Airworthiness Directives; Allison Engine Company AE 3007A and AE 3007C Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-ANE-60-AD; Amendment 39-10557, AD 98-11-32]

RIN 2120-AA64

Airworthiness Directives; Allison Engine Company AE 3007A and AE

3007C Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: This amendment adopts a new airworthiness directive (AD) that

is applicable to Allison Engine Company AE 3007A and AE 3007C series

turbofan engines. This action supersedes priority letter AD 98-02-09,

that currently requires certain checks of the center sump magnetic chip

collector plug for paste. Engines found with paste are required to be

removed from service. This action references revisions of the

applicable Alert Service Bulletins (ASB) providing clarifications of

check procedures. This amendment is prompted by a change in the part

number applicability, a change in the check interval, and the

publication of these revised ASBs. The actions specified by this AD are

intended to prevent No. 4 bearing failure due to excessive bearing

wear, which can result in an inflight engine shutdown.

DATES: Effective June 18, 1998.

The incorporation by reference of certain publications listed in

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

of June 18, 1998.

Comments for inclusion in the Rules Docket must be received on or

before August 3, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), New England Region, Office of the Regional

Counsel, Attention: Rules Docket No. 97-ANE-60-AD, 12 New England

Executive Park, Burlington, MA 01803-5299. Comments may also be sent

via the Internet using the following address: ``9-ad-

[email protected]''. Comments sent via the Internet must contain

the docket number in the subject line.

The service information referenced in this AD may be obtained from

Allison Engine Company, P.O. Box 420, Speed Code U-15, Indianapolis, IN

46206-0420; telephone (317) 230-6674. This information may be examined

at the FAA, New England Region, Office of the Regional 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.

FOR FURTHER INFORMATION CONTACT: Kyri Zaroyiannis, Aerospace Engineer,

Chicago Aircraft Certification Office, FAA, Small Airplane Directorate,

2300 East Devon Avenue, Des Plaines, IL 60018; telephone (847) 294-

7836, fax (847) 294-7834.

SUPPLEMENTARY INFORMATION: On January 16, 1998, the Federal Aviation

Administration (FAA) issued priority letter airworthiness directive

(AD) 98-02-09, applicable to Allison Engine Company AE 3007A and AE

3007C series turbofan engines, which requires each calendar day, for

Allison Engine Company AE 3007A series engines, and every three

calendar days, or prior to the next flight, whichever occurs later, for

Allison Engine Company AE 3007C series engines, alternating between the

left hand and right hand engines, checks of the center sump magnetic

chip collector plug. After checking the center sump magnetic chip

collector plug , that AD requires, if paste is found, collecting paste,

examining the O-ring for damage, cleaning the plug once during the

first check only and not subsequently, performing an engine ground run-

up and again examining the plug for paste. If paste is found on this

second examination or subsequent examinations, the engine must be

removed from service. There have been five inflight engine shutdowns

associated with these bearing failures since December 1, 1997, on

Allison Engine Company AE 3007A and AE 3007C series turbofan engines,

which occurred with total time in service since new (TSN) ranging from

36 to 1,284 hours. The investigation revealed that the No. 4 bearings

deteriorate due to manufacturing anomalies, which lead to excessive

bearing wear. Analysis of failed bearings and service history has

narrowed the unsafe condition to one particular bearing part number.

That condition, if not corrected, could result in No. 4 bearing failure

due to excessive bearing wear, which can result in an inflight engine

shutdown.

Since the issuance of that priority letter AD, Allison Engine

Company has issued Alert Service Bulletin (ASB) No. AE 3007A-A-79-014,

Revision 4, dated April 14, 1998, and ASB No. AE 3007C-A-79-018,

Revision 3, dated April 21, 1998, which provide clarifications of check

procedures. In addition, this final rule has added oil leak checks

after each magnetic chip detector inspection, in order to minimize the

possibility of

[[Page 30123]]

maintenance-induced errors. Also, this final rule adds a terminating

action which eliminates the requirement for repetitive magnetic chip

detector inspections by installing an improved No. 4 main engine

bearing.

Since an unsafe condition has been identified that is likely to

exist or develop on other engines of this same type design, this AD

supersedes priority letter AD 98-02-09 to reference revisions of the

applicable Allison Engine Company ASBs providing clarifications of

check procedures, change the part number applicability, and change the

check interval. The actions are required to be accomplished in

accordance with the ASBs described previously.

