67864 Federal Register / Vol. 69, No. 224 / Monday, November 22, 2004 / Proposed Rules 

5007D and provisions for replacing the 

fuel filter at this specified period (or a 

shorter period) are included in the 

maintenance scheduled for the engine 

installation. 

(g) Power setting, in percentage. 

(h) Fuel temperature. 

(i) Fuel flow (engine fuel 

consumption). 

9. Operating Limitations and 

Information—Powerplant Limitations—

Fuel Grade or Designation (Compliance 

With § 23.1521(d) Requirements) 

Instead of compliance with 

§ 23.1521(d), the applicant must comply 

with the following: 

The minimum fuel designation (for 

diesel engines) must be established so 

that it is not less than that required for 

the operation of the engines within the 

limitations in paragraphs (b) and (c) of 

§ 23.1521. 

10. Markings and Placards—

Miscellaneous Markings and Placards—

Fuel, Oil, and Coolant Filler Openings 

(Compliance With § 23.1557(c)(1) 

Requirements) 

Instead of compliance with 

§ 23.1557(c)(1), the applicant must 

comply with the following: 

Fuel filler openings must be marked 

at or near the filler cover with—

For diesel engine-powered 

airplanes—

(a) The words ‘‘Jet Fuel’’; and 

(b) The permissible fuel designations, 

or references to the Airplane Flight 

Manual (AFM) for permissible fuel 

designations.

(c) A warning placard or note that 

states the following or similar: 

‘‘Warning—this airplane equipped 

with an aircraft diesel engine, service 

with approved fuels only.’’

The colors of this warning placard 

should be black and white. 

11. Powerplant—Fuel System—FuelFreezing 

If the fuel in the tanks cannot be 

shown to flow suitably under all 

possible temperature conditions, then 

fuel temperature limitations are 

required. These will be considered as 

part of the essential operating 

parameters for the aircraft and must be 

limitations. 

(1) The takeoff temperature limitation 

must be determined by testing or 

analysis to define the minimum coldsoaked temperature of the fuel that the 

airplane can operate on. 

(2) The minimum operating 

temperature limitation must be 

determined by testing to define the 

minimum operating temperature 

acceptable after takeoff (with minimum 

takeoff temperature established in (1) 

above). 

12. Powerplant Installation—Vibration 

Levels 

Vibration levels throughout the 

engine operating range must be 

evaluated and: 

(1) Vibration levels imposed on the 

airframe must be less than or equivalent 

to those of the gasoline engine; or 

(2) Any vibration level that is higher 

than that imposed on the airframe by 

the replaced gasoline engine must be 

considered in the modification and the 

effects on the technical areas covered by 

the following paragraphs must be 

investigated: 14 CFR part 23, §§ 23.251; 

23.613; 23.627; 23.629 (or CAR 3.159, as 

applicable to various models); 23.572; 

23.573; 23.574 and 23.901. 

Vibration levels imposed on the 

airframe can be mitigated to an 

acceptable level by utilization of 

isolators, dampers clutches and similar 

provisions, so that unacceptable 

vibration levels are not imposed on the 

previously certificated structure. 

13. Powerful Installation—One Cylinder 

Inoperative 

It must be shown by test or analysis, 

or by a combination of methods, that the 

airframe can withstand the shaking or 

vibratory forces imposed by the engine 

if a cylinder becomes inoperative. Diesel 

engines of conventional design typically 

have extremely high levels of vibration 

when a cylinder become inoperative. 

Data must be provided to the airframe 

installer/modifier so either appropriate 

design considerations or operating 

procedures, or both, can be developed to 

prevent airframe and propeller damage. 

14. Powerplant Installation—High 

Energy Engine Fragments 

It may be possible for diesel engine 

cylinders (or portions thereof) to fail 

and physically separate from the engine 

at high velocity (due to the high internal 

pressures). This failure mode will be 

considered possible in engine designs 

with removable cylinders or other nonintegral block designs. The following is 

required. 

(1) It must be shown that the engine 

construction type (massive or integral 

block with nonremovable cylinders) is 

inherently resistant to liberating high 

energy fragments in the event of a 

catastrophic engine failure; or, 

(2) It must be shown by the design of 

the engine, that engine cylinders, other 

engine components or portions thereof 

(fragments) cannot be shed or blown off 

of the engine in the event of a 

catastrophic engine failure; or 

(3) It must be shown that all possible 

liberated engine parts or components do 

not have adequate energy to penetrate 

engine cowlings; or 

(4) Assuming infinite fragment 

energy, and analyzing the trajectory of 

the probable fragments and components, 

any hazard due to liberated engine parts 

or components will be minimized and 

the possibility of crew injury is 

eliminated. Minimization must be 

considered during initial design and not 

presented as an analysis after design 

completion.

