This section of the FEDERAL REGISTER

contains regulatory documents having general

applicability and legal effect, most of which

are keyed to and codified in the Code of

Federal Regulations, which is published under

50 titles pursuant to 44 U.S.C. 1510.

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REGISTER issue of each week.

Rules and Regulations Federal Register

22503 

Vol. 75, No. 82 

Thursday, April 29, 2010 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2010–0431; Directorate 

Identifier 2010–NM–072–AD; Amendment 

39–16272; AD 2010–09–07] 

RIN 2120–AA64 

Airworthiness Directives; Bombardier, 

Inc. Model DHC–8–400 Series 

Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Final rule; request for 

comments. 

SUMMARY: We are adopting a new 

airworthiness directive (AD) for the 

products listed above. This AD results 

from mandatory continuing 

airworthiness information (MCAI) 

originated by an aviation authority of 

another country to identify and correct 

an unsafe condition on an aviation 

product. The MCAI describes the unsafe 

condition as: 

* * * 1. A potential freezing of the AOA 

[angle of attack] Vane Resolver * * * may 

restrict the dynamic behavior (lag) of the 

vane and could lead to a potential seize-up 

condition at lower temperatures. This 

condition, if not corrected, may provide 

inaccurate AOA data to the Stall Protection 

System (SPS). 

2. As a result of ageing, the AOA vane 

heating element could degrade to a point 

where there is insufficient heat to prevent ice 

build-up on the AOA vanes. The ice buildup may lead to a change in the aerodynamic 

properties of the AOA vane and, under 

certain conditions, send inaccurate 

information to the SPS. This ageing condition 

cannot be detected by the aircraft AOA vane 

heater current monitor. 

These conditions, if not corrected, could 

result in inaccurate AOA data provided 

to the SPS and could lead to a change 

in the aerodynamic properties of the 

AOA vane and reduced ability of the 

flight crew to maintain safe flight and 

landing of the airplane. This AD 

requires actions that are intended to 

address the unsafe condition described 

in the MCAI. 

DATES: This AD becomes effective May 

14, 2010. 

The Director of the Federal Register 

approved the incorporation by reference 

of certain publications listed in the AD 

as of May 14, 2010. 

We must receive comments on this 

AD by June 14, 2010. 

ADDRESSES: You may send comments by 

any of the following methods: 

• Federal eRulemaking Portal: Go to 

http://www.regulations.gov. Follow the 

instructions for submitting comments. 

• Fax: (202) 493–2251. 

• Mail: U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–140, 1200 New Jersey Avenue, SE., 

Washington, DC 20590. 

• Hand Delivery: U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–40, 1200 New Jersey Avenue, SE., 

Washington, DC, between 9 a.m. and 5 

p.m., Monday through Friday, except 

Federal holidays. 

Examining the AD Docket 

You may examine the AD docket on 

the Internet at http:// 

www.regulations.gov; or in person at the 

Docket Operations office between 9 a.m. 

and 5 p.m., Monday through Friday, 

except Federal holidays. The AD docket 

contains this AD, the regulatory 

evaluation, any comments received, and 

other information. The street address for 

the Docket Operations office (telephone 

(800) 647–5527) is in the ADDRESSES

section. Comments will be available in 

the AD docket shortly after receipt. 

FOR FURTHER INFORMATION CONTACT: 

Joseph Licata, Aerospace Engineer, 

Avionics and Flight Test Branch, ANE– 

172, FAA, New York Aircraft 

Certification Office, 1600 Stewart 

Avenue, Suite 410, Westbury, New York 

11590; telephone (516) 228–7361; fax 

(516) 794–5531. 

SUPPLEMENTARY INFORMATION: 

Discussion 

Transport Canada Civil Aviation 

(TCCA), which is the aviation authority 

for Canada, has issued Canadian 

Airworthiness Directive CF–2010–05, 

dated February 2, 2010 (referred to after 

this as ‘‘the MCAI’’), to correct an unsafe 

condition for the specified products. 

