Federal Register / Vol. 70, No. 61 / Thursday, March 31, 2005 / Rules and Regulations 16403

the repetitive inspections requirement 

specified in paragraph (h) of this AD for that 

actuator. 

Credit for Actions Previously Completed 

(j) Inspections completed before the 

effective date of this AD using GE ASB No. 

CF34–8C–AL S/B 75–A0007, Revision 1 

dated November 7, 2003; or Revision 2 dated 

December 16, 2004; or Revision 3 dated 

February 14, 2005; are acceptable for 

compliance with the corresponding 

inspection in this AD. 

Alternative Methods of Compliance 

(k) 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. 

Special Flight Permits 

(l) Under 39.23, we impose the following 

conditions and limitations on the issuance 

and use of Special Flight Permits for this AD: 

(1) If both engines report FADEC fault 1 

messages at the same time, whether 

intermittent or continuous, review the MDC 

for master VG actuator faults before further 

flight. If actuator faults are still present for 

both engines, then replace at least one master 

VG actuator before further flight. 

(2) If a master VG actuator switches 

channels, replace the actuator before further 

flight. 

Material Incorporated by Reference 

(m) You must use GE Alert Service Bulletin 

No. CF34–8C–AL S/B 75–A0007, Revision 3, 

dated February 14, 2005, to perform the 

reviews and actuator dispositions required by 

this AD. The Director of the Federal Register 

approved the incorporation by reference of 

GE Alert Service Bulletin No. CF34–8C–AL 

S/B 75–A0007, Revision 3, dated February 

14, 2005, under 5 U.S.C. 552(a) and 1 CFR 

part 51. You can get a copy from General 

Electric Company via Lockheed Martin 

Technology Services, 10525 Chester Road, 

Suite C, Cincinnati, Ohio 45215, telephone 

(513) 672–8400, fax (513) 672–8422. You may 

review copies at the Federal Aviation 

Administration (FAA), New England Region, 

Office of the Regional Counsel, 12 New 

England Executive Park, Burlington, MA 

01803–5299; or at the National Archives and 

Records Administration (NARA). For 

information on the availability of this 

material at NARA, call 202–741–6030, or go 

to: http://www.archives.gov/federal_register/

code_of_federal_regulations/

ibr_locations.html.

Related Information 

(n) None.

Issued in Burlington, Massachusetts, on 

March 23, 2005. 

Peter A. White, 

Acting Manager, Engine and Propeller 

Directorate, Aircraft Certification Service.

[FR Doc. 05–6247 Filed 3–30–05; 8:45 am] 

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2004–18876; Directorate 

Identifier 2003–NM–254–AD; Amendment 

39–14032; AD 2005–07–08] 

RIN 2120–AA64 

Airworthiness Directives; Boeing 

Model 757–200 and –200PF Series 

Airplanes

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT).

ACTION: Final rule.

SUMMARY: The FAA is adopting a new 

airworthiness directive (AD) for certain 

Boeing Model 757–200 and –200PF 

series airplanes. This AD requires 

repetitive inspections and audible tap 

tests of the upper and lower skins of the 

trailing edge wedges on certain slats, 

and related investigative and corrective 

actions if necessary. This AD also 

provides an optional terminating action 

for the repetitive inspections and 

audible tap tests. This AD is prompted 

by a report of damage to the No. 4 

leading edge slat. We are issuing this 

AD to prevent delamination of the 

leading edge slats, possible loss of 

pieces of the trailing edge wedge 

assembly during flight, reduction of the 

reduced maneuver and stall margins, 

and consequent reduced controllability 

of the airplane.

DATES: This AD becomes effective May 

5, 2005. 

The incorporation by reference of a 

certain publication listed in the AD is 

approved by the Director of the Federal 

Register as of May 5, 2005.

