Airworthiness Directives; de Havilland Model DHC-8-100 and -300 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-89-AD]

Airworthiness Directives; de Havilland Model DHC-8-100 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

series airplanes. This proposal would require inspection to detect

corrosion on areas of the airplane structure where black film thermal

insulation is used, and repair, if necessary; and replacement of black

insulation blankets with certain aluminized (silver) insulation. This

proposal is prompted by reports of corrosion forming on areas of the

airplane structure where the black film covers the thermal insulation

blankets. The actions specified by the proposed AD are intended to

prevent degradation of the structural capability of the airplane

fuselage and sudden loss of cabin pressure due to corrosion of the

airplane fuselage structure.

DATES: Comments must be received by November 21, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-89-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., 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 94-NM-89-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. 94-NM-89-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-8-100 and -300 series airplanes.

Transport Canada Aviation advises that there have been reports of

corrosion forming on areas of the airplane structure where black Orcon

film covers the thermal insulation blankets. Investigation revealed

that the black Orcon film used to insulate the forward fuselage,

passenger compartment, flight compartment, and ventilation ducts

contains carbon. The cause of this corrosion has been attributed to the

formation of condensation on any aluminum airplane structure when it is

in contact with the carbon in the black Orcon film. Such corrosion, if

not detected and corrected in a timely manner, could result in

degradation of the strength of the airplane fuselage structure and

could lead to sudden loss of cabin pressure.

Bombardier, Inc. (formerly de Havilland) has issued Service

Bulletins S.B. 8-25-89, Revision D; S.B. 8-25-90, Revision B; S.B. 8-

25-91, Revision C; S.B. 8-25-92, Revision D; and S. B. 8-25-93,

Revision B; all dated January 19, 1994. These service bulletins

describe procedures for one-time visual inspection to detect corrosion

on areas of the airplane structure where black film thermal insulation

is used, and repaired, if necessary. The service bulletins also

describe procedures for replacement of black Orcon film insulation

blankets with AN4C aluminized (silver) film thermal insulation blankets

in various areas of the airplane structure. Transport Canada Aviation

classified these service bulletins as mandatory and issued Canadian

Airworthiness Directive CF-94-08, dated April 26, 1994, 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

section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) 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 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 a one-time visual

inspection to detect corrosion on areas of the airplane structure where

black film thermal insulation is used, and repaired, if necessary. This

proposed AD also would require replacement of black Orcon film thermal

insulation blankets with AN4C aluminized (silver) film insulation

blankets. The actions would be required to be accomplished in

accordance with the service bulletins described previously.

The FAA estimates that 125 airplanes of U.S. registry would be

affected by this proposed AD, that it would require approximately 650

work hours to accomplish the required actions, at an average labor

charge of $55 per work hour. The FAA has been advised that the

manufacturer plans to provide required parts and to accomplish the

required modification at no expense to operators. Therefore, there is

no cost impact on U.S. operators that is associated with this proposed

rule with regard to labor charges or parts costs.

The FAA does recognize, however, that while operators may incur

administrative costs associated with compliance to this proposed rule,

the one-year compliance time specified in paragraph (a) of this

proposed AD should allow ample time for the proposed requirements to be

accomplished coincidentally with scheduled major airplane inspection

and maintenance activities, thereby minimizing the costs associated

with special airplane scheduling.

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. 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 94-NM-89-AD.

-Applicability: Model DHC-8-100 and -300 series airplanes,

variants and serial numbers specified in paragraph (a) of this AD,

certificated in any category.

-Compliance: Required as indicated, unless accomplished

previously.

To prevent degradation of the structural capability of the

fuselage and sudden loss of cabin pressure, accomplish the

following:

(a) For airplanes listed in the following table: Within one year

after the effective date of this AD, accomplish paragraphs (a)(1)

and (a)(2) of this AD in accordance with the Bombardier Service

Bulletins, all dated January 19, 1994, as listed in the table below,

as applicable.

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Service bulletin Revision

DHC-8 models Airplane serial numbers number level

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101, 102, 103, and 106.............. 003 through 353 inclusive........... S.B. 8-25-89......... D

101, 102, 103, and 106.............. 003 through 380 inclusive........... S.B. 8-25-90......... B

101, 102, 103, 106, 301, 311, and 003 through 337 inclusive, 339, 341 S.B. 8-25-91......... C

314. through 347 inclusive, 349, 350,

351, 353, and 356.

301, 311, and 314 -................. 100 through 336 inclusive, 342, 350, S.B. 8-25-92-........ D

and 356.

301, 311, and 314-.................. 100 through 381 inclusive........... S.B. 8-25-93......... B

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(1) Perform a visual inspection to detect corrosion of the

passenger compartment, flight compartment, forward fuselage, and air

conditioning system. If any corrosion is found; prior to further

flight, repair damage in accordance with the applicable service

bulletin.

(2) Replace the black Orcon film insulation blankets with AN4C

aluminized (silver) film thermal insulation blankets in accordance

with the applicable service bulletin.

(b) As of one year after the effective date of this AD, no

person shall install black Orcon film insulation, part number AN46B/

AN36B, on any airplane.

(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), 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.

(d) 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.

Issued in Renton, Washington, on September 21, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-23813 Filed 9-26-94; 8:45 am]

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