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons are invited to comment on this 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 under the caption ``ADDRESSES.''

All communications received on or before the closing date for comments

will be considered, and this rule may be amended in light of the

comments received. Factual information that supports the commenter's

ideas and suggestions is extremely helpful in evaluating the

effectiveness of the AD action and determining whether additional

rulemaking action would be needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD 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 97-ANE-60-AD.'' The postcard will be date stamped and

returned to the commenter.

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.

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and is not a ``significant regulatory action''

under Executive Order 12866. It has been determined further that this

action involves an emergency regulation under DOT Regulatory Policies

and Procedures (44 FR 11034, February 26, 1979). If it is determined

that this emergency regulation otherwise would be significant under DOT

Regulatory Policies and Procedures, a final regulatory evaluation will

be prepared and placed in the Rules Docket. A copy of it, if filed, 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 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. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

98-11-32 Allison Engine Company: Amendment 39-10557. Docket No. 97-

ANE-60-AD. Supersedes AD 98-02-09.

Applicability: Allison Engine Company AE 3007A and AE 3007C

series turbofan engines with No. 4 bearing, Part Number (P/N)

23062504, installed on but not limited to EMBRAER EMB-145 and Cessna

750 series aircraft.

Note 1: This airworthiness directive (AD) applies to each engine

identified in the preceding applicability provision, regardless of

whether it has been modified, altered, or repaired in the area

subject to the requirements of this AD. For engines that have been

modified, altered, or repaired so that the performance of the

requirements of this AD is affected, the owner/operator must request

approval for an alternative method of compliance in accordance with

paragraph (e) of this AD. The request should include an assessment

of the effect of the modification, alteration, or repair on the

unsafe condition addressed by this AD; and, if the unsafe condition

has not been eliminated, the request should include specific

proposed actions to address it.

Compliance: Required as indicated, unless accomplished

previously.

To prevent No. 4 bearing failure due to excessive bearing wear,

which can result in an inflight engine shutdown, accomplish the

following:

(a) For Allison Engine Company AE 3007A series engines, within 8

flight hours after the effective date of this AD, accomplish the

following in accordance with Allison Engine Company Alert Service

Bulletin (ASB) No. AE 3007A-A-79-014, Revision 4, dated April 14,

1998.

(1) Remove the center sump magnetic chip collector plug (non-

indicating) on each engine and examine it for paste.

Note 2: Paste is a mixture of very fine metallic particles and

oil or soft carbon.

(2) If no paste is found, reinstall the center sump magnetic

chip collector, perform an oil leak check, and thereafter inspect

both engines at intervals not to exceed 8 flight hours.

(3) If paste is found, accomplish the following prior to further

flight:

(i) Remove the engine from service if paste was previously found

on the same engine during any previous checks performed in

accordance with this AD, otherwise continue with the following

procedure:

(ii) Collect the paste on a clean white paper. Cover the sample

with clear tape and retain it for analysis.

(iii) Examine the O-ring for damage and replace as necessary.

(iv) Clean the center sump magnetic chip collector plug.

(v) Reinstall the center sump magnetic chip collector plug.

(vi) Perform a ground run-up of the engine as follows:

(A) Ground Idle for 5 minutes.

(B) Maximum Takeoff for 2 minutes.

(C) 50% N1 (Fan speed) for 5 minutes.

(D) Ground Idle for 3 minutes.

(E) Stop the engine.

(vii) Re-examine the center sump magnetic chip collector plug

for paste. If paste is found, remove the engine from service. If no

paste is found, thereafter inspect in accordance with paragraph

(a)(2) of this AD.

(viii) Send any removed paste to a laboratory or facility

capable of analysis with a scanning electron microscope and an

energy dispersive x-ray microanalyzer for analysis.

Note 3: Two laboratories capable of performing this analysis

are:

[[Page 30124]]

Aviation Laboratories, 910 Maria Street, Kenner, LA 70062, 504-469-

6751

or

Spectro Oil Analysis, Palace Gate, High Street, Oldham, Hook,

Hampshire, RG 291 NP, United Kingdom.

Send documentation referencing this AD or ASB along with the

sample.

