[Federal Register Volume 63, Number 80 (Monday, April 27, 1998)]
[Proposed Rules]
[Pages 20552-20554]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-11093]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-336-AD]
RIN 2120-AA64


Airworthiness Directives; de Havilland Model DHC-8-100, -200, and 
-300 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 de Havilland Model DHC-8-
100, -200, and -300 series airplanes. This proposal would require 
modification of the lever assembly of the roll disconnect system. 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 uncommanded 
disconnects of the roll control system, which could result in a limited 
degree of roll control and consequent reduced controllability of the 
airplane.

DATES: Comments must be received by May 27, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-336-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: Anthony E. Gallo, Aerospace Engineer, 
Systems and Flight Test Branch, ANE-172, FAA, Engine and Propeller 
Directorate, New York Aircraft Certification Office, 10 Fifth Street, 
Third Floor, Valley Stream, New York

[[Page 20553]]

11581; telephone (516) 256-7510; 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 97-NM-336-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. 97-NM-336-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 certain de Havilland Model DHC-8-100, -200, and -300 series 
airplanes. TCA advises that it has received several reports of 
uncommanded disconnects of the roll control system during landing, 
while the airplane was flying in turbulent conditions. Such uncommanded 
disconnects have been attributed to a problem with the design of the 
lever assembly of the roll disconnect system, in which turbulence may 
cause the roll control system to disconnect without a member of the 
flightcrew moving the cockpit disconnect handle. Uncommanded 
disconnects of the roll control system may be especially hazardous if 
the flightcrew is unaware that a disconnect has occurred. Such 
uncommanded disconnects of the roll control system, if not corrected, 
could result in a limited degree of roll control and consequent reduced 
controllability of the airplane.
    This airplane model is equipped with a roll control system, which 
provides roll control by interconnecting the ailerons (which are 
controlled by inputs from the copilot's control wheel) and the roll 
spoilers (which are controlled by inputs from the pilot's control 
wheel), thus moving the pilot's and copilot's control wheels in tandem. 
If the roll control system jams, pulling the disconnect handle of the 
roll disconnect system (which is located in the cockpit) disengages the 
roll control system. Disengaging the roll control system causes the 
pilot's and copilot's control wheels to stop moving in tandem, and 
allows the ailerons and roll spoilers to be operated separately. Such 
separate operation limits the degree of roll control available through 
any one of the control wheels and results in reduced controllability of 
the airplane.

Explanation of Relevant Service Information

    The manufacturer has issued Bombardier Service Bulletin 8-27-79, 
Revision `A', dated March 20, 1998, which describes procedures for 
modifying the lever assembly of the roll disconnect system. The 
modification involves inspecting the existing lever return spring and 
replacing it with a new spring, if necessary; drilling a new hole in 
the lever assembly; filling the original hole with sealant; and 
installing the new spring with the lever end of the spring connected to 
a new attachment point for the lever return spring. 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-
98-04, dated February 27, 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 
Sec. 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 the 
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, 
except as discussed below.

Difference Between This Proposed AD and the Parallel Canadian AD 
and the Service Bulletin

    Operators should note that the service bulletin recommends 
accomplishing the action at ``operators' earliest convenience,'' and 
the parallel Canadian airworthiness directive requires compliance 
within 6 months. In light of the criticality of the unsafe condition 
(uncommanded disconnects of the roll control system, which could result 
in a limited degree of roll control and consequent reduced 
controllability of the airplane), the FAA finds a 3-month compliance 
time for accomplishing the proposed actions to be warranted, in that it 
represents an appropriate interval of time allowable for affected 
airplanes to continue to operate without compromising safety.

Cost Impact

    The FAA estimates that 180 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 2 work 
hours per airplane to accomplish the proposed modification, and that 
the average labor rate is $60 per work hour. Based on these figures, 
the cost impact of the proposed AD on U.S. operators is estimated to be 
$21,600, or $120 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

[[Page 20554]]

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:

De Havilland, Inc.: Docket 97-NM-336-AD.

    Applicability: Model DHC-8-100, -200, and -300 series airplanes 
on which Bombardier Modification 8/2376 was not accomplished during 
production; serial numbers 003 through 294 inclusive, and 296 
through 433 inclusive; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (c) 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 uncommanded disconnects of the roll control system, 
which could result in a limited degree of roll control and 
consequent reduced controllability of the airplane; accomplish the 
following:
    (a) Within 3 months after the effective date of this AD, modify 
the lever assembly of the roll disconnect system, in accordance with 
Bombardier Service Bulletin 8-27-79, Revision `A', dated March 20, 
1998.
    (b) As of the effective date of this AD, no person shall install 
on the roll disconnect system of any airplane a lever assembly 
having part number 82710200-001.
    (c) 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.

    (d) Special flight permits may be issued in accordance with 
Secs. 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-98-04, dated February 27, 1998.

    Issued in Renton, Washington, on April 21, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-11093 Filed 4-24-98; 8:45 am]
BILLING CODE 4910-13-U