65156 Federal Register / Vol. 78, No. 211 / Thursday, October 31, 2013 / Rules and Regulations 

CFR part 36 and the FAA must issue a 

finding of regulatory adequacy under 

§ 611 of Public Law 92–574, the ‘‘Noise 

Control Act of 1972.’’ 

The FAA issues special conditions, as 

defined in 14 CFR 11.19, under § 11.38, 

and they become part of the typecertification basis under § 21.17(a)(2). 

Novel or Unusual Design Features 

The Learjet Model 45 series airplanes 

will incorporate the following novel or 

unusual design features: The proposed 

architecture and network configuration 

may be used for, or interfaced with, a 

diverse set of functions, including: 

1. Flight-safety related control, 

communication, and navigation systems 

(aircraft control domain); 

2. Operator business and 

administrative support (operator 

information domain); and 

3. Passenger information and 

entertainment systems (passenger 

entertainment domain). 

In addition, the operating systems 

(OS) for current aircraft systems are 

usually and historically proprietary. 

Therefore, they are not as susceptible to 

corruption from worms, viruses, and 

other malicious actions as more widely 

used commercial operating systems, 

such as Microsoft Windows NT, because 

access to the design details of these 

proprietary OS is limited to the system 

developer and aircraft integrator. Some 

systems installed on the Learjet Model 

45 series airplanes will use operating 

systems that are widely used and 

commercially available from third party 

software suppliers. The security 

vulnerabilities of these operating 

systems may be more widely known 

than proprietary operating systems 

currently used by avionics 

manufacturers. 

Discussion 

The integrated network configurations 

in the Learjet Model 45 series airplanes 

may allow increased connectivity with 

external network sources and will have 

more interconnected networks and 

systems, such as passenger 

entertainment and information services 

than previous airplane models. This 

may allow the exploitation of network 

security vulnerabilities and increased 

risks potentially resulting in unsafe 

conditions for the airplanes and 

occupants. This potential exploitation of 

security vulnerabilities may result in 

intentional or unintentional destruction, 

disruption, degradation, or exploitation 

of data and systems critical to the safety 

and maintenance of the airplane. The 

existing regulations and guidance 

material did not anticipate these types 

of system architectures. Furthermore, 14 

CFR regulations and current system 

safety assessment policy and techniques 

do not address potential security 

vulnerabilities which could be exploited 

by unauthorized access to airplane 

networks and servers. Therefore, these 

special conditions are being issued to 

ensure that the security (i.e., 

confidentiality, integrity, and 

availability) of airplane systems is not 

compromised by unauthorized wired or 

wireless electronic connections between 

airplane systems and the passenger 

entertainment services. 

For the reasons discussed above, these 

special conditions contain the 

additional safety standards that the 

Administrator considers necessary to 

establish a level of safety equivalent to 

that established by the existing 

airworthiness standards. 

Applicability 

As discussed above, these special 

conditions are applicable to the Learjet 

Model 45 series airplanes. Should 

Learjet apply at a later date for a change 

to the type certificate to include another 

model incorporating the same novel or 

unusual design feature, the special 

conditions would apply to that model as 

well. 

Conclusion 

This action affects only certain novel 

or unusual design features on one model 

series of airplanes. It is not a rule of 

general applicability. 

The substance of these special 

conditions has been subjected to the 

notice and comment period in several 

prior instances and has been derived 

without substantive change from those 

previously issued. It is unlikely that 

prior public comment would result in a 

significant change from the substance 

contained herein. Therefore, because a 

delay would significantly affect the 

certification of the airplane, which is 

imminent, the FAA has determined that 

prior public notice and comment are 

unnecessary and impracticable, and 

good cause exists for adopting these 

special conditions upon publication in 

the Federal Register. The FAA is 

requesting comments to allow interested 

persons to submit views that may not 

have been submitted in response to the 

prior opportunities for comment 

described above. 

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 Special Conditions 

Accordingly, pursuant to the 

authority delegated to me by the 

Administrator, the following special 

conditions are issued as part of the type 

certification basis for Learjet Model 45 

series airplanes. 

