Skip to Content

Rule

Airworthiness Directives; General Electric Company CT64-820-4 Turboprop Engines

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Final rule; request for comments.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for General Electric Company (GE) CT64-820-4 turboprop engines with certain part number (P/N) rotating parts. The parts are in the compressor rotor assembly, gas generator turbine rotor assembly, and power turbine rotor assembly that are subject to low-cycle fatigue. This AD requires removing from service these affected rotating parts at reduced compliance times. This AD results from the manufacturer's discovery of cracks in some rotating parts. We are issuing this AD to prevent cracks in the rotating parts that could cause compressor and turbine wheel fracture and uncontained engine failure. An uncontained engine failure could cause possible damage to the airplane.

DATES:

This AD becomes effective May 24, 2006.

ADDRESSES:

Use one of the following addresses to comment on this AD:

  • DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
  • Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
  • Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590-0001.
  • Fax: (202) 493-2251.
  • Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact GE Aircraft Engines Customer Support Center, M/D 285, 1 Neumann Way, Evendale, OH 45215, telephone (513) 552-3272; fax (513) 552-3329; e-mail address: GEAE.csc@ae.ge.com, for the service information identified in this AD.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Anthony W. Cerra Jr., Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; telephone 781-238-7128; fax 781-238-7199; e-mail address: anthony.cerra@faa.gov.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

GE has informed us that cracks have been found in certain P/N rotating parts. The manufacturer reported that cracks were found in the outer rim of a stage 1 aft cooling plate, P/N 4022T37P01, installed on the gas generator turbine (GGT) rotor of a military T64 engine. They also found cracks in the sawcut slots of the GGT rear air seals of stage 2 aft cooling plates, P/N 4022T36P01, in the CT64-820-4 engine model and a similar military T64 engine model. There have been at least 13 reports of cracked GGT rear air seals.

Investigation by the manufacturer showed that compressor rotor assemblies, GGT rotor assemblies, and power turbine rotor assemblies have small feature locations. A “small feature” location is any rotating hardware feature with drawing radii less than 0.020 inch. Engineering analysis determined that the small feature locations and other life-limited locations of the rotating parts identified in this action have levels of stress during engine operation that are higher than originally anticipated and could result in cracks on these parts. This condition, if not corrected, could cause compressor and turbine wheel fracture and uncontained engine failure. An uncontained engine failure could cause possible damage to the airplane.

FAA's Determination and Requirements of This AD

Although no airplanes registered in the United States use these engines, the possibility exists that the engines could be used on airplanes that are registered in the United States in the future. The unsafe condition described previously is likely to exist or develop on other GE CT64-820-4 turboprop engines of the same type design. We are issuing this AD to prevent cracks in the rotating parts that could cause compressor and turbine wheel fracture and uncontained engine failure. An uncontained engine failure could cause possible damage to the airplane. This AD requires removing from service these affected life-limited rotating parts at reduced compliance times.

FAA's Determination of the Effective Date

Since there are currently no domestic operators of this engine model, notice and opportunity for public comment before issuing this AD are unnecessary. A situation exists that allows the immediate adoption of this regulation.

Comments Invited

This AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to send us any written relevant data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include “AD Docket No. FAA-2006-23705; Directorate Identifier 2005-NE-45-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify it. We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of the DMS Web site, Start Printed Page 20002anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit http://dms.dot.gov.

Examining the AD Docket

You may examine the docket that contains the AD, any comments received, and any final disposition in person at the Docket Management Facility Docket Offices between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone (800) 647-5227) is located on the plaza level of the Department of Transportation Nassif Building at the street address stated in ADDRESSES. Comments will be available in the AD docket shortly after the DMS receives them.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will 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. For the reasons discussed above, I certify that the 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. 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. We prepared a summary of the costs to comply with this AD and placed it in the AD Docket. You may get a copy of this summary at the address listed under ADDRESSES.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

Adoption of the Amendment

Start Amendment Part

Under the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (

End Amendment Part Start Part

PART 39—AIRWORTHINESS DIRECTIVES

End Part Start Amendment Part

1. The authority citation for part 39 continues to read as follows:

End Amendment Part Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]
Start Amendment Part

2. The FAA amends § 39.13 by adding the following new airworthiness directive:

End Amendment Part

2006-08-10 General Electric Company: Amendment 39-14567. Docket No. FAA-2006-23705; Directorate Identifier 2005-NE-45-AD.

