Airworthiness Directives; Short Brothers Model SD3-60 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-96-AD]

Airworthiness Directives; Short Brothers Model SD3-60 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 Short Brothers Model SD3-

60 series airplanes. This proposal would require installation of a

certain time delay relay and associated wiring into a circuit of the

rudder gust lock. This proposal is prompted by reports of inadvertent

engagements of the rudder gust lock on in-service Model SD3-60 series

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

prevent premature locking of the rudder gust lock, which could result

in reduced controllability of the airplane in flight and during landing

roll.

DATES: Comments must be received by September 26, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-96-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 Short Brothers, PLC, 2011 Crystal Drive, Suite 713,

Arlington, Virginia 22202-3719. This information may be examined at the

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

Washington.

FOR FURTHER INFORMATION CONTACT: Sam Grober, Aerospace Engineer,

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

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

227-1187; 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 94-NM-96-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-96-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The Civil Aviation Authority (CAA), which is the airworthiness

authority for United Kingdom, recently notified the FAA that an unsafe

condition may exist on certain Short Brothers Model SD3-60 series

airplanes. The CAA advises that it has received reports of inadvertent

engagements of the rudder gust lock on in-service Model SD3-60 series

airplanes. Investigation revealed that these inadvertent engagements

were caused by premature locking of the rudder gust lock system.

Premature locking of the rudder gust lock, if not corrected, could

result in reduced controllability of the airplane in flight and during

landing roll.

Short Brothers has issued Shorts Service Bulletin SD360-27-23,

Revision 1, dated April 15, 1994, which describes procedures for

installation of a 10-second time delay relay, having part number TDD-

AYOF-1002, and associated wiring into a circuit of the rudder gust

lock. Such an installation safeguards against inadvertent locking of

the rudder gust lock until the airplane can reach a ground speed at

which the nose wheel steering can be used. The CAA classified this

service bulletin as mandatory and issued CAA Airworthiness Directive

013-02-94, dated March 24, 1994, in order to assure the continued

airworthiness of these airplanes in the United Kingdom.

This airplane model is manufactured in the United Kingdom 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, the CAA has kept the FAA

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

findings of the CAA, 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 installation of a

certain 10-second time delay relay and associated wiring into a circuit

of the rudder gust lock. The actions would be required to be

accomplished in accordance with the service bulletin described

previously.

The FAA estimates that 88 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 29 work

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

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

supplied by the manufacturer at no cost to the operators. Based on

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

operators is estimated to be $140,360, or $1,595 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:

Short Brothers, PLC: Docket 94-NM-96-AD

Applicability: Model SD3-60 series airplanes on which

Modification 8112 (reference Shorts Service Bulletin SD360-27-16)

has been installed, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously. -

To prevent reduced controllability of the airplane in flight and

during landing roll, accomplish the following:

(a) Within 90 days after the effective date of this AD, install

a 10-second time delay relay, having part number TDD-AYOF-1002, and

associated wiring into a circuit of the rudder gust lock, in

accordance with Shorts Service Bulletin SD360-27-23, Revision 1,

dated April 15, 1994.

(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, 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.

(c) 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 August 11, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-20159 Filed 8-16-94; 8:45 am]

BILLING CODE 4910-13-P