[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