ADDRESSES: For service information 

identified in this AD, contact Boeing 

Commercial Airplanes, P.O. Box 3707, 

Seattle, Washington 98124–2207. You 

can examine this information at the 

National Archives and Records 

Administration (NARA). For 

information on the availability of this 

material at NARA, call (202) 741–6030, 

or go to: http://www.archives.gov/

federal_register/

code_of_federal_regulations/

ibr_locations.html. 

Docket: The AD docket contains the 

proposed AD, comments, and any final 

disposition. You can examine the AD 

docket on the Internet at http://

dms.dot.gov, or in person at the Docket 

Management Facility office between 9 

a.m. and 5 p.m., Monday through 

Friday, except Federal holidays. The 

Docket Management Facility office 

(telephone (800) 647–5227) is located on 

the plaza level of the Nassif Building at 

the U.S. Department of Transportation, 

400 Seventh Street SW., room PL–401, 

Washington, DC. This docket number is 

FAA–2004–18876; the directorate 

identifier for this docket is 2003–NM–

254–AD.

FOR FURTHER INFORMATION CONTACT:

Dennis Stremick, Aerospace Engineer, 

Airframe Branch, ANM–120S, FAA, 

Seattle Aircraft Certification Office, 

1601 Lind Avenue, SW., Renton, 

Washington 98055–4056; telephone 

(425) 917–6450; fax (425) 914–6590.

SUPPLEMENTARY INFORMATION: The FAA 

proposed to amend 14 CFR Part 39 with 

an AD for certain Boeing Model 757–

200 and -200PF series airplanes. That 

action, published in the Federal 

Register on August 17, 2004 (69 FR 

51015), proposed to require repetitive 

inspections and audible tap tests of the 

upper and lower skins of the trailing 

edge wedges on certain slats, and 

related investigative and corrective 

actions if necessary. The proposed AD 

also provided an optional terminating 

action for the repetitive inspections and 

audible tap tests. 

Comments 

We provided the public the 

opportunity to participate in the 

development of this AD. We have 

considered the comments that have 

been submitted on the proposed AD. 

Supportive Comment 

One commenter supports the 

proposed AD. 

Request To Correct Typographical 

Error in Applicability 

One commenter requests that the 

typographical error in paragraph (c), 

Applicability, of the proposed AD, be 

corrected. The Applicability in the 

proposed AD states that the AD applies 

to Boeing Model 737–200 and –200F 

series airplanes, as listed in Boeing 

Alert Service Bulletin 757–57A0063, 

dated June 26, 2003. The commenter 

states that the reference to Model 737–

200 and –200F series airplanes should 

be corrected to avoid confusion between 

the referenced service bulletin and 

proposed AD. 

We agree and the Applicability 

section of this AD has been corrected to 

reference ‘‘Boeing Model 757–200 and 

–200PF series airplanes identified in 

Boeing Alert Service Bulletin 757–

57A0063. * * *’’ We discovered this 

error after the proposed AD was 

published. We find that our intent in the 

proposed AD was clear, as all other 

references throughout the proposed AD 

were correct, and the referenced service 

16404 Federal Register / Vol. 70, No. 61 / Thursday, March 31, 2005 / Rules and Regulations 

bulletin applies to Boeing Model 757–

200 and –200PF series airplanes. Thus, 

we find no reason to re-open the 

comment period. 

Request To Clarify Applicability 

The Air Transport Association (ATA) 

states that its member airlines concur 

with the intent of the proposed AD, but 

that the applicability of the proposed 

AD is unclear. The commenter notes 

that actions specified in the proposed 

AD overlap or duplicate the 

requirements of AD 90–23–06, 

amendment 39–6794. The commenter 

also states that several slat wedge 

configurations exist in in-service 

airplanes as a result of AD 91–22–51, 

amendment 39–8129, and several other 

service bulletins that address trailing 

edge wedges. The commenter contends 

that the applicability of the proposed 

AD is unclear with respect to these 

configurations, and recommends that 

we revise the proposed AD to clearly 

state the applicability with respect to 

the various configurations resulting 

from the aforementioned airworthiness 

directives and service bulletins. 