The MCAI states: 

Although there have been no in-service 

reported incidents related to AOA [angle of 

attack] failures on the DHC–8 Series 400 

aeroplanes, two separate issues have been 

identified that would affect proper operation 

of the AOA vane, P/N [part number] 

C16177AC. These issues are: 

1. A potential freezing of the AOA Vane 

Resolver, which may restrict the dynamic 

behavior (lag) of the vane and could lead to 

a potential seize-up condition at lower 

temperatures. This condition, if not 

corrected, may provide inaccurate AOA data 

to the Stall Protection System (SPS). 

2. As a result of ageing, the AOA vane 

heating element could degrade to a point 

where there is insufficient heat to prevent ice 

build-up on the AOA vanes. The ice buildup may lead to a change in the aerodynamic 

properties of the AOA vane and, under 

certain conditions, send inaccurate 

information to the SPS. This ageing condition 

cannot be detected by the aircraft AOA vane 

heater current monitor. 

This directive mandates replacement of the 

vanes equipped with suspect resolvers and a 

periodic inspection of the in-rush current to 

verify the AOA vane heating capability. 

These conditions, if not corrected, could 

result in inaccurate AOA data provided 

to the SPS and could lead to a change 

in the aerodynamic properties of the 

AOA vane and reduced ability of the 

flight crew to maintain safe flight and 

landing of the airplane. You may obtain 

further information by examining the 

MCAI in the AD docket. 

Relevant Service Information 

Bombardier has issued Alert Service 

Bulletin A84–27–46, dated October 20, 

2009; and Alert Service Bulletin A84– 

27–51, dated December 22, 2009. The 

actions described in this service 

information are intended to correct the 

unsafe condition identified in the 

MCAI. 

FAA’s Determination and Requirements 

of This AD 

This product has been approved by 

the aviation authority of another 

country, and is approved for operation 

in the United States. Pursuant to our 

bilateral agreement with the State of 

Design Authority, we have been notified 

of the unsafe condition described in the 

MCAI and service information 

referenced above. We are issuing this 

AD because we evaluated all pertinent 

information and determined the unsafe 

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22504 Federal Register / Vol. 75, No. 82 / Thursday, April 29, 2010 / Rules and Regulations 

condition exists and is likely to exist or 

develop on other products of the same 

type design. 

Differences Between the AD and the 

MCAI or Service Information 

We have reviewed the MCAI and 

related service information and, in 

general, agree with their substance. But 

we might have found it necessary to use 

different words from those in the MCAI 

to ensure the AD is clear for U.S. 

operators and is enforceable. In making 

these changes, we do not intend to differ 

substantively from the information 

provided in the MCAI and related 

service information. 

We might also have required different 

actions in this AD from those in the 

MCAI in order to follow FAA policies. 

Any such differences are highlighted in 

a Note within the AD. 

FAA’s Determination of the Effective 

Date 

An unsafe condition exists that 

requires the immediate adoption of this 

AD. The FAA has found that the risk to 

the flying public justifies waiving notice 

and comment prior to adoption of this 

rule because potential freezing of the 

vane resolver of the angle of attack 

could restrict the dynamic behavior (lag) 

of the vane and could lead to a potential 

seize-up condition at lower 

temperatures. As a result of aging, the 

vane heating element of the AOA could 

degrade to a point where there is 

insufficient heat to prevent ice buildup 

on the AOA vanes. These conditions, if 

not corrected, could result in inaccurate 

AOA data provided to the SPS and 

could lead to a change in the 

aerodynamic properties of the AOA 

vane and reduced ability of the flight 

crew to maintain safe flight and landing 

of the airplane. Therefore, we 

determined that notice and opportunity 

for public comment before issuing this 

AD are impracticable and that good 

cause exists for making this amendment 

effective in fewer than 30 days. 

Comments Invited 

This AD is a final rule that involves 

requirements affecting flight safety, and 

we did not precede it by notice and 

opportunity for public comment. We 

invite you to send any written relevant 

data, views, or arguments about this AD. 

Send your comments to an address 

listed under the ADDRESSES section. 

