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

13835 

Vol. 78, No. 41 

Friday, March 1, 2013 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2013–0109; Notice No. 25– 

137] 

RIN 2120–AK13 

Harmonization of Airworthiness 

Standards—Miscellaneous Structures 

Requirements 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to amend 

certain airworthiness regulations for 

transport category airplanes, based on 

recommendations from the Aviation 

Rulemaking Advisory Committee 

(ARAC). Adopting this proposal would 

eliminate regulatory differences 

between the airworthiness standards of 

the FAA and European Aviation Safety 

Agency (EASA). This proposal would 

not add new requirements beyond what 

manufacturers currently meet for EASA 

certification and would not affect 

current industry design practices. This 

proposal would revise the structural test 

requirements necessary when analysis 

has not been found reliable; clarify the 

quality control, inspection, and testing 

requirements for critical and noncritical castings; add control system 

requirements that consider structural 

deflection and vibration loads; expand 

the fuel tank structural and system 

requirements regarding emergency 

landing conditions and landing gear 

failure conditions; add a requirement 

that engine mount failure due to 

overload must not cause hazardous fuel 

spillage; and revise the inertial forces 

requirements for cargo compartments by 

removing the exclusion of 

compartments located below or forward 

of all occupants in the airplane. 

DATES: Send comments on or before 

May 30, 2013. 

ADDRESSES: Send comments identified 

by docket number FAA–2013–0109 

using any of the following methods: 

• Federal eRulemaking 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 

dockets, 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: For 

technical questions concerning this 

action, contact Todd Martin, Airframe 

and Cabin Safety Branch, ANM–115, 

Transport Airplane Directorate, Aircraft 

Certification Service, Federal Aviation 

Administration, 1601 Lind Avenue SW., 

Renton, WA 98057–3356; telephone 

(425) 227–1178; facsimile (425) 227– 

1232; email Todd.Martin@faa.gov. 

For legal questions concerning this 

action, contact Sean Howe, Office of the 

Regional Counsel, ANM–7, Federal 

Aviation Administration, 1601 Lind 

Avenue SW., Renton, Washington 

98057–3356; telephone (425) 227–2591; 

facsimile (425) 227–1007; email 

Sean.Howe@faa.gov. 

SUPPLEMENTARY INFORMATION:

Authority for This Rulemaking 

The FAA’s authority to issue rules on 

aviation safety is found in Title 49 of the 

United States Code. 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. 

This rulemaking is promulgated 

under the authority described in 

Subtitle VII, Part A, Subpart III, Section 

44701, ‘‘General Requirements.’’ Under 

that section, the FAA is charged with 

promoting safe flight of civil aircraft in 

air commerce by prescribing regulations 

and minimum standards for the design 

and performance of aircraft that the 

Administrator finds necessary for safety 

in air commerce. This regulation is 

within the scope of that authority. It 

prescribes new safety standards for the 

design and operation of transport 

category airplanes. 

I. Background 

Part 25 of Title 14, Code of Federal 

Regulations (14 CFR) prescribes 

airworthiness standards for type 

certification of transport category 

airplanes, for products certified in the 

United States. Book 1 of the EASA 

Certification Specifications and 

Acceptable Means of Compliance for 

Large Aeroplanes (CS–25) prescribes the 

corresponding airworthiness standards 

for products certified in Europe. While 

part 25 and CS–25 Book 1 are similar, 

they differ in several respects. The 

necessity of meeting two sets of 

certification requirements raises the cost 

of developing new transport category 

airplanes with little to no increase in 

safety. Therefore, the FAA tasked ARAC 

through the Loads and Dynamics 

Harmonization Working Group 

(LDHWG) and the General Structures 

Harmonization Working Group 

(GSHWG) to review existing structures 

regulations and recommend changes 

that would eliminate differences 

between the U.S. and European 

airworthiness standards, while 

maintaining or improving the level of 

safety in the current regulations. This 

proposed rule is a result of this 

harmonization effort. 


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13836 Federal Register / Vol. 78, No. 41 / Friday, March 1, 2013 / Proposed Rules 

The LDHWG and GSHWG developed 

recommendations, which EASA has 

incorporated into CS–25 with some 

changes. The FAA agrees with the 

ARAC recommendations as adopted by 

EASA, and we propose to amend part 25 

accordingly. The proposals are not 

expected to be controversial and should 

reduce certification costs to industry 

without adversely affecting safety. The 

complete analyses for the proposed 

changes made in response to ARAC 

recommendations can be found in the 

ARAC recommendation reports, located 

in the docket for this rulemaking. 

II. Overview of Proposed Rule 

The FAA proposes to amend the 

airworthiness regulations described 

below. This action would harmonize 

part 25 requirements with the 

corresponding requirements in EASA 

CS–25 Book 1. 

1. Section 25.307(a), ‘‘Proof of 

structure,’’ would be revised to allow a 

‘‘sufficient’’ level of structural testing, in 

some cases less than ultimate, when 

analysis has not been shown to be 

reliable. 

2. Section 25.621, ‘‘Casting factors,’’ 

would be revised to clarify the— 

• Definition of critical casting and 

• Quality control, inspection, and 

testing requirements for critical and 

non-critical castings. 

3. Section 25.683, ‘‘Operation tests,’’ 

would be revised to add a requirement 

that— 

• The control system must remain 

free from jamming, friction, 

disconnection, and permanent damage 

in the presence of structural deflection 

and 

• Under vibration loads, no hazard 

may result from interference or contact 

of the control system with adjacent 

elements. 

4. Section 25.721, ‘‘Landing Gear— 

General,’’ would be revised to— 

• Expand the landing gear failure 

conditions to include side loads, in 

addition to up and aft loads, and expand 

this requirement to include nose 

landing gear in addition to the main 

landing gear, 

• Specify that the wheels-up landing 

conditions are assumed to occur at a 

descent rate of 5 feet per second, 

• Add a sliding-on-ground condition, 

and 

• Require the engine mount be 

designed so that, when it fails due to 

overload, this failure does not cause the 

spillage of enough fuel to constitute a 

fire hazard. 

5. Section 25.787, ‘‘Stowage 

compartments,’’ would be revised to 

expand the inertia forces requirements 

for cargo compartments by removing the 

exclusion of compartments located 

below or forward of all occupants in the 

airplane. 