Isolation or Security Protection of the 

Aircraft Control Domain and the Airline 

Information Services Domain From the 

Passenger Services Domain 

1. The applicant must ensure that the 

design provides isolation from, or 

airplane electronic system security 

protection against, access by 

unauthorized sources internal to the 

airplane. The design must prevent 

inadvertent and malicious changes to, 

and all adverse impacts upon, airplane 

equipment, systems, networks, or other 

assets required for safe flight and 

operations. 

2. The applicant must establish 

appropriate procedures to allow the 

operator to ensure that continued 

airworthiness of the aircraft is 

maintained, including all post-typecertification modifications that may 

have an impact on the approved 

electronic system security safeguards. 

Issued in Renton, Washington, on October 

22, 2013. 

Stephen P. Boyd, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. 2013–25851 Filed 10–30–13; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2013–0820; Notice No. 

25–499–SC] 

Special Conditions: Bombardier Inc., 

Models BD–500–1A10 and BD–500– 

1A11 Series Airplanes; Interactions of 

Systems and Structures 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final special conditions; request 

for comments. 

SUMMARY: These special conditions are 

issued for the Bombardier Inc. Models 

BD–500–1A10 and BD–500–1A11 series 

airplanes. These airplanes will have 

novel or unusual features when 

compared to the state of technology 

envisioned in the airworthiness 

standards for transport category 

airplanes. These design features include 

systems that, directly or as a result of 


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failure or malfunction, affect structural 

performance. The applicable 

airworthiness regulations do not contain 

adequate or appropriate safety standards 

for these design features. These special 

conditions contain the additional safety 

standards that the Administrator 

considers necessary to establish a level 

of safety equivalent to that established 

by the existing airworthiness standards. 

DATES: The effective date of these 

special conditions is October 31, 2013. 

We must receive your comments by 

December 16, 2013. 

ADDRESSES: Send comments identified 

by docket number FAA–2013–0820 

using any of the following methods: 

• Federal eRegulations Portal: Go to 

http://www.regulations.gov/ and follow 

the online instructions for sending your 

comments electronically. 

• Mail: Send comments to Docket 

Operations, M–30, U.S. Department of 

Transportation (DOT), 1200 New Jersey 

Avenue SE., Room W12–140, West 

Building Ground Floor, Washington, DC 

20590–0001. 

• Hand Delivery or Courier: Take 

comments to Docket Operations in 

Room W12–140 of the West Building 

Ground Floor at 1200 New Jersey 

Avenue SE., Washington, DC, between 9 

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

Friday, except federal holidays. 

• Fax: Fax comments to Docket 

Operations at 202–493–2251. 

Privacy: The FAA will post all 

comments it receives, without change, 

to http://www.regulations.gov/, 

including any personal information the 

commenter provides. Using the search 

function of the docket Web site, anyone 

can find and read the electronic form of 

all comments received into any FAA 

docket, including the name of the 

individual sending the comment (or 

signing the comment for an association, 

business, labor union, etc.). DOT’s 

complete Privacy Act Statement can be 

found in the Federal Register published 

on April 11, 2000 (65 FR 19477–19478), 

as well as at http://DocketsInfo 

.dot.gov/. 

Docket: Background documents or 

comments received may be read at 

http://www.regulations.gov/ at any time. 

Follow the online instructions for 

accessing the docket or go to the Docket 

Operations in Room W12–140 of the 

West Building Ground Floor at 1200 

New Jersey Avenue SE., Washington, 

DC, between 9 a.m. and 5 p.m., Monday 

through Friday, except federal holidays. 

FOR FURTHER INFORMATION CONTACT: 

Mark Freisthler, FAA, Airframe and 

Cabin Safety Branch, ANM–115, 

Transport Airplane Directorate, Aircraft 

Certification Service, 1601 Lind Avenue 

SW., Renton, Washington 98057–3356; 

telephone 425–227–1119; facsimile 

425–227–1232. 

SUPPLEMENTARY INFORMATION: The FAA 

has determined that notice of, and 

opportunity for prior public comment 

on, these special conditions is 

impracticable because these procedures 

would significantly delay issuance of 

the design approval and thus delivery of 

the affected aircraft. In addition, the 

substance of these special conditions 

has been subject to the public comment 

process in several prior instances with 

no substantive comments received. The 

FAA therefore finds that good cause 

exists for making these special 

conditions effective upon issuance. 

Comments Invited 

We invite interested people to take 

part in this rulemaking by sending 

written comments, data, or views. The 

most helpful comments reference a 

specific portion of the special 

conditions, explain the reason for any 

recommended change, and include 

supporting data. 

