Federal Register / Vol. 72, No. 80 / Thursday April 26, 2007 / Proposed Rules 20775 

electrical in origin (for example an 

electrical short circuit, arcing caused by 

chafed wiring, or a ruptured ballast 

case). 

In September 2003, in an effort to 

limit use of materials that sustain or 

propagate a fire in inaccessible areas, 

the FAA promulgated 14 CFR 25.856(a), 

which requires that thermal/acoustic 

insulation material installed in the 

fuselage meet newly developed flame 

propagation test requirements. That rule 

was Amendment 25–111. These 

requirements were developed to address 

a realistic fire threat. We consider that 

threat generally applicable to the 787. 

Conventional aluminum fuselage 

material does not contribute to in-flight 

fire propagation. As a result, there are 

no standards that address in-flight fire 

safety of the fuselage structure itself. 

The 787 will make extensive use of 

composite materials in the fabrication of 

the majority of the 

• Wing, 

• Fuselage skin, 

• Stringers, 

• Spars, and 

• Most other structural elements of all 

major sub-assemblies of the airplane. 

As a result of this extensive use of a new 

construction material, the fuselage 

cannot be assumed to have the fire 

resistance previously afforded by 

aluminum during the in-flight fire 

scenario mentioned above. These 

proposed special conditions would 

require that the 787 provide the same 

level of in-flight survivability as a 

conventional aluminum fuselage 

airplane. This includes its thermal/ 

acoustic insulation meeting 

requirements of § 25.856(a). Resistance 

to flame propagation must be shown, 

and all products of combustion that may 

result must be evaluated for toxicity and 

found acceptable. 

Applicability 

As discussed above, these proposed 

special conditions are applicable to the 

787. Should Boeing apply at a later date 

for a change to the type certificate to 

include another model incorporating the 

same novel or unusual design features, 

these proposed special conditions 

would apply to that model as well 

under the provisions of § 21.101. 

Conclusion 

This action affects only certain novel 

or unusual design features of the 787. It 

is not a rule of general applicability, and 

it affects only the applicant that applied 

to the FAA for approval of these features 

on the airplane. 

List of Subjects in 14 CFR Part 25 

Aircraft, Aviation safety, Reporting 

and recordkeeping requirements. 

The authority citation for these 

Special Conditions is as follows: 

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

44702, 44704. 

The Proposed Special Conditions 

Accordingly, the Administrator of the 

Federal Aviation Administration (FAA) 

proposes the following special 

conditions as part of the type 

certification basis for the Boeing Model 

787–8 airplane. 

In addition to the requirements of 14 

CFR 25.853(a) governing material 

flammability, the following special 

conditions apply: 

The 787 composite fuselage structure must 

be shown to be resistant to flame propagation 

under the fire threat used to develop 14 CFR 

25.856(a). If products of combustion are 

observed beyond the test heat source, they 

must be evaluated and found acceptable. 

Issued in Renton, Washington, on April 18, 

2007. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. E7–7840 Filed 4–25–07; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2007–28016; Directorate 

Identifier 2006–NM–227–AD] 

RIN 2120–AA64 

Airworthiness Directives; Learjet 

Model 31, 31A, 35, 35A (C–21A), 36, 

36A, 55, 55B, and 55C Airplanes, and 

Model 45 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 31, 31A, 35, 35A 

(C–21A), 36, 36A, 55, 55B, and 55C 

airplanes, and Model 45 airplanes. This 

proposed AD would require inspecting 

for unsealed gaps on the pylon side of 

the engine firewall and cleaning/sealing 

any unsealed gap; and, for certain 

airplanes, inspecting for unsealed gaps 

of the pylon trailing edge and cleaning/ 

sealing any gap. This proposed AD 

results from a report that unsealed gaps 

(penetration points) of the engine 

firewall were discovered during 

production. We are proposing this AD to 

prevent penetration of flammable 

liquids or fire through the engine 

firewall into the engine pylon, which 

could lead to fire inside the airplane. 

DATES: We must receive comments on 

this proposed AD by June 11, 2007. 

