[Federal Register Volume 60, Number 231 (Friday, December 1, 1995)]
[Rules and Regulations]
[Pages 61647-61649]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-29329]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-219-AD; Amendment 39-9444; AD 95-24-14]
Airworthiness Directives; de Havilland Model DHC-8 Series
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 de Havilland Model DHC-8 series airplanes.
This action requires eddy current inspections to detect cracking of the
pivot tubes in the drag strut of the nose landing gear (NLG), and
repair or replacement of any cracked tube with a serviceable or new
tube. This amendment is prompted by reports that the pivot tubes
cracked or failed completely due to fatigue. The actions specified in
this AD are intended to prevent such fatigue cracking and subsequent
failure of the pivot tube, which could result in a nose gear-up
landing.
DATES: Effective December 18, 1995.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of December 18, 1995.
Comments for inclusion in the Rules Docket must be received on or
before January 30, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-219-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
The service information referenced in this AD may be obtained from
Bombardier, Inc., Bombardier Regional Aircraft Division, 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, Engine and Propeller Directorate, 10 Fifth Street, Third Floor,
Valley Stream, New York; or at the Office of the Federal Register, 800
North Capitol Street, NW., suite 700, Washington, DC.
[[Page 61648]]
FOR FURTHER INFORMATION CONTACT: Jon Hjelm, Aerospace Engineer,
Airframe Branch, ANE-172, FAA, New York Aircraft Certification Office,
Engine and Propeller Directorate, 10 Fifth Street, Third Floor, Valley
Stream, New York 11581; telephone (516) 256-7523; fax (516) 568-2716.
SUPPLEMENTARY INFORMATION: Transport Canada Aviation, which is the
airworthiness authority for Canada, recently notified the FAA that an
unsafe condition may exist on certain de Havilland Model DHC-8 series
airplanes. Transport Canada Aviation advises that it has received
reports indicating that the pivot tube located in the drag strut of the
nose landing gear (NLG) cracked or failed completely on several Model
DHC-8 series airplanes. During one incident, the NLG failed to extend,
which resulted in damage to the airplane during the subsequent landing.
The cause of these pivot tube failures has been attributed to fatigue.
Fatigue cracking and subsequent failure of the pivot tube in the drag
strut of the NLG, if not detected and corrected in a timely manner,
could result in a nose gear-up landing.
Bombardier, Inc., has issued Service Bulletin S.B. 8-32-131, dated
September 8, 1995, which includes (as an attachment) Messier-Dowty
Service Bulletin M-DT DHC8-32-77, dated July 5, 1995. The Messier-Dowty
service bulletin describes procedures for repetitive high frequency
eddy current inspections to detect cracking of the pivot tube, part
number 8225-3, located in the drag strut of the NLG. The service
bulletin also describes procedures for repair or replacement of any
cracked pivot tube with a serviceable tube having the same part number,
or with a new strengthened tube having part number 8225-5 (de Havilland
Modification 8/2266). This new strengthened tube contains more material
in the waisted area of the center arm. Installation of a new
strengthened pivot tube would eliminate the need for inspections of the
pivot tubes. Transport Canada Aviation classified the Bombardier
service bulletin as mandatory and issued Canadian airworthiness
directive CF-95-15, dated September 11, 1995, in order to assure the
continued airworthiness of these airplanes in Canada.
This airplane model is manufactured in Canada and is 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, Transport Canada Aviation has kept
the FAA informed of the situation described above. The FAA has examined
the findings of Transport Canada Aviation, 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.
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 failure of the
pivot tube in the drag strut of the NLG and a subsequent nose gear-up
landing. This AD requires repetitive eddy current inspections to detect
cracking of the pivot tubes in the drag strut of the NLG, and repair or
replacement of any cracked tube with a serviceable tube having the same
part number or with a new strengthened tube. Installation of a new
strengthened pivot tube, if accomplished, constitutes terminating
action for the inspection requirements of this AD. The actions are
required to be accomplished in accordance with the Bombardier service
bulletin described previously.
Operators should note that the service bulletin recommends
accomplishing the initial eddy current inspection at the following
times: Prior to the accumulation of 13,400 total landings (for drag
strut assemblies with 12,650 or less total landings); within the next
750 landings (for drag strut assemblies with between 12,651 and 20,000
total landings); or within the next 500 landings (for drag strut
assemblies with 20,001 or more total landings). However, the FAA has
determined that these compliance times would not address the identified
unsafe condition in a timely manner. In developing an appropriate
compliance time for this AD, the FAA considered not only the
recommendation specified in the service bulletin, but the degree of
urgency associated with addressing the subject unsafe condition, the
average utilization of the affected fleet, the time necessary to
perform the inspection (less than one hour), and the availability of
replacement parts. In light of all of these factors, the FAA finds that
a compliance time of prior to the accumulation of 13,400 total landings
on the drag strut assembly, or within 30 days after the effective date
of this AD, is appropriate for initiating the required actions in that
it represents the maximum interval of time allowable for affected
airplanes to continue to operate without compromising safety.
