25788 Federal Register / Vol. 75, No. 89 / Monday, May 10, 2010 / Proposed Rules 

Issued in Renton, Washington, on April 30, 

2010. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. 2010–10996 Filed 5–7–10; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2010–0436; Directorate 

Identifier 2009–NM–230–AD] 

RIN 2120–AA64 

Airworthiness Directives; Bombardier, 

Inc. Model CL–600–2B19 (Regional Jet 

Series 100 & 440) Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: We propose to adopt a new 

airworthiness directive (AD) for the 

products listed above. This proposed 

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: 

* * * There have recently been several inservice occurrences that have highlighted the 

inability of the existing [wing anti-ice] 

system to detect a low-heat condition in the 

wing leading edge at all times, with the 

potential consequence of unannunciated 

asymmetric ice build-up on the wing. * * * 

Such a condition, in combination with 

maneuvers close to stick shaker activation, 

could possibly result in reduced 

controllability of the aircraft. 

* * * * * 

The proposed AD would require actions 

that are intended to address the unsafe 

condition described in the MCAI. 

DATES: We must receive comments on 

this proposed AD by June 24, 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. 

For service information identified in 

this proposed AD, contact Bombardier, 

Inc., 400 Coˆte-Vertu Road West, Dorval, 

Que ́bec H4S 1Y9, Canada; telephone 

514–855–5000; fax 514–855–7401; email thd.crj@aero.bombardier.com; 

Internet http://www.bombardier.com. 

You may review copies of the 

referenced 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. 

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 proposed 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: 

Wing Chan, Aerospace Engineer, 

Avionics and Flight Test Branch, ANE– 

172, FAA, New York Aircraft 

Certification Office (ACO), 1600 Stewart 

Avenue, Suite 410, Westbury, New York 

11590; telephone (516) 228–7311; fax 

(516) 794–5531. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite you to send any written 

relevant data, views, or arguments about 

this proposed AD. Send your comments 

to an address listed under the 

ADDRESSES section. Include ‘‘Docket No. 

FAA–2010–0436; Directorate Identifier 

2009–NM–230–AD’’ at the beginning of 

your comments. We specifically invite 

comments on the overall regulatory, 

economic, environmental, and energy 

aspects of this proposed AD. We will 

consider all comments received by the 

closing date and may amend this 

proposed AD based on those comments. 

We have lengthened the 30-day 

comment period for proposed ADs that 

address MCAI originated by aviation 

authorities of other countries to provide 

adequate time for interested parties to 

submit comments. The comment period 

for these proposed ADs is now typically 

45 days, which is consistent with the 

comment period for domestic transport 

ADs. 

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 proposed AD. 

Discussion 

Transport Canada Civil Aviation 

(TCCA), which is the aviation authority 

for Canada, has issued Canadian 

Airworthiness Directive CF–2009–37, 

dated September 30, 2009 (referred to 

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

unsafe condition for the specified 

products. The MCAI states: 

At present, the Wing Anti-Ice System 

(WAIS) sufficient heat switches/sensors on 

CL–600–2B19 aircraft are located at the 

inboard end of each wing and require a 

simultaneous low-pressure signal to generate 

a L or R WING A/ICE amber caution. 

However, there have recently been several inservice occurrences that have highlighted the 

inability of the existing system to detect a 

low-heat condition in the wing leading edge 

at all times, with the potential consequence 

of unannunciated asymmetric ice build-up 

on the wing. These have included partial 

failure of several piccolo ducts [ref: 

Airworthiness Directive (AD) CF–2008–30] 

and partial (not fully closed or open) failure 

of a modulating and shut-off valve, the latter 

resulting in unannunciated asymmetric ice 

build-up on the wing leading edge. Such a 

condition, in combination with maneuvers 

close to stick shaker activation, could 

possibly result in reduced controllability of 

the aircraft. 

This directive mandates: 

(a) Revision of the Airplane Flight Manual 

(AFM) to notify the flight crew that, 

following installation and activation of the 

low-heat detection switches, certain WAIS 

mode selection changes may result in a twominute inhibition of the wing anti-ice 

message, if posted; 

(b) Revision of the approved maintenance 

schedule to include one revised and three 

new functional checks that are required 

following activation of the low-heat detection 

switches; 

(c) Replacement of the Data Concentrator 

Units (DCUs) with DCUs incorporating a 

software update that caters for the new 

outboard low-heat detection switches and 

generates the appropriate anti-ice message for 

the flight crew when a low-heat condition is 

detected; 

Note: Although not related to this 

directive, the software update also corrects 

the sampling rate of two previously noncompliant Flight Data Recorder (FDR) 

parameters, normal acceleration and pitch 

attitude. 