We will consider all comments we 

receive on or before the closing date for 

comments. We may change these special 

conditions based on the comments we 

receive. 

Background 

On December 10, 2009, Bombardier 

Inc. applied for a type certificate for 

their new Models BD–500–1A10 and 

BD–500–1A11 series airplanes. The 

Models BD–500–1A10 and BD–500– 

1A11 series airplanes are swept-wing 

monoplanes with a pressurized cabin, 

and they share an identical supplier 

base and significant common design 

elements. The fuselage is aluminum 

alloy material, blended double-bubble 

design, sized for nominal 5-abreast 

seating. Each airplane’s powerplant 

includes two under-wing Pratt and 

Whitney PW1524G ultra high-bypass, 

geared turbofan engines. Flight controls 

are fly-by-wire systems with two 

passive/uncoupled side sticks. Avionics 

include five landscape primary cockpit 

displays. The dimensions of the 

airplanes encompass a wingspan of 115 

feet; a height of 37.75 feet; and a length 

of 114.75 feet for the Model BD–500– 

1A10 and 127 feet for the Model BD– 

500–1A11. Passenger capacity is 

designated as 110 for the Model BD– 

500–1A10 and 125 for the Model BD– 

500–1A11. Maximum takeoff weight is 

131,000 pounds for the Model BD–500– 

1A10 and 144,000 pounds for the Model 

BD–500–1A11. Maximum takeoff thrust 

is 21,000 pounds for the Model BD– 

500–1A10 and 23,300 pounds for the 

Model BD–500–1A11. The range is 

3,394 miles (5,463 kilometres) for both 

models of airplanes. The maximum 

operating altitude is 41,000 feet for both 

models of airplanes. 

Type Certification Basis 

Under the provisions of Title 14, Code 

of Federal Regulations (14 CFR) 21.17, 

Bombardier Inc. must show that the 

Model BD–500–1A10 and BD–500– 

1A11 series airplanes meet the 

applicable provisions of 14 CFR part 25 

as amended by Amendments 25–1 

through 25–129 thereto. 

If the Administrator finds that the 

applicable airworthiness regulations 

(i.e., 14 CFR part 25) do not contain 

adequate or appropriate safety standards 

for the Models BD–500–1A10 and BD– 

500–1A11 series airplanes because of a 

novel or unusual design feature, special 

conditions are prescribed under the 

provisions of § 21.16. 

Special conditions are initially 

applicable to the model for which they 

are issued. Should the type certificate 

for that model be amended later to 

include any other model that 

incorporates the same or similar novel 

or unusual design feature, the special 

conditions would also apply to the other 

model. 

In addition to the applicable 

airworthiness regulations and special 

conditions, the Model BD–500–1A10 

and BD–500–1A11 series airplanes must 

comply with the fuel vent and exhaust 

emission requirements of 14 CFR part 

34 and the noise certification 

requirements of 14 CFR part 36, and the 

FAA must issue a finding of regulatory 

adequacy under § 611 of Public Law 92– 

574, the ‘‘Noise Control Act of 1972.’’ 

The FAA issues special conditions, as 

defined in 14 CFR 11.19, in accordance 

with § 11.38, and they become part of 

the type-certification basis under 

§ 21.17(a)(2). 

Novel or Unusual Design Features 

The Models BD–500–1A10 and BD– 

500–1A11 series airplanes will 

incorporate the following novel or 

unusual design features: Systems that 

affect the airplane’s structural 

performance, either directly or as a 

result of failure or malfunction. That is, 

the airplane’s systems affect how it 

responds in maneuver and gust 

conditions, and thereby affect its 

structural capability. These systems may 

also affect the aeroelastic stability of the 

airplane. Such systems include flight 

control systems, autopilots, stability 

augmentation systems, load alleviation 

systems, and fuel management systems. 

These systems represent novel and 

unusual features when compared to the 


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technology envisioned in the current 

airworthiness standards. 

Discussion 

The flight control system of the 

Models BD–500–1A10 and BD–500– 

1A11 series airplanes will consist of a 

full authority fly-by-wire system with 

normal and direct modes of operation. 

