Airworthiness Directives; British Aerospace Model Viscount 744, 745D, and 810 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-104-AD]

Airworthiness Directives; British Aerospace Model Viscount 744,

745D, and 810 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 all British Aerospace Model

Viscount 744, 745D, and 810 series airplanes. This proposal would

require various inspections to detect damage, corrosion, or cracking of

certain taper plugs and split bushings of the engine mount, and

replacement of taper plugs or split bushings with serviceable parts, if

necessary. This proposal is prompted by a report of damage of the taper

plug and split bushing of the engine mount due to the effects of

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

prevent such damage, which could lead to failure of the engine mount

attachment assembly and consequent separation of the engine from the

airplane.

DATES: Comments must be received by October 24, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No.94-NM-104-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 British Aerospace Regional Aircraft Ltd., Engineering

Support Manager, Military Business Unit, Chadderton Works, Greengate,

Middleton, Manchester M24 1SA, England. This information may be

examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue,

SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: William Schroeder, Aerospace Engineer,

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

Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056;

telephone (206) 227-2148; 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-104-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-104-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 all British Aerospace Model Viscount 744, 745D,

and 810 series airplanes. The CAA advises that it has received a report

of damage to the taper plug and split bushing (bush) of the engine

mount. Investigation revealed that the taper plug and split bushing had

corroded. The effects of such corrosion could lead to the failure of

the taper plug and split bushing, which consequently could lead to the

failure of the engine mount attachment assembly. This condition, if not

corrected, could result in separation of the engine from the airplane.

British Aerospace has issued Viscount Preliminary Technical Leaflet

(PTL) 200, Disc 9 Doc.5, dated December 6, 1991 (for Model Viscount 810

series airplanes), and Viscount PTL 329, Disc 9 Doc.2, dated April 1,

1992 (for Model Viscount 744 and 745D series airplanes). These service

documents describe procedures for performing detailed visual and

nondestructive test (NDT) inspections to detect damage, corrosion, or

cracking of taper plugs, having part number (P/N) 60216-1017, and split

bushings, having P/N 60216-1019, of the engine mount; and replacement

of discrepant parts. The CAA classified these PTL's as mandatory.

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 detailed visual and

nondestructive test (NDT) inspections to detect damage, corrosion, or

cracking of certain taper plugs and split bushings of the engine mount;

and replacement of discrepant parts. The actions would be required to

be accomplished in accordance with the applicable PTL described

previously.

The FAA estimates that 25 Model Viscount 744 and 745D series

airplanes of U.S. registry would be affected by this proposed AD, that

it would take approximately 25 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 $34,375, or $1,375 per airplane.

The FAA estimates that 4 Model Viscount 810 series airplanes of

U.S. registry would be affected by this proposed AD, that it would take

approximately 25 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 $5,500, or $1,375 per airplane.

Based on the above figures, the total cost impact of the actions

proposed by this AD on U.S. operators is estimated to be $39,875, or

$1,375 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:

British Aerospace Regional Aircraft Limited (Formerly British

Aerospace Commercial Aircraft Limited, Vickers-Armstrongs Aircraft

Limited): Docket 94-NM-104-AD.

Applicability: All Model Viscount 744, 745D, and 810 series

airplanes, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent separation of the engine from the airplane,

accomplish the following:

(a) At the next unscheduled engine removal, but no later than 12

months after the effective date of this AD, perform a detailed

visual inspection to detect damage, corrosion, or cracking of taper

plugs, having part number (P/N) 60216-1017, and split bushings

(bushes), having P/N 60216-1019, of the engine mount, in accordance

with British Aerospace Viscount Preliminary Technical Leaflet (PTL)

200, Disc 9 Doc.5, dated December 6, 1991 (for Model Viscount 810

series airplanes); or British Aerospace Viscount PTL 329, Disc. 9

Doc.2, dated April 1, 1992 (for Model Viscount 744 and 745D series

airplanes); as applicable.

(1) If no taper plugs or split bushings are damaged, corroded,

or cracked, repeat the inspection thereafter at each unscheduled

engine removal, but no later than 48 months after the last visual

inspection of the taper plugs and split bushings.

(2) If any taper plug or split bushing is damaged, corroded, or

cracked, prior to further flight, replace the taper plug or split

bushing with a serviceable part, in accordance with the applicable

PTL. Thereafter, repeat the inspection at each unscheduled engine

removal, but no later than 48 months after the last visual

inspection of the taper plugs and split bushings.-

(b) At the next scheduled engine removal, but no later than 12

months after the effective date of this AD, perform detailed visual

and nondestructive test (NDT) inspections to detect damage,

corrosion, or cracking of all taper plugs and split bushings of the

engine mount, in accordance with British Aerospace Viscount PTL 200,

Disc 9 Doc.5, dated December 6, 1991 (for Model Viscount 810 series

airplanes); or British Aerospace Viscount PTL 329, Disc. 9 Doc.2,

dated April 1, 1992 (for Model Viscount 744 and 745D series

airplanes); as applicable.

(1) If no taper plug or split bushing is damaged, corroded, or

cracked, repeat the visual and NDT inspections thereafter at each

scheduled engine removal, but no later than 48 months after the last

visual and NDT inspections of the taper plugs and split bushings.

(2) If any taper plug or split bushing is damaged, corroded, or

cracked, prior to further flight, replace the taper plug or split

bushing with a serviceable part, in accordance with the applicable

PTL. Thereafter, repeat the visual and NDT inspections at each

scheduled engine removal, but no later than 48 months after the last

visual and NDT inspections of the taper plugs and split bushings.

(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, 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.

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

Secs. 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 8, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-22672 Filed 9-13-94; 8:45 am]

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