(ix) Send the results of the analysis to Allison as follows:

Manager, AE Customer Support, Large Commercial Engines, fax (317)

230-4010.

(x) An engine found with paste either after the engine ground

run-up or during subsequent checks performed in accordance with this

AD may not be operated again without the approval of the Manager,

Chicago Aircraft Certification Office.

(b) For Allison AE 3007C series engines, within 8 flight hours

after the effective date of this AD, accomplish the following in

accordance with Allison Engine ASB No. AE 3007C-A-79-018, Revision

3, dated April 21, 1998:

(1) Remove the center sump magnetic chip collector plug (non-

indicating) on each engine and examine it for paste. (See Note 2)

(2) If no paste is found, reinstall the center sump magnetic

chip collector, perform an oil leak check, and thereafter inspect

both engines at intervals not to exceed 8 flight hours.

(3) If paste is found, accomplish the following prior to further

flight:

(i) Remove the engine from service if paste was previously found

on the same engine during any previous checks performed in

accordance with this AD.

(ii) Collect the paste on a clean white paper. Cover the sample

with clear tape and retain it for analysis.

(iii) Examine the O-ring for damage and replace as necessary.

(iv) Clean the center sump magnetic chip collector plug.

(v) Reinstall the center sump magnetic chip collector plug.

(vi) Perform a ground run-up of the engine as follows:

(A) Ground Idle for 5 minutes.

(B) Maximum Takeoff for 2 minutes.

(C) 50% N1 (Fan speed) for 5 minutes.

(D) Ground Idle for 3 minutes.

(E) Stop the engine.

(vii) Re-examine the center sump magnetic chip collector plug

for paste. If paste is found, remove the engine from service. If no

paste is found, thereafter inspect in accordance with paragraph

(b)(2) of this AD.

(viii) Send any removed paste to a laboratory or facility

capable of analysis with a scanning electron microscope and an

energy dispersive x-ray microanalyzer for analysis. Send

documentation referencing this AD or ASB along with the sample. (See

Note 3)

(ix) Send the results of the analysis to Allison as follows:

Manager, AE Customer Support, Large Commercial Engines, fax (317)

230-4010.

(x) An engine found with paste either after the engine ground

run-up or during subsequent checks performed in accordance with this

AD may not be operated again without the approval of the Manager,

Chicago Aircraft Certification Office.

(c) For Allison Engine Company AE 3007A series and AE 3007C

series engines, remove from service No. 4 main engine bearings, P/N

23062504, at the next engine shop visit, and replace with

serviceable parts. Installation of an improved No. 4 main engine

bearing constitutes terminating action to the repetitive magnetic

chip detector checks required by paragraphs (a) and (b) of this AD.

(d) For the purpose of this AD, the following definitions apply:

(1) A serviceable part is defined as any No. 4 main engine

bearing P/N other than 23062504.

(2) A shop visit is defined as any maintenance action resulting

in the separation of any major engine flange.

(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, Chicago Aircraft Certification

Office. Operators shall submit their requests through an appropriate

FAA Principal Maintenance Inspector, who may add comments and then

send it to the Manager, Chicago Aircraft Certification Office.

Note 4: Information concerning the existence of approved

alternative methods of compliance with this airworthiness directive,

if any, may be obtained from the Chicago Aircraft Certification

Office.

(f) 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 aircraft to a location where

the check requirements of this AD can be accomplished.

(g) The actions required by this AD shall be accomplished in

accordance with the following Allison Engine Company ASBs:

------------------------------------------------------------------------

Document No. Page Revision Date

------------------------------------------------------------------------

AE 3007A-A-79-014............. 1-7 4 April 14, 1998.

Total Pages: 7.

AE 3007C-A-79-018............. 1-6 3 April 21, 1998.

Total Pages: 6.

------------------------------------------------------------------------

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 Allison Engine Company, P.O. Box

420, Speed Code U-15, Indianapolis, IN 46206-0420; telephone (317)

230-6674. Copies may be inspected at the FAA, New England Region,

Office of the Regional 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 98-02-09,

issued January 16, 1998.

(i) This amendment becomes effective on June 18, 1998.

Issued in Burlington, Massachusetts, on May 22, 1998.

Thomas A. Boudreau,

Acting Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 98-14339 Filed 6-2-98; 8:45 am]

BILLING CODE 4910-13-U