate, Special Certification Office, 2601 Meacham Boulevard, Fort 
Worth, Texas 76193-0190; telephone: (817) 222-5195; facsimile: (817) 
222-5959.
     For STC No. SA09857SC: Peter W. Hakala, 
Aerospace Engineer, FAA, Special Certification Office, Rotorcraft 
Directorate, 2601 Meacham Boulevard, Fort Worth, Texas 76193-0190; 
telephone: (817) 222-5145; facsimile: (817) 222-5785.

SUPPLEMENTARY INFORMATION:

Discussion

    What events have caused this AD? The FAA has received several 
reports of situations where pilots of Bombardier Inc. Model Otter DHC-3 
airplanes with installed turbine engines have experienced buffeting of 
the elevators. All pilots declared an emergency and safely landed their 
aircraft.
    Investigation found that the control rod to the elevator servo-tab 
system detached from the elevator servo-tab and caused the elevator 
servo-tab to flutter. In all cases, the aircraft had been modified with 
a Pratt and Whitney PT6A-135 or a PT6A-34 turbine engine per STC No. 
SA3777NM.
    The certification basis for STC SA3777NM includes freedom from 
flutter and control reversal and divergence, required by 14 CFR 
23.629(f)(1). Further review reveals that this requirement was not 
complied with when the STC was issued. Subsequent to the issuance of 
the STC, single failures of the control system for the servo-tab began 
causing the servo-tab to flutter. The failures were attributed to the 
increased velocity and airflow over the servo-tab caused by the turbine 
conversion.
    As a method of compliance with 14 CFR 23.629(f)(1), American 
Aeromotives has identified the installation of STC No. SA01059SE (a new 
elevator servo-tab and redundant control linkage) on aircraft modified 
with a Pratt and Whitney PT6A-34/-135 turbine engine per STC No. 
SA3777NM.
    FAA has inspected affected airplanes with STC No. SA09866SC or STC 
No. SA09857SC installed and confirmed that the same unsafe condition 
exists. At this time, neither of these two STC holders has identified a 
method of compliance with 14 CFR 23.629(f)(1).
    As a method of compliance with 14 CFR 23.629(f)(1), FAA has 
identified the installation of STC No. SA01059SE (a new elevator servo-
tab and redundant control linkage) on aircraft modified with STC No. 
SA09866SC or STC No. SA09857SC.
    What is the potential impact if FAA took no action? A single 
failure of the elevator servo-tab system could cause severe tab flutter 
and lead to possible loss of control of the airplane.

[[Page 9524]]

    Has FAA taken any action to this point? We issued a proposal to 
amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to 
include an AD that would apply to certain Bombardier Inc. (formerly 
deHavilland Inc.) Model Otter DHC-3 airplanes that have turbine engines 
installed per one of three supplemental type certificates (STC). This 
proposal was published in the Federal Register as a notice of proposed 
rulemaking (NPRM) on November 5, 2003 (68 FR 62454). The NPRM proposed 
to prohibit you from operating any affected airplane that incorporates 
STC No. SA3777NM, STC No. SA09866SC, or STC No. SA09857SC without 
incorporation of STC No. SA01059SE.

Comments

    Was the public invited to comment? We provided the public the 
opportunity to participate in developing this AD. The following 
presents the comments received on the proposal and FAA's response to 
each comment:

Comment Issue No. 1: Remove the Link Between STCs SA01059SE and 
ST01243NY

    What is the commenter's concern? One commenter requests removing 
the link between STCs SA01059SE and ST01243NY. The STC SA01059SE 
references STC ST01243NY by permitting a combined installation of both. 
The STC ST01243NY is an FAA version of the Canadian STC SA99-129.
    The STC SA99-129 introduced a mass-balance servo-tab which 
experienced failures until corrected in STC SA99-129, Revision 3, which 
required structural modifications to attach the mass-balance servo-tab 
(which does not exist in that model).
    The use of dissimilar actuators increases the risk of ``force 
fighting'' and an additional loading unaccounted for in STC SA99-129, 
Revision 3.
    What is FAA's response to the concern? We do not believe it is 
necessary to remove any link between STCs SA01059SE and ST01243NY since 
a link is not discussed in the proposed AD. The proposed AD requires 
only the installation of STC SA01059SE.
    During testing, FAA investigated the interaction of STC SA01059SE 
with STC ST01243NY and found that the STCs are compatible. The link is 
noted in STC SA01059SE only to assist the installer in establishing the 
compatibility between the two STCs.
    The risk of ``force fighting'' was addressed during the development 
of STC SA01059SE. The geometry differences are not significant and, 
during the flight test program, the mass-balance servo-tab was 
demonstrated to work smoothly throughout the elevator control travel.
    We are not making any changes to the final rule AD action.

