This section of the FEDERAL REGISTER

contains notices to the public of the proposed

issuance of rules and regulations. The

purpose of these notices is to give interested

persons an opportunity to participate in the

rule making prior to the adoption of the final

rules.

Proposed Rules Federal Register

19023 

Vol. 74, No. 79 

Monday, April 27, 2009 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. NM403 Special Conditions No. 

25–09–05–SC] 

Special Conditions: Boeing Model 

747–8/–8F Airplanes, Structural Design 

Requirements for Four-Post Main 

Landing Gear System 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed special 

conditions. 

SUMMARY: This action proposes special 

conditions for the Boeing Model 

747–8/–8F airplane. This airplane will 

have novel or unusual design features 

associated with a four-post main 

landing gear system. The applicable 

airworthiness regulations do not contain 

adequate or appropriate safety standards 

for this design feature. These proposed 

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: Comments must be received on 

or before June 11, 2009. 

ADDRESSES: Comments on this proposal 

may be mailed in duplicate to: Federal 

Aviation Administration, Transport 

Airplane Directorate, Attention: Rules 

Docket (ANM–113), Docket No. NM403, 

1601 Lind Avenue, SW., Renton, 

Washington 98057–3356; or delivered in 

duplicate to the Transport Airplane 

Directorate at the above address. All 

comments must be marked Docket No. 

NM403. Comments may be inspected in 

the Rules Docket weekdays, except 

Federal holidays, between 7:30 a.m. and 

4 p.m. 

FOR FURTHER INFORMATION CONTACT: 

Mark Freisthler, FAA, Airframe & 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) 227–1149. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

The FAA invites interested persons to 

participate in this rulemaking by 

submitting 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 ask that 

you send us two copies of written 

comments. 

We will file in the docket all 

comments we receive as well as a report 

summarizing each substantive public 

contact with FAA personnel concerning 

these proposed special conditions. The 

docket is available for public inspection 

before and after the comment closing 

date. If you wish to review the docket 

in person, go to the address in the 

ADDRESSES section of this notice 

between 7:30 a.m. and 4 p.m., Monday 

through Friday, except Federal holidays. 

We will consider all comments we 

receive on or before the closing date for 

comments. We will consider comments 

filed late if it is possible to do so 

without incurring expense or delay. We 

may change the proposed special 

conditions based on comments we 

receive. 

If you want the FAA to acknowledge 

receipt of your comments on this 

proposal, include with your comments 

a pre-addressed, stamped postcard on 

which the docket number appears. We 

will stamp the date on the postcard and 

mail it back to you. 

Background 

On November 4, 2005, The Boeing 

Company, PO Box 3707, Seattle, WA 

98124, applied for an amendment to 

Type Certificate Number A20WE to 

include the new Model 747–8 passenger 

airplane and the new Model 747–8F 

freighter airplane. The Model 747–8 and 

the Model 747–8F are derivatives of the 

747–400 and the 747–400F, 

respectively. Both the Model 747–8 and 

the Model 747–8F are four-engine jet 

transport airplanes that will have a 

maximum takeoff weight of 970,000 

pounds and new General Electric GEnx– 

2B67 engines. The Model 747–8 will 

have two flight crew and the capacity to 

carry 660 passengers. The Model 747– 

8F will have two flight crew and a zero 

passenger capacity, although Boeing has 

submitted a petition for exemption to 

allow the carriage of supernumeraries. 

Type Certification Basis 

Under the provisions of 14 CFR 

21.101, Boeing must show that the 

Model 747–8 and 747–8F (hereafter 

referred as 747–8/–8F) meet the 

applicable provisions of part 25, as 

amended by Amendments 25–1 through 

25–117, except for earlier amendments 

as agreed upon by the FAA. These 

regulations will be incorporated into 

Type Certificate No. A20WE after type 

certification approval of the 747–8/–8F. 

In addition, the certification basis 

includes other regulations, special 

conditions and exemptions that are not 

relevant to these proposed special 

conditions. Type Certificate No. A20WE 

will be updated to include a complete 

description of the certification basis for 

these model airplanes. 

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 747–8/–8F because of a novel or 

unusual design feature, special 

conditions are prescribed under the 

provisions of § 21.16. 

In addition to the applicable 

airworthiness regulations and special 

conditions, the 747–8/–8F 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. 