We do not agree that the applicability 

of this AD requires revision. The 

applicability of this AD states that the 

AD applies to Boeing Model 757–200 

and -200PF series airplanes, certificated 

in any category, identified in Boeing 

Alert Service Bulletin 757–57A0063, 

dated June 26, 2003. The effectivity in 

that service bulletin is all Boeing Model 

757 series airplanes with line numbers 

1 through 139 inclusive. This AD 

addresses line numbers 1 through 139 

inclusive, regardless of configuration. 

Also, the airplane applicability for AD 

91–22–51 has different line numbers 

from those in this AD. The applicability 

for that AD is Boeing Model 757 series 

airplanes, line numbers 140 through 

335. We have not changed this AD 

regarding this issue. 

Request To Give Credit for Actions 

Accomplished Previously 

One commenter requests that the 

proposed AD be revised to indicate that 

actions accomplished previously in 

accordance with Boeing Service Bulletin 

757–57A0038 or 757–57A0045 are 

acceptable for compliance with the 

requirements of the proposed AD. The 

commenter states that the actions 

described in those service bulletins have 

the same results as the actions described 

in Boeing Alert Service Bulletin 757–

57A0063, dated June 26, 2003.

SERVICE BULLETINS WITH SIMILAR ACTIONS

Service Bulletin— Dated— Is cited in— As the appropriate source of 

service information for—

Boeing Alert Service Bulletin 757–

57A0063.

June 26, 2003 ........................... The proposed AD ..................... Inspecting, repairing, and replacing trailing edge wedges. 

Boeing Service Bulletin 757–57A0038, 

Revision 2.

October 10, 1990 ...................... AD 90–23–06, amendment 39–

6794.

Inspecting, repairing, and replacing trailing edge wedges. 

Boeing Service Bulletin 757–57A0045 ...... October 16, 1991 ...................... AD 91–22–51, amendment 39–

8129.

Repetitive detailed inspections 

of the trailing edge wedges 

of slats 1 through 4 and 7 

through 10. 

We agree that accomplishment of the 

actions specified in Boeing Service 

Bulletin 757–57A0038, Revision 5, 

dated July 16, 1992, or Revision 6, dated 

November 10, 1994, only, are acceptable 

for compliance with the requirements of 

this AD. We do not agree that 

accomplishment of the actions specified 

in Boeing Service Bulletin 757–57A0045 

is acceptable for compliance with the 

requirements of this AD. As stated 

previously, the applicability of AD 91–

22–51 is Boeing Model 757 series 

airplanes, line numbers 140 through 335 

inclusive, and the applicability of this 

AD is line numbers 1 through 139 

inclusive. 

We have included a new paragraph 

(h) in this AD, and reidentified the 

subsequent paragraphs accordingly. 

Paragraph (h) specifies that 

accomplishment of the actions in the 

Accomplishment Instructions of Boeing 

Service Bulletin 757–57A0038, Revision 

5 or Revision 6 only, in conjunction 

with the use of BMS 5–137 adhesive, is 

acceptable for compliance with the 

requirements of this AD. 

Request To Revise Compliance Time for 

Repetitive Inspections and Tests 

One commenter requests an extension 

of the compliance time from 18 months 

to 24 months for the repetitive detailed 

inspections and audible tap tests of the 

upper and lower skins of the trailing 

edge wedges. The commenter states that 

it performs maintenance checks (‘‘Cchecks’’) on its fleet every 24 months. 

The commenter also states that a 

compliance time of 18 months would 

require special maintenance visits in 

addition to the normally scheduled ‘‘Cchecks,’’ and the associated costs and 

downtime would be considerable. The 

commenter has reviewed its 

maintenance program, and the subject 

slats are currently inspected every 48 

months. A review of the associated 

maintenance task cards did not reveal 

any discrepancies. The commenter 

notes that this change to the proposed 

AD would prevent operators from 

having to request approval of an AMOC 

for the proposed AD. 

