49210 Federal Register / Vol. 70, No. 162 / Tuesday, August 23, 2005 / Proposed Rules 

actions actually required by the AD. 

These figures typically do not include 

incidental costs, such as the time 

required to gain access and close up, 

planning time, or time necessitated by 

other administrative actions. 

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 Impact 

The regulations proposed herein 

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. Therefore, 

it is determined that this proposal 

would not have federalism implications 

under Executive Order 13132. 

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 [Amended] 

2. Section 39.13 is amended by 

adding the following new airworthiness 

directive:

Boeing: Docket 2001–NM–213–AD.

Applicability: All Model 747SP, 747SR, 

747–100, –100B, –100B SUD, –200B, –200C, 

–200F, and –300 series airplanes; certificated 

in any category. 

Compliance: Required as indicated, unless 

accomplished previously. 

To prevent improper deployment of the 

escape slide/raft or blockage of the 

passenger/crew doors in the event of an 

emergency evacuation, which could result in 

injury to passengers or crewmembers, 

accomplish the following:

Modification 

(a) Within 36 months after the effective 

date of this AD: Accomplish the actions 

specified in paragraphs (a)(1) and (a)(2) of 

this AD, as applicable, in accordance with 

Boeing Special Attention Service Bulletin 

747–25–3274, Revision 3, dated December 

16, 2004. Previously accomplishing the 

modification in accordance with Boeing 

Special Attention Service Bulletin 747–25–

3274, Revision 1, dated January 9, 2003; or 

Revision 2, dated August 26, 2004; is 

acceptable for compliance with paragraph 

(a)(1) of this AD, except as specified in 

paragraph 1.D, ‘Description’, of Revision 3 of 

the service bulletin. 

(1) For airplanes on which the actions 

specified in Boeing Service Bulletin 747–25–

2666, Revision 2, dated April 24, 2003; and 

Goodrich Service Bulletin 25–238, Revision 

1, dated January 31, 2003, have been 

accomplished: Replace cable assemblies 

having part number (P/N) 69B55462–( ) with 

new cable assemblies having P/N 416U6004–

1. 

(2) For airplanes on which the 

modification required by paragraph (a)(1) of 

this AD has not been accomplished: Modify 

the escape slide/raft pack assembly (includes 

removing the slide packs, replacing the cover 

release pin cable assemblies with new 

assemblies, and removing the cable guard 

bracket, as applicable). 

Concurrent Modification 

(b) For Groups 2, 5, 6, 7, 8, 11, 12, 13, 14, 

and 15 airplanes: Prior to or concurrently 

with accomplishment of paragraph (a) of this 

AD, modify the outboard cover panel of the 

cable release sliders of the floor-mounted 

upper deck slide pack assembly, as specified 

in Figure 2 of Boeing Special Attention 

Service Bulletin 747–25–3307, Revision 2, 

dated July 8, 2004. 

Alternative Methods of Compliance 

(c) 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.

Issued in Renton, Washington, on August 

12, 2005. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service.

[FR Doc. 05–16751 Filed 8–22–05; 8:45 am] 

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration 

14 CFR Part 39

[Docket No. FAA–2005–22169; Directorate 

Identifier 2005–NM–094–AD] 

RIN 2120–AA64

Airworthiness Directives; Learjet 

Model 23, 24, 24A, 24B, 24B–A, 24C, 

24D, 24D–A, 24E, 24F, 24F–A, 25, 25A, 

25B, 25C, 25D, and 25F Airplanes

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT).

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to adopt a 

new airworthiness directive (AD) for 

certain Learjet Model 23, 24, 24A, 24B, 

24B–A, 24C, 24D, 24D–A, 24E, 24F, 

24F–A, 25, 25A, 25B, 25C, 25D, and 25F 

airplanes. This proposed AD would 

require replacement of the spherical 

accumulator for the main hydraulic 

system with a new cylindrical 

accumulator. For certain airplanes, this 

proposed AD would also require 

modification of the accumulator 

pressure gauge. This proposed AD is 

prompted by reports of the failure of 

two thrust reverser accumulators (which 

are similar to the main hydraulic 

system’s spherical accumulator) and 

fatigue cracks found on four thrust 

reverser accumulators. We are 

proposing this AD to prevent failure of 

the spherical accumulator for the main 

hydraulic system, due to fatigue 

cracking on the threads, which could 

result in the loss of hydraulic power, 

damage to the surrounding airplane 

structure, and loss of airplane control. 

The failure of the accumulator could 

also result in injury to any persons in 

the surrounding area. The loss of 

hydraulic fluid could also leak onto a 

potential source of ignition and result in 

a consequent fire.

DATES: We must receive comments on 

this proposed AD by October 7, 2005.

Federal Register / Vol. 70, No. 162 / Tuesday, August 23, 2005 / Proposed Rules 49211

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. 

• By 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. 