Issued in Kansas City, Missouri, on 

November 1, 2004. 

James E. Jackson, 

Acting Manager, Small Airplane Directorate, 

Aircraft Certification Service.

[FR Doc. 04–25697 Filed 11–19–04; 8:45 am] 

BILLING CODE 4910–13–M

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2004–19444; Directorate 

Identifier 2004–CE–33–AD] 

RIN 2120–AA64 

Airworthiness Directives; Pacific 

Aerospace Corporation, Ltd. Model 

750XL Airplanes

AGENCY: Federal Aviation 

Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to adopt a 

new airworthiness directive (AD) for all 

Pacific Aerospace Corporation, Ltd. 

(Pacific Aerospace) Model 750XL 

airplanes. This proposed AD would 

require you to replace any type TLP–D 

or TLED rivets on the aileron pushrod 

ends and elevator control pushrod ends. 

This proposed AD results from 

mandatory continuing airworthiness 

information (MCAI) issued by the 

airworthiness authority for New 

Zealand. We are issuing this proposed 

AD to replace the above identified rivets 

on the aileron pushrod ends and 

elevator control pushrod ends, which, if 

not replaced, could result in loose 

mechanical elements in the control 

systems. This could lead to control 

anomalies and loss of airplane control.

DATES: We must receive any comments 

on this proposed AD by December 27, 

2004.

ADDRESSES: Use one of the following to 

submit comments on this proposed AD: 

• DOT Docket Web site: Go to

http://dms.dot.gov and follow the 

Federal Register / Vol. 69, No. 224 / Monday, November 22, 2004 / Proposed Rules 67865

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. 

• Fax: 1–202–493–2251. 

• 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. 

To get the service information 

identified in this proposed AD, contact 

Pacific Aerospace Corporation, Ltd., 

Hamilton Airport, Private Bag HN 3027, 

Hamilton, New Zealand; telephone: 64 7 

843 6144; facsimile: 64 7 843 6134. 

To view the comments to this 

proposed AD, go to http://dms.dot.gov.

This is docket number FAA–2004–

19444.

FOR FURTHER INFORMATION CONTACT: Karl 

Schletzbaum, Aerospace Engineer, 

Small Airplane Directorate, 901 Locust, 

Room 302, Kansas City, MO 64106; 

telephone: (816) 329–4146; facsimile: 

(816) 329–4090.

SUPPLEMENTARY INFORMATION: 

Comments Invited 

How do I comment on this proposed 

AD? We invite you to submit any 

written relevant data, views, or 

arguments regarding this proposal. Send 

your comments to an address listed 

under ADDRESSES. Include the docket 

number, ‘‘FAA–2004–19444; Directorate 

Identifier 2004–CE–33–AD’’ at the 

beginning of your comments. 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 

proposed rulemaking. Using the search 

function of our docket Web site, anyone 

can find and read the comments 

received into 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.). This is 

docket number FAA–2004–19444. 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.

Are there any specific portions of this 

proposed AD I should pay attention to?

We specifically invite comments on the 

overall regulatory, economic, 

environmental, and energy aspects of 

this proposed AD. If you contact us 

through a nonwritten communication 

and that contact relates to a substantive 

part of this proposed AD, we will 

summarize the contact and place the 

summary in the docket. We will 

consider all comments received by the 

closing date and may amend this 

proposed AD in light of those comments 

and contacts. 

Docket Information 

Where can I go to view the docket 

information? You may view the AD 

docket that contains the proposal, any 

comments received, and any final 

disposition in person at the DMS Docket 

Offices between 9 a.m. and 5 p.m. 

(eastern standard time), Monday 

through Friday, except Federal holidays. 

The Docket Office (telephone 1–800–

647–5227) is located on the plaza level 

of the Department of Transportation 

NASSIF Building at the street address 

stated in ADDRESSES. You may also view 

the AD docket on the Internet at

http://dms.dot.gov. The comments will 

be available in the AD docket shortly 

after the DMS receives them. 