6. Section 25.963, ‘‘Fuel tanks: 

general,’’ would be revised to— 

• Require that fuel tanks be designed 

so that no fuel is released in or near the 

fuselage, or near the engines, in 

quantities that would constitute a fire 

hazard in otherwise survivable 

emergency landing conditions, 

• Define fuel tank pressure loads for 

fuel tanks located within and outside 

the fuselage pressure boundary and near 

the fuselage or near the engines, and 

• Specify the wheels-up landing 

conditions and landing gear and engine 

mount failure conditions that must be 

considered when evaluating fuel tank 

structural integrity. 

7. Section 25.994, ‘‘Fuel system 

components,’’ would be revised to 

specify the wheels-up landing 

conditions to be considered when 

evaluating fuel system components. 

III. Discussion of the Proposal 

A. Section 25.307(a), ‘‘Proof of 

Structure’’ 

Section 25.307(a) currently requires 

that applicants for a type design 

conduct strength testing unless 

structural analysis has been shown to be 

reliable. When analysis has not been 

shown to be reliable, the regulation 

states that the FAA ‘‘may require 

ultimate load tests in cases where limit 

load tests may be inadequate.’’ 

Rather than specifying ‘‘limit load’’ or 

‘‘ultimate load,’’ the GSHWG proposed 

that the harmonized requirement state 

that substantiating load tests must be 

made that are ‘‘sufficient’’ to verify 

structural behavior up to the load levels 

required by § 25.305 (strength and 

deformation). Where it is justified, these 

test load levels may be less than 

ultimate. 

We propose to revise § 25.307(a) to 

state that, when analysis has not been 

shown to be reliable, tests must be 

conducted to ‘‘sufficient’’ load levels. 

Normally, testing to ultimate load levels 

is required, but when previous relevant 

test evidence can be used to support the 

analysis, then a lower level of testing 

may be accepted. The proposed rule 

would allow this intermediate level of 

testing. While the rule has changed, the 

intent remains the same: to ensure that 

the structure will not have any 

structural deformation under limit load 

or any failure under ultimate load. 

This action would harmonize 

§ 25.307(a) with the corresponding 

EASA standard. 

B. Section 25.621, ‘‘Casting Factors’’ 

Section 25.621 currently requires 

classification of structural castings as 

either critical or non-critical, and 

depending on classification, specifies 

inspection requirements, test 

requirements, and casting factors for 

strength and deformation. These casting 

factors are applied in addition to the 

factor of safety required by § 25.303, 

‘‘Factor of safety.’’ The application of 

factors of safety to castings is necessary 

because the casting process can be 

inconsistent. Castings are subject to 

variability in mechanical properties due 

to this casting process, which can result 

in imperfections (such as voids) within 

the cast part. 

We propose to revise § 25.621 to 

define ‘‘critical casting’’ and to clarify 

the quality control, inspection, and 

testing requirements for critical and 

non-critical castings. The proposed rule 

would specify the inspection and testing 

requirements based on the casting factor 

chosen by the applicant—from 1.0 to 2.0 

or greater. 

Section 25.621 currently requires that 

critical castings in structural 

applications have a minimum casting 

factor of 1.25. A casting factor of 1.0 

would be allowed by the proposed rule, 

as described below, because casting 

technology has improved since the 

current § 25.621 was adopted, and much 

higher quality castings can be produced 

using improved foundry methods. The 

proposed rule would require the 

following for critical castings: 

• A visual and special nondestructive inspections. The special 

non-destructive inspections would be 

limited to specified areas of the casting 

where defects are likely to occur. 

• A casting factor of 1.5 or greater 

would be allowed provided that one 

casting undergoes static testing and is 

shown to meet the relevant strength and 

deformation requirements. A casting 

factor of 1.25 or greater would be 

allowed provided that three castings 

undergo static testing and are shown to 

meet the relevant strength and 

deformation requirements. 

• A casting factor of 1.0 or greater 

would be allowed provided that one 

casting undergoes static testing and is 

shown to meet the relevant strength and 

deformation requirements, and it is 

demonstrated that a process is in place 

to ensure the castings produced have 

material variation equivalent to those of 

wrought alloy products of similar 

composition. Draft Advisory Circular 

(AC) 25.621–X, ‘‘Casting Factors,’’ will 

be published concurrently with this 

NPRM. This draft AC outlines a process 

for using a casting factor of 1.0, 


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including any changes to that process 

that may occur over time. The proposed 

rule requires ‘‘process monitoring,’’ 

which is intended to mean continuous 

process monitoring for the entire 

production lifecycle. 

The proposed rule would also specify 

quality control, inspection, and testing 

requirements for non-critical castings 

with casting factors ranging from 1.0 to 

2.0 or greater. 

C. Section 25.683, ‘‘Operation Tests’’ 

Section 25.683 currently requires the 

airplane control system to be free from 

jamming, excessive friction, and 

excessive deflection when subjected to 

pilot effort and control system loads. We 

propose to revise § 25.683 by adding a 

requirement to substantiate that, in the 

presence of deflections of the airplane 

structure due to maneuver loads, the 

control system can be exercised and 

remain free from jamming, friction, 

disconnection, and any form of 

permanent damage. In addition, we 

propose adding a requirement to 

substantiate that, under vibration loads, 

no interference or contact of the control 

system with adjacent elements can 

result in hazard. 

Since control systems are typically 

attached or routed through adjacent 

aircraft structure, it is necessary to 

ensure that deflections of that adjacent 

structure do not adversely affect the safe 

operation of the control system through 

interference, jamming, or induced 

loading. Also, the control system design 

should be such that the effects of 

vibration loads in normal flight and 

ground operating conditions will not 

affect the safe operation of the control 

system. 

These actions would harmonize 

§ 25.683 with the corresponding EASA 

standard. 

D. Section 25.721, ‘‘Landing Gear— 

General (Emergency Landing 

Conditions)’’ 

Section 25.721(a) currently requires 

that the main landing gear system be 

designed so that if it fails due to 

overloads during takeoff and landing, 

the failure does not cause the spillage of 

enough fuel to constitute a fire hazard. 

This is intended to protect fuel tanks 

from rupture and puncture due to the 

failure of the landing gear and its 

supports. This requirement applies only 

to fuel systems inside the fuselage for 

airplanes with 9 seats or less, and all 

fuel systems for airplanes with 10 seats 

or more. We propose to revise 

§ 25.721(a) to: 

1. Apply to the nose landing gear as 

well as the main landing gear, 

2. Clarify that landing gear failure is 

assumed, 

3. Expand the failure conditions to 

include side loads, in addition to up 

and aft loads, and 

4. Remove the exception for airplanes 

with less than 10 seats. 