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. 

• 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 Learjet, Inc., One Learjet Way, 

Wichita, Kansas 67209–2942, for the 

service information identified in this 

proposed AD. 

FOR FURTHER INFORMATION CONTACT: 

James Galstad, 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) 

946–4135; 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 in the 

ADDRESSES section. Include the docket 

number ‘‘FAA–2007–28016; Directorate 

Identifier 2006–NM–227–AD’’ at the 

beginning 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 that web 

site, anyone can find and read the 


jlentini on PROD1PC65 with PROPOSALS
20776 Federal Register / Vol. 72, No. 80 / Thursday April 26, 2007 / Proposed Rules 

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 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 Docket 

You may 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 receives them. 

Discussion 

We have received a report indicating 

that the engine firewall sealing 

application on certain Learjet Model 45 

airplanes does not meet engineering 

standards, as unsealed gaps (penetration 

points) of the engine firewall were 

discovered during production. Further 

investigation revealed that the same 

condition could be present on Model 31, 

31A, 35, 35A (C–21A), 36, 36A, 55, 55B, 

and 55C airplanes. Such gaps could 

include those provided for bleed air, 

anti-ice, fuel, and fire extinguishing 

systems, as well as engine mounts, 

control cables, access panels, and others 

not described. This condition, if not 

corrected, could result in penetration of 

flammable liquids or fire through the 

engine firewall into the engine pylon, 

which could lead to fire inside the 

airplane. 

Relevant Service Information 

We have reviewed the service 

bulletins specified in the following 

table. For all airplanes, the service 

bulletins describe procedures for 

inspecting for unsealed gaps on the 

pylon side of the engine firewall and 

cleaning/sealing any unsealed gap. For 

Model 45 airplanes only, Service 

Bulletin 45–54–3 also describes 

procedures for inspecting for unsealed 

gaps on the pylon trailing edge and 

cleaning/sealing any unsealed gap. 

Accomplishing the actions specified in 

the service information is intended to 

adequately address the unsafe 

condition. 

APPLICABLE SERVICE INFORMATION

Learjet airplane model Service bulletin Revision level Date 

31/31A ......................................... Bombardier Service Bulletin 31–54–2 ............................................. 1 ....................... August 21, 2006. 

45 ................................................ Bombardier Service Bulletin 45–54–3 ............................................. 2 ....................... August 15, 2003. 

35/35A (C–21A) and 36/36A ...... Learjet Service Bulletin 35/36–54–3 ............................................... Original ............. March 16, 2001. 

55/55B/55C ................................. Learjet Service Bulletin 55–54–3 .................................................... Original ............. March 16, 2001. 

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. For this reason, we are 

proposing this AD, which would require 

accomplishing the actions specified in 

the service information described 

previously. 

Costs of Compliance 

There are about 1,243 airplanes of the 

affected design in the worldwide fleet. 

This proposed AD would affect about 

945 airplanes of U.S. registry. The 

following table provides the estimated 

costs for U.S. operators to comply with 

this proposed AD, at an average labor 

rate of $80 per work hour. Parts and 

materials may be supplied from operator 

stores or procured locally. 

ESTIMATED COSTS TO PERFORM INSPECTION AND MODIFICATIONS

Learjet airplane model Work hours Cost per 

airplane 

Number of 

U.S.-registered 

airplanes 

Fleet cost 

31/31A .............................................................................................................. 2 $160 173 $27,680 

35/35A (C–21A) ............................................................................................... 2 160 507 81,120 

36/36A .............................................................................................................. 2 160 42 6,720 

45 ..................................................................................................................... 5 400 102 40,800 

55/55B/55C ...................................................................................................... 2 160 121 19,360 

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 


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Federal Register / Vol. 72, No. 80 / Thursday April 26, 2007 / Proposed Rules 20777 

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 and placed it in the 

AD docket. 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 Federal Aviation 

Administration (FAA) amends § 39.13 

by adding the following new 

airworthiness directive (AD): 

LEARJET: Docket No. FAA–2007–28016; 

Directorate Identifier 2006–NM–227–AD. 