Although installation of new strengthened pivot tubes is provided
as an optional terminating action, the FAA is considering further
rulemaking to require the installation of those pivot tubes on all
affected airplanes. Therefore, this AD is considered to be interim
action.
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.
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 95-NM-219-AD.'' The postcard will be date stamped and
returned to the commenter.
The regulations adopted herein will not have substantial direct
effects 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, in
accordance with Executive Order 12612, it is determined that this final
rule does
[[Page 61649]]
not have sufficient federalism implications to warrant the preparation
of a Federalism Assessment.
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
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
1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 106(g), 40101, 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
95-24-14 De Havilland, Inc.: Amendment 39-9444. Docket 95-NM-219-
AD.
Applicability: Model DHC-8 series airplanes, serial numbers 003
through 403 inclusive; and Model DHC-8 series airplanes on which a
drag strut having serial numbers DEC 001/83 through DCL 432/94
inclusive is installed; as listed in Bombardier Service Bulletin
S.B. 8-32-131, dated September 8, 1995; 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 use the authority
provided in paragraph (d) of this AD to request approval from the
FAA. This approval may address either no action, if the current
configuration eliminates the unsafe condition; or different actions
necessary to address the unsafe condition described in this AD. Such
a request should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent failure of the pivot tube in the drag strut of the
nose landing gear (NLG) and a subsequent nose gear-up landing,
accomplish the following:
(a) Prior to the accumulation of 13,400 total landings on the
drag strut assembly, or within 30 days after the effective date of
this AD, whichever occurs later: Perform an eddy current inspection
to detect cracking of the pivot tube, part number (P/N) 8225-3,
located in the drag strut of the NLG, in accordance with Bombardier
Service Bulletin S.B. 8-32-131, dated September 8, 1995.
Note 2: The Bombardier service bulletin includes (as an
attachment) Messier- Dowty Service Bulletin M-DT DHC8-32-77, dated
July 5, 1995. The Messier-Dowty service bulletin details the
specific procedures for accomplishment of the requirements of this
AD.
(1) If no cracking is found, repeat the inspection required by
paragraph (a) of this AD thereafter at intervals not to exceed 2,000
landings.
(2) If any cracking is found that can be removed completely by
reworking the pivot tube in accordance with the service bulletin,
prior to further flight, repair the pivot tube in accordance with
the service bulletin. Thereafter, repeat the inspection required by
paragraph (a) of this AD at intervals not to exceed 1,000 landings.
(3) If any cracking is found that cannot be removed completely
by reworking the pivot tube in accordance with the service bulletin,
prior to further flight, accomplish paragraph (a)(3)(i) or
(a)(3)(ii) of this AD in accordance with the service bulletin.
(i) Replace the cracked pivot tube with a serviceable tube
having P/N 8225-3. Thereafter, perform the repetitive inspections
required by paragraph (a) of this AD. Or
(ii) Replace the cracked pivot tube with a new strengthened tube
having P/N 8225-5. No further action is required by this AD.
(b) Replacement of a pivot tube having P/N 8225-3 with a pivot
tube having P/N 8225-5 (de Havilland Modification 8/2266), in
accordance with Bombardier Service Bulletin S.B. 8-32-131, dated
September 8, 1995, constitutes terminating action for the inspection
requirements of this AD.
(c) As of the effective date of this AD, no person shall install
a drag strut assembly having serial numbers DEC 001/83 through DCL
432/94 inclusive on any airplane unless that assembly has been
inspected and found to be crack-free, or unless that assembly has
been inspected and repaired, in accordance with the requirements of
this AD.
(d) 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, New York Aircraft Certification
Office (ACO), FAA, Engine and Propeller Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, New York ACO.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the New York ACO.
(e) 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.
(f) The actions shall be done in accordance with Bombardier
Service Bulletin S.B. 8-32-131, dated September 8, 1995. 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, 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, Engine and
Propeller Directorate, 10 Fifth Street, Third Floor, Valley Stream,
New York; or at the Office of the Federal Register, 800 North
Capitol Street, NW., suite 700, Washington, DC.
(g) This amendment becomes effective on December 18, 1995.
Issued in Renton, Washington, on November 22, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-29329 Filed 11-30-95; 8:45 am]
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