We propose revising § 25.721(a) to 

apply to the nose gear as well as the 

main landing gear because nose gear 

failures can also impact fuel tanks. We 

would also clarify that landing gear 

failure is assumed by stating that the 

design must consider such failures 

‘‘when’’ they occur, rather than ‘‘if’’ 

they occur. This clarification is needed 

because in some past cases, applicants 

relied on over-designing the landing 

gear beyond ultimate strength 

requirements rather than showing safe 

separation in the event of failure. 

We would expand the failure 

conditions to consider side loads to 

ensure that a comprehensive range of 

failure conditions are considered. 

Lastly, we would remove the exception 

for airplanes with less than 10 seats. 

This exception in § 25.721 was 

originally introduced at Amendment 

25–32 (37 FR 3969, February 24, 1972). 

In the preamble to that final rule, the 

FAA determined that: 

[C]ertain of the requirements in proposed 

Secs. 25.562, 25.721, 25.787, 25.807, and 

25.812 are inappropriate and unnecessary, or 

are unnecessarily severe, for transport 

category airplanes that have maximum 

passenger seating configurations, excluding 

pilots seats, of nine seats or less. In those 

instances, the proposed requirements have 

been revised to provide exceptions and to 

include requirements for such airplanes that 

provide a level of safety for such airplanes 

equivalent to that for airplanes with larger 

passenger seating configurations. 

This exception is appropriate for 

certain cabin safety provisions that 

necessitate the egress of large numbers 

of passengers. However, the FAA 

believes that for the hazards associated 

with fuel fires, there is no technical 

justification for limiting the 

applicability of any of the fuel tank 

protection provisions based on the 

passenger seating capacity. 

Section 25.721(b) currently states that 

airplanes must be able to land on a 

paved runway, with any one or more 

landing gear legs not extended, without 

failures that result in spillage of enough 

fuel to constitute a fire hazard. This 

condition is not intended to treat a 

collapsed gear condition, but is 

intended to cover cases in which one or 

more gear legs do not extend for 

whatever reason, and the airplane must 

make a controlled landing on a paved 

runway in this condition. The current 

requirement applies only to airplanes 

with 10 seats or more. We propose to 

revise § 25.721(b) to: 

1. Specify that the wheels-up landing 

conditions are assumed to occur at a 

descent rate of 5 feet per second, 

2. Clarify the combinations of 

retracted landing gear that must be 

considered, 

3. Add a sliding-on-ground condition, 

and 

4. Remove the exception for airplanes 

with less than 10 seats. 

At the time § 25.721(b) was adopted 

by Amendment 25–32 (37 FR 3969, 

February 24, 1972), § 25.561 contained a 

landing descent speed of ‘‘5 feet per 

second’’ as an alternative criterion that 

could allow a reduction in the specified 

vertical emergency landing design load 

factor. Amendment 25–64 (53 FR 17646, 

May 17, 1988) removed this alternative 

to make the specified vertical design 

load factor the minimum design 

condition. However, the 5-feet-persecond descent speed contained in 

§ 25.561 had become, by design practice 

and interpretation, the design descent 

velocity for the wheels-up landing 

conditions addressed in §§ 25.721 and 

25.994. By removing it, the quantitative 

definition of the wheels-up landing 

condition on a paved runway was lost. 

We propose to revise § 25.721(b) to reestablish the 5-feet-per-second descent 

rate for the ‘‘minor crash landing’’ 

condition. 

We would add a sliding-on-ground 

condition to ensure that the wheels-up 

landing conditions are evaluated 

beyond the initial impact. The 

exception for airplanes with less than 10 

seats would be removed from 

§ 25.721(a) and (b) as noted above. 

We propose to replace § 25.721(c) 

with a new requirement that the engine 

mount and pylon be designed so that, 

when it fails due to overload, the failure 

mode is not likely to cause the spillage 

of enough fuel to constitute a fire 

hazard. Service experience has shown 

that landing gear malfunctions can lead 

to the airplane landing on the engine 

nacelles for some configurations. This 

can result in the engine nacelle breaking 

away, creating much the same fuel tank 

rupture potential as the landing gear 

breaking away. 

These actions would harmonize 

§ 25.721 with the corresponding EASA 

standard. 

E. Section 25.787(a), ‘‘Stowage 

Compartments’’ 

Section 25.787(a) currently requires 

that cargo compartments be designed to 

the emergency landing conditions of 

§ 25.561(b), but excludes compartments 

located below or forward of all 

occupants in the airplane. We propose 


emcdonald on DSK67QTVN1PROD with PROPOSALS
13838 Federal Register / Vol. 78, No. 41 / Friday, March 1, 2013 / Proposed Rules 

to revise § 25.787(a) to include 

compartments located below or forward 

of all occupants in the airplane. This 

change would ensure that, in these 

compartments, inertia forces in the up 

and aft direction will not injure 

passengers, and inertia forces in any 

direction will not cause penetration of 

fuel tanks or lines, or cause other 

hazards. This action would harmonize 

§ 25.787(a) with the corresponding 

EASA standard. 

The LDHWG originally recommended 

that § 25.561(c) be revised to achieve 

this objective of addressing cargo 

compartments below or forward of 

airplane occupants. However, when 

evaluating the LDHWG 

recommendation, EASA determined 

that CS 25.787 already addressed the 

issue and noted that § 25.787(a) and CS 

25.787(a) were different in this regard. 

Separately, ARAC also tasked the Cabin 

Safety Harmonization Working Group 

with reviewing § 25.787, and that group 

also recommended that the FAA 

harmonize § 25.787(a) with CS 

25.787(a). The FAA agrees that the 

change should be made to § 25.787(a), 

rather than § 25.561. 

F. Section 25.963(d), ‘‘Fuel Tanks: 

General (Emergency Landing 

Conditions)’’ 

Section 25.963(d) currently requires 

that fuel tanks within the fuselage 

contour be able to resist rupture and 

retain fuel under the inertia forces 

defined in § 25.561. In addition, these 

tanks must be in a protected position so 

that exposure of the tanks to scraping 

action with the ground is unlikely. We 

propose to revise § 25.963(d), as 

described below, based on 

recommendations provided by the 

LDHWG. 

1. The introductory sentence to 

§ 25.963(d) would require that, ‘‘so far 

as it is practicable,’’ fuel tanks be 

designed, located and installed so that 

no fuel is released in or near the 

fuselage, or near the engines, in 

quantities that would constitute a fire 

hazard in ‘‘otherwise survivable 

emergency landing conditions.’’ This is 

considered a general requirement, while 

more specific criteria are provided in 

§ 25.963(d)(1) through (d)(5). The term 

‘‘practicable’’ here means that any 

feasible or workable design should be 

considered in order to protect the fuel 

tanks. The phrase ‘‘otherwise survivable 

emergency landing conditions’’ is not 

specifically quantified. However, past 

events should be considered in 

developing a robust fuel tank design. 

