Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-233-AD]

Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B

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 Saab Model SAAB SF340A and

SAAB 340B series airplanes. This proposal would require an inspection

of the elevator and aileron coves, and further inspections and repair,

if necessary. This proposal is prompted by a report of delamination

between the composite structure and the aluminum foil on the elevator

cove on a Model SAAB SF340B series airplane. The design of the aileron

cove is similar to that of the elevator cove on Model SAAB SF340A and

SAAB 340B series airplanes. The actions specified by the proposed AD

are intended to prevent jamming of the aileron or elevator.

DATES: Comments must be received by April 4, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 93-NM-233-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 Saab Aircraft AB, SAAB Aircraft Product Support, S-

581.88, Linkoping, Sweden. This information may be examined at the FAA,

Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington.

FOR FURTHER INFORMATION CONTACT: Mark Quam, Aerospace Engineer,

Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)

227-2145; fax (206) 227-1320.

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-233-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-233-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The Luftfartsverket (LFV), which is the airworthiness authority for

Sweden, recently notified the FAA that an unsafe condition may exist on

certain Saab Aircraft AB Model SAAB SF340A and SAAB 340B series

airplanes. The LFV advises that, when the pilot of a Model SAAB SF340B

series airplane disengaged the autopilot during approach for landing,

the elevators required additional force in order to be operated

correctly. Investigation revealed that delamination had occurred

between the composite structure and the aluminum foil on the elevator

cove. When water entered the delaminated area and froze, the aluminum

foil was raised further, causing contact with the elevator. The design

of the aileron cove is similar to that of the elevator cove on Model

SAAB SF340A and SAAB 340B series airplanes. The design consists of a

composite structure with a conductive layer, which is composed of

aluminum foil, conductive paint, or expanded aluminum foil (stretched

metal--aluminum net). Delamination and freezing of trapped water in the

aileron or elevator could lead to jamming of these parts.

Saab has issued Service Bulletin 340-51-012, dated November 10,

1993, that describes procedures for an inspection of the elevator and

aileron coves to verify the type of antistatic protection (black

conductive paint or expanded aluminum foil (an aluminum net)) applied

to the coves. For coves that are found without conductive paint or

expanded aluminum foil, the service bulletin describes procedures for a

detailed visual inspection and delamination tap test to detect aluminum

foil delamination on the coves; and either a temporary repair and

repetitive detailed visual inspections and delamination tap tests of

the coves, or a permanent repair of the coves. The temporary repair

involves applying aluminum tape or conductive paint to the delaminated

area, and accomplishing repetitive detailed visual inspections and

delamination tap tests of the cove. The permanent repair entails either

applying conductive paint or expanded aluminum foil (stretched metal--

aluminum net) to the cove. Accomplishment of the permanent repair would

terminate the repetitive detailed visual inspections and delamination

tap tests. The LFV classified this service bulletin as mandatory and

issued Swedish Airworthiness Directive No. 1-060, dated November 15,

1993, in order to assure the continued airworthiness of these airplanes

in Sweden.

This airplane model is manufactured in Sweden 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, the LFV has kept the FAA informed of the

situation described above. The FAA has examined the findings of the

LFV, 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 an inspection of

the elevator and aileron coves to verify the type of antistatic

protection applied to the coves. For coves that are found without

conductive paint or expanded aluminum foil, the proposed AD would

require a detailed visual inspection and delamination tap test to

detect aluminum foil delamination on the coves; and either a temporary

repair and repetitive detailed visual inspections and delamination tap

tests of the coves, or a permanent repair of the coves. Accomplishment

of the permanent repair would terminate the repetitive detailed visual

inspections and delamination tap tests. The actions would be required

to be accomplished in accordance with the service bulletin described

previously.

The FAA estimates that 152 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 20 work

hours per airplane to accomplish the proposed inspection, 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 $167,200, or $1,100 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:

SAAB Aircraft AB: Docket 93-NM-233-AD.

Applicability: Model SAAB SF340A series airplanes, serial

numbers -004 through -159 inclusive; and Model SAAB 340B series

airplanes, serial numbers -160 through -260 inclusive; certificated

in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent jamming of the aileron or elevator, accomplish the

following:

(a) Within 500 hours time-in-service or 90 days after the

effective date of this AD, whichever occurs first, perform an

inspection of the elevator and aileron coves to verify the type of

antistatic protection applied to the coves, in accordance with SAAB

Service Bulletin 340-51-012, dated November 10, 1993.

(b) If a cove has conductive paint or expanded aluminum foil

(stretched metal--aluminum net), no further action is required by

this AD for that cove.

(c) If a cove does not have conductive paint or expanded

aluminum foil (stretched metal--aluminum net), prior to further

flight, perform a detailed visual inspection and delamination tap

test to detect aluminum foil delamination on the elevator or aileron

cove, in accordance with the service bulletin.

(1) If no delamination is found, repeat the detailed visual

inspection and delamination tap test thereafter at intervals not to

exceed 800 hours time-in-service in accordance with the service

bulletin.

(2) If any delamination is found, prior to further flight,

accomplish either paragraph (c)(2)(i) or (c)(2(ii) of this AD.

(i) Perform a temporary repair of the cove in accordance with

the service bulletin. Thereafter, repeat the detailed visual

inspection and delamination tap test required by paragraph (c) of

this AD at intervals not to exceed 800 hours time-in-service. Or

(ii) Perform a permanent repair of the cove in accordance with

the service bulletin. Accomplishment of this permanent repair

constitutes terminating action for the repetitive inspection

required by this AD.

(d) 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, Standardization Branch, ANM-113,

FAA, Transport Airplane Directorate. Operators shall submit their

requests through an appropriate FAA Principal Maintenance Inspector,

who may add comments and then send it to the Manager,

Standardization Branch, ANM-113.

Note: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Standardization Branch, ANM-113.

(e) Special flight permits may be issued in accordance with

Federal Aviation Regulations (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 31, 1994.

James V. Devany,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-2526 Filed 2-3-94; 8:45 am]

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