Discussion 

What events have caused this 

proposed AD? The Civil Aviation 

Authority (CAA), which is the 

airworthiness authority for New 

Zealand, recently notified FAA that an 

unsafe condition may exist on all Pacific 

Aerospace Corporation, Ltd. (Pacific 

Aerospace) Model 750XL airplanes. The 

CAA reports occurrences of loose type 

TLP–D or TLED rivets on the aileron 

pushrod ends and elevator control 

pushrod ends on Model 750XL 

airplanes in service in New Zealand.

What is the potential impact if FAA 

took no action? Any type TLP–D or 

TLED rivets on the aileron pushrod ends 

and elevator control pushrod ends could 

result in loose mechanical elements in 

the control systems. This could lead to 

control anomalies and loss of airplane 

control. 

Is there service information that 

applies to this subject? Pacific 

Aerospace has issued Mandatory 

Service Bulletin No. PACSB/XL/007, 

dated June 22, 2004. 

What are the provisions of this service 

information? The service bulletin 

includes procedures for:

—Inspecting for any type TLP–D or 

TLED rivets on the aileron pushrod 

ends and elevator control pushrod 

ends; and 

—Replacing any type TLP–D or TLED 

rivets found on the aileron pushrod 

ends and elevator control pushrod 

ends with new Cherry Max 3213–4–

2 or 3243–4–2 (oversize nominal 1⁄8-

inch) rivets.

What action did the CAA take? The 

CAA classified this service bulletin as 

mandatory and issued New Zealand AD 

Number DCA/40XL/1, dated June 24, 

2004, to ensure the continued 

airworthiness of these airplanes in New 

Zealand. 

Did the CAA inform the United States 

under the bilateral airworthiness 

agreement? These Pacific Aerospace 

Model 750XL airplanes are 

manufactured in New Zealand and are 

type-certificated for operation in the 

United States under the provisions of 

section 21.29 of the Federal Aviation 

Regulations (14 CFR 21.29) and the 

applicable bilateral airworthiness 

agreement. 

Under this bilateral airworthiness 

agreement, the CAA has kept us 

informed of the situation described 

above. 

FAA’s Determination and Requirements 

of This Proposed AD 

What has FAA decided? We have 

examined the CAA’s findings, reviewed 

all available information, and 

determined that AD action is necessary 

for products of this type design that are 

certificated for operation in the United 

States. 

Since the unsafe condition described 

previously is likely to exist or develop 

on other Pacific Aerospace Model 

750XL airplanes of the same type design 

that are registered in the United States, 

we are proposing AD action to replace 

any type TLP–D or TLED rivets on the 

aileron pushrod ends and elevator 

control pushrod ends, which, if not 

replaced, could result in loose 

mechanical elements in the control 

systems. This could lead to control 

anomalies and loss of airplane control. 

What would this proposed AD 

require? This proposed AD would 

require you to replace any type TLP–D 

or TLED rivets on the aileron pushrod 

ends and elevator control pushrod ends. 

How does the revision to 14 CFR part 

39 affect this proposed AD? On July 10, 

2002, we published a new version of 14 

CFR part 39 (67 FR 47997, July 22, 

2002), which governs FAA’s AD system. 

This regulation now includes material 

that relates to altered products, special 

flight permits, and alternative methods 

of compliance. This material previously 

was included in each individual AD. 

Since this material is included in 14 

CFR part 39, we will not include it in 

future AD actions. 

Costs of Compliance 

How many airplanes would this 

proposed AD impact? We estimate that 

67866 Federal Register / Vol. 69, No. 224 / Monday, November 22, 2004 / Proposed Rules 

this proposed AD affects 6 airplanes in 

the U.S. registry. 

What would be the cost impact of this 

proposed AD on owners/operators of the 

affected airplanes? We estimate the 

following costs to do this proposed 

replacement of any type TLP–D or TLED 

rivets on the aileron pushrod ends and 

elevator control pushrod ends:

Labor cost Parts cost Total cost per 

airplane Total cost on U.S. Operators 

6 workhours × $65 per hour = $390 ....... $37 for 100 Cherry Max 3213–4–2 or 

3243–4–2 (oversize nominal 1⁄8-inch) 

rivets.

$427 $427 × 6 = $3,562. 

The Cherry Max 3213–4–2 or 3243–4–

2 rivets are available in a specially 

sealed 100-count package. The costs 

above cover this 100-count package 

although you may need less than 100 

rivets. 

Regulatory Findings 

Would this proposed AD impact 

various entities? We have determined 

that this proposed AD would not have 

federalism implications under Executive 

Order 13132. This proposed AD 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. 