2. Section 25.963(d)(1) through (d)(3) 

would define fuel tank pressure loads 

for fuel tanks located within and outside 

the fuselage pressure boundary, and 

near the fuselage or near the engines, as 

described below. 

The LDHWG recommended revising 

§ 25.963(d) to delete the reference to 

§ 25.561 for emergency landing load 

factors, which are used to develop the 

fuel tank pressure loads. The emergency 

landing load factors of § 25.561(b)(3) are 

based upon the restraint of fixed mass 

items, and the response of a fluid during 

emergency landings is different and 

much more complex to quantify. The 

proposed requirements for fuel tanks 

both within and outside of the fuselage 

pressure boundary have been simply 

formulated in terms of equations with 

factors that are justified based upon the 

satisfactory service experience of the 

existing fleet. 

The current regulation addresses only 

fuel tanks within the fuselage contour, 

although the FAA has issued special 

conditions to require fuel inertia loading 

conditions on horizontal tail tanks 

outside the fuselage contour. 

The LDHWG determined that the 

safety record for fuel tank rupture 

caused solely by fuel inertia loads is 

excellent. Manufacturers’ records of 

accidents and serious incidents 

involving large transport airplanes 

showed no event where fuel inertia 

pressure caused significant loss of fuel. 

Fuel losses that did occur were mainly 

caused by direct impact and externalobject punctures. 

Nevertheless, a fuel inertia criterion 

for wing fuel tanks is needed to ensure 

that future designs meet the same level 

of safety achieved by the current fleet. 

The wing fuel tanks of many current 

aircraft types were designed to a simple 

criterion in which fuel pressure was 

calculated using an inertia head equal to 

the local geometrical stream-wise 

distance between the fuel tank solid 

boundaries. Service experience has 

shown this criterion produces fuel tank 

designs with an acceptable level of 

safety. Therefore, it is appropriate that 

the future airworthiness standards for 

fuel tanks should require a similar level 

of design fuel pressure for similar fuel 

tank designs. 

For fuel tanks within the fuselage 

pressure boundary, the current fuel 

inertia load criterion, as generally 

applied, covers up to a full fuel tank, an 

inertia head equal to maximum pressure 

head, and inertia load factors equal to 

those of § 25.561(b)(3). This level of 

rupture resistance for fuel tanks is 

justified based upon occupant 

survivability considerations. Therefore, 

the LDHWG recommended, and the 

FAA concurs, that the current minimum 

level of rupture resistance should be 

retained for fuel tanks within the 

fuselage pressure boundary. For fuel 

tanks outside the fuselage pressure 

boundary, the design load factors for the 

inboard and outboard (lateral) loading 

conditions and forward loading 

conditions are proposed as one-half of 

those for fuel tanks within the fuselage. 

The design load factors for the up, 

down, and aft loading conditions would 

be the same for all fuel tanks. 

When EASA adopted the LDHWG 

recommendations, it noted an objection 

that had been raised by the Joint 

Aviation Authorities (JAA) Power Plant 

Study Group (PPSG). The PPSG did not 

agree with the LDHWG recommendation 

regarding fuel tank pressure loads for 

fuel tanks ‘‘near the fuselage or near the 

engines,’’ which had been specifically 

addressed by Joint Aviation Regulation. 

In response to the PPSG objection, 

EASA added criteria for fuel tanks near 

the fuselage and near the engines. We 

agree with these criteria and propose to 

add the same to § 25.963(d). 

3. Section 25.963(d)(4) would require 

that the effects of crushing and scraping 

actions with the ground not cause fuel 

spillage, or generate temperatures that 

would constitute a fire hazard under the 

conditions specified in proposed 

§ 25.721(b). By reference to § 25.721(b), 

this rule would require consideration of 

the 5 feet-per-second wheels-up landing 

criteria and subsequent sliding on the 

ground. The potential effects of crushing 

and scraping, including thermal effects, 

must be evaluated for these minor crash 

landing conditions. 

4. Section 25.963(d)(5) would require 

that fuel tank installations be such that 

the tanks will not rupture as a result of 

an engine pylon or engine mount or 

landing gear tearing away as specified in 

proposed § 25.721(a) and (c). This 

requirement would be largely redundant 

to the proposed § 25.721(a) and (c), but 

is included in § 25.963(d) for 

completeness. 

These actions would harmonize 

§ 25.963(d) with the corresponding 

EASA standard with the following two 

exceptions: 

CS 25.963(d) requires that fuel tanks 

be designed and located so that no fuel 

is released in quantities ‘‘sufficient to 

start a serious fire’’ in otherwise 

survivable emergency landing 

conditions. The proposed rule would 

require that no fuel is released in 

quantities ‘‘that would constitute a fire 

hazard.’’ The two phrases have the same 

intent and meaning, and the latter 

phrase is consistent with the wording in 

CS 25.721/§ 25.721, CS 25.963(d)(4)/ 

§ 25.963(d)(4), and CS 25.994/§ 25.994. 

The fuel tank pressure criteria in CS 

25.963(d) vary depending on whether 

the fuel tank is ‘‘within the fuselage 


emcdonald on DSK67QTVN1PROD with PROPOSALS
Federal Register / Vol. 78, No. 41 / Friday, March 1, 2013 / Proposed Rules 13839 

contour’’ or ‘‘outside the fuselage 

contour.’’ The proposed rule would be 

more specific by referring to ‘‘those 

parts of fuel tanks within the fuselage 

pressure boundary or that form part of 

the fuselage pressure boundary’’ versus 

‘‘those parts of fuel tanks outside the 

fuselage pressure boundary.’’ The 

proposed wording is clearer and has the 

same intent and meaning as that 

specified in CS 25.963(d). 

G. Section 25.994, ‘‘Fuel System 

Components’’ 

Section 25.994 currently requires that 

fuel system components in an engine 

nacelle or in the fuselage be protected 

from damage that could result in 

spillage of enough fuel to constitute a 

fire hazard as a result of a wheels-up 

landing on a paved runway. We propose 

to revise § 25.994 to specify that the 

wheels-up landing conditions that must 

be considered are those defined in 

proposed § 25.721(b). This action would 

harmonize § 25.994 with the 

corresponding EASA standard. 

