[Federal Register Volume 63, Number 229 (Monday, November 30, 1998)]
[Proposed Rules]
[Pages 65716-65718]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-31700]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-295-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-7 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Bombardier Model DHC-7 series 
airplanes. This proposal would require removal of all attachment bolts 
and pre-load indicating (PLI) washers of the wing-to-fuselage 
attachment fittings; a one-time visual inspection to detect corrosion 
of each attachment bolt; and installation of new attachment bolts and 
PLI washers of the wing-to-fuselage attachment fittings. 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 prevent failure of the 
attachment bolts of the wing-to-fuselage attachment fittings due to 
stress corrosion cracking, which could result in reduced structural 
integrity of the airplane.

DATES: Comments must be received by December 30, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-295-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: Serge Napoleon, 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) 256-7512; 
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

[[Page 65717]]

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 98-NM-295-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. 98-NM-295-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    Transport Canada Aviation (TCA), which is the airworthiness 
authority for Canada, notified the FAA that an unsafe condition may 
exist on all Bombardier Model DHC-7 series airplanes. TCA advises that 
on two Model DHC-7 series airplanes, two attachment bolts of the wing-
to-fuselage attachment fittings were found broken on each airplane. On 
one airplane, two attachment bolts were corroded and the head of one 
attachment bolt had been completely sheared off, and was attached only 
by the lock wire. A similar incident occurred on another airplane. 
Failure of the attachment bolts was attributed to stress corrosion 
cracking, which was caused by moisture contamination of the wing-to-
fuselage interface. Such cracking, if not detected and corrected, could 
result in reduced structural integrity of the airplane.

Explanation of Relevant Service Information

    The manufacturer has issued Bombardier Service Bulletin S.B. 7-57-
37, dated August 8, 1997, which describes procedures for removal of all 
attachment bolts (one at a time) and pre-load indicating (PLI) washers 
of the wing-to-fuselage attachment fittings; a one-time visual 
inspection to detect corrosion of each attachment bolt; and 
installation of new attachment bolts and PLI washers of the wing-to-
fuselage attachment fittings. The service bulletin also describes 
procedures for notifying Bombardier in the event that corrosion is 
detected on any attachment bolt of the wing-to-fuselage attachment 
fittings.
    Accomplishment of the actions specified in the service bulletin is 
intended to adequately address the identified unsafe condition. TCA 
classified this service bulletin as mandatory and issued Canadian 
airworthiness directive CF-98-12, dated June 24, 1998, 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, TCA has kept the FAA informed of the 
situation described above. The FAA has examined the findings of TCA, 
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.

Cost Impact

    The FAA estimates that 50 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 65 work 
hours per airplane to accomplish the proposed actions and that the 
average labor rate is $60 per work hour. Required parts would cost 
approximately $3,200 per airplane. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be 
$355,000, or $7,100 per airplane.
    The cost impact figure discussed above is based on assumptions 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 98-NM-295-AD.

    Applicability: All Model DHC-7 series airplanes, 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

[[Page 65718]]

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 (b) 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 prevent failure of the attachment bolts of the wing-to-
fuselage attachment fittings due to stress corrosion cracking, which 
could result in reduced structural integrity of the airplane, 
accomplish the following:
    (a) Within 12 months after the effective date of this AD, 
accomplish the requirements of paragraphs (a)(1), (a)(2), and (a)(3) 
of this AD, in accordance with Bombardier Service Bulletin S.B. 7-
57-37, dated August 8, 1997.
    (1) Remove all attachment bolts (one at a time), and pre-load 
indicating (PLI) washers of the wing-to-fuselage attachment 
fittings.
    (2) Perform a one-time visual inspection to detect corrosion of 
each attachment bolt. If any corrosion is detected, within 10 days 
after accomplishing the visual inspection, or within 10 days after 
the effective date of this AD, whichever occurs later, submit a 
report of the inspection results to Bombardier, Inc., Bombardier 
Regional Aircraft Division, Garratt Boulevard, Downsview, Ontario 
M3K 1Y5, Canada. Information collection requirements contained in 
this regulation have been approved by the Office of Management and 
Budget (OMB) under the provisions of the Paperwork Reduction Act of 
1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control 
Number 2120-0056.
    (3) Install new attachment bolts (one at a time), and new PLI 
washers of the wing-to-fuselage attachment fittings.
    (b) 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the New York ACO.

    (c) 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-98-12, dated June 24, 1998.

    Issued in Renton, Washington, on November 20, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-31700 Filed 11-27-98; 8:45 am]
BILLING CODE 4910-13-P