Airworthiness Directives; AlliedSignal, Inc. TFE731-3 Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-ANE-49; Amendment 39-8861; AD 94-07-03]

Airworthiness Directives; AlliedSignal, Inc. TFE731-3 Series

Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing priority letter

airworthiness directive (AD), applicable to certain AlliedSignal, Inc.

TFE731-3 series turbofan engines, that currently requires a revision to

the Limitations Section of the Airplane Flight Manual (AFM) to provide

procedures for monitoring engine performance in order to detect A5 seal

cracking and opening before first stage low pressure (LP) turbine disk

failure. Additionally, the revision to the AFM requires a procedure for

verification of LP rotor (N1) rotation during engine start to detect

rotor lockup due to first stage LP turbine rotor creep. This amendment

maintains those requirements for engine and flight data monitoring,

adds a more stringent procedure for verifying rotor lockup during

engine start and for detection of rubbing noises, and requires

replacement of A5 seals with a redesigned seal. Replacement of A5 seals

with a redesigned seal constitutes terminating action to the monitoring

requirements. This amendment is prompted by reports of an additional

first stage LP turbine disk failure due to A5 seal cracking. The

actions specified by this AD are intended to prevent uncontained

failure of the first stage LP turbine disk.

DATES: Effective June 6, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of June 6, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from AlliedSignal, Inc., Aviation Services Division, Data

Distribution, Dept. 64-3/2102-1M, P.O. Box 29003, Phoenix, AZ 85038-

9003. This information may be examined at the Federal Aviation

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

Counsel, 12 New England Executive Park, Burlington, MA 01803-5299; or

at the Office of the Federal Register, 800 North Capitol Street NW.,

suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Joseph Costa, Aerospace Engineer, Los

Angeles Aircraft Certification Office, FAA, Transport Airplane

Directorate, 3229 East Spring Street, Long Beach, CA 90806-2425;

telephone (310) 988-5246; fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations by superseding priority letter airworthiness

directive (AD) 92-12-09, issued June 8, 1992, which is applicable to

certain Allied-Signal Aerospace Company, Garrett Engine Division,

TFE731-3 series turbofan engines, was published in the Federal Register

on October 4, 1993 (58 FR 51587). That action proposed to continue the

engine and flight data monitoring requirements of priority letter AD

92-12-09 by revising the Limitations Section of the Airplane Flight

Manual (AFM) to provide for procedures to trend monitor engine

performance in order to detect A5 seal cracking and opening before

first stage low pressure (LP) turbine disk failure. In addition, that

action proposed to require a more stringent procedure for verifying N1

rotation during engine start to detect rotor lockup and for detecting

rubbing noises due to first stage LP turbine rotor creep. Also, that

action proposed to add the Allied-Signal Aerospace Company, Garrett

Engine Division, Model TFE731-2A engine to the AD applicability.

Finally, that action proposed to require replacement of current A5

seals with a redesigned A5 seal within 150 hours time in service after

the effective date of the proposed AD. Installation of the redesigned

A5 seal would constitute terminating action to the engine and flight

data monitoring requirements.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter states that paragraph (a)(1) in the proposed rule

requires that the engine and flight data monitoring must be

accomplished for any engine that has more than 500 hours time in

service since new (TSN). The commenter further states that the greater

than 500 hours TSN qualification should be added to the applicability

paragraph, as this qualification is applicable to all succeeding

paragraphs. The FAA concurs in part. The FAA has added for clarity a

compliance table in paragraph (d) that instructs operators on the

replacement schedule for the A5 seal installed on engines with less or

more than 500 hours TSN.

One commenter states that paragraph (a)(4) of the proposed rule

requires checking for rubbing noises and free rotation of the N1 spool

following each engine shutdown. Paragraphs (a)(4) and (c) go on to

state that if any rubbing noises are detected, the operator must

discontinue further flight. The commenter suggests requiring

discontinuation of further flight if the N1 spool locks up, or engine

rubbing noises are detected during this check. The FAA concurs and the

final rule has been changed accordingly.

The Type Certification Data Sheet for the Allied-Signal Aerospace

Company, Garrett Engine Division, TFE731-3 series turbofan engines was

officially changed by the FAA during November 1993 to show the current

corporate name of the manufacturer, AlliedSignal, Inc. All references

to the corporate name have been changed accordingly in this final rule.