As noted previously, the 5-feet-persecond descent speed contained in an 

earlier amendment to § 25.561 had 

become, by design practice and 

interpretation, the design descent 

velocity for the wheels-up landing 

conditions addressed in §§ 25.721 and 

25.994. In fact, Advisory Circular (AC) 

25.994–1, ‘‘Design Considerations to 

Protect Fuel Systems During a WheelUp Landing,’’ dated July 24, 1986, 

specifically referred to § 25.561 for the 

design conditions, which at that time 

contained the 5-feet-per-second landing 

descent criteria. 

H. Advisory Material 

The FAA is developing three new 

proposed ACs to be published 

concurrently with the proposed 

regulations in this NPRM. The proposed 

ACs would provide guidance material 

for acceptable means, but not the only 

means, of demonstrating compliance 

with proposed §§ 25.307, 25.561, 

25.621, 25.721, 25.963, and 25.994. We 

will accept public comments to the 

following proposed ACs on the 

‘‘Aviation Safety Draft Documents Open 

for Comment’’ Internet Web site at 

http://www.faa.gov/aircraft/draft_docs/: 

• AC 25–X, ‘‘Fuel Tank Strength in 

Emergency Landing Conditions.’’ (AC 

25–X would provide guidance for the 

fuel tank structural integrity 

requirements of §§ 25.561, 25.721, and 

25.963.) 

• AC 25.307–X, ‘‘Proof of Structure.’’ 

• AC 25.621–X, ‘‘Casting Factors.’’ 

IV. Regulatory Notices and Analyses 

A. Regulatory Evaluation 

Proposed changes to Federal 

regulations must undergo several 

economic analyses. First, Executive 

Order 12866 and Executive Order 13563 

direct that each Federal agency shall 

propose or adopt a regulation only upon 

a reasoned determination that the 

benefits of the intended regulation 

justify its costs. Second, the Regulatory 

Flexibility Act of 1980 (Pub. L. 96–354) 

requires agencies to analyze the 

economic impact of regulatory changes 

on small entities. Third, the Trade 

Agreements Act (Pub. L. 96–39) 

prohibits agencies from setting 

standards that create unnecessary 

obstacles to the foreign commerce of the 

United States. In developing U.S. 

standards, the Trade Act requires 

agencies to consider international 

standards and, where appropriate, that 

they be the basis of U.S. standards. 

Fourth, the Unfunded Mandates Reform 

Act of 1995 (Pub. L. 104–4) requires 

agencies to prepare a written assessment 

of the costs, benefits, and other effects 

of proposed or final rules that include 

a Federal mandate likely to result in the 

expenditure by State, local, or tribal 

governments, in the aggregate, or by the 

private sector, of $100 million or more 

annually (adjusted for inflation with 

base year of 1995). This portion of the 

preamble summarizes the FAA’s 

analysis of the economic impacts of this 

proposed rule. 

Department of Transportation Order 

DOT 2100.5 prescribes policies and 

procedures for simplification, analysis, 

and review of regulations. If the 

expected cost impact is so minimal that 

a proposed or final rule does not 

warrant a full evaluation, this order 

permits that a statement to that effect 

and the basis for it be included in the 

preamble if a full regulatory evaluation 

of the cost and benefits is not prepared. 

Such a determination has been made for 

this proposed rule. The reasoning for 

this determination follows. 

The FAA proposes to amend certain 

airworthiness standards for transport 

category airplanes. Adopting this 

proposal would eliminate regulatory 

differences between the airworthiness 

standards of the FAA and EASA. This 

proposal would not add new 

requirements beyond what 

manufacturers currently meet for EASA 

certification and would not affect 

current industry design practices. 

Meeting two sets of certification 

requirements raises the cost of 

developing new transport category 

airplanes with little to no increase in 

safety. In the interest of fostering 

international trade, lowering the cost of 

manufacturing new transport category 

airplanes, and making the certification 

process more efficient, the FAA, EASA, 

and several industry working groups 

came together to create, to the maximum 

extent possible, a single set of 

certification requirements that would be 

accepted in both the United States and 

Europe. Therefore, as a result of these 

harmonization efforts, the FAA 

proposes to amend the airworthiness 

regulations described in section II of 

this NPRM, ‘‘Overview of the Proposed 

Rule.’’ This action would harmonize 

part 25 requirements with the 

corresponding requirements in EASA 

CS–25 Book 1. 

Currently, all manufacturers of 

transport category airplanes, certificated 

under part 25 are expected to continue 

their current practice of compliance 

with the EASA certification 

requirements in CS–25 Book 1. Since 

future certificated transport airplanes 

are expected to meet CS–25 Book 1, and 

this rule simply adopts the same EASA 

requirements, manufacturers will incur 

minimal or no additional cost resulting 

from this proposed rule. Therefore, the 

FAA estimates that there are no 

additional costs associated with this 

proposed rule. 

In fact, manufacturers could receive 

cost savings because they will not have 

to build and certificate transport 

category airplanes to two different 

authorities’ certification specifications 

and rules. 

The FAA, however, has not attempted 

to quantify the cost savings that may 

accrue from this rule, beyond noting 

that while they may be minimal, they 

contribute to a potential harmonization 

savings. The agency concludes that 

because the compliance cost for this 

proposed rule is minimal and there may 

be harmonization cost savings, further 

analysis is not required. 

The FAA has, therefore, determined 

that this proposed rule is not a 

‘‘significant regulatory action’’ as 

defined in section 3(f) of Executive 

Order 12866, and is not ‘‘significant’’ as 

defined in DOT’s Regulatory Policies 

and Procedures. 

B. Regulatory Flexibility Determination 

The Regulatory Flexibility Act of 1980 

(Pub. L. 96–354) (RFA) establishes ‘‘as a 

principle of regulatory issuance that 

agencies shall endeavor, consistent with 

the objectives of the rule and of 

applicable statutes, to fit regulatory and 

informational requirements to the scale 

of the businesses, organizations, and 

governmental jurisdictions subject to 

regulation. To achieve this principle, 

agencies are required to solicit and 


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consider flexible regulatory proposals 

and to explain the rationale for their 

actions to assure that such proposals are 

given serious consideration.’’ The RFA 

covers a wide-range of small entities, 

including small businesses, not-forprofit organizations, and small 

governmental jurisdictions. 

Agencies must perform a review to 

determine whether a rule will have a 

significant economic impact on a 

substantial number of small entities. If 

the agency determines that it will, the 

agency must prepare a regulatory 

flexibility analysis as described in the 

RFA. 

However, if an agency determines that 

a rule is not expected to have a 

significant economic impact on a 

substantial number of small entities, 

section 605(b) of the RFA provides that 

the head of the agency may so certify, 

and a regulatory flexibility analysis is 

not required. The certification must 

include a statement providing the 

factual basis for this determination, and 

the reasoning should be clear. 