(d) Installation of the low-heat detection 

switches in the wing outboard leading edges, 

the wing A/ICE box assembly and associated 

wires; and 

(e) Activation of the low-heat detection 

switches. 

You may obtain further information by 

examining the MCAI in the AD docket. 

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Federal Register / Vol. 75, No. 89 / Monday, May 10, 2010 / Proposed Rules 25789 

Relevant Service Information 

Bombardier has issued the service 

information in the following table. 

TABLE—SERVICE INFORMATION

Service information Revision Date 

Bombardier Service Bulletin 601R–30–031 ............................................................................................. D ........................... February 3, 2010. 

Bombardier Service Bulletin 601R–31–034 ............................................................................................. A ............................ April 10, 2008. 

Bombardier Temporary Revision 2A–46 to Appendix A—Certification Maintenance Requirements of 

Part 2 of the Bombardier Maintenance Requirements Manual.

Original .................. July 24, 2009. 

Bombardier Temporary Revision RJ/164–2 to the Canadair Regional Jet Airplane Flight Manual, CSP 

A–012.

Original .................. May 14, 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 Proposed 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 proposing this 

AD because we evaluated all pertinent 

information and determined an unsafe 

condition exists and is likely to exist or 

develop on other products of the same 

type design. 

Differences Between This 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 proposed 

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 

proposed AD. 

Costs of Compliance 

Based on the service information, we 

estimate that this proposed AD would 

affect about 599 products of U.S. 

registry. We also estimate that it would 

take about 21 work-hours per product to 

comply with the basic requirements of 

this proposed AD. The average labor 

rate is $85 per work-hour. Based on 

these figures, we estimate the cost of the 

proposed AD on U.S. operators to be 

$1,069,215, or $1,785 per product. 

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 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 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. 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. 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Incorporation by reference, 

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 AD: 

Bombardier, Inc.: Docket No. FAA–2010– 

0436; Directorate Identifier 2009–NM– 

230–AD. 

Comments Due Date 

(a) We must receive comments by June 24, 

2010. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to Bombardier, Inc. 

Model CL–600–2B19 (Regional Jet Series 100 

& 440) airplanes, certificated in any category, 

serial numbers 7003 through 8101 inclusive. 

Note 1: This AD requires revisions to 

certain operator maintenance documents to 

include new inspections. Compliance with 

these inspections is required by 14 CFR 

91.403(c). For airplanes that have been 

previously modified, altered, or repaired in 

the areas addressed by these inspections, the 

operator may not be able to accomplish the 

inspections described in the revisions. In this 

situation, to comply with 14 CFR 91.403(c), 

the operator must request approval for an 

alternative method of compliance according 

to paragraph (h)(1) of this AD. The request 

should include a description of changes to 

the required inspections that will ensure the 

continued operational safety of the airplane. 

mstockstill on DSKH9S0YB1PROD with PROPOSALS

25790 Federal Register / Vol. 75, No. 89 / Monday, May 10, 2010 / Proposed Rules 

Subject 

(d) Air Transport Association (ATA) of 

America Code 30 and 31: Ice and rain 

protection, and instruments, respectively. 

Reason 

(e) The mandatory continuing 

airworthiness information (MCAI) states: 

At present, the Wing Anti-Ice System 

(WAIS) sufficient heat switches/sensors on 

CL–600–2B19 aircraft are located at the 

inboard end of each wing and require a 

simultaneous low-pressure signal to generate 

a L or R WING A/ICE amber caution. 

However, there have recently been several inservice occurrences that have highlighted the 

inability of the existing system to detect a 

low-heat condition in the wing leading edge 

at all times, with the potential consequence 

of unannunciated asymmetric ice build-up 

on the wing. These have included partial 

failure of several piccolo ducts [ref: 

Airworthiness Directive (AD) CF–2008–30] 

and partial (not fully closed or open) failure 

of a modulating and shut-off valve, the latter 

resulting in unannunciated asymmetric ice 

build-up on the wing leading edge. Such a 

condition, in combination with maneuvers 

close to stick shaker activation, could 

possibly result in reduced controllability of 

the aircraft. 

This directive mandates: 

(a) Revision of the Airplane Flight Manual 

(AFM) to notify the flight crew that, 

following installation and activation of the 

low-heat detection switches, certain WAIS 

mode selection changes may result in a twominute inhibition of the wing anti-ice 

message, if posted; 

(b) Revision of the approved maintenance 

schedule to include one revised and three 

new functional checks that are required 

following activation of the low-heat detection 

switches; 

(c) Replacement of the Data Concentrator 

Units (DCUs) with DCUs incorporating a 

software update that caters for the new 

outboard low-heat detection switches and 

generates the appropriate anti-ice message for 

the flight crew when a low-heat condition is 

detected; 

Note: Although not related to this 

directive, the software update also corrects 

the sampling rate of two previously noncompliant Flight Data Recorder (FDR) 

parameters, normal acceleration and pitch 

attitude. 

