Federal Register / Vol. 79, No. 152 / Thursday, August 7, 2014 / Rules and Regulations 46169 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2013–0897; Special 

Conditions No. 25–523–SC] 

Special Conditions: Airbus Model 

A350–900 Airplane; Transient EngineFailure Loads 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final special conditions. 

SUMMARY: These special conditions are 

issued for Airbus Model A350–900 

airplanes. These airplanes will have a 

novel or unusual design feature 

associated with the new generation of 

high-bypass engines and the potential 

loads resulting from extreme enginefailure conditions. 

The applicable airworthiness 

regulations do not contain adequate or 

appropriate safety standards for this 

design feature. 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: Effective Date: September 8, 

2014. 

FOR FURTHER INFORMATION CONTACT: 

Todd Martin, FAA, Airframe and Cabin 

Safety Branch, ANM–115, Transport 

Airplane Directorate, Aircraft 

Certification Service, 1601 Lind Avenue 

SW., Renton, Washington 98057–3356; 

telephone (425) 227–1178; facsimile 

(425) 227–1320. 

SUPPLEMENTARY INFORMATION: 

Background 

On August 25, 2008, Airbus applied 

for a type certificate for their new Model 

A350–900 airplane. Later, Airbus 

requested, and the FAA approved, an 

extension to the application for FAA 

type certification to November 15, 2009. 

The Model A350–900 airplane has a 

conventional layout with twin wingmounted Rolls-Royce Trent XWB 

engines. It features a twin-aisle, 

9-abreast, economy-class layout, and 

accommodates side-by-side placement 

of LD–3 containers in the cargo 

compartment. The basic Model A350– 

900 airplane configuration 

accommodates 315 passengers in a 

standard two-class arrangement. The 

design cruise speed is Mach 0.85 with 

a maximum take-off weight of 602,000 

lbs. 

The existing regulations are 

inadequate because the new, largebypass fan engines of the Model A350– 

900 airplanes can cause more damage in 

a failure event than could the previous 

engines. To maintain the level of safety 

envisioned by Title 14, Code of Federal 

Regulations (14 CFR) 25.61(b), more 

comprehensive criteria are needed for 

the new generation of high-bypass 

engines. The more severe events 

resulting from extreme engine-failure 

conditions would be treated as 

dynamic-load conditions. The special 

conditions would distinguish between 

the more common engine-failure events 

and those rare events resulting from 

structural failures. The more common 

events would continue to be treated as 

static torque-limit load conditions. The 

severe events would be considered 

ultimate loads, and include all transient 

loads associated with the event. An 

additional safety factor would be 

applied to the more critical airframe 

supporting structure. 

Type Certification Basis 

Under 14 CFR 21.17, Airbus must 

show that the Model A350–900 airplane 

meets the applicable provisions of 14 

CFR part 25, as amended by 

Amendments 25–1 through 25–129. 

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 Model A350–900 airplane 

airplane because of a novel or unusual 

design feature, special conditions are 

prescribed under § 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 under § 21.101. 

In addition to the applicable 

airworthiness regulations and special 

conditions, the Model A350–900 

airplane must comply with the fuel-vent 

and exhaust-emission requirements of 

14 CFR part 34, and the noisecertification requirements of 14 CFR 

part 36. The FAA must issue a finding 

of regulatory adequacy under section 

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 Model A350–900 airplane will 

incorporate the following novel or 

unusual design features: engines with 

large-bypass fans capable of producing 

much higher failure loads than previous 

engines. The Model A350–900 airplane 

will therefore require additional 

dynamic-load analyses to assess the 

most severe engine-failure events. The 

loads resulting from these conditions 

would be considered as ultimate loads, 

with an additional safety factor applied 

to the airframe supporting structure. 

Discussion 

The size, configuration, and failure 

modes of jet engines has changed 

considerably from those envisioned by 

14 CFR 25.361(b) when the engineseizure requirement was first adopted. 

Engines have become larger and are now 

designed with large-bypass fans capable 

of producing much higher failure loads. 

Relative to the engine configurations 

that existed when the rule was 

developed in 1957, the present 

generation of engines are sufficiently 

different and novel to justify special 

conditions for Model A350–900 

airplanes. Service history has shown 

that the engine-failure events that tend 

to cause the most severe loads are fanblade failures, and these events occur 

much less frequently than the typical 

‘‘limit’’ load condition. 

The regulatory authorities and 

industry developed a standardized 

requirement in the Aviation Rulemaking 

Advisory Committee (ARAC) forum. 

The technical aspects of this 

requirement have been agreed upon and 

have been accepted by the ARAC Loads 

and Dynamics Harmonization Working 

Group. These special conditions reflect 

the ARAC recommendation and are 

essentially harmonized with the 

corresponding European Aviation Safety 

Agency (EASA) Certification 

Specifications (CS) 25. In addition, the 

ARAC recommendation includes 

corresponding advisory material that is 

incorporated in CS–25. This advisory 

material is considered an acceptable 

means of compliance to the special 

conditions. 

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. 