Special conditions have been applied on 

past airplane programs, with similar 

systems, in order to require 

consideration of the effects of those 

systems on structures. The regulatory 

authorities and industry developed 

standardized criteria in the Aviation 

Rulemaking Advisory Committee 

(ARAC) forum based on the criteria 

defined in Advisory Circular 25.672, 

dated November 11, 1983. The ARAC 

recommendations have been 

incorporated in European Aviation 

Safety Agency (EASA) Certification 

Specifications (CS) 25.302 and CS–25 

Appendix K. FAA rulemaking on this 

subject is not complete, thus the need 

for special conditions. 

These special conditions are similar 

to those previously applied to other 

airplane models and to EASA CS 

25.302. Transport Canada Civil Aviation 

(TCCA) plans to apply the CS 25.302 

version of the special conditions. The 

differences between FAA special 

conditions and the current CS 25.302, 

which the FAA regards as minor, are 

shown below. 

(1) Both these special conditions and 

CS 25.302 specify the design load 

conditions to be considered. Paragraphs 

2a(1) and 2b(2)(i) of these special 

conditions clarify that, in some cases, 

different load conditions are to be 

considered due to other special 

conditions or equivalent level of safety 

findings. 

(2) Both these special conditions and 

CS 25.302 allow consideration of the 

probability of being in a dispatched 

configuration when assessing 

subsequent failures and potential 

‘‘continuation of flight’’ loads (see 

paragraph 2d below). These special 

conditions, however, also allow using 

probability when assessing failures that 

induce loads at the ‘‘time of 

occurrence,’’ whereas CS 25.302 does 

not. The FAA provision is relieving. The 

FAA chooses to preserve these minor 

differences and go forward with this 

version of the special conditions. 

Applicability 

As discussed above, these special 

conditions are applicable to the Models 

BD–500–1A10 and BD–500–1A11 series 

airplanes. Should Bombardier Inc. apply 

at a later date for a change to the type 

certificate to include another model 

incorporating the same novel or unusual 

design feature, the special conditions 

would apply to that model as well. 

Conclusion 

This action affects only certain novel 

or unusual design features on two 

models of airplanes. It is not a rule of 

general applicability. 

The substance of these special 

conditions has been subjected to the 

notice and comment period in several 

prior instances and has been derived 

without substantive change from those 

previously issued. It is unlikely that 

prior public comment would result in a 

significant change from the substance 

contained herein. Therefore, because a 

delay would significantly affect the 

certification of the airplane, which is 

imminent, the FAA has determined that 

prior public notice and comment are 

unnecessary and impracticable, and 

good cause exists for adopting these 

special conditions upon publication in 

the Federal Register. The FAA is 

requesting comments to allow interested 

persons to submit views that may not 

have been submitted in response to the 

prior opportunities for comment 

described above. 

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 Special Conditions 

Accordingly, pursuant to the 

authority delegated to me by the 

Administrator, the following special 

conditions are issued as part of the type 

certification basis for Bombardier Inc. 

Models BD–500–1A10 and BD–500– 

1A11 series airplanes. 

1. Interaction of Systems and 

Structures. General. 

a. For airplanes equipped with 

systems that affect structural 

performance, either directly or as a 

result of a failure or malfunction, the 

influence of these systems and their 

failure conditions must be taken into 

account when showing compliance with 

the requirements of Title 14, Code of 

Federal Regulations (14 CFR) part 25 

subparts C and D. 

b. The following criteria must be used 

for showing compliance with these 

special conditions for airplanes 

equipped with flight control systems, 

autopilots, stability augmentation 

systems, load alleviation systems, flutter 

control systems, fuel management 

systems, and other systems that either 

directly or as a result of failure or 

malfunction affect structural 

performance. If these special conditions 

are used for other systems, it may be 

necessary to adapt the criteria to the 

specific system. 

c. The criteria defined herein only 

address the direct structural 

consequences of the system responses 

and performances and cannot be 

considered in isolation but should be 

included in the overall safety evaluation 

of the airplane. These criteria may in 

some instances duplicate standards 

already established for this evaluation. 

These criteria are only applicable to 

structure whose failure could prevent 

continued safe flight and landing. 