Would this proposed AD involve a 

significant rule or regulatory action? For 

the reasons discussed above, I certify 

that this proposed AD: 

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 proposed AD and 

placed it in the AD Docket. You may get 

a copy of this summary by sending a 

request to us at the address listed under 

ADDRESSES. Include ‘‘AD Docket FAA–

2004–19444; Directorate Identifier 

2004–CE–33–AD’’ in your request. 

This proposed rulemaking is 

promulgated under the authority in 

Subtitle VII, Part A, Subpart III, Section 

44701, General requirements. Under 

that section, the FAA is charged with 

prescribing minimum standards 

required in the interest of safety for the 

design of aircraft. This proposed 

regulation is within the scope of that 

authority since it corrects an unsafe 

condition in the design of the aircraft 

caused by type TLP–D or TLED rivets, 

which, if not replaced, could result in 

loose mechanical elements in the 

control systems. This could lead to 

control anomalies and loss of airplane 

control.

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Safety.

The Proposed Amendment 

Accordingly, under the authority 

delegated to me by the Administrator, 

the Federal Aviation Administration 

proposes to amend 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 [Amended] 

2. The FAA amends § 39.13 by adding 

the following new airworthiness 

directive (AD):

Pacific Aerospace Corporation, Ltd.: Docket 

No. FAA–2004–19444; Directorate 

Identifier 2004–CE–33–AD 

When Is the Last Date I can Submit 

Comments on This Proposed AD? 

(a) We must receive comments on This 

proposed airworthiness directive (AD) by 

December 27, 2004. 

What Other ADs are Affected by This Action? 

(b) None. 

What Airplanes are Affected by This AD? 

(c) This AD affects Model 750XL airplanes, 

all serial numbers, that are certificated in any 

category.

What Is the Unsafe Condition Presented in 

This AD? 

(d) This AD is the result of mandatory 

continuing airworthiness information (MCAI) 

issued by the airworthiness authority for 

New Zealand. The actions specified in this 

AD are intended to replace any type TLP–D 

or TLED rivets on the aileron pushrod ends 

and elevator control pushrod ends, which, if 

not replaced, could result in loose 

mechanical elements in the control systems. 

This could lead to control anomalies and loss 

of airplane control. 

What Must I Do To Address This Problem? 

(e) To address this problem, you must do 

the following:

Actions Compliance Procedures 

(1) Replace any type TLP–D or TLED rivets on 

the aileron pushrod ends and elevator control 

pushrod ends with a new Cherry Max 3213–

4–2 or 3243–4–2 (oversize nominal 1⁄8-inch) 

rivet.

With 50 hours time-in-service (TIS) after the 

effective date of this AD, unless already 

done.

Follow the ACCOMPLISHMENT INSTRUCTIONS in Pacific Aerospace Corporation 

Mandatory Service Bulletin No. PACSB/XL/

007, dated June 22, 2004. 

(2) Do not install: (i) any type TLP–D or TLED 

rivets on the aileron pushrod ends and elevator control pushrod ends; or (ii) any aileron 

pushrods or elevator control pushrods with 

type TLP–D or TLED rivets on the ends.

As of the effective date of this AD ................... Not Applicable. 

May I Request an Alternative Method of 

Compliance? 

(f) You may request a different method of 

compliance or a different compliance time 

for this AD by following the procedures in 14 

CFR 39.19. Unless FAA authorizes otherwise, 

send your request to your principal 

inspector. The principal inspector may add 

comments and will send your request to the 

Manager, Standards Office, Small Airplane 

Directorate, FAA. For information on any 

already approved alternative methods of 

compliance, contact Karl Schletzbaum, 

Aerospace Engineer, Small Airplane 

Federal Register / Vol. 69, No. 224 / Monday, November 22, 2004 / Proposed Rules 67867

Directorate, 901 Locust, Room 302, Kansas 

City, MO 64106; telephone: (816) 329–4146; 

facsimile: (816) 329–4090. 

Is There Other Information That Relates to 

This Subject? 

(g) New Zealand Airworthiness Directive 

Number DCA/40XL/1, dated June 24, 2004, 

also addresses the subject of this AD. 

May I Get Copies of the Documents 

Referenced in This AD? 

(h) To get copies of the documents 

referenced in this AD, contact Pacific 

Aerospace Corporation, Ltd., Hamilton 

Airport, Private Bag HN 3027, Hamilton, New 

Zealand; telephone: 64 7 843 6144; facsimile: 

64 7 843 6134. To view the AD docket, go 

to the Docket Management Facility; U.S. 

