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

SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain de Havilland Model DHC-8-

100 and -300 series airplanes. This proposal would require an

inspection to verify the integrity of the shield grounds for the cable

harness of the electronic engine control (EEC), and correction of any

discrepancy. This proposal also would require measurement of the

electrical resistance of certain shield grounds, and repair, if

necessary. This proposal is prompted by a report of an engine flameout

after a lightning strike, due to several shields for the cable harness

of the EEC not being properly grounded to the airframe. The actions

specified by the proposed AD are intended to prevent engine flameout

due to insufficient protection of the EEC.

DATES: Comments must be received by October 31, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-127-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, Canada M3K 1Y5. 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: Richard Fiesel, Aerospace Engineer,

Propulsion Branch, ANE-174, FAA, Engine and Propeller Directorate, New

York Aircraft Certification Office, 181 South Franklin Avenue, Room

202, Valley Stream, New York 11581; telephone (516) 791-7421; 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-127-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-127-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

On April 25, 1989, the FAA issued AD 85-14-51 R2, amendment 39-6207

(54 FR 19875, May 9, 1989), which is applicable to certain de Havilland

Model DHC-8-100 series airplanes. That AD requires revising the

Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to

prohibit takeoff, landing, and climb in the vicinity of lightning or

thunderstorms; and to require continuous ignition operation during

takeoffs, takeoff climb to 1500 feet above ground level, final

approach, and landing within 5 nautical miles of lightning and

thunderstorms. That AD also requires the installation of four

modifications designed to protect the electronic engine control (EEC)

from the effects of lightning strike, which, when accomplished,

terminates the requirements of that AD and allows for the removal of

the AFM limitations.

Since issuance of that AD, Transport Canada Aviation, which is the

airworthiness authority for Canada, has advised the FAA of a report of

an engine flameout after a lightning strike on a Model DHC-8 series

airplane. Modifications required by AD 85-14-51 R2 had been

accomplished on that airplane. Investigation revealed that the engine

flameout occurred because several shields for the cable harness of the

EEC were not properly grounded to the airframe. This condition, if not

corrected, could result in insufficient protection of the EEC and may

lead to an engine flameout following a lightning strike.

Bombardier has issued Service Bulletins S.B. 8-73-18 (for Model

DHC-8-100 series airplanes) and S.B. 8-73-19 (for Model DHC-8-300

series airplanes), both dated April 29, 1994, which describe procedures

for a visual inspection to verify the integrity of the shield grounds

for the cable harness of the EEC, and correction of any discrepancy.

The service bulletins also describe procedures for measurement of the

electrical resistance of certain shield grounds, and repair, if

necessary. The repair procedures consist of ensuring that the metal

overbraid (which provides lightning protection for the EEC cable

harness) is electrically bonded to the connector and the electrical

receptacles are electrically bonded to the airframe. Transport Canada

Aviation classified these service bulletins as mandatory and issued

Canadian Airworthiness Directive CF-94-09, dated May 5, 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 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 a visual inspection

to verify the integrity of the shield grounds for the cable harness of

the EEC, and correction of any discrepancy. This AD also would require

measurement of the electrical resistance of certain shield grounds, and

repair, if necessary. The actions would be required to be accomplished

in accordance with the service bulletins described previously.

The FAA estimates that 141 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 16 work

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

average labor rate is $55 per work hour. Based on these figures, the

total cost impact of the proposed AD on U.S. operators is estimated to

be $124,080, or $880 per airplane.

The total 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.

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.: 94-NM-127-AD.

Applicability: Model DHC-8-102, -103, and -106 series airplanes,

serial numbers 3 through 369 inclusive; and Model DHC-8-301, -311,

and -314 series airplanes, serial numbers 100 through 370 inclusive;

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent engine flameout following a lightning strike,

accomplish the following:

(a) Within 45 days after the effective date of this AD, perform

a visual inspection of the mounting clamps and ``breakout

junctions'' in the metal overbraid to verify the integrity of the

shield grounds for the cable harness of the electronic engine

control (EEC), in accordance with de Havilland Service Bulletin S.B.

8-73-18 (for Model DHC-8-100 series airplanes), or S.B. 8-73-19 (for

Model DHC-8-300 series airplanes), both dated April 29, 1994, as

applicable. If any discrepancy is found, prior to further flight,

correct the discrepancy in accordance with the applicable service

bulletin.

(b) Within 45 days after the effective date of this AD, perform

an electrical resistance measurement of Class A and Class B shield

grounds in accordance with de Havilland Service Bulletin S.B. 8-73-

18 (for Model DHC-8-100 series airplanes), or S.B. 8-73-19 (for

Model DHC-8-300 series airplanes), both dated April 29, 1994, as

applicable.

(1) For Class A shield grounds: If the electrical resistance

exceeds the value specified in the service bulletin, within 50

flight hours after performing the resistance measurement repair in

accordance with the applicable service bulletin.

(2) For Class B shield grounds: If the electrical resistance

exceeds the value specified in the service bulletin, within 180 days

after performing the resistance measurement repair in accordance

with the applicable service bulletin.

(c) For Model DHC-8-102, -103, and -106 series airplanes on

which an interim shield ground is installed in accordance with

paragraphs 19 and 93 of the Accomplishment Instructions of de

Havilland Service Bulletin S.B. 8-73-18, dated April 29, 1994:

Within one year after the effective date of this AD, restore the

airplane to the Post-Modification 8/0772 configuration in accordance

with paragraph 161 of the Accomplishment Instructions of that

service bulletin.

(d) For Model DHC-8-301, -311, and -314 series airplanes on

which an interim shield ground is installed in accordance with

paragraphs 19 and 112 of the Accomplishment Instructions of de

Havilland Service Bulletin S.B. 8-73-19, dated April 29, 1994:

Within one year after the effective date of this AD, restore the

airplane to the Post-Modification 8/0772 configuration in accordance

with paragraph 200 of the Accomplishment Instructions of that

service bulletin.

(e) 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.

(f) 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 15, 1994.

Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-23327 Filed 9-20-94; 8:45 am]

BILLING CODE 4910-13-U