Specific criteria that define acceptable 

limits on handling characteristics or 

stability requirements when operating 

in the system degraded or inoperative 

mode are not provided in these special 

conditions. 

d. Depending upon the specific 

characteristics of the airplane, 

additional studies may be required that 

go beyond the criteria provided in these 

special conditions in order to 

demonstrate the capability of the 

airplanes to meet other realistic 

conditions such as alternative gust or 

maneuver descriptions for an airplane 

equipped with a load alleviation system. 

e. The following definitions are 

applicable to these special conditions: 

(1) Structural performance: Capability 

of the airplane to meet the structural 

requirements of 14 CFR part 25. 

(2) Flight limitations: Limitations that 

can be applied to the airplane flight 

conditions following an in-flight 

occurrence and that are included in the 

flight manual (e.g., speed limitations 

and avoidance of severe weather 

conditions). 

(3) Operational limitations: 

Limitations, including flight limitations, 

that can be applied to the airplane 

operating conditions before dispatch 

(e.g., fuel, payload and Master 

Minimum Equipment List limitations). 

(4) Probabilistic terms: The 

probabilistic terms (probable, 

improbable, extremely improbable) used 

in these special conditions are the same 

as those used in § 25.1309. 

(5) Failure condition: The term 

‘‘failure condition’’ is the same as that 

used in § 25.1309. However, these 

special conditions apply only to system 

failure conditions that affect the 

structural performance of the airplane 

(e.g., system failure conditions that 

induce loads, change the response of the 

airplane to inputs such as gusts or pilot 

actions, or lower flutter margins). 

2. Effect on Systems and Structures. 

The following criteria will be used in 

determining the influence of a system 


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Federal Register / Vol. 78, No. 211 / Thursday, October 31, 2013 / Rules and Regulations 65159 

and its failure conditions on the 

airplane structure. 

a. System fully operative. With the 

system fully operative, the following 

apply: 

(1) Limit loads must be derived in all 

normal operating configurations of the 

system from all the limit conditions 

specified in subpart C (or defined by 

special conditions or equivalent level of 

safety in lieu of those specified in 

subpart C), taking into account any 

special behavior of such a system or 

associated functions or any effect on the 

structural performance of the airplane 

that may occur up to the limit loads. In 

particular, any significant nonlinearity 

(rate of displacement of control surface, 

thresholds, or any other system 

nonlinearities) must be accounted for in 

a realistic or conservative way when 

deriving limit loads from limit 

conditions. 

(2) The airplane must meet the 

strength requirements of part 25 (static 

strength, residual strength) using the 

specified factors to derive ultimate loads 

from the limit loads defined above. The 

effect of nonlinearities must be 

investigated beyond limit conditions to 

ensure the behavior of the system 

presents no anomaly compared to the 

behavior below limit conditions. 

However, conditions beyond limit 

conditions need not be considered when 

it can be shown that the airplane has 

design features that will not allow it to 

exceed those limit conditions. 

(3) The airplane must meet the 

aeroelastic stability requirements of 

§ 25.629. 

b. System in the failure condition. For 

any system failure condition not shown 

to be extremely improbable, the 

following apply: 

(1) At the time of occurrence. Starting 

from 1-g level flight conditions, a 

realistic scenario, including pilot 

corrective actions, must be established 

to determine the loads occurring at the 

time of failure and immediately after 

failure. 

(i) For static strength substantiation, 

these loads, multiplied by an 

appropriate factor of safety that is 

related to the probability of occurrence 

of the failure, are ultimate loads to be 

considered for design. The factor of 

safety (FS) is defined in Figure 1. 

(ii) For residual strength 

substantiation, the airplane must be able 

to withstand two thirds of the ultimate 

loads defined in subparagraph 2b(1)(i). 

For pressurized cabins, these loads must 

be combined with the normal operating 

differential pressure. 

(iii) Freedom from aeroelastic 

instability must be shown up to the 

speeds defined in § 25.629(b)(2). For 

failure conditions that result in speeds 

beyond VC/MC, freedom from 

aeroelastic instability must be shown to 

increased speeds, so that the margins 

intended by § 25.629(b)(2) are 

maintained. 

(iv) Failures of the system that result 

in forced structural vibrations (e.g., 

oscillatory failures) must not produce 

loads that could result in detrimental 

deformation of primary structure. 

(2) For the continuation of the flight. 