In addition, AlliedSignal, Inc. has issued service bulletin (SB)

No. TFE731-72-3509, dated January 4, 1994, that describes installation

of a redesigned A5 seal and air cooled HP turbine blades and associated

parts for TFE731-3B and -3BR models. Installation of a redesigned A5

seal and air cooled HP turbine blades and associated parts in

accordance with this SB constitutes an additional method of compliance

to paragraph (d) of this AD.

After careful review of the available data, including the comments

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule with the changes described

previously. The FAA has determined that these changes will neither

increase the economic burden on any operator nor increase the scope of

the AD.

There are approximately 3,300 engines of the affected design in the

worldwide fleet. The FAA estimates that 2,000 engines installed on

aircraft of U.S. registry are affected by this AD, that it will take

approximately 55 work hours per engine to accomplish the proposed

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

parts will cost approximately $7,500 per engine. Based on these

figures, the total cost impact of the AD on U.S. operators is estimated

to be $21,050,000.

The regulations adopted herein will 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 final

rule does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action: (1) Is

not a ``significant regulatory action'' under Executive Order 12866;

(2) is not a ``significant rule'' under DOT Regulatory Policies and

Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it may be obtained

from the Rules Docket at the location provided under the caption

ADDRESSES.

List of Subjects in 14 CFR Part 39

Air Transportation, Aircraft, Aviation Safety, Incorporation by

reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends 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:

94-07-03: AlliedSignal, Inc. Amendment 39-8861. Docket 93-ANE-49.

Applicability: AlliedSignal, Inc. Model TFE731-2A, -3, -3A, -3R,

-3AR, -3B, and -3BR turbofan engines that have first stage low

pressure (LP) turbine nozzles, Part Number (P/N) 3072842-1 or P/N's

3072319-1 through -8, installed. These engines are installed on but

not limited to Avions Marcel Dassault Falcon 50, AiResearch Aviation

Company 731 Jetstar, Lockheed 1329-25 (Jetstar II), Israel Aircraft

Industries Ltd. 1124 series (Westwind) and 1125, Westwind Astra,

British Aerospace DH/HS/BH 125 series, Learjet 55 series, Cessna 650

Citation III series, and Sabreliner NA265-65 (Sabreliner 65 and 65

series) aircraft.

Compliance: Required as indicated, unless accomplished

previously.

To prevent uncontained failure of the first stage LP turbine

disk, accomplish the following:

(a) Prior to further flight revise the Limitations Section of

the FAA-approved Airplane Flight Manual (AFM) to include the

following paragraphs (1) through (4) relating to engine and flight

data monitoring. This may be accomplished by inserting a copy of

this AD in the AFM.

``Engine and Flight Data Monitoring

(1) If any engine has more than 500 hours time in service since

new (TSN), record the flight data set forth in paragraph (2) once

every two flights while meeting the following conditions:

a. Matched low pressure rotor (N1) speed;

b. Turn engine anti-ice off (consistent with safe operation);

and

c. Attain a stabilized cruise speed for five minutes or longer.

Note: If flight operations do not permit all of these conditions

to be met, the engine to engine comparison data may be unreliable.

(2) When the conditions specified in paragraph (1) are met,

record the following flight data and retain this data for six

months:

a. Date of flight;

b. Aircraft altitude or flight level;

c. Outside static air temperature in degrees celsius ( deg.C);

d. Mach number;

e. Engine N1 speed for each engine;

f. Engine high pressure rotor (N2) speed for each engine;

g. Fuel flow for each engine; and

h. Interstage turbine temperature (ITT) for each engine.

(3) Verify N1 rotation during engine start by allowing N2 to

increase to approximately 12 to 15 percent and confirm N1 rotation

prior to fuel initiation. If no N1 rotation is observed, discontinue

further attempts at engine start.

(4) Check for rubbing noises and free rotation of the N1 spool

following each engine shutdown. If any rubbing noises are detected,

or if the N1 spool locks up, discontinue further flight.''

(b) When engine and flight data monitoring is required by the

AFM revision of paragraph (a) of this AD, accomplish the following:

(1) After each flight, calculate the difference (i.e., No. 1

minus No. 2, No. 1 minus No. 3, and No. 1 minus No. 4) between the

engines' ITT, N2 speed, and fuel flow readings for each flight

having recorded data. Compare these differences to the differences

calculated from previous flights.

(2) Discontinue further flight if a change of 20 deg.C or more

occurs in the ITT difference between two engines, (on three and four

engine airplanes compare No. 2, No. 3 and No. 4 engine parameters to

the No. 1 engine) with the last ten flights having recorded data.