For service information identified in 

this proposed AD, contact Learjet, Inc., 

One Learjet Way, Wichita, Kansas 

67209–2942. 

You can examine the contents of this 

AD docket on the Internet at http://

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

Management Facility, U.S. Department 

of Transportation, 400 Seventh Street 

SW., room PL–401, on the plaza level of 

the Nassif Building, Washington, DC. 

This docket number is FAA–2005–

22169; the directorate identifier for this 

docket is 2005–NM–094–AD.

FOR FURTHER INFORMATION CONTACT:

Robert Busto, Aerospace Engineer, 

Systems and Propulsion Branch, ACE–

116W, FAA, Wichita Aircraft 

Certification Office, 1801 Airport Road, 

Room 100, Mid-Continent Airport, 

Wichita, Kansas 67209; telephone (316) 

946–4157; fax (316) 946–4107.

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite you to submit any relevant 

written data, views, or arguments 

regarding this proposed AD. Send your 

comments to an address listed under 

ADDRESSES. Include ‘‘Docket No. FAA–

2005–22169; Directorate Identifier 

2005–NM–094–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 

submitted 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 that 

website, 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 can 

review DOT’s complete Privacy Act 

Statement in the Federal Register

published on April 11, 2000 (65 FR 

19477–78), or you can visit http://

dms.dot.gov. 

Examining the Docket 

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 DOT 

street address stated in the ADDRESSES

section. Comments will be available in 

the AD docket shortly after the Docket 

Management System (DMS) receives 

them.

Discussion 

We have received a report indicating 

that two failures of thrust reverser 

accumulators occurred, and inspections 

have found four thrust reverser 

accumulators with fatigue cracks. One 

failure occurred during flight on a 

Learjet Model 25B airplane and led to 

an emergency landing. The second 

failure occurred during bench testing 

and resulted in injury to a person. 

Detailed inspections of four thrust 

reverser accumulators found fatigue 

cracks on the inner threads that hold the 

two halves of the accumulator together. 

The spherical accumulator used for the 

main airplane hydraulic system is 

similar to the spherical accumulator 

used for the thrust reverser hydraulic 

system. Therefore, these spherical 

accumulators may be subject to the 

same unsafe condition. This fatigue 

cracking, if not corrected, could result 

in the failure of the accumulator, which 

could cause loss of hydraulic fluid and 

the hydraulic systems, resulting in a 

loss of airplane control. The failure of 

the accumulator could also result in 

damage to the surrounding airplane 

structure and injury to any persons in 

the surrounding area. The loss of 

hydraulic fluid could also leak onto a 

potential source of ignition and result in 

a consequent fire. 

Other Relevant Rulemaking 

We have published a notice of 

proposed rulemaking (NPRM) in the 

Federal Register on April 14, 2005 (70 

FR 19718), applicable to Learjet Model 

23, 24, 24A, 24B, 24B–A, 24D, 24D–A, 

24E, 24F, 25, 25A, 25B, 25C, 25D, and 

25F airplanes modified by 

Supplemental Type Certificate 

SA1731SW, SA1669SW, or SA1670SW; 

equipped with certain Nordam thrust 

reversers. That NPRM proposed to 

require removing the thrust reverser 

accumulator, and making the thrust 

reverser hydraulic system and the thrust 

reversers inoperable. The actions 

proposed in that NPRM are intended to 

prevent failure of the thrust reverser 

accumulators, due to fatigue cracking on 

the female threads, which could result 

in the loss of hydraulic power and 

damage to the surrounding airplane 

structure. 

Relevant Service Information 

We have reviewed Bombardier Alert 

Service Bulletin A23/24/25–29–4, 

Revision 1, dated January 17, 2005. The 

service bulletin describes procedures for 

replacing certain spherical accumulators 

with new cylindrical accumulators, and 

reporting accomplishment of the service 

bulletin to the manufacturer. Replacing 

the accumulators may involve replacing 

the supports and attachment hardware. 

For certain airplanes, Bombardier 

Alert Service Bulletin A23/24/25–29–4 

recommends prior or concurrent 

accomplishment of Learjet Service Kit 

SK23–215, dated April 4, 1966. The 

concurrent service bulletin describes 

procedures for relocating the 

accumulator pressure gauge. 

Accomplishing the actions specified 

in the service information is intended to 

adequately address the unsafe 

condition. 

FAA’s Determination and Requirements 

of the Proposed AD 

We have evaluated all pertinent 

information and identified an unsafe 

condition that is likely to exist or 

develop on other airplanes of this same 

type design. Therefore, we are 

proposing this AD, which would require 

accomplishing the actions specified in 

the service information described 

previously, except as discussed under 

‘‘Differences Between the Proposed AD 

and the Service Bulletin.’’