(d) Installation of the low-heat detection 

switches in the wing outboard leading edges, 

the wing A/ICE box assembly and associated 

wires; and 

(e) Activation of the low-heat detection 

switches. 

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) Do the following actions. 

(1) Within 30 days after the effective date 

of this AD, revise the Limitations and Normal 

Procedures sections of the Canadair Regional 

Jet Airplane Flight Manual (AFM), CSP A– 

012, to include the information in Canadair 

(Bombardier) Temporary Revision (TR) RJ/ 

164–2, dated May 14, 2009. This TR 

introduces procedures for operation in icing 

conditions. Operate the airplane according to 

the limitations and procedures in the TR. 

Note 2: This may be done by inserting a 

copy of Canadair (Bombardier) TR RJ/164–2, 

dated May 14, 2009, into the AFM. When this 

TR has been included in general revisions of 

the AFM, the general revisions may be 

inserted in the AFM, provided the relevant 

information in the general revision is 

identical to that in Canadair (Bombardier) TR 

RJ/164–2, dated May 14, 2009. 

(2) Within 30 days after the effective date 

of this AD, revise the Airworthiness 

Limitations Instructions (ALI) of the 

Instructions for Continued Airworthiness 

(ICA) by incorporating the inspection 

requirements contained in Bombardier TR 

2A–46, dated July 24, 2009, into Appendix A, 

‘‘Certification Maintenance Requirements,’’ of 

Part 2 of the Bombardier CL–600–2B19 

Maintenance Requirements Manual (MRM). 

The initial compliance times for the tasks 

identified in Bombardier TR 2A–46, dated 

July 24, 2009, are specified in Table 1 of this 

AD. 

Note 3: The actions required by paragraph 

(g)(2) of this AD may be done by inserting a 

copy of Bombardier TR 2A–46, dated July 24, 

2009, into the Bombardier CL–600–2B19 

MRM. When this TR has been included in 

general revisions of the MRM, the general 

revisions may be inserted into the MRM, 

provided the relevant information in the 

general revision is identical to that in 

Bombardier TR 2A–46, dated July 24, 2009. 

TABLE 1—INITIAL COMPLIANCE TIMES FOR TASKS IN BOMBARDIER TR 2A–46 

Task Applicabilty Initial compliance time 

(whichever occurs later) 

C30–10–141–01 ......... All airplanes ....................................................................... Before the accumulation of 

6,000 total flight hours.

Within 5 flight hours after 

the effective date of this 

AD. 

C30–10–141–03 ......... Airplanes on which Modification Summary TC601R17494 

or actions specified in Bombardier Service Bulletin 

601R–30–031 have been done.

Before the accumulation of 

6,000 total flight hours.

Within 5 flight hours after 

the effective date of this 

AD. 

C30–10–141–05 ......... Airplanes with outboard sufficient heat switches installed 

in accordance with Modification Summary 

TC601R17494 or actions specified in Bombardier 

Service Bulletin 601R–30–031 have been done.

Before the accumulation of 

6,000 total flight hours.

Within 5 flight hours after 

the effective date of this 

AD. 

C30–10–141–07 ......... Airplanes with outboard sufficient heat switches installed 

in accordance with Modification Summary 

TC601R17494 or actions specified in Bombardier 

Service Bulletin 601R–30–031 have been done.

Before the accumulation of 

6,000 total flight hours.

Within 5 flight hours after 

the effective date of this 

AD. 

(3) For airplanes having S/Ns 7003 through 

8095 inclusive: Before or concurrently with 

accomplishing the actions required by 

paragraph (g)(5) of this AD: Replace any data 

concentrator units (DCUs) having part 

number (P/N) 622–9820–007, 622–9820–008, 

or 622–9820–009 with modified DCUs having 

P/N 622–9820–010, and, if applicable, 

modify the configuration strapping units 

(CSUs), in accordance with the 

Accomplishment Instructions of Bombardier 

Service Bulletin 601R–31–034, Revision A, 

dated April 10, 2008. 

(4) Before or concurrently with 

accomplishing the actions required by 

paragraph (g)(5) of this AD: Install the 

outboard low-heat detection switches, wing 

A/ICE box assembly and associated wires, in 

accordance with the Accomplishment 

Instructions of Parts A, C, D, and E of 

Bombardier Service Bulletin 601R–30–031, 

Revision D, dated February 3, 2010. 