For the airplane, in the system-failed 

state and considering any appropriate 

reconfiguration and flight limitations, 

the following apply: 

(i) The loads derived from the 

following conditions (or defined by 

special conditions or equivalent level of 

safety in lieu of the following 

conditions) at speeds up to VC/MC, or 

the speed limitation prescribed for the 

remainder of the flight, must be 

determined: 

(A) The limit symmetrical 

maneuvering conditions specified in 

§ 25.331 and in § 25.345. 

(B) The limit gust and turbulence 

conditions specified in § 25.341 and in 

§ 25.345. 

(C) The limit rolling conditions 

specified in § 25.349 and the limit 

unsymmetrical conditions specified in 

§ 25.367 and § 25.427(b) and (c). 

(D) The limit yaw maneuvering 

conditions specified in § 25.351. 

(E) The limit ground loading 

conditions specified in §§ 25.473, 

25.491, 25.493(d) and 25.503. 

(ii) For static strength substantiation, 

each part of the structure must be able 

to withstand the loads in paragraph 

2b(2)(i) of these special conditions 

multiplied by a factor of safety 

depending on the probability of being in 

this failure state. The factor of safety 

(FS) is defined in Figure 2. 


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(iii) For residual strength 

substantiation, the airplane must be able 

to withstand two thirds of the ultimate 

loads defined in paragraph 2b(2)(ii) of 

these special conditions. For 

pressurized cabins, these loads must be 

combined with the normal operating 

differential pressure. 

(iv) If the loads induced by the failure 

condition have a significant effect on 

fatigue or damage tolerance, then their 

effects must be taken into account. 

(v) Freedom from aeroelastic 

instability must be shown up to a speed 

determined from Figure 3. Flutter 

clearance speeds V′ and V′′ may be 

based on the speed limitation specified 

for the remainder of the flight using the 

margins defined by § 25.629(b). 

(vi) Freedom from aeroelastic 

instability must also be shown up to V′ 

in Figure 3 above, for any probable 

system failure condition combined with 

any damage required or selected for 

investigation by § 25.571(b). 

(3) Consideration of certain failure 

conditions may be required by other 

sections of 14 CFR part 25 regardless of 

calculated system reliability. Where 

analysis shows the probability of these 

failure conditions to be less than 10¥9, 

criteria other than those specified in this 

paragraph may be used for structural 

substantiation to show continued safe 

flight and landing. 

c. Failure indications. For system 

failure detection and indication, the 

following apply: 

(1) The system must be checked for 

failure conditions, not extremely 

improbable, that degrade the structural 

capability below the level required by 

part 25 or significantly reduce the 


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Federal Register / Vol. 78, No. 211 / Thursday, October 31, 2013 / Rules and Regulations 65161 

reliability of the remaining system. As 

far as reasonably practicable, the flight 

crew must be made aware of these 

failures before flight. Certain elements 

of the control system, such as 

mechanical and hydraulic components, 

may use special periodic inspections, 

and electronic components may use 

daily checks, in lieu of detection and 

indication systems to achieve the 

objective of this requirement. These 

certification maintenance requirements 

must be limited to components that are 

not readily detectable by normal 

detection and indication systems and 

where service history shows that 

inspections will provide an adequate 

level of safety. 

(2) The existence of any failure 

condition, not extremely improbable, 

during flight that could significantly 

affect the structural capability of the 

airplane and for which the associated 

reduction in airworthiness can be 

minimized by suitable flight limitations, 

must be signaled to the flight crew. For 

example, failure conditions that result 

in a factor of safety between the airplane 

strength and the loads of subpart C 

below 1.25, or flutter margins below V′′, 

must be signaled to the crew during 

flight. 

d. Dispatch with known failure 

conditions. If the airplane is to be 

dispatched in a known system failure 

condition that affects structural 

performance, or affects the reliability of 

the remaining system to maintain 

structural performance, then the 

provisions of these special conditions 

must be met, including the provisions of 

paragraph 2a for the dispatched 

condition, and paragraph 2b for 

subsequent failures. Expected 

operational limitations may be taken 

into account in establishing Pj as the 

probability of failure occurrence for 

determining the safety margin in Figure 

1. Flight limitations and expected 

operational limitations may be taken 

into account in establishing Qj as the 

combined probability of being in the 

dispatched failure condition and the 

subsequent failure condition for the 

safety margins in Figures 2 and 3. These 

limitations must be such that the 

probability of being in this combined 

failure state and then subsequently 

encountering limit load conditions is 

extremely improbable. No reduction in 

these safety margins is allowed if the 

subsequent system failure rate is greater 

than 10¥3 per hour. 