Differences Between the Proposed AD 

and the Service Bulletin 

Although Bombardier Alert Service 

Bulletin A23/24/25–29–4, Revision 1, 

dated January 17, 2005, recommends 

replacing the spherical accumulator for 

the main hydraulic system within 25 

flight hours after the receipt of the 

service bulletin, this proposed AD 

specifies a compliance time of 60 days 

after the effective date of the AD. In 

developing an appropriate compliance 

49212 Federal Register / Vol. 70, No. 162 / Tuesday, August 23, 2005 / Proposed Rules 

time for this AD, we considered the 

manufacturer’s recommendation, the 

degree of urgency associated with the 

subject unsafe condition, the average 

utilization of the affected fleet, and the 

time necessary to perform the actions 

required by the proposed AD. In light of 

all of these factors, we find that a longer 

compliance time represents an 

appropriate interval of time for affected 

airplanes to continue to operate without 

compromising safety. This difference 

has been coordinated with Learjet. 

Operators should also note that, 

although the Accomplishment 

Instructions of the referenced service 

bulletin describe procedures for 

submitting a comment sheet related to 

service bulletin quality and a sheet 

recording compliance with the service 

bulletin, this proposed AD would not 

require those actions. We do not need 

this information from operators. 

Costs of Compliance 

There are about 434 airplanes of the 

affected design in the worldwide fleet. 

This proposed AD would affect about 

242 airplanes of U.S. registry. The 

proposed actions would take about 9 to 

13 work hours per airplane, at an 

average labor rate of $65 per work hour. 

Required parts would cost about $1,336 

to $1,363 per airplane. Based on these 

figures, the estimated cost of the 

proposed AD for U.S. operators is 

$464,882 to $534,336, or $1,921 to 

$2,208 per airplane. 

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 

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. 

For the reasons discussed above, I 

certify that the 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. 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 proposed 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, Safety.

The Proposed Amendment 

Accordingly, under the authority 

delegated to me by the Administrator, 

the FAA 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):

Learjet: Docket No. FAA–2005–22169; 

Directorate Identifier 2005–NM–094–AD. 

Comments Due Date 

(a) The Federal Aviation Administration 

(FAA) must receive comments on this AD 

action by October 7, 2005. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to Learjet Model 23, 24, 

24A, 24B, 24B–A, 24C, 24D, 24D–A, 24E, 

24F, 24F–A, 25, 25A, 25B, 25C, 25D, and 25F 

airplanes, certificated in any category; having 

serial numbers 23–003 through 23–099 

inclusive, 24–100 through 24–284 inclusive, 

and 25–003 through 25–153 inclusive. 

Unsafe Condition 

(d) This AD was prompted by reports of the 

failure of two thrust reverser accumulators 

(which are similar to the main hydraulic 

system’s accumulator) and fatigue cracks 

found on four thrust reverser accumulators. 

We are issuing this AD to prevent failure of 

the spherical accumulator for the main 

hydraulic system, due to fatigue cracking on 

the threads, which could result in the loss of 

hydraulic power, damage to the surrounding 

airplane structure, and loss of airplane 

control. The failure of the accumulator could 

also result in injury to any persons in the 

surrounding area. The loss of hydraulic fluid 

could also leak onto a potential source of 

ignition and result in a consequent fire. 

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. 

Replacement 

(f) Within 60 days after the effective date 

of this AD, replace the spherical accumulator 

having part number (P/N) 2380025–( ) or P/

N 2380167–( ) with a new cylindrical 

accumulator having P/N 2497202–801 in 

accordance with the Accomplishment 

Instructions of Bombardier Alert Service 

Bulletin A23/24/25–29–4, Revision 1, dated 

January 17, 2005. 

Concurrent Action 

(g) For airplanes having serial numbers 23–

003 through 23–014 inclusive: Prior to or 

concurrently with the actions in Bombardier 

Alert Service Bulletin A23/24/25–29–4, 

Revision 1, dated January 17, 2005, relocate 

the accumulator pressure gauge in 

accordance with Learjet Service Kit SK23–

215, dated April 4, 1966. 

Parts Installation 

(h) As of the effective date, no spherical 

accumulator having P/N 2380025–() or P/N 

2380167–() may be installed on any airplane. 

Previous Actions 

(i) Replacements done before the effective 

date of this AD in accordance with 

Bombardier Alert Service Bulletin A23/24/

25–29–4, dated August 20, 2004, are 

acceptable for compliance with the 

requirements of paragraph (f) of this AD. 

No Reporting Required 

(j) Although the service bulletin referenced 

in this AD specifies to submit certain 

information to the manufacturer, this AD 

does not include that requirement. 

Alternative Methods of Compliance 

(AMOCs) 

(k) The Manager, Wichita Aircraft 

Certification Office, FAA, has the authority to 

approve AMOCs for this AD, if requested in 

accordance with the procedures found in 14 

CFR 39.19.

Issued in Renton, Washington, on August 

12, 2005. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service.

[FR Doc. 05–16752 Filed 8–22–05; 8:45 am] 

BILLING CODE 4910–13–P