Include ‘‘Docket No. FAA–2010–0431; 

Directorate Identifier 2010–NM–072– 

AD’’ at the beginning of your comments. 

We specifically invite comments on the 

overall regulatory, economic, 

environmental, and energy aspects of 

this AD. We will consider all comments 

received by the closing date and may 

amend this AD because of those 

comments. 

We will post all comments we 

receive, without change, to http:// 

www.regulations.gov, including any 

personal information you provide. We 

will also post a report summarizing each 

substantive verbal contact we receive 

about this AD. 

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 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 this 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 regulatory evaluation 

of the estimated costs to comply with 

this AD and placed it in the AD docket. 

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 AD: 

2010–09–07 Bombardier, Inc.: Amendment 

39–16272. Docket No. FAA–2010–0431; 

Directorate Identifier 2010–NM–072–AD. 

Effective Date 

(a) This airworthiness directive (AD) 

becomes effective May 14, 2010. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to Bombardier, Inc. 

Model DHC–8–400, –401, and –402 

airplanes; certificated in any category, that 

are equipped with Thales angle of attack 

(AOA) vanes having part number (P/N) 

C16177AC. 

Subject 

(d) Air Transport Association (ATA) of 

America Code 27: Flight Controls. 

Reason 

(e) The mandatory continued airworthiness 

information (MCAI) states: 

Although there have been no in-service 

reported incidents related to AOA failures on 

the DHC–8 Series 400 aeroplanes, two 

separate issues have been identified that 

would affect proper operation of the AOA 

vane, P/N C16177AC. These issues are: 

1. A potential freezing of the AOA Vane 

Resolver, which may restrict the dynamic 

behavior (lag) of the vane and could lead to 

a potential seize-up condition at lower 

temperatures. This condition, if not 

corrected, may provide inaccurate AOA data 

to the Stall Protection System (SPS). 

2. As a result of ageing, the AOA vane 

heating element could degrade to a point 

where there is insufficient heat to prevent ice 

build-up on the AOA vanes. The ice buildup may lead to a change in the aerodynamic 

properties of the AOA vane and, under 

certain conditions, send inaccurate 

information to the SPS. This ageing condition 

cannot be detected by the aircraft AOA vane 

heater current monitor. This directive 

mandates replacement of the vanes equipped 

with suspect resolvers and a periodic 

inspection of the in-rush current to verify the 

AOA vane heating capability. 

These conditions, if not corrected, could 

result in inaccurate AOA data provided to 

the SPS and could lead to a change in the 

aerodynamic properties of the AOA vane and 

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Federal Register / Vol. 75, No. 82 / Thursday, April 29, 2010 / Rules and Regulations 22505 

reduced ability of the flight crew to maintain 

safe flight and landing of the airplane. 

Compliance 

(f) You are responsible for having the 

actions required by this AD performed within 

the compliance times specified, unless the 

actions have already been done. 

Actions 

(g) Within 250 flight hours after the 

effective date of this AD: Do an inspection to 

determine the serial number of the AOA 

sensors installed on the airplane, in 

accordance with the Accomplishment 

Instructions of Bombardier Alert Service 

Bulletin A84–27–51, dated December 22, 

2009. A review of airplane maintenance 

records is acceptable in lieu of this 

inspection if the serial number of the AOA 

sensors can be conclusively determined from 

that review. 

(1) If neither serial number is specified in 

paragraph 1.A., Table 1, of Bombardier Alert 

Service Bulletin A84–27–51, dated December 

22, 2009, do the actions required by 

paragraph (h) of this AD. 

(2) If the serial numbers of both AOA 

sensors are specified in paragraph 1.A., Table 

1, of Bombardier Alert Service Bulletin A84– 

27–51, dated December 22, 2009, and both 

serial numbers have suffix ‘‘B,’’ do the actions 

required by paragraph (h) of this AD. 

(3) If the serial numbers of both AOA 

sensors are specified in paragraph 1.A., Table 

1, of Bombardier Alert Service Bulletin A84– 

27–51, dated December 22, 2009, do the 

actions required by either paragraph (g)(3)(i) 

or (g)(3)(ii) of this AD. 

