[Federal Register: March 1, 2004 (Volume 69, Number 40)]
[Rules and Regulations]
[Page 9523-9526]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr01mr04-4]
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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:
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Actions Compliance Procedures
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(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.
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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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