We do not agree with the commenter’s 

request to extend the compliance time. 

In developing an appropriate 

compliance time for this AD, we 

considered the urgency associated with 

the subject unsafe condition, the 

manufacturer’s recommended 

compliance time, and the practical 

aspect of accomplishing the required 

inspections within a period of time that 

corresponds to the normal scheduled 

maintenance program for most affected 

operators. However, according to the 

provisions of paragraph (k) of this AD, 

we may approve a request to adjust the 

compliance time if the request includes 

data that prove that the new compliance 

time would provide an acceptable level 

of safety. 

Explanation of Additional Change to 

This AD 

Since the publication of the proposed 

AD, Boeing has received a Delegation 

Option Authorization (DOA). We have 

revised this AD to delegate the authority 

to approve an AMOC for any repair 

required by this AD to the Authorized 

Representative for the Boeing DOA 

Organization rather than the Designated 

Engineering Representative. 

Conclusion 

We have carefully reviewed the 

available data, including the comments 

that have been submitted, and 

determined that air safety and the 

Federal Register / Vol. 70, No. 61 / Thursday, March 31, 2005 / Rules and Regulations 16405

public interest require adopting the AD 

with the changes described previously. 

We have determined that these changes 

will neither increase the economic 

burden on any operator nor increase the 

scope of the AD. 

Costs of Compliance 

This AD affects about 139 airplanes 

worldwide. The following table 

provides the estimated costs for U.S. 

operators to comply with this AD.

ESTIMATED COSTS

Action Work

hours 

Average

labor

rate per

hour 

Parts Cost per

airplane 

Number

of U.S.-

registered

airplanes 

Fleet cost 

Inspection test, per inspection 

cycle.

6 (1 work hour per 

slat, 6 slats per airplane.).

$65 None .. $390, per inspection/

test cycle.

97 $37,830, per inspection/test cycle 

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 this AD: 

(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. 

We prepared a regulatory evaluation 

of the estimated costs to comply with 

this AD. See the ADDRESSES section for 

a location to examine the regulatory 

evaluation.

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Incorporation by reference, 

Safety.

Adoption of the Amendment

■ Accordingly, under the authority 

delegated to me by the Administrator, 

the FAA amends 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):

2005–07–08 Boeing: Amendment 39–14032. 

Docket No. FAA–2004–18876; 

Directorate Identifier 2003–NM–254–AD. 

Effective Date 

(a) This AD becomes effective May 5, 2005. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to Boeing Model 757–

200 and –200PF series airplanes, certificated 

in any category, identified in Boeing Alert 

Service Bulletin 757–57A0063, dated June 

26, 2003. 

Unsafe Condition 

(d) This AD was prompted by a report of 

damage to the No. 4 leading edge slat. We are 

issuing this AD to prevent delamination of 

the leading edge slats, possible loss of pieces 

of the trailing edge wedge assembly during 

flight, reduction of the reduced maneuver 

and stall margins, and consequent reduced 

controllability of the airplane. 

Compliance 

(e) You are responsible for having the 

actions required by this AD performed within 

the compliance times specified, unless the 

actions have already been done. 

Repetitive Inspections and Tests 

(f) Within 18 months after the effective 

date of this AD: Do a detailed inspection and 

an audible tap test of the upper and lower 

skins of the trailing edge wedges on slats No. 

2 through No. 4 inclusive and No. 7 through 

No. 9 inclusive, for evidence of damage or 

cracking, in accordance with the 

Accomplishment Instructions of Boeing Alert 

Service Bulletin 757–57A0063, dated June 

26, 2003. Repeat the detailed inspection and 

audible tap test thereafter at intervals not to 

exceed 18 months.