Comment Issue No. 2: Identify STC ST01243NY (Canadian STC SA99-129, 
Revision 3) as an Approved Alternative Method of Compliance

    What is the commenter's concern? Two commenters request that FAA 
identify STC ST01243NY (STC SA99-129, Revision 3) as an approved 
alternative method of compliance since this STC has been demonstrated 
to prevent the elevator servo-tab from fluttering when the control rod 
to the servo-tab system becomes detached.
    What is FAA's response to the concern? We agree that Canadian STC 
SA99-129, Revision 3, is an acceptable method of compliance to the AD. 
However, FAA has not determined if the latest version of STC ST01243NY 
(amended March 18, 2002) corresponds to the Canadian STC SA99-216, 
Revision 3. Aircraft that have been modified under STC ST01243NY will 
be evaluated under paragraph (f), alternative method of compliance, of 
the AD and the procedures in 14 CFR 39.19 to determine if the 
modification corresponds to the Canadian STC SA99-216, Revision 3.
    We are not making any changes to the final rule AD action.

Comment Issue No. 3: Inspection and Maintenance of the New Mass-Balance 
Servo-tab and the Servo-tab System

    What is the commenter's concern? One commenter notes that one cause 
of the problems with the first version of STC ST01243NY (STC SA99-129) 
was the retrofit of the existing mass-balance servo-tab. Therefore, the 
use of a completely new mass-balance servo-tab is fundamental. The 
commenter recommends that maintenance and inspection requirements 
include the critical points in the design.
    What is FAA's response to the concern? We agree with the 
commenter's suggestion. The STC SA01059SE requires a completely new 
mass-balance servo-tab, reinforced at the second attachment. In 
addition, the trailing edge is an extrusion and the outboard end block 
is one-piece aluminum. The Instructions for Continuing Airworthiness 
(ICA) for STC SA01059SE require periodic inspection and maintenance of 
the new mass-balance servo-tab and the servo-tab system.
    Since the commenter's recommendation is in effect, we are not 
making any changes to the final rule AD action.

Comment Issue No. 4: Carefully Review Any Proposed Structural 
Modification to the Tab and Elevator

    What is the commenter's concern? There have been several reports of 
servo-tab failures on piston-powered Model DHC-3 airplanes. At least 
one reported failure involved a severed servo-tab and distressed 
elevator in the region where the second actuator is installed following 
STC SA01059SE. Although the failure progression for the severed servo 
and distressed elevator is not known, one commenter suggests a cautious 
approach to any proposed structural modifications to the servo-tab and 
elevator.
    What is FAA's response to the concern? The FAA agrees with the 
suggestion of taking a cautious approach to any proposed structural 
modifications to the servo-tab and elevator. We considered this failure 
mode during the design of the completely new servo-tab installed 
following STC SA01059SE. The structural modifications to the rear spar 
of the horizontal stabilizer for mounting of the second control rod 
acts to strengthen the rear spar area. The new servo-tab is designed to 
handle a conservative aerodynamic load with only the second rod 
attached. The new servo-tab is considerably stronger in bending than 
the original servo-tab.
    We are not making any changes to the final rule AD action.

Comment Issue No. 5: Lack of a Dual Actuator for the Rudder Tab

    What is the commenter's concern? One commenter requests that the 
proposed AD also address the lack of a dual actuator for the rudder 
tab. The commenter explains that although only the elevator servo-tab 
has displayed service difficulties in the past, strict application of 
14 CFR 39.13 would also require modifying the rudder tab to either a 
dual actuator or a mass balanced configuration.
    There is no reference to modifying the rudder trim system in STC 
SA01059SE. In this context, the rudder is less affected by the 
increased swirl of the propeller stream since the rudder is already in 
the turbulent body flow region, whereas, the servo-tab actuator is more 
exposed to the increased propeller tip effects. Therefore, the lack of 
reference to the rudder trim system is not contentious as there have 
been no reports of increased difficulties in this area.
    What is FAA's response to the concern? We disagree with the

[[Page 9525]]

recommendation that the proposed AD address the lack of a dual actuator 
for the rudder tab. Since the rudder is less affected by the increased 
swirl of the propeller stream and due to the lack of reported service 
difficulties with the rudder trim system, we will not require a dual 
actuator for the rudder trim system in this AD.
    We are not making any changes to the final rule AD action.