Issued in Renton, Washington, on 

September 12, 2013. 

Jeffrey E. Duven, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. 2013–25448 Filed 10–30–13; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2013–0518; Directorate 

Identifier 2009–SW–021–AD; Amendment 

39–17607; AD 2013–20–01] 

RIN 2120–AA64 

Airworthiness Directives; Agusta 

S.p.A. (Type Certificate Currently Held 

by AgustaWestland S.p.A) (Agusta) 

Helicopters 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: We are adopting a new 

airworthiness directive (AD) for Agusta 

Model A109A, A109AII, and A109C 

helicopters with a certain third stage 

turbine wheel installed. This AD 

requires installing a placard on the 

instrument panel and revising the 

limitations section of the rotorcraft 

flight manual (RFM). This AD was 

prompted by several incidents of third 

stage engine turbine wheel failures, 

which were caused by excessive 

vibrations at certain engine speeds 

during steady-state operations. These 

actions are intended to alert pilots to 

avoid certain engine speeds during 

steady-state operations, prevent failure 

of the third stage engine turbine, engine 

power loss, and subsequent loss of 

control of the helicopter. 

DATES: This AD is effective December 5, 

2013. 

The Director of the Federal Register 

approved the incorporation by reference 

of a certain document listed in this AD 

as of December 5, 2013. 

ADDRESSES: For service information 

identified in this AD, contact Agusta 

Westland, Customer Support & Services, 

Via Per Tornavento 15, 21019 Somma 

Lombardo (VA) Italy, ATTN: Giovanni 

Cecchelli; telephone 39 0331 711133; 

fax 39 0331 711180; or at http://

www.agustawestland.com/technicalbullettins. You may review the 

referenced service information at the 

FAA, Office of the Regional Counsel, 

Southwest Region, 2601 Meacham 

Blvd., Room 663, Fort Worth, Texas 

76137. 

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 foreign 

authority’s AD, any incorporated-byreference service information, the 

economic evaluation, any comments 

received, and other information. The 

street address for the Docket Operations 

Office (phone: 800–647–5527) is U.S. 

Department of Transportation, Docket 

Operations Office, M–30, West Building 

Ground Floor, Room W12–140, 1200 

New Jersey Avenue SE., Washington, 

DC 20590. 

FOR FURTHER INFORMATION CONTACT: 

Chinh Vuong, Aviation Safety Engineer, 

Safety Management Group, Rotorcraft 

Directorate, FAA, 2601 Meacham Blvd., 

Fort Worth, Texas 76137; telephone 

(817) 222–5110; email chinh.vuong@

faa.gov. 

SUPPLEMENTARY INFORMATION: 

Discussion 

On June 20, 2013, at 78 FR 37162, the 

Federal Register published our notice of 

proposed rulemaking (NPRM), which 

proposed to amend 14 CFR part 39 by 

adding an AD that would apply to 

Agusta Model A109A, A109AII, and 

A109C helicopters with a third stage 

turbine wheel, part number (P/N) 

23065833, installed. The NPRM 

proposed to require installing a placard 

on the instrument panel adjacent to the 

engine and rotor RPM power turbine 

(N2) indicator and revising the 

Operating Limitations sections of the 

Model A109A, A109AII, and A109C 

RFMs to limit steady-state operations 

between speeds of 95% and 97%. The 

proposed requirements were intended to 

alert pilots to avoid certain engine 

speeds during steady-state operations, 

prevent failure of the third stage engine 

turbine, engine power loss, and 

subsequent loss of control of the 

helicopter. 

The NPRM was prompted by AD No. 

2009–0037–E, dated February 19, 2009, 

issued by the European Aviation Safety 

Agency (EASA), which is the Technical 

Agent for the Member States of the 

European Union. EASA issued AD No. 

2009–0037–E to correct an unsafe 

condition for Agusta Model A109A, 

A109AII, and A109C helicopters with a 

Rolls Royce Corporation (RRC) engine 

Model 250–C20B or 250–C20R/1 having 

a third stage turbine wheel P/N 

23065833 installed. EASA advises that 

following several third stage turbine 

wheel failures, the engine type 


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