Special conditions, as defined in 

§ 11.19, are issued under § 11.38, and 

become part of the type certification 

basis under § 21.101. 

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, or should any 

other model already included on the 

same type certificate be modified to 

incorporate the same or similar novel or 

unusual design feature, the special 

conditions would also apply to the other 

model under § 21.101. 

Novel or Unusual Design Features 

The Boeing Model 747–8/–8F airplane 

will incorporate the following novel or 

unusual design features: a four-post 

main landing gear system with two wing 


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19024 Federal Register / Vol. 74, No. 79 / Monday, April 27, 2009 / Proposed Rules 

main landing gears and two body main 

landing gears. 

Discussion 

The Boeing Model 747–8/–8F airplane 

will retain the landing gear arrangement 

which is unique to the 747 family of 

airplanes. The conventional 

arrangement for the main landing gear 

of transport category airplanes is twounderwing posts. The 747 was the first 

to introduce a four-post main landing 

gear arrangement, two underwing posts 

supplemented by two body posts. This 

arrangement was adopted to 

accommodate the then unprecedented 

increased weight and size of the Model 

747 airplane. 

Existing regulations are written to 

address the conventional landing gear 

configuration commonly found on 

transport category airplanes. This being 

the case, they are not appropriate to 

address the unique features of the 

Boeing 747 design. The increased 

number of posts alters the load 

distribution between the gear units 

during landing and ground handling 

conditions addressed by the regulations. 

This arrangement also loads the 

airframe differently than conventional 

landing gear designs. The FAA 

determined that, while the general 

conditions addressed by §§ 25.473 and 

25.479 through 25.485 were still 

applicable, specific details contained in 

these regulations may not be directly 

relatable to the four-post arrangement. 

In 1968 the FAA issued Special 

Condition A–4 to address the ground 

load requirements for the main landing 

gear system for Boeing Model 747–100 

series airplanes. That special condition 

provided clarification on the 

applicability of §§ 25.473 and 25.479 

through 25.485 to the Model 747 

airplane. In 1971 Special Condition 

A–4 was amended to address Boeing 

Model 747 airplanes with the landing 

gear load evener system deleted or made 

inoperable. 

The FAA has determined that Special 

Condition A–4 is applicable to the 747– 

8/8F series airplanes, provided that all 

the applicable part 25 regulations cited 

in Special Condition A–4 (recorded as 

an enclosure to FAA Letter WE–120/ 

8110 (CT3488WE–D) to the Boeing 

Company, dated May 12, 1971) are 

upgraded to the latest amendment level 

(i.e., 25–117). Furthermore, as several of 

these regulations have been updated or 

consolidated, and acceptable methods of 

compliance have been described for 

some of these regulations via advisory 

circular (AC), new special conditions 

are needed to clarify the applicable 

requirements. By updating these special 

conditions, we are ensuring that the 

Boeing design provides an equivalent 

level of safety to conventional landing 

gear meeting these regulations. 

Applicability 

As discussed above, these proposed 

special conditions are applicable to 

Boeing Model 747–8/–8F airplanes. 

Should Boeing apply at a later date for 

a change to the type certificate to 

include another model incorporating the 

same novel or unusual design features, 

these proposed special conditions 

would apply to that model as well 

under the provisions of § 21.101. 

Conclusion 

This action affects only certain novel 

or unusual design features of the Boeing 

Model 747–8/–8F 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 Proposed Special Conditions 

Accordingly, the Federal Aviation 

Administration (FAA) proposes the 

following special conditions as part of 

the type certification basis for the 

Boeing Model 747–8/–8F airplanes. 

The requirements of §§ 25.471, 

25.473, and 25.479 through 25.485 

apply as follows: 

1. General. The general design criteria 

of § 25.471 are directly applicable. The 

basic landing gear dimensional data 

must be expanded to include the 

additional main landing gear units. 

2. Ground Load Conditions and 

Assumptions. The criteria specified in 

§ 25.473 are applicable for the design 

landing conditions except as noted in 

paragraph 6 of these special conditions. 

3. Landing Gear Arrangement. The 

multiple oleo main landing gear 

configuration does not meet the 

‘‘conventional arrangement’’ criterion of 

§ 25.477, with respect to the application 

of paragraphs 4 through 7 of this special 

condition. Nevertheless, the landing 

impact design conditions must meet the 

intent of §§ 25.473 through 25.485. 