The FAA believes that this rule would 

not have a significant economic impact 

on a substantial number of small entities 

for the following reason. The net effect 

of this rule is minimum regulatory cost 

relief as the proposed rule would adopt 

those EASA requirements that industry 

already complies with. Moreover, 

manufacturers of part 25 airplanes are 

not small entities. Because those 

manufacturers already meet or expect to 

meet this CS–25 standard as well as the 

existing CFR requirement, the net effect 

of this proposed rule is regulatory cost 

relief. 

Because manufacturers of transport 

category airplanes are not small entities, 

this proposed rule is expected to have 

minimal to no additional costs, and 

could be cost-relieving, as the acting 

FAA Administrator, I certify that this 

proposed rule would not have a 

significant economic impact on a 

substantial number of small entities. 

C. International Trade Impact 

Assessment 

The Trade Agreements Act of 1979 

(Pub. L. 96–39), as amended by the 

Uruguay Round Agreements Act (Pub. 

L. 103–465), prohibits Federal agencies 

from establishing standards or engaging 

in related activities that create 

unnecessary obstacles to the foreign 

commerce of the United States. 

Pursuant to these Acts, the 

establishment of standards is not 

considered an unnecessary obstacle to 

the foreign commerce of the United 

States, so long as the standard has a 

legitimate domestic objective, such the 

protection of safety, and does not 

operate in a manner that excludes 

imports that meet this objective. The 

statute also requires consideration of 

international standards and, where 

appropriate, that they be the basis for 

U.S. standards. The FAA has assessed 

the potential effect of this proposed rule 

and determined that it is in accord with 

the Trade Agreements Act as the rule 

uses European standards as the basis for 

United States regulation. 

D. Unfunded Mandates Assessment 

Title II of the Unfunded Mandates 

Reform Act of 1995 (Pub. L. 104–4) 

requires each Federal agency to prepare 

a written statement assessing the effects 

of any Federal mandate in a proposed or 

final agency rule that may result in an 

expenditure of $100 million or more (in 

1995 dollars) in any one year by State, 

local, and tribal governments, in the 

aggregate, or by the private sector; such 

a mandate is deemed to be a ‘‘significant 

regulatory action.’’ The FAA currently 

uses an inflation-adjusted value of 

$143.1 million in lieu of $100 million. 

This proposed rule does not contain 

such a mandate; therefore, the 

requirements of Title II of the Act do not 

apply. 

E. Paperwork Reduction Act 

The Paperwork Reduction Act of 1995 

(44 U.S.C. 3507(d)) requires that the 

FAA consider the impact of paperwork 

and other information collection 

burdens imposed on the public. The 

FAA has determined that there would 

be no new requirement for information 

collection associated with this proposed 

rule. 

F. International Compatibility and 

Cooperation 

(1) In keeping with U.S. obligations 

under the Convention on International 

Civil Aviation, it is FAA policy to 

conform to International Civil Aviation 

Organization (ICAO) Standards and 

Recommended Practices to the 

maximum extent practicable. The FAA 

has reviewed the corresponding ICAO 

Standards and Recommended Practices 

and has identified no differences with 

these proposed regulations. 

(2) Executive Order (EO) 13609, 

Promoting International Regulatory 

Cooperation, (77 FR 26413, May 4, 

2012) promotes international regulatory 

cooperation to meet shared challenges 

involving health, safety, labor, security, 

environmental, and other issues and 

reduce, eliminate, or prevent 

unnecessary differences in regulatory 

requirements. The FAA has analyzed 

this action under the policy and agency 

responsibilities of Executive Order 

13609, Promoting International 

Regulatory Cooperation. The agency has 

determined that this action would 

eliminate differences between U.S. 

aviation standards and those of other 

civil aviation authorities by creating a 

single set of certification requirements 

for transport category airplanes that 

would be acceptable in both the United 

States and Europe. 

G. Environmental Analysis 

FAA Order 1050.1E identifies FAA 

actions that are categorically excluded 

from preparation of an environmental 

assessment or environmental impact 

statement under the National 

Environmental Policy Act in the 

absence of extraordinary circumstances. 

The FAA has determined this 

rulemaking action qualifies for the 

categorical exclusion identified in 

paragraph 312f of Order 1050.1E and 

involves no extraordinary 

circumstances. 

V. Executive Order Determinations 

A. Executive Order 13132, Federalism 

The FAA has analyzed this proposed 

rule under the principles and criteria of 

Executive Order 13132, Federalism. The 

agency has determined that this action 

would not have a substantial direct 

effect on the States, or the relationship 

between the Federal Government and 

the States, or on the distribution of 

power and responsibilities among the 

various levels of government, and, 

therefore, would not have Federalism 

implications. 

B. Executive Order 13211, Regulations 

That Significantly Affect Energy Supply, 

Distribution, or Use 

The FAA analyzed this proposed rule 

under Executive Order 13211, Actions 

Concerning Regulations that 

Significantly Affect Energy Supply, 

Distribution, or Use (May 18, 2001). The 

agency has determined that it would not 

be a ‘‘significant energy action’’ under 

the executive order and would not be 

likely to have a significant adverse effect 

on the supply, distribution, or use of 

energy. 

VI. Additional Information 

A. Comments Invited 

The FAA invites interested persons to 

participate in this rulemaking by 

submitting written comments, data, or 

views. The agency also invites 

comments relating to the economic, 

environmental, energy, or federalism 

impacts that might result from adopting 

the proposals in this document. The 

most helpful comments reference a 

specific portion of the proposal, explain 

the reason for any recommended 


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change, and include supporting data. To 

ensure the docket does not contain 

duplicate comments, commenters 

should send only one copy of written 

comments, or if comments are filed 

electronically, commenters should 

submit only one time. 

The FAA will file in the docket all 

comments it receives, as well as a report 

summarizing each substantive public 

contact with FAA personnel concerning 

this proposed rulemaking. Before acting 

on this proposal, the FAA will consider 

all comments it receives on or before the 

closing date for comments. The FAA 

will consider comments filed after the 

comment period has closed if it is 

possible to do so without incurring 

expense or delay. The agency may 

change this proposal in light of the 

comments it receives. 

Proprietary or Confidential Business 

Information: Commenters should not 

file proprietary or confidential business 

information in the docket. Such 

information must be sent or delivered 

directly to the person identified in the 

FOR FURTHER INFORMATION CONTACT

section of this document, and marked as 

proprietary or confidential. If submitting 

information on a disk or CD ROM, mark 

the outside of the disk or CD ROM, and 

identify electronically within the disk or 

CD ROM the specific information that is 

proprietary or confidential. 