(i) Before further flight, replace the AOA 

sensors with new or serviceable sensors, in 

accordance with the Accomplishment 

Instructions of Bombardier Alert Service 

Bulletin A84–27–51, dated December 22, 

2009. 

(ii) Before further flight, replace one of the 

two AOA sensors with a new or serviceable 

sensor, in accordance with the 

Accomplishment Instructions of Bombardier 

Alert Service Bulletin A84–27–51, dated 

December 22, 2009. Replace the remaining 

sensor with a new or serviceable sensor 

within 750 flight hours after the inspection 

required by paragraph (g) of this AD. 

(4) If only one of the serial numbers of the 

AOA sensors is specified in paragraph 1.A., 

Table 1, of Bombardier Alert Service Bulletin 

A84–27–51, dated December 22, 2009, 

replace that sensor with a new or serviceable 

sensor within 750 flight hours after the 

inspection required by paragraph (g) of this 

AD. 

(h) At the applicable compliance time 

specified in Table 1 of this AD: Measure the 

inrush current of the AOA vane, in 

accordance with the Accomplishment 

Instructions of Bombardier Alert Service 

Bulletin A84–27–46, dated October 20, 2009. 

(1) If, during any measurement required by 

paragraph (h) of this AD, an AOA vane is 

found to have an inrush current less than or 

equal to 1.6 amps, before further flight, 

replace the vane with a new or serviceable 

vane, in accordance with the 

Accomplishment Instructions of Bombardier 

Alert Service Bulletin A84–27–46, dated 

October 20, 2009. Repeat the measurement of 

the newly installed vane within 2,000 flight 

hours after replacement. 

(2) If, during any measurement required by 

paragraph (h) of this AD, an AOA vane is 

found to have an inrush current greater than 

1.6 amps, repeat the measurement of the vane 

at the applicable compliance time specified 

in Table 2 of this AD. 

TABLE 1—INITIAL MEASUREMENT

For any AOA vane that, as of the effective date of this AD, has accumulated— Do the initial inrush current measurement— 

Less than 5,000 total flight hours ............................................................. Before the AOA vane has accumulated 5,900 total flight hours. 

5,000 or more total flight hours, but less than 6,000 total flight hours .... Within 900 flight hours after the effective date of this AD, or before the 

AOA vane has accumulated 6,500 total flight hours, whichever occurs first. 

6,000 or more total flight hours ................................................................ Within 500 flight hours after the effective date of this AD. 

TABLE 2—REPETITIVE MEASUREMENT INTERVALS

If the last inrush current measurement of the serviceable AOA transducer is— Then repeat the measurement— 

More than 1.60 amps, but less than or equal to 1.70 amps ................... Within 1,000 flight hours after the last inrush current measurement of 

the serviceable AOA transducer. 

More than 1.70 amps ............................................................................... Within 2,000 flight hours after the last inrush current measurement of 

the serviceable AOA transducer. 

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

person may install, on any airplane, an AOA 

sensor having P/N C16177AC with any serial 

number specified in paragraph 1.A., Table 1, 

of Bombardier Alert Service Bulletin A84– 

27–51, dated December 22, 2009, unless the 

sensor has been inspected in accordance with 

this AD and unless the serial number has a 

suffix ‘‘B.’’ 

FAA AD Differences 

Note 1: This AD differs from the MCAI 

and/or service information as follows: 

(1) Canadian Airworthiness Directive CF– 

2010–05, dated February 2, 2010, requires an 

inspection to determine the serial number of 

the AOA vanes installed on the airplane. 

However, for clarification, we are requiring 

an inspection to determine the serial number 

of the AOA sensors (which are part of the 

vane), as specified in Bombardier Alert 

Service Bulletin A84–27–51, dated December 

22, 2009. 

(2) Canadian Airworthiness Directive CF– 

2010–05, dated February 2, 2010, states that 

an airplane may be dispatched with one 

serviceable unit for a maximum of 1,000 

flight hours. However, paragraph (g)(3)(ii) of 

this AD allows an airplane to be dispatched 

with one serviceable unit for a maximum of 

750 flight hours. This difference has been 

coordinated with Transport Canada Civil 

Aviation (TCCA). 

