7372 Federal Register / Vol. 79, No. 26 / Friday, February 7, 2014 / Rules and Regulations 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2013–0857; Special 

Conditions No. 25–528–SC] 

Special Conditions: Learjet Inc., Model 

LJ–200–1A10 Airplane; 

Crashworthiness, Emergency Landing 

Conditions 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final special conditions. 

SUMMARY: These special conditions are 

issued for the Learjet Inc. Model LJ– 

200–1A10 airplane. This airplane will 

have a novel or unusual design feature 

when compared to the state of 

technology envisioned in the 

airworthiness standards for transport 

category airplanes. This feature is a 

hybrid construction that uses both 

composite and metallic materials in the 

structure for which the crashworthiness 

responses for occupant safety may not 

be equivalent to current all-metallic 

airplanes. 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: March 10, 2014. 

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 

425–227–1320. 

SUPPLEMENTARY INFORMATION: 

Background 

On February 9, 2009, Learjet Inc. 

applied for a type certificate for their 

new Model LJ–200–1A10 airplane 

(hereafter referred to as the ‘‘Model LJ– 

200’’). The Model LJ–200 is a business 

class airplane powered by two highbypass turbine engines with an 

estimated maximum takeoff weight of 

35,550 pounds and an interior 

configuration for up to 10 passengers. 

The current design includes a skinstringer fuselage configuration. The 

pressure fuselage will consist of 

monolithic carbon fiber reinforced 

plastic (CFRP) skin, with CFRP and 

metallic frames above floor level, and 

CFRP longerons and stringers. All 

substructure will be mechanically 

fastened to the skin. Fasteners for 

stringers aligned along the length of the 

co-cured splice will provide fail-safe 

capability for the splice. Cabin entry 

door frames, over-wing exit door frames, 

and frames below floor level will be 

metallic. Attachment of pressure 

bulkheads, windshield frame, and 

splicing concepts will be adjusted for 

any skin thickness variation that occurs. 

The wing consists of resin transfer 

infusion skins with composite spars and 

metallic ribs. The empennage consists of 

composite sandwich skins with metallic 

spars and ribs. The airframe has a 

sandwich construction for the nose and 

empennage structures. 

There are no existing regulations that 

adequately address the potential 

difference between metallic fabricated 

airplanes and composite fabricated 

airplanes with regards to impact 

response characteristics for what are 

considered survivable crash conditions. 

The CFRP fuselage constitutes a novel 

and unusual design feature for a 

transport category airplane. These 

special conditions are necessary to 

ensure a level of safety equivalent to 

that provided by Title 14, Code of 

Federal Regulations (14 CFR) part 25. 

Type Certification Basis 

Under the provisions of 14 CFR 21.17, 

Learjet Inc. must show that the Model 

LJ–200 meets the applicable provisions 

of part 25, as amended by Amendment 

25–1 through 25–127 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 Model LJ–200 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 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 LJ–200 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 Model LJ–200 will incorporate 

the following novel or unusual design 

feature: Hybrid construction using both 

composite and metallic materials in the 

structure for which the crashworthiness 

responses for occupant safety may not 

be equivalent to that of all-metallic 

structure. 

Discussion 

The Model LJ–200 fuselage is 

fabricated using CFRP skins with 

aluminum ribs and stringers. This 

hybrid construction may behave 

differently from similar, fully-metallic 

structure due to differences in material 

ductility, stiffness, failure modes, and 

energy absorption characteristics. 

Therefore, the impact response 

characteristics of the Model LJ–200 

must be evaluated to ensure the 

survivable crashworthiness 

characteristics are not significantly 

different than those of a similarly-sized 

airplane fabricated from traditionallyused metallic materials. 

The FAA and industry have been 

working together for many years to 

understand how transport airplane 

occupant safety can be improved for 

what are considered survivable 

accidents. This work has involved 

examining airplane accidents, 

conducting tests to simulate crash 

conditions, and developing analytical 

modeling of a range of crash conditions, 

all with the purpose of providing further 

insight into the factors that can 

influence occupant safety. Results of 

this on-going effort have enabled 

specific changes to regulatory standards 

and design practices to improve 

occupant safety. This evolution is 

reflected in changes to the part 25 

emergency landing condition 

regulations. For example, airplane 

emergency load factors in § 25.561, 

General, have been increased, and 

passenger seat dynamic load conditions 

have been added (§ 25.562, Emergency 

landing dynamic conditions). 

The seat dynamic load conditions 

were added to the regulations based on 

FAA and industry tests and a review of 

accidents. They reflect horizontal and 

vertical accelerations/time environment 

generated by previously certificated 

airplane designs given conditions that 

were survivable. These tests also 

demonstrated that the performance of 

the airframe was acceptable in a 

dynamic impact event. In the evolution 

of the regulations, there is at present no 

specific dynamic regulatory requirement 

for airplane-level crashworthiness. 

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Federal Register / Vol. 79, No. 26 / Friday, February 7, 2014 / Rules and Regulations 7373 

However, the FAA requires an 

assessment of each new model airplane 

to ensure that the airplane will not 

significantly depart from typical 

dynamic characteristics found in 

previously certificated designs. 