Effective Date

(a) This airworthiness directive (AD) becomes effective May 24, 2006.

Affected ADs

(b) None.

Applicability

(c) This AD applies to General Electric Company (GE) CT64-820-4 turboprop engines that use any of the rotating parts listed in Table 1 of this AD. These engines are installed on, but not limited to, DeHavilland DHC-5D Buffalo airplanes.

Table 1.—Affected Rotating Parts

Rotor assemblyPart nomenclaturePart No.
CompressorShaft, Front5007T03P03
Disk, Stage 15015T92P01
Retainer, Disk, Stage 15013T71P01
Disk, Stage 25015T93P01
Spacer, Disk, Stage 25015T94P01
Disk, Stage 35015T95P01
Spool, Rotor, Front6003T84P02
Spool, Rotor, Rear6005T18P01
Shaft, Rear6005T26P01
Gas Generator TurbineDisk and Shaft, Stage 16014T70P02
Disk, Stage 24007T83P02
Ring, Torque3008T60P02
Seal, Air, Stage 14007T94G02
Plate, Cooling3008T52P02
Plate, Cooling4022T37P01
Seal, Interstage5006T54P02
Seal, Air, Rear4022T36P01
Seal, Air, Rear4022T36P03
Power TurbineDisk, Stage 34008T65P02
Disk, Stage 45006T16P03
Disk, Stage 45006T16P04
Seal, Interstage4008T29P01
Shaft, Main5009T73P02
Shaft, Main6012T83P02
Tiebolt, Power Turbine Rotor3008T44P02
Start Printed Page 20003

Unsafe Condition

(d) This AD results from the manufacturer's discovery of cracks in some rotating parts. We are issuing this AD to prevent cracks in the rotating parts that could cause compressor and turbine wheel fracture and uncontained engine failure. An uncontained engine failure could cause possible damage to the airplane.

Definition of “Data Fleet” and “No-Data” Fleet Engines

(e) For the purposes of this AD, “Data Fleet” is defined as a category of engines for which the engine serial numbers (SNs) are listed in Table 2 of this AD, and the following information has been provided to the manufacturer and included in the data analysis:

(1) Current configuration of all life-limited parts.

(2) Current cycles of life-limited parts.

(3) Engine utilization rate (hours/month).

Table 2.—Engine SNs in the Data Fleet

268504268565268605268646268662
268505268569268606268647268666
268509268573268608268648268667
268511268574268620268649268669
268514268575268622268650268670
268529268580268636268653268672
268534268583268637268655268674
268535268588268638268656268679
268537268589268641268658268686
268545268590268642268659268689
268549268596268643268660268690
268562268603268644268661268691

(f) For the purposes of this AD, “No-Data Fleet” is defined as a category of engines for which the engine SNs are not listed in Table 2 of this AD. The operators of the “No Data Fleet” engines did not supply the data listed in paragraph (e) to the manufacturer.

Compliance

(g) You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.

(h) If performing the actions required by this AD for “Data Fleet” engines, follow paragraphs (j) through (o).

(i) If performing the actions required by this AD for “No-Data Fleet” engines, follow paragraphs (p) through (u).

Data Fleet Rotating Part Removal Requirements

(j) For parts listed in Table 3 of this AD and installed in serviceable engines (those that are in service or have met the requirements for and have been approved for return to service) on the effective date of this AD, do the following:

(1) If the cycles-since-new (CSN) of a part listed in Table 3 of this AD are equal to or more than Table 3, Limit 2 as of the effective date of this AD, remove the part before exceeding 900 additional cycles-in-service (CIS) or Table 3, Limit 1, whichever occurs first, but not later than July 31, 2013.

(2) If the CSN for a part listed in Table 3 of this AD are fewer than Table 3, Limit 2 as of the effective date of this AD, remove the part from service before exceeding Table 3, Limit 3, but not later than July 31, 2013.