(3) Canadian Airworthiness Directive CF– 

2010–05, dated February 2, 2010, states that 

if only one of the serial numbers of the 

affected AOA sensors is found, replace that 

sensor with a new or serviceable sensor 

within 1,000 flight hours. However, 

paragraph (g)(4) of this AD requires 

replacement with a new or serviceable sensor 

within 750 flight hours. This difference has 

been coordinated with TCCA. 

Other FAA AD Provisions 

(j) The following provisions also apply to 

this AD: 

(1) Alternative Methods of Compliance 

(AMOCs): The Manager, New York Aircraft 

Certification Office (ACO), FAA, has the 

authority to approve AMOCs for this AD, if 

requested using the procedures found in 14 

CFR 39.19. Send information to ATTN: 

Program Manager, Continuing Operational 

Safety, FAA, New York ACO, 1600 Stewart 

Avenue, Suite 410, Westbury, New York 

11590; telephone 516–228–7300; fax 516– 

794–5531. Before using any approved AMOC 

on any airplane to which the AMOC applies, 

notify your principal maintenance inspector 

(PMI) or principal avionics inspector (PAI), 

as appropriate, or lacking a principal 

inspector, your local Flight Standards District 

Office. The AMOC approval letter must 

specifically reference this AD. 

(2) Airworthy Product: For any requirement 

in this AD to obtain corrective actions from 

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22506 Federal Register / Vol. 75, No. 82 / Thursday, April 29, 2010 / Rules and Regulations 

a manufacturer or other source, use these 

actions if they are FAA-approved. Corrective 

actions are considered FAA-approved if they 

are approved by the State of Design Authority 

(or their delegated agent). You are required 

to assure the product is airworthy before it 

is returned to service. 

(3) Reporting Requirements: For any 

reporting requirement in this AD, under the 

provisions of the Paperwork Reduction Act 

(44 U.S.C. 3501 et seq.), the Office of 

Management and Budget (OMB) has 

approved the information collection 

requirements and has assigned OMB Control 

Number 2120–0056. 

Related Information 

(k) Refer to MCAI Canadian Airworthiness 

Directive CF–2010–05, dated February 2, 

2010; Bombardier Alert Service Bulletin 

A84–27–46, dated October 20, 2009; and 

Bombardier Alert Service Bulletin A84–27– 

51, dated December 22, 2009; for related 

information. 

Material Incorporated by Reference 

(l) You must use Bombardier Alert Service 

Bulletin A84–27–46, dated October 20, 2009; 

and Bombardier Alert Service Bulletin A84– 

27–51, dated December 22, 2009; as 

applicable; to do the actions required by this 

AD, unless the AD specifies otherwise. 

(1) The Director of the Federal Register 

approved the incorporation by reference of 

this service information under 5 U.S.C. 

552(a) and 1 CFR part 51. 

(2) For service information identified in 

this AD, contact Bombardier, Inc., 400 CoˆteVertu Road West, Dorval, Que ́bec H4S 1Y9, 

Canada; telephone 514–855–5000; fax 514– 

855–7401; e-mail 

thd.qseries@aero.bombardier.com; Internet 

http://www.bombardier.com. 

(3) You may review copies of the service 

information at the FAA, Transport Airplane 

Directorate, 1601 Lind Avenue, SW., Renton, 

Washington. For information on the 

availability of this material at the FAA, call 

425–227–1221. 

(4) You may also review copies of the 

service information that is incorporated by 

reference 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. 

Issued in Renton, Washington, on April 15, 

2010. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. 2010–9520 Filed 4–28–10; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2009–1111; Directorate 

Identifier 2009–NM–147–AD; Amendment 

39–16271; AD 2010–09–06] 

RIN 2120–AA64 

Airworthiness Directives; Bombardier, 

Inc., Model CL–600–2C10 (Regional Jet 

Series 700, 701 & 702), CL–600–2D15 

(Regional Jet Series 705), and CL–600– 

2D24 (Regional Jet Series 900) 

Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Final rule. 