4. Level Landing Conditions. The level 

landing criteria of § 25.479 are directly 

applicable. The four main landing gear 

units must be assumed to contact the 

ground with the airplane longitudinal 

axis in a horizontal attitude. 

5. Tail-Down Landing Conditions. The 

airplane must be assumed to contact the 

ground in any tail down attitude 

between level and the maximum tail 

down attitude allowing clearance with 

the ground of each part of the airplane 

other than the main landing gear 

wheels. The airplane forward velocity 

component must be the most critical 

value from V L1 to 1.25 V L2 where V L1

and V L2 are defined in § 25.481. Each 

main landing gear unit must be 

designed for its most critical 

combination of vertical load and drag 

load. All other criteria in § 25.481, not 

superseded by the above criteria shall be 

directly applicable. The distribution of 

loads between the gear units for the 

effects of critical combinations of spinup and spring-back loadings on the 

main landing gear units must be 

considered for the gear units and their 

supporting structure. 

6. One-Wheel Landing Conditions. 

Unless the airplane and landing gears 

are designed for equivalent or more 

critical conditions, the airplane will be 

assumed to land in a level pitch attitude 

at design landing weight with a descent 

velocity of 7 fps at the maximum roll 

angle attainable within the geometric 

limitations of the airplane with the 

contact velocities and gear landing 

conditions of §§ 25.479(a), (c) and (d). 

Note: This condition need not be coupled 

with either a 6 fps landing at maximum take 

off weight or a 12 fps reserve energy drop 

test. 

7. Side Load Conditions. On the main 

landing gear units, side loads of 80% of 

the vertical reaction (on one side) acting 

inward and 60% of the vertical reaction 

(on the other side) acting outward must 

be combined with one-half of the 

maximum vertical ground reactions 

obtained in the level landing, tail-down 

landing, or rolled attitude landing 

conditions. These loads shall be 

assumed applied at the ground contact 

point and to be resisted by the inertia of 

the airplane. Drag loads may be 

assumed to be zero. 

8. Rebound Landing Condition. The 

criteria of § 25.487 are directly 

applicable. 

9. Ground Handling Conditions. The 

criteria of § 25.489 are directly 

applicable. The effects of runway crown 

as defined in § 25.511(b)(4) shall be 

considered in distributing the loads to 

the individual main landing gear units. 

The ground reactions must be 

distributed to the individual landing 

gear units in a rational or conservative 

manner, accounting for airframe 

flexibility and shock strut and tire 

stiffness. 

10. Take-Off Run. The criteria of 

§ 25.491 are directly applicable. 

Compliance may be shown in 

accordance with Advisory Circular (AC) 

25.491–1. 


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Federal Register / Vol. 74, No. 79 / Monday, April 27, 2009 / Proposed Rules 19025 

11. Braked Roll Conditions. The 

criteria of §§ 25.493(b), (c), and (d) shall 

be directly applicable. The formula in 

§ 25.493(e) is not applicable to the B747 

due to the 4-post gear arrangement. 

12. Turning. The criteria of § 25.495 

are directly applicable. 

13. Nose-Wheel Yaw. The criteria of 

§ 25.499 are directly applicable. The 

criteria are interpreted to apply braking 

to all main landing gear wheels on one 

side of the airplane centerline. 

14. Pivoting. The criteria of § 25.503 

are applied individually to each wing 

main landing gear unit. In addition, all 

main landing gear units must be 

designed for the scrubbing and/or 

torsion loads induced by pivoting about 

the most critical point consistent with 

the available main gear braking on one 

side of the airplane and the available 

thrust and torque on the airplane. 

Maximum static engine thrust must be 

considered only on the engines on the 

opposite side of the airplane centerline 

from the pivot point. 

15. Reversed Braking. The criteria of 

§ 25.507 are directly applicable, except 

that the phrase ‘‘three point’’ is 

expanded to include ‘‘five point.’’ 

16. Towing Loads. The criteria of 

§ 25.509 are directly applicable. 

17. Fatigue Evaluation of Landing 

Gear. The criteria of § 25.573 at 

Amendment 25–0 are directly 

applicable to main landing gear units. 

18. Shock Absorption Tests. The 

criteria of § 25.723 are directly 

applicable. Compliance may be shown 

in accordance with AC 25.723–1. 