Note 1: For the purposes of this AD, a 

detailed inspection is: ‘‘An intensive 

examination of a specific item, installation, 

or assembly to detect damage, failure, or 

irregularity. Available lighting is normally 

supplemented with a direct source of good 

lighting at an intensity deemed appropriate. 

Inspection aids such as mirror, magnifying 

lenses, etc., may be necessary. Surface 

cleaning and elaborate procedures may be 

required.’’

Related Investigative and Corrective Actions 

(g) If any damage or cracking is found 

during any inspection or audible tap test 

required by paragraph (f) of this AD: Before 

further flight, do the related investigative 

action, if applicable, and replace the affected 

part with a new trailing edge wedge assembly 

or repair the affected part, in accordance with 

the Accomplishment Instructions of Boeing 

Alert Service Bulletin 757–57A0063, dated 

June 26, 2003. Accomplishing the 

replacement terminates the repetitive 

inspections and audible tap tests required by 

paragraph (f) of this AD for that wedge 

assembly only. 

Actions Accomplished Previously 

(h) Previous accomplishment of all of the 

actions specified in the Accomplishment 

Instructions of Boeing Service Bulletin 757–

57A0038, Revision 5, dated July 16, 1992; or 

Revision 6, dated November 10, 1994; in 

conjunction with the use of BMS 5–137 

adhesive; is acceptable for compliance with 

the inspection requirements of paragraph (f) 

of this AD. 

16406 Federal Register / Vol. 70, No. 61 / Thursday, March 31, 2005 / Rules and Regulations 

Parts Installation 

(i) As of the effective date of this AD, no 

trailing edge wedge assembly having a part 

number listed in the ‘‘Existing Part Number’’

column of the table in paragraph 2.C.3. of 

Boeing Alert Service Bulletin 757–57A0063, 

dated June 26, 2003, may be installed on any 

airplane unless it has been inspected, tested, 

and had any necessary corrective actions 

accomplished in accordance with this AD. 

Optional Terminating Action 

(j) Replacing all trailing edge wedge 

assemblies with new, improved wedge 

assemblies in accordance with Part III of the 

Accomplishment Instructions of Boeing Alert 

Service Bulletin 757–57A0063, dated June 

26, 2003, terminates the requirements of 

paragraph (f) of this AD. 

Alternative Methods of Compliance 

(AMOCs) 

(k)(1) The Manager, Seattle Aircraft 

Certification Office (ACO), FAA, has the 

authority to approve AMOCs for this AD, if 

requested in accordance with the procedures 

found in 14 CFR 39.19. 

(2) An AMOC that provides an acceptable 

level of safety may be used for any repair 

required by this AD, if it is approved by an 

Authorized Representative for the Boeing 

Delegation Option Authorization 

Organization who has been authorized by the 

Manager, Seattle ACO, to make those 

findings. For a repair method to be approved, 

the repair must meet the certification basis of 

the airplane, and the approval must 

specifically refer to this AD. 

Material Incorporated by Reference 

(l) You must use Boeing Alert Service 

Bulletin 757–57A0063, dated June 26, 2003, 

to perform the actions that are required by 

this AD, unless the AD specifies otherwise. 

The Director of the Federal Register approves 

the incorporation by reference of this 

document in accordance with 5 U.S.C. 552(a) 

and 1 CFR part 51. For copies of the service 

information, contact Boeing Commercial 

Airplanes, P.O. Box 3707, Seattle, 

Washington 98124–2207. For information on 

the availability of this material at the 

National Archives and Records 

Administration (NARA), call (202) 741–6030, 

or go to http://www.archives.gov/

federal_register/code_of_federal_regulations/

ibr_locations.html. 

You may view the AD docket at the Docket 

Management Facility, U.S. Department of 

Transportation, 400 Seventh Street SW., 

room PL–401, Nassif Building, Washington, 

DC.

Issued in Renton, Washington, on March 

22, 2005. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service.