Under 14 CFR 11.35(b), if the FAA is 

aware of proprietary information filed 

with a comment, the agency does not 

place it in the docket. It is held in a 

separate file to which the public does 

not have access, and the FAA places a 

note in the docket that it has received 

it. If the FAA receives a request to 

examine or copy this information, it 

treats it as any other request under the 

Freedom of Information Act (5 U.S.C. 

552). The FAA processes such a request 

under Department of Transportation 

procedures found in 49 CFR part 7. 

B. Availability of Rulemaking 

Documents 

An electronic copy of rulemaking 

documents may be obtained from the 

Internet by— 

1. Searching the Federal eRulemaking 

Portal at http://www.regulations.gov, 

2. Visiting the FAA’s Regulations and 

Policies Web page at http:// 

www.faa.gov/regulations_policies, or 

3. Accessing the Government Printing 

Office’s Web page at http:// 

www.gpo.gov/fdsys/. 

Copies may also be obtained by 

sending a request to the Federal 

Aviation Administration, Office of 

Rulemaking, ARM–1, 800 Independence 

Avenue SW., Washington, DC 20591, or 

by calling (202) 267–9680. Commenters 

must identify the docket or notice 

number of this rulemaking. 

All documents the FAA considered in 

developing this proposed rule, 

including economic analyses and 

technical reports, may be accessed from 

the Internet through the Federal 

eRulemaking Portal referenced in item 

(1) above. 

List of Subjects in 14 CFR Part 25 

Aircraft, Aviation safety, Reporting 

and recordkeeping requirements. 

The Proposed Amendment 

In consideration of the foregoing, the 

Federal Aviation Administration 

proposes to amend chapter I of title 14, 

Code of Federal Regulations as follows: 

PART 25—AIRWORTHINESS 

STANDARDS: TRANSPORT 

CATEGORY AIRPLANES 

■ 1. The authority citation for part 25 

continues to read as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701, 

44702, and 44704. 

■ 2. Amend § 25.307 by revising 

paragraph (a) to read as follows: 

§ 25.307 Proof of structure. 

(a) Compliance with the strength and 

deformation requirements of this 

subpart must be shown for each critical 

loading condition. Structural analysis 

may be used only if the structure 

conforms to that for which experience 

has shown this method to be reliable. In 

other cases, substantiating tests must be 

made to load levels that are sufficient to 

verify structural behavior up to loads 

specified in § 25.305. 

* * * * * 

■ 3. Amend § 25.621 by revising 

paragraphs (a), (c), and (d) to read as 

follows: 

§ 25.621 Casting factors. 

(a) General. For castings used in 

structural applications, the factors, tests, 

and inspections specified in paragraphs 

(b) through (d) of this section must be 

applied in addition to those necessary to 

establish foundry quality control. The 

inspections must meet approved 

specifications. Paragraphs (c) and (d) of 

this section apply to any structural 

castings, except castings that are 

pressure tested as parts of hydraulic or 

other fluid systems and do not support 

structural loads. 

(b) * * * 

(c) Critical castings. Each casting 

whose failure could preclude continued 

safe flight and landing of the airplane or 

could result in serious injury to 

occupants is considered a critical 

casting. Each critical casting must have 

a factor associated with it for showing 

compliance with strength and 

deformation requirements, and must 

comply with the following criteria 

associated with that factor: 

(1) A casting factor of 1.0 or greater 

may be used, provided that— 

(i) It is demonstrated, in the form of 

process qualification, proof of product, 

and process monitoring that, for each 

casting design and part number, the 

castings produced by each foundry and 

process combination have coefficients of 

variation of the material properties that 

are equivalent to those of wrought alloy 

products of similar composition. 

Process monitoring must include testing 

of coupons cut from the prolongations 

of each casting (or each set of castings, 

if produced from a single pour into a 

single mold in a runner system) and, on 

a sampling basis, coupons cut from 

critical areas of production castings. The 

acceptance criteria for the process 

monitoring inspections and tests must 

be established and included in the 

process specifications to ensure the 

properties of the production castings are 

controlled to within levels used in 

design. 

(ii) Each casting receives: 

(A) Inspection of 100% of its surface, 

using visual and liquid penetrant, or 

equivalent, inspection methods; and 

(B) Inspection of structurally 

significant internal areas and areas 

where defects are likely to occur, using 

radiographic, or equivalent, inspection 

methods. 

(iii) One casting undergoes a static 

test and is shown to meet the strength 

and deformation requirements of 

§ 25.305(a) and (b). 

(2) A casting factor of 1.25 or greater 

may be used, provided that— 

(i) Each casting receives: 

(A) Inspection of 100% of its surface, 

using visual and liquid penetrant, or 

equivalent inspection methods; and 

(B) Inspection of structurally 

significant internal areas and areas 

where defects are likely to occur, using 

radiographic, or equivalent, inspection 

methods. 

(ii) Three castings undergo static tests 

and are shown to meet: 

(A) The strength requirements of 

§ 25.305(b) at an ultimate load 

corresponding to a casting factor of 1.25; 

and 

(B) The deformation requirements of 

§ 25.305(a) at a load of 1.15 times the 

limit load. 

(3) A casting factor of 1.50 or greater 

may be used, provided that— 

(i) Each casting receives: 

(A) Inspection of 100% of its surface, 

using visual and liquid penetrant, or 

equivalent, inspection methods; and 


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(B) Inspection of structurally 

significant internal areas and areas 

where defects are likely to occur, using 

radiographic, or equivalent, inspection 

methods. 

(ii) One casting undergoes a static test 

and is shown to meet: 

(A) The strength requirements of 

§ 25.305(b) at an ultimate load 

corresponding to a casting factor of 1.50; 

and 

(B) The deformation requirements of 

§ 25.305(a) at a load of 1.15 times the 

limit load. 

(d) Non-critical castings. For each 

casting other than critical castings, as 

specified in paragraph (c) of this 

section, the following apply: 

(1) A casting factor of 1.0 or greater 

may be used, provided that the 

requirements of (c)(1) of this section are 

met, or all of the following conditions 

are met: 

(i) Castings are manufactured to 

approved specifications that specify the 

minimum mechanical properties of the 

material in the casting and provides for 

demonstration of these properties by 

testing of coupons cut from the castings 

on a sampling basis. 

(ii) Each casting receives: 

(A) Inspection of 100% of its surface, 

using visual and liquid penetrant, or 

equivalent, inspection methods; and 

(B) Inspection of structurally 

significant internal areas and areas 

where defects are likely to occur, using 

radiographic, or equivalent, inspection 

methods. 