Comment Issue No. 6: Use Correct and Consistent Terminology

    What is the commenter's concern? One commenter requests that we 
change the term ``Servo trim tab'' to ``elevator servo-tab'' and 
``elevator flutter'' to ``tab flutter''. These changes are for 
consistency and correctness.
    What is FAA's response to the concern? We agree and will make these 
changes throughout the AD.

Conclusion

    What is FAA's final determination on this issue? We have carefully 
reviewed the available data and determined that air safety and the 
public interest require adopting the AD as proposed except for the 
changes discussed above and minor editorial corrections. We have 
determined that these changes and minor corrections:

--Are consistent with the intent that was proposed in the NPRM for 
correcting the unsafe condition; and
--Do not add any additional burden upon the public than was already 
proposed in the NPRM.

Changes to 14 CFR Part 39--Effect on the AD

    How does the revision to 14 CFR part 39 affect this AD? On July 10, 
2002, the FAA published a new version of 14 CFR part 39 (67 FR 47997, 
July 22, 2002), which governs the FAA's AD system. This regulation now 
includes material that relates to altered products, special flight 
permits, and alternative methods of compliance. This material 
previously was included in each individual AD. Since this material is 
included in 14 CFR part 39, we will not include it in future AD 
actions.

Costs of Compliance

    How many airplanes does this AD impact? We estimate that this AD 
affects 32 airplanes in the U.S. registry.
    What is the cost impact of this AD on owners/operators of the 
affected airplanes? We estimate the following costs to do the 
modification (on Model DHC-3 airplanes with a turbine engine) for 
installing STC No. SA01059SE, a new elevator servo-tab and redundant 
control linkage. We have no way of determining the number of airplanes 
that may need such modification:

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                                                   Parts
                   Labor cost                       cost                   Total cost per airplane
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20 workhours x $65 per hour = $1,300...........     $3,000  $1,300 + $3,000 = $4,300.
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Compliance Time of This AD

    What will be the compliance time of this AD? The compliance time of 
this AD is within 3 calendar months or 250 hours time-in-service (TIS) 
after the effective date of this AD, whichever occurs first.
    Why is the compliance time of this AD presented in both hours TIS 
and calendar time? A single failure of the elevator servo-tab system is 
a direct result of airplane operation with a turbine engine installed. 
For example, a single failure of the elevator servo-tab system could 
occur on an affected airplane within a short period of airplane 
operation while you could operate another affected airplane for a 
considerable amount of time without experiencing a single failure of 
the elevator servo-tab system. Therefore, to assure that a single 
failure of the elevator servo-tab system is detected and corrected in a 
timely manner without inadvertently grounding any of the affected 
airplanes, we are using a compliance time based upon both hours TIS and 
calendar time.

Regulatory Findings

    Will this AD impact various entities? We have determined that this 
AD will not have federalism implications under Executive Order 13132. 
This AD 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.
    Will this AD involve a significant rule or regulatory action? For 
the reasons discussed above, I certify that this AD:
    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 summary of the costs to comply with this AD and 
placed it in the AD Docket. You may get a copy of this summary by 
sending a request to us at the address listed under ADDRESSES. Include 
``AD Docket No. 2000-CE-73-AD'' in your request.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under 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. FAA amends Sec.  39.13 by adding a new AD to read as follows:

2004-05-01 Bombardier Inc.: Amendment 39-13493; Docket No. 2000-CE-
73-AD.

When Does This AD Become Effective?

    (a) This AD becomes effective on April 20, 2004.

What Other ADs Are Affected by This Action?

    (b) None.

What Airplanes Are Affected by This AD?

    (c) This AD affects any Model Otter DHC-3 airplane (all serial 
numbers) that:
    (1) Has a turbine engine installed per:
    (i) Supplemental Type Certificate (STC) No. SA3777NM (A.M. Luton 
installation of Pratt and Whitney PT6A-34/-135 engine);
    (ii) STC No. SA09866SC (Texas Turbines Conversions, Inc. 
installation of Honeywell TPE-331 engine); or
    (iii) STC No. SA09857SC (Canada Turbine Conversions, Inc. 
installation of Walter M601E-11 engine); and
    (2) Is certificated in any category.

What Is the Unsafe Condition Presented in This AD?