19. Substantiation of the design 

criteria must include a dynamic taxi and 

landing analysis. 

Issued in Renton, Washington, on April 14, 

2009. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. E9–9529 Filed 4–24–09; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2009–1369; Directorate 

Identifier 2003–NE–03–AD] 

RIN 2120–AA64 

Airworthiness Directives; Rolls-Royce 

plc RB211 Trent 800 Series Turbofan 

Engines 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to 

supersede an existing airworthiness 

directive (AD) for Rolls-Royce plc 

RB211 Trent 875–17, Trent 877–17, 

Trent 884–17, Trent 892–17, Trent 

892B–17, and Trent 895–17 turbofan 

engines with high pressure (HP) 

compressor rotor rear stage 5 and 6 discs 

and cone shafts, part numbers (P/Ns) 

FK25230 and FK27899 installed. This 

proposed AD would require removing 

these parts at new reduced cycle limits. 

This proposed AD results from RollsRoyce plc reducing the lives of these 

parts and changing the life calculating 

method to use ‘‘Standard Duty Cycles’’ 

with ‘‘Multiple Flight Profile 

Monitoring’’ and ‘‘Flight Cycles’’ with 

‘‘Heavy Flight Profile Monitoring’’. We 

are proposing this AD to prevent stage 

5 and 6 disc crack initiation and 

propagation that might lead to 

uncontained disc failure and damage to 

the airplane. 

DATES: We must receive any comments 

on this proposed AD by June 26, 2009. 

ADDRESSES: Use one of the following 

addresses to comment on this proposed 

AD. 

• Federal eRulemaking Portal: Go to 

http://www.regulations.gov and follow 

the instructions for sending your 

comments electronically. 

• Mail: Docket Management Facility, 

U.S. Department of Transportation, 1200 

New Jersey Avenue SE., West Building 

Ground Floor, Room W12–140, 

Washington, DC 20590–0001. 

• Hand Delivery: Deliver to Mail 

address above between 9 a.m. and 5 

p.m., Monday through Friday, except 

Federal holidays. 

• Fax: (202) 493–2251. 

FOR FURTHER INFORMATION CONTACT: 

James Lawrence, Aerospace Engineer, 

Engine Certification Office, FAA, Engine 

and Propeller Directorate, 12 New 

England Executive Park, Burlington, MA 

01803, e-mail james.lawrence@faa.gov; 

telephone (781) 238–7176; fax (781) 

238–7199. 

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–2009–1369; Directorate Identifier 

2003–NE–03–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 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 with FAA 

personnel concerning this proposed AD. 

Using the search function of the Web 

site, anyone can find and read the 

comments in any of our dockets, 

including, if provided, the name of the 

individual who sent the comment (or 

signed the comment on behalf of an 

association, business, labor union, etc.). 

You may review the DOT’s complete 

Privacy Act Statement in the Federal 

Register published on April 11, 2000 

(65 FR 19477–78). 

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 the same as the Mail 

address provided in the ADDRESSES

section. Comments will be available in 

the AD docket shortly after receipt. 

Discussion 

On July 23, 2003, we issued AD 2003– 

15–06, Amendment 39–13249 (68 FR 

44610, July 30, 2003). That AD requires 

removal from service of HP compressor 

rotor rear stage 5 and 6 discs and cone 

shafts, P/Ns FK25230 and FK27899, 

before reaching newly reduced life 

limits. The Civil Aviation Authority 

(CAA), which is the airworthiness 

authority for the United Kingdom 

(U.K.), had notified the FAA that an 

unsafe condition may exist on RollsRoyce plc RB211 Trent 875, Trent 877, 

Trent 884, Trent 892, Trent 892B, and 

Trent 895 turbofan engines. The CAA 

advised that three HP compressor rotor 

rear stage 5 and 6 discs and cone shafts, 

P/Ns FK25230 and FK27899, were 

found with crack indications in the 

stage 5 and 6 blade loading slots, during 

overhaul inspection. The manufacturer’s 

analysis had not yet been able to 

identify the root cause of these cracks, 

or to fully explain the crack propagation 

rate. As a result of the analysis, a new 

lower life limit of 7,500 cycles-sincenew had been assigned by the 

manufacturer to these HP compressor 

rotor rear stage 5 and 6 discs and cone 

shafts. This condition, if not corrected, 


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