The nature of the assessment is 

largely dependent on the similarities 

and differences between the new type 

design and previously certificated 

airplanes. Such an assessment ensures 

that the level of safety of the new 

composite designs corresponds to the 

level of safety achieved with similar 

metallic designs around which the 

existing regulations were written. If 

significant trends in industry warrant 

change to the existing regulations, the 

FAA and industry rulemaking process 

may be used to develop an appropriate 

dynamic regulatory requirement for 

airplane level crashworthiness. 

The FAA and industry have collected 

a significant amount of experimental 

data as well as data from crashes of 

transport category airplanes that 

demonstrated a high occupant survival 

rate at vertical descent velocities up to 

30 ft/sec (on a single aisle airplane). 

Based on this information, the FAA 

finds it appropriate and necessary for an 

assessment of the Model LJ–200 to span 

a range of airplane vertical descent 

velocities (up to 30 ft/sec, or that 

appropriate for a comparable size 

airplane). 

The FAA expects the Model LJ–200 to 

exhibit similar crashworthiness 

capabilities under foreseeable 

survivable impact events as achieved by 

previously certificated transport 

category airplanes of similar size and 

configuration. In order to make this 

assessment, criteria need to be 

established by which the similarities 

and differences between new type 

designs and previously certificated 

airplanes may be analytically evaluated. 

Based on the FAA’s evaluation of the 

intent of existing regulations, the 

following areas need to be evaluated to 

demonstrate comparable behavior of the 

Model LJ–200 design to currently 

certificated transport category airplanes: 

• Retention of items of mass. It must 

be shown that the occupants, i.e., 

passengers, flight attendants, and flight 

crew, will be protected during the 

impact event from release of seats, 

overhead bins, and other items of mass 

due to the impact loads and resultant 

structural deformation of the supporting 

airframe and floor structures. 

• Maintenance of occupant 

emergency egress paths. The airframe 

must not deform such that rapid 

evacuation of occupants is impeded. 

• Maintenance of acceptable 

acceleration and loads experienced by 

the occupants. 

• Maintenance of a survivable 

volume. All areas of the airplane 

occupied for takeoff and landing must 

be shown to provide a survivable 

volume during and after the impact 

event. 

Discussion of Comments 

Notice of proposed special conditions 

No. 25–13–08–SC for the Learjet Inc. 

Model LJ–200 airplanes was published 

in the Federal Register on October 31, 

2013 (78 FR 65235). No comments were 

received, and the special conditions are 

adopted as proposed. 

Applicability 

As discussed above, these special 

conditions are applicable to the Learjet 

Inc. Model LJ–200–1A10. Should Learjet 

Inc. apply at a later date for a change to 

the type certificate to include another 

model on the same type certificate 

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 

of 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 Learjet Inc. Model 

LJ–200–1A10 airplanes. 

Crashworthiness, Emergency Landing 

Conditions 

In order to demonstrate an equivalent 

level of occupant safety and 

survivability to that provided by 

previously certificated transport 

category airplanes of similar size and 

configuration under foreseeable 

survivable impact events, Learjet Inc. 

must demonstrate that the Model LJ– 

200–1A10 meets the following criteria 

for a range of airplane vertical descent 

velocities up to 30 ft/sec: 

1. Retention of items of mass. The 

occupants, i.e., passengers, flight 

attendants, and flightcrew, must be 

protected during the impact event from 

release of seats, overhead bins, and 

other items of mass due to the impact 

loads and resultant structural 

deformation of the supporting airframe 

and floor structures. The applicant must 

show that loads due to the impact event 

and resultant structural deformation of 

the supporting airframe and floor 

structure at the interface of the airplane 

structure to seats, overhead bins, and 

other items of mass are comparable to 

those of previously certificated transport 

category airplanes of similar size for the 

range of descent velocities stated above. 

The attachments of these items need not 

be designed for static emergency 

landing loads in excess of those defined 

in § 25.561 if impact response 

characteristics of the Model LJ–200– 

1A10 yield load factors at the attach 

points comparable with those expected 

for a previously certificated transport 

category airplane of similar size. 

2. Maintenance of acceptable 

acceleration and loads experienced by 

the occupants. The applicant must show 

that the vertical acceleration levels 

experienced at the seat/floor interface 

and loads experienced by the occupants 

during the impact event are consistent 

with those found in § 25.562(b) or with 

the levels expected for a previously 

certificated comparable transport 

category airplane of similar size. 

3. Maintenance of a survivable 

volume. The applicant must show that 

all areas of the airplane occupied for 

takeoff and landing provide a survivable 

volume comparable to that of previously 

certificated transport category airplanes 

of similar size during and after the 

impact event. This means that structural 

deformation will not result in 

infringement of the occupants’ normal 

living space significantly affecting their 

survivability or egress. 

4. Maintenance of occupant 

emergency egress paths. The applicant 

must show that the airframe 

deformation after the vertical impact 

event does not impede the rapid 

evacuation of occupants comparable to 

previously certified transport category 

airplanes of similar size. 

Issued in Renton, Washington, on January 

31, 2014. 

John P. Piccola, Jr., 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. 2014–02611 Filed 2–6–14; 8:45 am] 

BILLING CODE 4910–13–P 

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