Note 4: A small number of cases have been 

reported in which piccolo ducts were found 

to have been installed in the opposite wing, 

resulting in the incorrect orientation of the 

bleed holes. During reinstallation of the 

piccolo ducts and leading edge assemblies 

after installing the low-heat detection 

switches, particular attention should be paid 

to the correct alignment of the piccolo ducts. 

Guidance can be found in Task 30–11–41– 

820–801 of the Bombardier Aircraft 

Maintenance Manual. 

(5) Within 11 months after the effective 

date of this AD: Activate the outboard lowheat detection switches in accordance with 

Part F of the Accomplishment Instructions of 

Service Bulletin 601R–30–031, Revision D, 

dated February 3, 2010. 

mstockstill on DSKH9S0YB1PROD with PROPOSALS

Federal Register / Vol. 75, No. 89 / Monday, May 10, 2010 / Proposed Rules 25791 

(6) Actions accomplished in accordance 

with the service information specified in 

Table 2 of this AD, before the effective date 

of this AD, are acceptable for compliance 

with the corresponding actions required by 

paragraphs (g)(4) and (g)(5) of this AD. 

TABLE 2—ACCEPTABLE SERVICE INFORMATION

Bombardier Service Bulletin— Revision— Dated— 

601R-30–031 ....................................................................................................................................... Original .................. May 15, 2009. 

601R-30–031 ....................................................................................................................................... A ............................ September 8, 2009. 

601R-30–031 ....................................................................................................................................... B ............................ October 28, 2009. 

601R-30–031 ....................................................................................................................................... C ............................ December 23, 2009. 

(7) Replacing DCUs P/N 622–9820–007, 

622–9820–008, or 622–9820–009 with 

modified DCUs having P/N 622–9820–010, 

and modifying CSUs, are also acceptable for 

compliance with the requirements of 

paragraph (g)(3) of this AD if done before the 

effective date of this AD, in accordance with 

Accomplishment Instructions of Bombardier 

Service Bulletin 601R–30–034, dated 

November 19, 2007. 

FAA AD Differences 

Note 5: This AD differs from the MCAI 

and/or service information as follows: No 

differences. 

Other FAA AD Provisions 

(h) The following provisions also apply to 

this AD: 

(1) Alternative Methods of Compliance 

(AMOCs): The Manager, New York Aircraft 

Certification Office (ACO), ANE–170, 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 

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 

(i) Refer to MCAI Transport Canada Civil 

Aviation (TCCA) Airworthiness Directive 

CF–2009–37, dated September 30, 2009; and 

the service information specified in Table 3 

of this AD; for related information. 

TABLE 3—SERVICE INFORMATION

Service information Revision Date 

Bombardier Service Bulletin 601R–30–031 ........................................................................................ D ............................ February 3, 2010. 

Bombardier Service Bulletin 601R–31–034 ........................................................................................ A ............................ April 10, 2008. 

Bombardier Temporary Revision 2A–46 to Appendix A—Certification Maintenance Requirements 

of Part 2 of the Bombardier CL-600–2B19 Maintenance Requirements Manual.

Original .................. July 24, 2009. 

Canadair (Bombardier) Temporary Revision RJ/164–2 to the Canadair Regional Jet Airplane 

Flight Manual CSP A–012.

Original .................. May 14, 2009. 

Issued in Renton, Washington, on April 28, 

2010. 

Jeffrey E. Duven, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. 2010–10884 Filed 5–7–10; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2010–0438; Directorate 

Identifier 2009–NM–265–AD] 

RIN 2120–AA64 

Airworthiness Directives; Bombardier, 

Inc. Model CL–600–2C10 (Regional Jet 

Series 700, 701, & 702) Airplanes, 

Model CL–600–2D15 (Regional Jet 

Series 705) Airplanes, and Model CL– 

600–2D24 (Regional Jet Series 900) 

Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: We propose to adopt a new 

airworthiness directive (AD) for the 

products listed above that would 

supersede an existing AD. This 

proposed 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: 

The heating capability of several [angle of 

attack] AOA transducer heating elements 

removed from in-service aircraft has been 

found to be below the minimum requirement. 

Also, it was discovered that a large number 

of AOA transducers repaired in an approved 

maintenance facility were not calibrated 

accurately. 

Inaccurate calibration of the AOA 

transducer and/or degraded AOA transducer 

heating elements can result in early or late 

activation of the stall warning, stick shaker 

and stick pusher by the Stall Protection 

Computer (SPC). 

Inaccurate calibration of the AOA 

transducers and/or degraded AOA 

transducer heating elements could 

result in an ineffective response to an 

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