Comments Due Date 

(a) The FAA must receive comments on 

this AD action by June 11, 2007. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to Learjet Model 31, 

31A, 35, 35A (C–21A), 36, 36A, 55, 55B, and 

55C airplanes, and Model 45 airplanes; 

certificated in any category; as identified in 

the service information specified in Table 1 

of this AD. 

TABLE 1.—APPLICABLE SERVICE INFORMATION

Learjet airplane model Service bulletin Revision level Date 

31/31A ......................................... Bombardier Service Bulletin 31–54–2 ............................................. 1 ....................... August 21, 2006. 

45 ................................................ Bombardier Service Bulletin 45–54–3 ............................................. 2 ....................... August 15, 2003. 

35/35A (C–21A) and 36/36A ...... Learjet Service Bulletin 35/36–54–3 ............................................... Original ............. March 16, 2001. 

55/55B/55C ................................. Learjet Service Bulletin 55–54–3 .................................................... Original ............. March 16, 2001. 

Unsafe Condition 

(d) This AD results from a report that 

unsealed gaps (penetration points) of the 

engine firewall were discovered during 

production. We are issuing this AD to 

prevent penetration of flammable liquids or 

fire through the engine firewall into the 

engine pylon, which could lead to fire inside 

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. 

Inspecting, Cleaning, and Sealing of Gaps in 

Engine Firewall 

(f) Within 12 months after the effective 

date of this AD, do the actions described in 

paragraphs (f)(1) and (f)(2) of this AD, in 

accordance with the applicable service 

information specified in Table 1 of this AD. 

(1) For all airplanes: Inspect for unsealed 

gaps on the pylon side of the engine firewall 

and clean and seal any unsealed gap. 

(2) For Learjet Model 45 airplanes only: 

Inspect the engine pylon trailing edge for 

unsealed gaps, and clean and seal any 

unsealed gap. 

Credit for Actions Done Using Previous 

Service Information 

(g) Actions accomplished before the 

effective date of this AD according to 

Bombardier Service Bulletin 31–54–2, dated 

March 16, 2001; or Bombardier Service 

Bulletin 45–54–3, dated March 16, 2001; or 

Revision 1, dated December 12, 2001; as 

applicable; are considered acceptable for 

compliance with the corresponding action 

specified in this AD. 

Alternative Methods of Compliance 

(AMOCs) 

(h)(1) The Manager, Wichita 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) To request a different method of 

compliance or a different compliance time 

for this AD, follow the procedures in 14 CFR 

39.19. Before using any approved AMOC on 

any airplane to which the AMOC applies, 

notify your appropriate principal inspector 

(PI) in the FAA Flight Standards District 

Office (FSDO), or lacking a PI, your local 

FSDO. 

Issued in Renton, Washington, on April 19, 

2007. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. E7–8001 Filed 4–25–07; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2006–26353; Directorate 

Identifier 2006–NM–189–AD] 

RIN 2120–AA64 

Airworthiness Directives; Bombardier 

Model CL–600–1A11 (CL–600), CL–

600–2A12 (CL–601), CL–600–2B16 (CL–

601–3A, CL–601–3R, and CL–604) 

Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Supplemental notice of 

proposed rulemaking (NPRM); 

reopening of comment period. 

SUMMARY: The FAA is revising an earlier 

NPRM for an airworthiness directive 

(AD) that applies to certain Bombardier 

Model CL–600–1A11 (CL–600) 

airplanes, CL–600–2A12 (CL–601) 

airplanes, and CL–600–2B16 (CL–601–

3A, CL–601–3R, and CL–604) airplanes. 

The original NPRM would have 

required inspecting to identify the part 

number and serial number of the 

selector valves of the nose landing gear 

(NLG) and the nose gear door; and doing 

related investigative and corrective 

actions if necessary. The original NPRM 

resulted from reports of uncommanded 

partial retractions of the NLG. This 

action revises the original NPRM by 

adding airplanes to the applicability. 


jlentini on PROD1PC65 with PROPOSALS