Discussion of Comments 

Notice of proposed special conditions 

no. 25–13–29–SC for Airbus Model 

A350–900 airplanes was published in 

the Federal Register on November 12, 

2013 (78 FR 67323). No substantive 

comments were received, and the 

special conditions are adopted as 

proposed. 


emcdonald on DSK67QTVN1PROD with RULES
46170 Federal Register / Vol. 79, No. 152 / Thursday, August 7, 2014 / Rules and Regulations 

Applicability 

As discussed above, these special 

conditions apply to the Airbus Model 

A350–900 airplanes. Should Airbus 

apply later 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 the Model 

A350–900 airplanes. It is not a rule of 

general applicability. 

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 Airbus Model A350–900 

airplanes. 

In lieu of § 25.361(b), the following 

special conditions apply: 

1. For turbine-engine installations, the 

engine mounts, pylons, and adjacent 

supporting airframe structure must be 

designed to withstand 1g level flight 

loads acting simultaneously with the 

maximum limit torque loads imposed 

by each of the following: 

a. Sudden engine deceleration due to 

a malfunction that could result in a 

temporary loss of power or thrust, and 

b. the maximum acceleration of the 

engine. 

2. For auxiliary power-unit 

installations, the power-unit mounts 

and adjacent supporting airframe 

structure must be designed to withstand 

1g level flight loads acting 

simultaneously with the maximum limit 

torque loads imposed by each of the 

following: 

a. Sudden auxiliary power-unit 

deceleration due to malfunction or 

structural failure, and 

b. the maximum acceleration of the 

power unit. 

3. For engine-supporting structure, an 

ultimate loading condition must be 

considered that combines 1g flight loads 

with the transient dynamic loads 

resulting from: 

a. The loss of any fan, compressor, or 

turbine blade, and separately 

b. where applicable to a specific 

engine design, any other engine 

structural failure that results in higher 

loads. 

4. The ultimate loads developed from 

the conditions specified in special 

conditions 3.a. and 3.b. are to be 

multiplied by a factor of 1.0 when 

applied to engine mounts and pylons, 

and multiplied by a factor of 1.25 when 

applied to adjacent supporting airframe 

structure. 

5. The airplane must be capable of 

continued safe flight considering the 

aerodynamic effects on controllability 

due to any permanent deformation that 

results from the conditions specified in 

special condition 3. 

Issued in Renton, Washington, on July 15, 

2014. 

John P. Piccola, Jr., 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. 2014–18657 Filed 8–6–14; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2013–0903; Special 

Conditions No. 25–525–SC] 

Special Conditions: Airbus Model 

A350–900 Series Airplane; Side-Stick 

Controllers 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final special conditions. 

SUMMARY: These special conditions are 

issued for Airbus Model A350–900 

airplanes. These airplanes will have a 

novel or unusual design feature 

associated with side-stick controllers for 

pitch and roll control, instead of 

conventional wheels and columns. The 

applicable airworthiness regulations do 

not contain adequate or appropriate 

safety standards for this design feature. 

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: Effective Date: September 8, 

2014. 

FOR FURTHER INFORMATION CONTACT: 

Loran Haworth, FAA, Airplane and 

Flight Interface Branch, ANM–111, 

Transport Airplane Directorate, Aircraft 

Certification Service, 1601 Lind Avenue 

SW., Renton, Washington 98057–3356; 

telephone (425) 227–1133; facsimile 

(425) 227–1320. 

SUPPLEMENTARY INFORMATION: 

Background 

On August 25, 2008, Airbus applied 

for a type certificate for their new Model 

A350–900 airplane. Later, Airbus 

requested, and the FAA approved, an 

extension to the application for FAA 

type certification to November 15, 2009. 

The Model A350–900 airplane has a 

conventional layout with twin wingmounted Rolls-Royce Trent XWB 

engines. It features a twin-aisle, 9- 

abreast, economy-class layout, and 

accommodates side-by-side placement 

of LD–3 containers in the cargo 

compartment. The basic Model A350– 

900 airplane configuration 

accommodates 315 passengers in a 

standard two-class arrangement. The 

design cruise speed is Mach 0.85 with 

a maximum take-off weight of 602,000 

lbs. 

The Airbus Model A350–900 airplane, 

like its predecessors the Model A320, 

A330, A340 and A380 airplanes, will 

use side-stick controllers for pitch and 

roll control. Regulatory requirements 

pertaining to conventional wheel and 

column controls, such as pilot strength 

and controllability, are not directly 

applicable for the side stick. In addition, 

pilot-control authority may be uncertain 

because the side sticks are not 

mechanically interconnected as with 

conventional wheel and column 

controls. 

Type Certification Basis 

Under Title 14, Code of Federal 

Regulations (14 CFR) 21.17, Airbus must 

show that the Model A350–900 airplane 

meets the applicable provisions of 14 

CFR part 25, as amended by 

Amendments 25–1 through 25–129. 

The FAA has determined that Airbus 

Model A350–900 airplanes must comply 

with §§ 25.143, 25.145(b), 25.175(b), 

25.671, and 25.1329(a). 

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 Airbus Model A350–900 airplane 

because of a novel or unusual design 

feature, special conditions are 

prescribed under § 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 under § 21.101. 

In addition to the applicable 

airworthiness regulations and special 

conditions, the Airbus Model A350–900 

airplane must comply with the fuel-vent 


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