    (d) This AD is the result of reports that the control rod to the 
elevator servo-tab system detached from the elevator servo-tab 
causing the elevator servo-tab to flutter on airplanes

[[Page 9526]]

with a turbine engine installed. The actions specified in this AD 
are intended to prevent a single failure of the elevator servo-tab 
system causing severe tab flutter. This failure could lead to 
possible loss of control of the airplane.

What Must I Do To Address This Problem?

    (e) To address this problem, you must do the following:

------------------------------------------------------------------------
           Actions                 Compliance            Procedures
------------------------------------------------------------------------
(1) Do not operate any        As of 3 calendar      Not Applicable.
 airplane that has a turbine   months or 250 hours
 engine installed per: STC     time-in-service
 No. SA3777NM, SA09866SC, or   (TIS) after April
 SA09857SC and DOES NOT have   20, 2004 (the
 a new elevator servo-tab      effective date of
 and redundant control         this AD), whichever
 linkage per STC No.           occurs first.
 SA01059SE.
(2) You may install at the    Before further        Follow American
 same time a turbine engine    flight as of April    Aeromotives, Inc.
 per STC No. SA3777NM,         20, 2004 (the         DHC-3 Otter Service
 SA09866SC, or SA09857SC and   effective date of     Letter No. AAI-DHC3-
 a new elevator servo-tab      this AD).             01.01, Revision No.
 and redundant control                               IR, dated April 9,
 linkage per STC No.                                 2002.
 SA01059SE.
(3) You may operate an        Within 3 calendar     Follow American
 affected airplane installed   months or 250 hours   Aeromotives, Inc.
 with a turbine engine per     TIS after April 20,   DHC-3 Otter Service
 STC No. SA777NM, SA09866SC,   2004 (the effective   Letter No. AAI-DHC3-
 or SA09857SC if you install   date of this AD),     02.01, Revision No.
 a new elevator servo-tab      whichever occurs      IR, dated April 9,
 and redundant contol          first.                2002.
 linkage per STC No.
 SA01059SE.
(4) Do not install a turbine  As of April 20, 2004  No Applicable.
 engine per STC No.            (the effective date
 SA3777NM, SA09866SC, or       of this AD).
 SA09857SC, unless you have
 installed a new elevator
 servo-tab and redundant
 control linkage per STC No.
 SA01059SE.
------------------------------------------------------------------------

May I Request an Alternative Method of Compliance?

    (f) You may request a different method of compliance or a 
different compliance time for this AD by following the procedures in 
14 CFR 39.19. Unless FAA authorizes otherwise, send your request to 
your principal inspector. The principal inspector may add comments 
and will send your request to the Manager, Seattle Aircraft 
Certification Office (ACO), FAA. For information on any already 
approved alternative methods of compliance, contact:
    (1) For STC No. SA3777NM or STC No. SA01059SE: Richard Simonson, 
Aerospace Engineer, FAA, Seattle Aircraft Certification Office 
(ACO), 1601 Lind Avenue, SW., Renton, Washington 98055; telephone: 
(425) 917-6507; facsimile: (425) 917-6590.
    (2) For STC No. SA09866SC: Richard Karanian, Aerospace Engineer, 
Special Certification Office, FAA, Rotorcraft Directorate, Special 
Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 
76193-0190; telephone: (817) 222-5195; facsimile: (817) 222-5959.
    (3) For STC No. SA09857SC: Peter W. Hakala, Aerospace Engineer, 
FAA, Special Certification Office, Rotorcraft Directorate, 2601 
Meacham Boulevard, Fort Worth, Texas 76193-0190; telephone: (817) 
222-5145; facsimile: (817) 222-5785.

Does This AD Incorporate Any Material by Reference?

    (g) You must do the actions required by this AD following the 
instructions in American Aeromotives, Inc. DHC-3 Otter Service 
Letter No. AAI-DHC3-02.01, Revision No. IR, dated April 9, 2002. The 
Director of the Federal Register approved the incorporation by 
reference of this service letter in accordance with 5 U.S.C. 552(a) 
and 1 CFR part 51. You may get a copy from American Aeromotives, 
Inc., 3025 Eldridge Avenue, Bellingham, Washington 98225, telephone: 
(360) 671-7817; facsimile: (360) 671-7820. You may review copies at 
FAA, Central Region, Office of the Regional Counsel, 901 Locust, 
Room 506, Kansas City, Missouri 64106; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.


    Issued in Kansas City, Missouri, on February 20, 2004.
Dorenda D. Baker,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 04-4373 Filed 2-27-04; 8:45 am]
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