SUMMARY: We are adopting a new 

airworthiness directive (AD) for the 

products listed above. This AD results 

from mandatory continuing 

airworthiness information (MCAI) 

originated by an aviation authority of 

another country to identify and correct 

an unsafe condition on an aviation 

product. The MCAI describes the unsafe 

condition as: 

During an elevator Power Control Unit 

(PCU) Centering Functional Check on two 

CL–600–2C10 aircraft, sustained oscillations 

were discovered when a control rod was 

disconnected. These sustained oscillations 

could render the elevator surface inoperable 

and cause subsequent loss of pitch control of 

the aircraft. 

* * * * * 

Loss of pitch control could result in 

reduced controllability of the airplane. 

We are issuing this AD to require 

actions to correct the unsafe condition 

on these products. 

DATES: This AD becomes effective June 

3, 2010. 

The Director of the Federal Register 

approved the incorporation by reference 

of a certain publication listed in this AD 

as of June 3, 2010. 

ADDRESSES: You may examine the AD 

docket on the Internet at http:// 

www.regulations.gov or in person at the 

U.S. Department of Transportation, 

Docket Operations, M–30, West 

Building Ground Floor, Room W12–140, 

1200 New Jersey Avenue, SE., 

Washington, DC. 

FOR FURTHER INFORMATION CONTACT: 

Christopher Alfano, Aerospace 

Engineer, Airframe and Mechanical 

Systems Branch, ANE–171, FAA, New 

York Aircraft Certification Office, 1600 

Stewart Avenue, Suite 410, Westbury, 

New York 11590; telephone (516) 228– 

7340; fax (516) 794–5531. 

SUPPLEMENTARY INFORMATION: 

Discussion 

We issued a notice of proposed 

rulemaking (NPRM) to amend 14 CFR 

part 39 to include an AD that would 

apply to the specified products. That 

NPRM was published in the Federal 

Register on December 3, 2009 (74 FR 

63331). That NPRM proposed to correct 

an unsafe condition for the specified 

products. The MCAI states: 

During an elevator Power Control Unit 

(PCU) Centering Functional Check on two 

CL–600–2C10 aircraft, sustained oscillations 

were discovered when a control rod was 

disconnected. These sustained oscillations 

could render the elevator surface inoperable 

and cause subsequent loss of pitch control of 

the aircraft. 

This directive mandates incorporation of a 

new centering mechanism on the elevator 

torque tube to prevent these sustained 

oscillations. 

Loss of pitch control could result in 

reduced controllability of the airplane. 

You may obtain further information by 

examining the MCAI in the AD docket. 

Comments 

We gave the public the opportunity to 

participate in developing this AD. We 

considered the comment received. 

Request To Include Revised Service 

Information 

Comair, Inc., asks that we allow the 

use of Revision C instead of Revision B 

of Bombardier Service Bulletin 670BA– 

27–042 for accomplishing the actions 

specified in paragraph (f)(1) of the 

NPRM. Comair, Inc., states that 

Bombardier has issued Bombardier 

Service Bulletin 670BA–27–042, 

Revision C, dated December 10, 2009. 

We referred to Bombardier Service 

Bulletin 670BA–27–042, Revision B, 

dated June 2, 2009, in paragraph (f)(1) 

of the NPRM as the appropriate source 

of service information for accomplishing 

the specified actions. 

We agree with the commenter. 

Bombardier Service Bulletin 670BA–27– 

042, Revision C, dated December 10, 

2009, makes minor updates and 

editorial changes; no additional work is 

necessary on airplanes modified in 

accordance with Revision B. Therefore, 

we have revised paragraph (f)(1) of this 

final rule to refer to Bombardier Service 

Bulletin 670BA–27–042, Revision C, 

dated December 10, 2009, for 

accomplishing the specified actions. We 

have also revised paragraph (f)(2) of this 

AD to give credit for actions done in 

accordance with Bombardier Service 

Bulletin 670BA–27–042, Revision B, 

dated June 2, 2009. 

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