[FR Doc. 05–6259 Filed 3–30–05; 8:45 am] 

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration 

14 CFR Part 39

[Docket No. FAA–2004–18024; Directorate 

Identifier 2003–NE–39–AD; Amendment 39–

14034; AD 2005–07–10] 

RIN 2120–AA64

Airworthiness Directives; Rolls-Royce 

(1971) Limited, Bristol Engine Division 

Model Viper Mk.601–22 Turbojet 

Engines

AGENCY: Federal Aviation 

Administration (FAA), DOT.

ACTION: Final rule.

SUMMARY: The FAA is superseding an 

existing airworthiness directive (AD) for 

Rolls-Royce (1971) Limited, Bristol 

Engine Division (RR) model Viper 

Mk.601–22 turbojet engines. That AD 

currently requires reducing the life of 

certain 1st stage turbine rotor blades 

from 7,000 hours time-in-service (TIS) 

to 4,600 hours TIS, and provides a 

drawdown schedule for blades that have 

already exceeded the new reduced life 

limit. This AD requires the same actions 

but changes certain compliance times to 

be in agreement with RR Alert Service 

Bulletin (ASB) No. 72–A184, dated 

January 2001. This AD results from 

comments received on AD 2004–13–03, 

that the AD is unnecessarily more 

restrictive than the requirements in the 

associated RR ASB No. 72–A184. We are 

issuing this AD to prevent multiple 

failures of 1st stage turbine rotor blades 

that could result in a dual-engine 

shutdown.

DATES: This AD becomes effective May 

5, 2005.

ADDRESSES: You can get the service 

information identified in this proposed 

AD from Rolls-Royce Limited, Bristol 

Engines Division, Technical 

Publications Department CLS–4, P.O. 

Box 3, Filton, Bristol, BS34 7QE 

England; telephone 117–979–1234, fax 

117–979–7575. 

You may examine the AD docket on 

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

Room PL–401 on the plaza level of the 

Nassif Building, 400 Seventh Street, 

SW., Washington, DC.

FOR FURTHER INFORMATION CONTACT: Ian 

Dargin, Aerospace Engineer, Engine 

Certification Office, FAA, Engine and 

Propeller Directorate, 12 New England 

Executive Park, Burlington, MA 01803–

5299; telephone (781) 238–7178; fax 

(781) 238–7199.

SUPPLEMENTARY INFORMATION: The FAA 

proposed to amend 14 CFR part 39 with 

a proposed airworthiness directive (AD). 

The proposed AD applies to Rolls-Royce 

(1971) Limited, Bristol Engine Division 

(RR) model Viper Mk.601–22 turbojet 

engines. We published the proposed AD 

in the Federal Register on October 29, 

2004 (69 FR 63104). That action 

proposed to require reducing the life of 

certain 1st stage turbine rotor blades 

from 7,000 hours TIS to 4,600 hours 

TIS, provide a drawdown schedule for 

blades that have already exceeded the 

new reduced life limit, and change 

certain compliance times to be in 

agreement with RR ASB No. 72–A184, 

dated January 2001. 

Examining the AD Docket 

You may examine the docket that 

contains the AD, 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. 

Comments 

We provided the public the 

opportunity to participate in the 

development of this AD. We received no 

comments on the proposal or on the 

determination of the cost to the public. 

Conclusion 

We have carefully reviewed the 

available data and determined that air 

safety and the public interest require 

adopting the AD as proposed. 

Costs of Compliance 

We estimate that 84 RR model Viper 

Mk.601–22 turbojet engines installed on 

airplanes of U.S. registry will be affected 

by this AD. We estimate that no 

additional labor cost will be incurred to 

replace 1st stage turbine rotor blades 

when done at time of engine overhaul. 

A replacement set 1st stage turbine rotor 

blades costs about $166,987. Based on 

these figures, we estimate the total cost 

of the AD to U.S. operators to be 

$14,026,950.

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.