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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NE-46] 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

The Federal Aviation Administration (FAA) proposes to supersede an existing airworthiness directive (AD), applicable to certain Rolls-Royce Corporation (formerly Allison Engine Company) AE 3007 series turbofan engines. That AD currently requires removal of certain compressor cone shafts from service before exceeding new cyclic life limits and replacement with serviceable parts. This proposal would require increasing the cyclic life limit for certain serial numbers of new compressor cone shafts, part number (P/N) 23070729, that are used on AE3007A1/3 and AE3007A1P engines. This proposal is prompted by recent approved changes in engineering and manufacturing processes for new compressor cone shafts P/N 23070729. The actions specified by the proposed AD are intended to prevent low-cycle fatigue (LCF) failure of cone shafts, which could result in an uncontained engine failure and damage to the airplane. 

# DATES:

Comments must be received by July 24, 2001. 

# ADDRESSES:

                        Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-46-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address:                         *9-ane-adcomment@faa.dot.gov.*                         Comments sent via the Internet must contain the docket number in the subject line. Comments may be inspected at this location between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.                     

# FOR FURTHER INFORMATION CONTACT:

Michael Downs, Aerospace Engineer, Chicago Aircraft Certification Office, FAA, Small Airplane Directorate, 2300 East Devon Avenue, Des Plaines, IL 60018; telephone: (847) 294-7870, fax: (847) 294-7834 

# 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 action 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 action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 99-NE-46-AD.” The postcard will be date stamped and returned to the commenter. 

## Availability of NPRM's 

Any person may obtain a copy of this NPRM by submitting a request to the FAA, New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-46-AD, 12 New England Executive Park, Burlington, MA 01803-5299. 

## Discussion 

On April 27, 2000, the FAA issued AD 2000-09-05, Amendment 39-11714 (65 FR 26121, May 5, 2000), to require removal of certain compressor cone shafts from service before exceeding new cyclic life limits, and replacement with serviceable parts. That action was prompted by additional testing and low-cycle fatigue (LCF) life analysis that substantiated lower cyclic lives than originally determined. That condition, if not corrected, could result in LCF failure of compressor cone shafts, uncontained engine failure, and damage to the airplane. Since the issuance of that AD, the manufacturer has made changes to the engineering and manufacturing processes for new cone shafts, P/N 23070729, that increase the cyclic life limit, based on approved FAA and Rolls-Royce methodology for establishing cycle life. 

## FAA's Determination of an Unsafe Condition and Proposed Actions 

Since an unsafe condition has been identified that is likely to exist or develop on other Rolls-Royce Corporation AE 3007 series turbofan engines of this same type design, the proposed AD would revise AD 2000-09-05 to require increasing the cyclic life limit for certain serial numbers of new compressor cone shafts, part number (P/N) 23070729, that are used on AE3007A1/3 and AE3007A1P engines. 

## Economic Impact 

There are approximately 598 engines of the affected design in the worldwide fleet. The FAA estimates that 364 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take approximately 150 work hours per engine to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Required parts would cost approximately $3,921 per engine. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $4,703,244. 

## Regulatory Impact 

                    This proposed rule does not have federalism implications, as defined in                           ( print page 28851)    Executive Order 13132, because it would not have a substantial direct effect 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. Accordingly, the FAA has not consulted with state authorities prior to publication of this proposed rule.                 

                    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. 106(g), 40113, 44701. 

§ 39.13 

2. Section 39.13 is amended by removing Amendment 39-11714 (65 FR 26121, May 5, 2000), and by adding a new airworthiness directive (AD), to read as follows:

**Rolls-Royce Corporation (formerly Allison Engine Company):**                                 Docket No. 99-NE-46-AD. Supersedes AD 2000-09-05, Amendment 39-11714.                             

## Applicability 

This AD is applicable to Rolls-Royce Corporation (formerly Allison Engine Company) models AE 3007A, AE 3007A1, AE 3007A1/1, AE 3007A1/2, AE 3007A1/3, AE 3007A1P, and AE 3007C turbofan engines, with compressor cone shafts, part numbers (P/Ns) 23050728 and 23070729, installed. These engines are installed on but not limited to EMBRAER EMB-135 and EMB-145 series and Cessna 750 series airplanes. 

# Note 1:

This 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 (h) 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 

Compliance with this AD is required as indicated, unless already done. 

To prevent low-cycle fatigue failure of cone shafts, which could result in an uncontained engine failure and damage to the airplane, accomplish the following: 

## Removal From Service 

(a) For Rolls-Royce Corporation model AE 3007A engines, remove cone shafts from service prior to accumulating 9,500 cycles-since-new (CSN) and replace with serviceable parts. 

(b) For Rolls-Royce Corporation model AE 3007C engines, remove cone shafts from service prior to accumulating 14,500 CSN and replace with serviceable parts. 

(c) For Roll-Royce Corporation models AE 3007A1, AE 3007A1/1, and AE 3007A1/2 engines, remove cone shafts from service prior to accumulating 7,500 CSN and replace with serviceable parts. 

(d) For Rolls-Royce Corporation model AE 3007A1/3 engines: 

(1) With compressor cone shafts P/N 23070729, serial number (SN) MM78599, MM78615, MM78632, MM78650, MM78651, MM78652, MM78653, MM78654, MM78655, MM78656, MM78657, MM78658, MM78659, MM78660, MM78661, MM78662, MM78663, MM78665 or higher, remove cone shafts from service prior to accumulating 9,300 CSN and replace with serviceable parts. 

(2) With compressor cone shafts P/N 23050728, or P/N 23070729 having other than the S/N's listed in paragraph (d)(1) of this AD, remove cone shafts from service prior to accumulating 3,500 CSN and replace with serviceable parts. 

(e) For Rolls-Royce Corporation AE 3007A1P engines: 

(1) With compressor cone shafts P/N 23070729, SN MM78599, MM78615, MM78632, MM78650, MM78651, MM78652, MM78653, MM78654, MM78655, MM78656, MM78657, MM78658, MM78659, MM78660, MM78661, MM78662, MM78663, MM78665 or higher, remove cone shafts from service prior to accumulating 7,300 CSN and replace with serviceable parts. 

(2) With compressor cone shafts P/N 23050728, or P/N 23070729 having other than the SN's listed in paragraph (e)(1) of this AD, remove cone shafts from service prior to accumulating 2,400 CSN and replace with serviceable parts. 

## New Life Limits 

(f) Paragraphs (a), (b), (c), (d) and (e) of this AD establish new, lower life limits for cone shafts, P/Ns 23050728 and 23070729. 

(g) Except for the provisions of paragraph (h) of this AD, no cone shafts, P/Ns 23050728 and 23070729, may remain in service exceeding the life limits established in paragraphs (a), (b), (c), (d) and (e) of this AD. 

## Alternative Method of Compliance 

(h) 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 (ACO). Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Chicago ACO. 

# Note 2:

Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Chicago ACO.

## Special Flight Permits 

(i) 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 requirements of this AD can be accomplished.

Issued in Burlington, Massachusetts, on May 18, 2001. 

Diane S. Romanosky, 

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service. 

[FR Doc. 01-13183 Filed 5-24-01; 8:45 am] 

BILLING CODE 4910-13-P