[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]
BILLING CODE 4910-13-U