Table 3.—Affected Data Fleet Rotating Part Removal Requirements

RotorNomenclaturePart No.Limit 1 (cycles)Limit 2 (cycles)Limit 3 (cycles)
CompressorShaft, Front5007T03P0330,00029,10030,000
Disk, Stage 15015T92P0113,0008,1009,000
Retainer, Disk, Stage 15013T71P0130,00029,10030,000
Disk, Stage 25015T93P0123,0008,1009,000
Spacer, Disk, Stage 25015T94P0130,0008,1009,000
Disk, Stage 35015T95P019,0008,1009,000
Spool, Rotor, Front6003T84P025,1002,1003,000
Spool, Rotor, Rear6005T18P0119,0003,5004,400
Shaft, Rear6005T26P0130,0008,1009,000
Gas Generator TurbineDisk and Shaft, Stage 16014T70P027,00061007000
Disk, Stage 24007T83P0211,3005,4006,300
Ring, Torque3008T60P0230,0006,1007,000
Seal, Air, Stage 14007T94G0230,00011,70012,600
Plate, Cooling3008T52P025,0004,1005,000
Plate, Cooling4022T37P015,0004,1005,000
Seal, Interstage5006T54P025,1004,2005,100
Seal, Air, Rear4022T36P015,0004,1005,000
Seal, Air, Rear4022T36P035,0004,1005,000
Power TurbineDisk, Stage 34008T65P0230,00012,10013,000
Disk, Stage 45006T16P0330,00012,10013,000
Disk, Stage 45006T16P0430,00012,10013,000
Seal, Interstage4008T29P0130,00012,10013,000
Shaft, Main5009T73P0213,00012,10013,000
Shaft, Main6012T83P0213,00012,10013,000
Tiebolt, Power Turbine Rotor3008T44P0213,00012,10013,000

(k) For all rotating parts listed in Table 3 of this AD and put into service after the effective date of this AD, remove from service before the CSN exceeds Table 3, Limit 3, but not later than July 31, 2013. Start Printed Page 20004

(l) After the effective date of this AD:

(1) Do not install any part listed in Table 3 of this AD that has a CSN equal to or more than Table 3, Limit 3.

(2) If the CSN for a part listed in Table 3 of this AD are fewer than Table 3, Limit 3:

(i) Until July 31, 2007, you may return the part to service, if the part passes the applicable inspections specified in the CT64-820-4 Engine Overhaul Manual, SEI-448.

(ii) You must remove the part from service before Table 3, Limit 3 is exceeded, but no later than July 31, 2013.

(iii) After July 31, 2007, do not install any part listed in Table 3 of this AD.

(m) On July 31, 2007, for engines in service that have a part listed in Table 3 of this AD, remove the affected part before exceeding Table 3, Limit 3, but no later than July 31, 2013.

(n) For main shafts, P/N 5009T73P02, and P/N 6012T83P02, and power turbine rotor tiebolt, P/N 3008T44P02, with unknown CSN do the following:

(1) Assign each part a CSN value of 7,400 CSN as of the effective date of this AD and refer to Table 3 of this AD for removal requirements.

(2) Continue to track the parts starting from 7,400 CSN and remove from service as specified in paragraphs (j) through (n) of this AD, but no later than July 31, 2013.

(o) For rear air seal, P/N 4022T36P03, and power turbine stage 4 disk, P/N 5006T16P04, with unknown CSN, remove the part before exceeding 10 additional cycles, but no later than July 31, 2013.

No-Data Fleet Rotating Part Removal Requirements

(p) For parts listed in Table 4 of this AD and installed in serviceable engines (those that are in service, or have met the requirements for and have been approved for return to service) on the effective date of this AD, do the following:

(1) If the CSN of a part listed in Table 4 of this AD are equal to or more than Table 4, Limit 2 as of the effective date of this AD, remove the part before exceeding 50 additional CIS or Table 4, Limit 1, whichever occurs first, but not later than July 31, 2013.

(2) If the CSN for a part listed in Table 4 of this AD are fewer than Table 4, Limit 2 as of the effective date of this AD, remove the part from service before exceeding Table 4, Limit 3, but not later than July 31, 2013.

