[Federal Register Volume 64, Number 198 (Thursday, October 14, 1999)]
[Proposed Rules]
[Pages 55640-55642]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-26870]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-165-AD]
RIN 2120-AA64
Airworthiness Directives; Bombardier Model DHC-7 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Bombardier Model DHC-7
series airplanes. This proposal would require a one-time visual
inspection to detect corrosion on the upper half of the lower longerons
on the inboard nacelles; and corrective actions, if necessary. This
proposal also would require modification of the upper and lower
longeron halves. This proposal is prompted by issuance of mandatory
continuing airworthiness information by a foreign civil airworthiness
authority. The actions specified by the proposed AD are intended to
detect and correct corrosion in the upper halves of the left and right
hand lower longerons on the inboard nacelles, which could result in a
landing gear failure.
DATES: Comments must be received by November 15, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 99-NM-165-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. Comments may be inspected at this
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except
Federal holidays.
The service information referenced in the proposed rule 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, Engine and Propeller
Directorate, New York Aircraft Certification Office, 10 Fifth Street,
Third Floor, Valley Stream, New York.
FOR FURTHER INFORMATION CONTACT: Franco Pieri, Aerospace Engineer,
Airframe and Propulsion Branch, ANE-171, FAA, Engine and Propeller
Directorate, New York Aircraft Certification Office, 10 Fifth Street,
Third Floor, Valley Stream, New York 11581; telephone (516) 256-7526;
fax (516) 568-2716.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed 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 above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 99-NM-165-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules
Docket No. 99-NM-165-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
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-7 series airplanes. TCCA advises
that severely corroded areas have been found in the upper halves of the
left and right lower longerons on the inboard engine nacelles. The
corrosion was caused by accumulation of moisture in the vicinity of the
longeron cavities and around or under retaining bolt seats. This
condition, if not corrected, could result in landing gear failure.
[[Page 55641]]
Explanation of Relevant Service Information
Bombardier has issued Service Bulletin S.B. 7-54-19, Revision `C,'
dated April 16, 1999, which describes procedures for a one-time visual
inspection to detect corrosion on the upper half of the lower longerons
on the inboard nacelles; and corrective actions, if necessary. The
corrective actions involve blending out corroded areas; performing a
fluorescent penetrant or eddy current inspection to detect cracks in
areas where corrosion was blended out; and repair or replacement of the
longeron with a new longeron, if necessary. The service bulletin also
describes procedures for modification of the upper and lower longeron
halves. The modification involves drilling drainage holes through the
upper and lower longeron halves; finishing all cleaned surfaces with
alodine and chromate epoxy primer; refinishing the longeron assembly
with polyurethane paint; and applying an anti-corrosion compound.
Accomplishment of the actions specified in the service bulletin is
intended to adequately address the identified unsafe condition. TCCA
classified this service bulletin as mandatory and issued Canadian
airworthiness directive CF-99-07, dated March 15, 1999, in order to
assure the continued airworthiness of these airplanes in Canada.
FAA's Conclusions
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, 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 Proposed 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, the proposed AD would require accomplishment of
the actions specified in the service bulletin described previously,
except as discussed below.
Differences Between Proposed Rule and Service Bulletin
Operators should note that, although the service bulletin specifies
that the manufacturer may be contacted for disposition of certain
cracks, this proposal would require the repair of those conditions to
be accomplished in accordance with a method approved by either the FAA,
or TCCA (or it's delegated agent). In light of the type of repair that
would be required to address the identified unsafe condition, and in
consonance with existing bilateral airworthiness agreements, the FAA
has determined that, for this proposed AD, a repair approved by either
the FAA or TCCA (or it's delegated agent) would be acceptable for
compliance with this proposed AD.
Cost Impact
The FAA estimates that 32 airplanes of U.S. registry would be
affected by this proposed AD.
It would take approximately 8 work hours per airplane to accomplish
the proposed inspection, at an average labor rate of $60 per work hour.
Based on these figures, the cost impact of the proposed AD on U.S.
operators is estimated to be $15,360, or $480 per airplane.
It would take approximately 12 work hours per airplane to
accomplish the proposed modification, at an average labor rate of $60
per work hour. Based on these figures, the cost impact of the
modification proposed by this AD on U.S. operators is estimated to be
$23,040, or $720 per airplane.
The cost impact figures discussed above are based on the assumption
that no operator has yet accomplished any of the proposed requirements
of this AD action, and that no operator would accomplish those actions
in the future if this AD were not adopted.
Regulatory Impact
The regulations proposed herein would 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
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (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) if promulgated, 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. A copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting the Rules
Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
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 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Bombardier, Inc. (Formerly de Havilland, Inc.): Docket 99-NM-165-AD.
Applicability: Model DHC-7 series airplanes, serial numbers 004
through 113 inclusive, except serial numbers 037 and 061;
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 request approval for an
alternative method of compliance in accordance with paragraph (d) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated, unless accomplished
previously.
To detect and correct corrosion in the upper halves of the left and
right hand lower longerons on the inboard nacelles, which could result
in a landing gear failure, accomplish the following:
Inspection
(a) Within 6 months after the effective date of this AD, perform
a visual inspection to detect corrosion on the upper half of the
[[Page 55642]]
lower longerons on the inboard nacelles in accordance with
Bombardier Service Bulletin S.B. 7-54-19, Revision `C,' dated April
16, 1999.
Modification
(b) If no corrosion is detected, prior to further flight, modify
the upper and lower longeron halves in accordance with Bombardier
Service Bulletin S.B. 7-54-19, Revision `C,' dated April 16, 1999.
Corrective Action
(c) If any corrosion is detected, prior to further flight,
accomplish the actions specified in paragraph (c)(1) or (c)(2) of
this AD, as applicable, in accordance with Bombardier Service
Bulletin S.B. 7-54-19, Revision `C,' dated April 16, 1999.
(1) For corrosion that is within the limits specified in the
service bulletin: Accomplish the corrective actions specified in the
service bulletin, and perform a fluorescent penetrant inspection or
high frequency eddy current inspection to detect cracks in areas
where corrosion was blended out. The corrective actions and
inspections shall be done in accordance with the service bulletin.
(i) If no crack is detected, prior to further flight, modify the
upper and lower longeron halves in accordance with the service
bulletin.
(ii) If any crack is detected, prior to further flight,
accomplish the actions required by paragraphs (c)(1)(ii)(A) and
(c)(1)(ii)(B) of this AD.
(A) Either replace the longeron with a new longeron in
accordance with the service bulletin, or repair in accordance with a
method approved by either the Manager, New York Aircraft
Certification Office (ACO), FAA, Engine and Propeller Directorate;
or Transport Canada Civil Aviation (or it's delegated agent). For a
repair method to be approved by the Manager, New York ACO, as
required by this paragraph, the Manager's approval letter must
specifically reference this AD.
(B) Modify the upper and lower longeron halves in accordance
with the service bulletin.
(2) For corrosion that exceeds the limits specified in the
service bulletin: Accomplish the actions required in paragraphs
(c)(1)(ii)(A) and (c)(1)(ii)(B) of this AD.
Alternative Methods of Compliance
(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 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 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the New York ACO.
Special Flight Permits
(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.
Note 3: The subject of this AD is addressed in Canadian
airworthiness directive CF-99-07, dated March 15, 1999.
Issued in Renton, Washington, on October 7, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-26870 Filed 10-13-99; 8:45 am]
BILLING CODE 4910-13-P