Department of Transportation, 400 Seventh 

Street, SW., Nassif Building, Room PL–401, 

Washington, DC, or on the Internet at

http://dms.dot.gov. This is docket number 

FAA–2004–19444.

Issued in Kansas City, Missouri, on 

November 15, 2004. 

Scott L. Sedgwick, 

Acting Manager, Small Airplane Directorate, 

Aircraft Certification Service.

[FR Doc. 04–25795 Filed 11–19–04; 8:45 am] 

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2004–19648; Directorate 

Identifier 2004–NE–31–AD] 

RIN 2120–AA64 

Airworthiness Directives; Rolls-Royce 

Corporation (formerly Allison Engine 

Company) 250–B17B, –B17C, –B17D, 

–B17E, –C20, –C20B, –C20F, –C20J, 

–C20S, and –C20W Turboprop and 

Turboshaft Engines

AGENCY: Federal Aviation 

Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to adopt a 

new airworthiness directive (AD) for 

Rolls-Royce Corporation (RRC) 

(formerly Allison Engine Company) 

250–B17B, –B17C, –B17D, –B17E, –C20, 

–C20B, –C20F, –C20J, –C20S, and 

–C20W turboprop and turboshaft 

engines that do not have turbine energy 

absorbing ring, part number (P/N) 

23035175, installed. This proposed AD 

would require installation of a turbine 

energy absorbing ring in the plane of the 

1st stage turbine wheel. This proposed 

AD may also require installation of 1st 

stage turbine nozzles, 2nd stage turbine 

nozzles, and a gas producer support 

assembly, all modified to allow for 

installation of the turbine energy 

absorbing ring. This proposed AD 

results from an unacceptable rate of 

uncontained 1st stage turbine wheel 

failures. We are proposing this AD to 

minimize the risk of uncontained 1st 

stage turbine wheel fragments from 

causing damage to the aircraft or 

damage to the second engine on twinengine installations which could lead to 

loss of control and loss of the aircraft.

DATES: We must receive any comments 

on this proposed AD by January 21, 

2005.

ADDRESSES: Use one of the following 

addresses to submit comments on this 

proposed 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–

001. 

• 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. 

You can get the service information 

identified in this proposed AD from 

Rolls-Royce Corporation, P.O. Box 420, 

Indianapolis, IN 46206–0420; telephone 

(317) 230–6400; fax (317) 230–4243. 

You may examine the comments on 

this proposed AD in the AD docket on 

the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT:

Melissa T. Bradley, Aerospace Engineer, 

Chicago Aircraft Certification Office, 

FAA, 2300 East Devon Avenue, Des 

Plaines, IL 60018–4696; telephone (847) 

294–8110; fax (847) 294–7834.

SUPPLEMENTARY INFORMATION: 

Docket Management System (DMS) 

We have implemented new 

procedures for maintaining AD dockets 

electronically. As of May 17, 2004, we 

post new AD actions on the DMS and 

assign a DMS docket number. We track 

each action and assign a corresponding 

Directorate identifier. The DMS docket 

No. is in the form ‘‘Docket No. FAA–

200X–XXXXX.’’ Each DMS docket also 

lists the Directorate identifier (‘‘Old 

Docket Number’’) as a cross-reference 

for searching purposes. 

Comments Invited 

We invite you to submit any written 

relevant data, views, or arguments 

regarding this proposal. Send your 

comments to an address listed under 

ADDRESSES. Include ‘‘Docket No. FAA–

2004–19648; Directorate Identifier 

2004–NE–31–AD’’ in the subject line of 

your comments. We specifically invite 

comments on the overall regulatory, 

economic, environmental, and energy 

aspects of the proposed AD. We will 

consider all comments received by the 

closing date and may amend the 

proposed AD in light of those 

comments. 

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 proposed AD. 

Using the search function of the DMS 

Web site, anyone 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 proposal, any comments 

received and, any final disposition in 

person at the DMS 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. 

Discussion 

RRC conducted an analysis of 

uncontained 1st stage turbine wheel 

failures and the effects on aircraft. The 

1st stage turbine wheel can fail as a 

result of in-service damage or gas 

producer tiebolt failure. The in-service 

damage is caused primarily by thermal 

fatigue to the turbine wheels during hot 

starts but has also been linked to 

improper alignment of the combustion 

liner and oil fires. 

The manufacturer developed a turbine 

energy absorbing ring to render turbine 

wheel fragments non-hazardous. We 

have determined the present rate of 

hazardous 1st stage turbine wheel