(q) For all rotating parts listed in Table 4 of this AD and put into service after the effective date of this AD, remove from service before the CSN exceeds Table 4, Limit 3, but not later than July 31, 2013.

Table 4.—Affected No-Data Fleet Rotating Part Removal Requirements

RotorNomenclaturePart No.Limit 1 (cycles)Limit 2 (cycles)Limit 3 (cycles)
CompressorShaft, Front5007T03P0330,00029,95030,000
Disk, Stage 15015T92P0113,0008,9509,000
Retainer, Disk, Stage 15013T71P0130,00029,95030,000
Disk, Stage 25015T93P0123,0008,9509,000
Spacer, Disk, Stage 25015T94P0130,0008,9509,000
Disk, Stage 35015T95P019,0008,9509,000
Spool, Rotor, Front6003T84P025,1002,9503,000
Spool, Rotor, Rear6005T18P0119,0004,3504,400
Shaft, Rear6005T26P0130,0008,9509,000
Gas Generator TurbineDisk and Shaft, Stage 16014T70P027,0006,9507,000
Disk, Stage 24007T83P0211,3006,2506,300
Ring, Torque3008T60P0230,0006,9507,000
Seal, Air, Stage 14007T94G0230,00012,55012,600
Plate, Cooling3008T52P025,0004,9505,000
Plate, Cooling4022T37P015,0004,9505,000
Seal, Interstage5006T54P025,1005,0505,100
Seal, Air, Rear4022T36P015,0004,9505,000
Seal, Air, Rear4022T36P035,0004,9505,000
Power TurbineDisk, Stage 34008T65P0230,00012,95013,000
Disk, Stage 45006T16P0330,00012,95013,000
Disk, Stage 45006T16P0430,00012,95013,000
Seal, Interstage4008T29P0130,00012,95013,000
Shaft, Main5009T73P0213,00012,95013,000
Shaft, Main6012T83P0213,00012,95013,000
Tiebolt, Power Turbine Rotor3008T44P0213,00012,95013,000

(r) After the effective date of this AD:

(1) Do not install any part listed in Table 4 of this AD that has a CSN equal to or more than Table 4, Limit 3.

(2) If the CSN for a part listed in Table 4 of this AD are fewer than Table 4, Limit 3:

(i) Until July 31, 2007, you may return the part to service, if the part passes the applicable inspections specified in the CT64-820-4 Engine Overhaul Manual, SEI-448.

(ii) You must remove the part from service before Table 4, Limit 3 is exceeded, but no later than July 31, 2013.

(iii) After July 31, 2007, do not install any part listed in Table 4 of this AD.

(s) On July 31, 2007, for engines in service that have a part listed in Table 4 of this AD, remove the affected part before exceeding Table 4, Limit 3, but no later than July 31, 2013.

(t) For main shafts P/N 5009T73P02, and P/N 6012T83P02, and power turbine rotor tiebolt, PN 3008T44P02, with unknown CSN, remove the part before exceeding 50 additional cycles

(u) For rear air seal, P/N 4022T36P03, and power turbine stage 4 disk, P/N 5006T16P04, with unknown CSN, remove the part before exceeding 10 additional cycles, but no later than July 31, 2013.

Log Book Entry

(v) For all engines, calculate the cycles remaining on the affected rotating parts and make an entry in the Engine Log Book marked with the engine S/N and its fleet category, either “DATA FLEET” or “NO-DATA FLEET.”

(1) Date and file the record in the Engine Log Book.

(2) Note in the Engine Log Book that AD 2006-08-10 has been complied with.

Alternative Methods of Compliance

(w) The Manager, Engine Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19.

Related Information

(x) GE Aircraft Engines CT64 Alert Service Bulletin CT64 S/B 72-A0130, dated January 24, 2006, pertains to the subject of this AD.

Start Signature
Start Printed Page 20005

Issued in Burlington, Massachusetts, on April 12, 2006.

Francis A. Favara,

Manager, Engine and Propeller Directorate, Aircraft Certification Service.

End Signature End Supplemental Information

[FR Doc. 06-3724 Filed 4-18-06; 8:45 am]

BILLING CODE 4910-13-P