Airworthiness Directives; Rolls-Royce, plc RB.211 Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-ANE-39]

Airworthiness Directives; Rolls-Royce, plc RB.211 Series Turbofan

Engines

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 Rolls-Royce, plc (R-R) RB.211

series turbofan engines. This proposal would require removing and

replacing the existing rigid low pressure (LP) fuel system tube

assembly with a tube assembly having flexible sections and revised clip

points to preclude cracking and subsequent fuel leakage. This proposal

is prompted by multiple reports of fuel leaks. The actions specified by

the proposed AD are intended to prevent a fuel system leak, which could

result in rapid atomization of fuel and an engine fire.

DATES: Comments must be received by February 27, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), New England Region, Office of the Assistant Chief

Counsel, Attention: Rules Docket No. 94-ANE-39, 12 New England

Executive Park, Burlington, MA 01803-5299. Comments may be inspected at

this location between 8:00 a.m. and 4:30 p.m., Monday through Friday,

except Federal holidays.

The service information referenced in the proposed rule may be

obtained from Rolls-Royce, plc., P.O. Box 31, Derby, England. This

information may be examined at the FAA, New England Region, Office of

the Assistant Chief Counsel, 12 New England Executive Park, Burlington,

MA.

FOR FURTHER INFORMATION CONTACT: Daniel Kerman, Aerospace Engineer,

Engine Certification Office, FAA, Engine and Propeller Directorate, 12

New England Executive Park, Burlington, MA 01803-5299; telephone (617)

238-7130, fax (617) 238-7199.

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 should 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-ANE-39.'' 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, New England Region, Office of the Assistant Chief Counsel,

Attention: Rules Docket No. 94-ANE-39, 12 New England Executive Park,

Burlington, MA 01803-5299.

Discussion

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

authority for the United Kingdom, recently notified the Federal

Aviation Administration (FAA) that an unsafe condition may exist on

Rolls-Royce, plc. (R-R) Models RB.211-535E4 series and -535E4-B series

turbofan engines. The CAA advises that it has received multiple reports

of fuel leaks. These fuel leaks have occurred due to fracture of the

ferrule retainer of the existing low pressure (LP) fuel system tube

assembly, which runs from the LP fuel filter to the inlet of the high

pressure (HP) fuel pump. This condition, if not corrected, could result

in a fuel system leak, which could result in rapid atomization of fuel

and an engine fire.

In response to this problem the Boeing Aircraft Co. has issued an

Operations Manual Bulletin (OMB) to provide the flight crew with

enhanced fuel loss detection capability. The FAA made this OMB

mandatory through Airworthiness Directive (AD) 94-09-10 in order to

prevent fuel exhaustion due to undetected fuel leakage. In addition, R-

R has issued Service Bulletin (SB) No. RB.211-73-B048, Revision 1,

dated July 22, 1994, that specifies replacing the existing rigid LP

fuel system tube assembly with a new soft mounting design that includes

a flexible section at each end and revised clip points. Engineering

analysis shows that the original rigid system under transient

conditions is failure prone due to high stress levels that can induce

low cycle fatigue cracking. The CAA classified this service bulletin as

mandatory in order to assure the airworthiness of these R-R engines in

the United Kingdom.

This engine model is manufactured in the United Kingdom and is type

certificated for operation in the United States under the provisions of

Sec. 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 engines 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 R-R engines of the same type design

registered in the United States, the proposed AD would require

replacement of the LP fuel tube assembly. This new fuel tube assembly

has been redesigned to incorporate a flexible mounting system at both

ends and revised clip points, which reduce stress loading by providing

multiple degrees of freedom in which to deflect, thus eliminating the

rigid constraint of the fuel tube. The proposed compliance time of one

year after the effective date of this AD has been established based on

FAA review of past service history. The actions would be required to be

accomplished in accordance with the service bulletin described

previously.

There are approximately 558 engines of the affected design in the

worldwide fleet. The FAA estimates that 292 engines installed on

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

it would take approximately 2 work hours per engine to accomplish the

proposed actions, and that the average labor rate is $55 per work hour.

Required parts would cost approximately $1,000 per engine. Based on

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

operators is estimated to be $324,120.

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:

Rolls-Royce, plc.: Docket No. 94-ANE-39.

Applicability: Rolls-Royce, plc. (R-R) Models RB.211-535E4

series and -535E4-B series turbofan engines, installed on but not

limited to Boeing 757 series aircraft.

Compliance: Required as indicated, unless accomplished

previously.

To prevent a fuel system leak, which could result in rapid

atomization of fuel and an engine fire, accomplish the following:

(a) Within one year after the effective date of this AD, remove

the existing rigid low pressure (LP) fuel system tube assembly and

replace with the new flexible LP fuel system tube design with

revised clip points, in accordance with R-R Service Bulletin No.

RB.211-73-B048, Revision 1, dated July 22, 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, Engine Certification Office. The

request should be forwarded through an appropriate FAA Principal

Maintenance Inspector, who may add comments and then send it to the

Manager, Engine Certification Office.

Note: Information concerning the existence of approved

alternative methods of compliance with this airworthiness directive,

if any, may be obtained from the Engine Certification Office.

Issued in Burlington, Massachusetts, on December 14, 1994.

Kirk E. Gustafson,

Acting Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 94-31871 Filed 12-27-94; 8:45 am]

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