Flight operation can be continued when the cause of the ITT

temperature shift has been determined and appropriate corrective

action has been accomplished. Engine and flight data monitoring must

be continued upon return to flight operations.

Note: A suspect engine may indicate an increase in ITT

temperature and an increase in N2 speed greater than 1% and an

increase in fuel flow to a lesser degree with respect to the other

normal engine(s).

Additional guidance and information regarding flight data

collection, trend monitoring, and corrective actions, may be

obtained from Allied-Signal Aerospace Company, Garrett Engine

Division, Operating Information Letter No. OI 731-13, Revision C,

dated November 20, 1992.

(c) Discontinue further flight if no N1 rotation is observed

during engine start, or if engine rubbing noises are detected or the

N1 spool locks up after engine shutdown. Flight operation can be

continued when the cause of the N1 rotor lockup or engine rubbing

noises has been determined and appropriate corrective action has

been accomplished. Engine and flight data monitoring must be

continued upon return to flight operations.

(d) Replace the A5 seal assembled in affected first stage LP

turbine nozzles and install a redesigned A5 seal in accordance with

the Accomplishment Instructions of Allied-Signal Aerospace Company,

Garrett Engine Division, Service Bulletin (SB) No. TFE731-72-3502,

Revision 2, dated March 15, 1993, SB No. TFE731-72-3502, Revision 1,

dated December 21, 1992, or SB No. TFE731-72-3502, Original, dated

November 25, 1992; or SB No. TFE731-72-3503, Revision 1, dated

December 21, 1992; or AlliedSignal, Inc. SB No. TFE731-72-3509,

dated January 4, 1994, as applicable, as follows:

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Time in service since new (TSN) on

the effective date of this AD Replacement schedule

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500 hours TSN or more.............. Within 150 hours time in service

(TIS) after the effective date of

this AD.

Less than 500 hours TSN............ Prior to accumulating 650 hours

TSN.

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Installation of the redesigned A5 seal constitutes terminating

action to the engine and flight data monitoring and AFM revision

required by this AD.

(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, Los Angeles Aircraft 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, Los Angeles Aircraft Certification Office.

Note: Information concerning the existence of approved

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

obtained from the Los Angeles Aircraft Certification Office.

(f) Special flight permits may be issued in accordance with 14

CFR 21.197 and 21.199 to operate the aircraft to a location where

the requirements of this AD can be accomplished.

(g) The replacement of the A5 seal shall be done in accordance

with the following service bulletins:

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Document No. Pages Revision Date

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Allied-Signal 1-18 2............ Mar. 15, 1993.

Aerospace Company,

Garrett Engine

Division SB No.

TFE731-72-3502.

Total pages: 18.

Allied-Signal 1-16 1............ Dec. 21, 1992.

Aerospace Company,

Garrett Engine

Division SB No.

TFE731-72-3502.

Total pages: 16.

Allied-Signal 1-14 Original..... Nov. 25, 1992.

Aerospace Company,

Garrett Engine

Division SB No.

TFE731-72-3502.

Total pages: 14.

Allied-Signal 1 1............ Dec. 21, 1992.

Aerospace Company,

Garrett Engine

Division SB No.

TFE731-72-3503.

2-3 Original..... Dec. 9, 1992.

4 1............ Dec. 21, 1992.

5 Original..... Dec. 9, 1992.

6 1............ Dec. 21, 1992.

7-9 Original..... Dec. 9, 1992.

10-16 1............ Dec. 21, 1992.

Total pages: 16.

AlliedSignal, Inc. SB 1-10 Original..... Jan. 4, 1994.

No. TFE731-72-3509.

Total pages: 10.

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This incorporation by reference was approved by the Director of the

Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part

51. Copies may be obtained from AlliedSignal Inc., Aviation Services

Division, Data Distribution, Dept. 64-3/2102-1M, P.O. Box 29003,

Phoenix, AZ 85038-9003. Copies may be inspected at the FAA, New

England Region, Office of the Assistant Chief Counsel, 12 New

England Executive Park, Burlington, MA; or at the Office of the

Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

(h) This amendment supersedes priority letter AD 92-12-09,

issued June 8, 1992.

(i) This amendment becomes effective on June 6, 1994.

Issued in Burlington, Massachusetts, on April 11, 1994.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification

Service.

[FR Doc. 94-9468 Filed 4-19-94; 8:45 am]

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