Airworthiness Directives; de Havilland Model DHC-8-301 Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-203-AD]

Airworthiness Directives; de Havilland Model DHC-8-301 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-

301 airplanes. This proposal would require modification of the sidewall

panels in the passenger cabin. This proposal is prompted by a report

that inadequate venting between the cabin and the compartments beneath

the floor could occur during rapid fuselage decompression. The actions

specified by the proposed AD are intended to prevent collapse of the

floor and subsequent injury to passengers.

DATES: Comments must be received by March 29, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 93-NM-203-AD, 1601 Lind Avenue SW., Renton,

Washington 98055-4056. Comments may be inspected at this location

between 9 a.m. and 3 p.m., Monday through Friday, except Federal

holidays.

The service information referenced in the proposed rule may be

obtained from de Havilland, Inc., 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, 181 South Franklin Avenue, room 202, Valley

Stream, New York.

FOR FURTHER INFORMATION CONTACT: Jon Hjelm, Aerospace Engineer,

Airframe Branch, ANE-172, FAA, Engine and Propeller Directorate, New

York Aircraft Certification Office, 181 South Franklin Avenue, room

202, Valley Stream, New York 11581; telephone (516) 791-6220; fax (516)

791-9024.

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 93-NM-203-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-103, Attention: Rules

Docket No. 93-NM-203-AD, 1601 Lind Avenue SW., Renton, Washington

98055-4056.

Discussion

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-8-301 airplanes. Transport Canada

Aviation advises that, during a post-certification review of the design

for cabin venting between compartments, the manufacturer discovered

that the cabin and the compartments beneath the floor could be

inadequately vented during rapid fuselage decompression of these

airplanes. This condition is the result of movement of the sidewall

panels in the passenger cabin, which may partially block the vents

along the bottom edges of the panels. This condition, if not corrected,

could result in collapse of the floor and subsequent injury to

passengers.

De Havilland has issued Service Bulletin No. 8-25-53, dated August

4, 1989, that describes procedures for modification of the sidewall

panels in the passenger cabin (Modification No. 8/1339). The

modification entails bonding spacers along the lower edge of the cabin

sidewall panels to provide support. Installation of the spacers will

ensure that intercompartmental venting is maintained in the event of

rapid fuselage decompression. Transport Canada Aviation classified this

service bulletin as mandatory and issued Canadian Airworthiness

Directive No. CF-90-26, dated November 29, 1990, 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

Sec. 21.29 of the Federal Aviation Regulations 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, the proposed AD would require modification of the

sidewall panels in the passenger cabin. The actions would be required

to be accomplished in accordance with the service bulletin described

previously.

The FAA estimates that 23 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 32 work

hours per airplane to accomplish the proposed actions, and that the

average labor rate is $55 per work hour. Required parts would be

provided by the manufacturer at no cost to operators. Based on these

figures, the total cost impact of the proposed AD on U.S. operators is

estimated to be $40,480, or $1,760 per airplane. This total cost figure

assumes that no operator has yet accomplished the proposed requirements

of this AD action.

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 14

CFR part 39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

De Havilland, Inc: Docket 93-NM-203-AD.

Applicability: Model DHC-8-301 airplanes; serial numbers 116

through 185 inclusive, 187, and 188; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent collapse of the floor and subsequent injury to

passengers, accomplish the following:

(a) Within 6 months after the effective date of this AD, modify

the sidewall panels in the passenger cabin (Modification No. 8/1339)

in accordance with de Havilland Service Bulletin No. 8-25-53, dated

August 4, 1989.

(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), ANE-170, 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: 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 FAR

21.197 and 21.199 to operate the airplane to a location where the

requirements of this AD can be accomplished.

Issued in Renton, Washington, on January 27, 1994.

James V. Devany,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-2333 Filed 2-1-94; 8:45 am]

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