(iii) Three sample castings undergo 

static tests and are shown to meet the 

strength and deformation requirements 

of § 25.305(a) and (b). 

(2) A casting factor of 1.25 or greater 

may be used, provided that each casting 

receives: 

(i) Inspection of 100% of its surface, 

using visual and liquid penetrant, or 

equivalent, inspection methods; and 

(ii) Inspection of structurally 

significant internal areas and areas 

where defects are likely to occur, using 

radiographic, or equivalent, inspection 

methods. 

(3) A casting factor of 1.5 or greater 

may be used, provided that each casting 

receives inspection of 100% of its 

surface using visual and liquid 

penetrant, or equivalent, inspection 

methods. 

(4) A casting factor of 2.0 or greater 

may be used, provided that each casting 

receives inspection of 100% of its 

surface using visual inspection 

methods. 

(5) The number of castings per 

production batch to be inspected by 

non-visual methods in accordance with 

paragraphs (d)(2) and (d)(3) of this 

section may be reduced when an 

approved quality control procedure is 

established. 

■ 4. Amend § 25.683 by redesignating 

the introductory text as paragraph (a), 

redesignating paragraphs (a), (b), and (c) 

as paragraphs (a)(1), (a)(2), and (a)(3) 

respectively, and adding paragraphs (b) 

and (c) to read as follows: 

§ 25.683 Operation tests. 

(a) It must be shown by operation 

tests that when portions of the control 

system subject to pilot effort loads are 

loaded to 80% of the limit load 

specified for the system and the 

powered portions of the control system 

are loaded to the maximum load 

expected in normal operation, the 

system is free from— 

(1) Jamming; 

(2) Excessive friction; and 

(3) Excessive deflection. 

(b) It must be shown by analysis and, 

where necessary, by tests that in the 

presence of deflections of the airplane 

structure due to the separate application 

of pitch, roll, and yaw limit maneuver 

loads, the control system, when loaded 

to obtain these limit loads and operated 

within its operational range of 

deflections, can be exercised about all 

control axes and remain free from— 

(1) Jamming; 

(2) Excessive friction; 

(3) Disconnection, and 

(4) Any form of permanent damage. 

(c) It must be shown that under 

vibration loads in the normal flight and 

ground operating conditions, no hazard 

can result from interference or contact 

with adjacent elements. 

■ 5. Revise § 25.721 to read as follows: 

§ 25.721 General. 

(a) The landing gear system must be 

designed so that when it fails due to 

overloads during takeoff and landing, 

the failure mode is not likely to cause 

spillage of enough fuel to constitute a 

fire hazard. The overloads must be 

assumed to act in the upward and aft 

directions in combination with side 

loads acting inboard and outboard. In 

the absence of a more rational analysis, 

the side loads must be assumed to be up 

to 20% of the vertical load or 20% of the 

drag load, whichever is greater. 

(b) The airplane must be designed to 

avoid any rupture leading to the spillage 

of enough fuel to constitute a fire hazard 

as a result of a wheels-up landing on a 

paved runway, under the following 

minor crash landing conditions: 

(1) Impact at 5 feet-per-second vertical 

velocity, with the airplane under 

control, at Maximum Design Landing 

Weight— 

(i) With the landing gear fully 

retracted and, as separate conditions, 

(ii) With any other combination of 

landing gear legs not extended. 

(2) Sliding on the ground, with— 

(i) The landing gear fully retracted 

and with up to a 20° yaw angle and, as 

separate conditions, 

(ii) Any other combination of landing 

gear legs not extended and with 0° yaw 

angle. 

(c) For configurations where the 

engine nacelle is likely to come into 

contact with the ground, the engine 

pylon or engine mounting must be 

designed so that when it fails due to 

overloads (assuming the overloads to act 

predominantly in the upward direction 

and separately, predominantly in the aft 

direction), the failure mode is not likely 

to cause the spillage of enough fuel to 

constitute a fire hazard. 

■ 6. Amend § 25.787 by revising 

paragraph (a) to read as follows: 

§ 25.787 Stowage compartments. 

(a) Each compartment for the stowage 

of cargo, baggage, carry-on articles, and 

equipment (such as life rafts), and any 

other stowage compartment, must be 

designed for its placarded maximum 

weight of contents and for the critical 

load distribution at the appropriate 

maximum load factors corresponding to 

the specified flight and ground load 

conditions, and to the emergency 

landing conditions of § 25.561(b)(3) 

where the breaking loose of the contents 

of such compartments could— 

(1) Cause direct injury to occupants; 

(2) Penetrate fuel tanks or lines or 

cause fire or explosion hazard by 

damage to adjacent systems; or 

(3) Nullify any of the escape facilities 

provided for use after an emergency 

landing. 

If the airplane has a passenger-seating 

configuration, excluding pilot seats, of 

10 seats or more, each stowage 

compartment in the passenger cabin, 

except for under seat and overhead 

compartments for passenger 

convenience, must be completely 

enclosed. 

* * * * * 

■ 7. Amend § 25.963 by revising 

paragraph (d) to read as follows: 

§ 25.963 Fuel tanks: general. 

* * * * * 

(d) Fuel tanks must, so far as it is 

practicable, be designed, located, and 

installed so that no fuel is released in or 

near the fuselage, or near the engines, in 

quantities that would constitute a fire 

hazard in otherwise survivable 

emergency landing conditions, and— 

(1) Fuel tanks must be able to resist 

rupture and retain fuel under ultimate 

hydrostatic design conditions in which 


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the pressure P within the tank varies in 

accordance with the formula: 

P = KrgL 

Where 

P = fuel pressure at each point within the 

tank. 

r = typical fuel density. 

g = acceleration due to gravity. 

L = a reference distance between the point of 

pressure and the tank farthest boundary 

in the direction of loading. 

K = 4.5 for the forward loading condition for 

those parts of fuel tanks outside the 

fuselage pressure boundary. 

K = 9 for the forward loading condition for 

those parts of fuel tanks within the 

fuselage pressure boundary, or that form 

part of the fuselage pressure boundary. 

K = 1.5 for the aft loading condition. 

K = 3.0 for the inboard and outboard loading 

conditions for those parts of fuel tanks 

within the fuselage pressure boundary, 

or that form part of the fuselage pressure 

boundary. 

K = 1.5 for the inboard and outboard loading 

conditions for those parts of fuel tanks 

outside the fuselage pressure boundary. 

K = 6 for the downward loading condition. 

K = 3 for the upward loading condition. 

(2) For those parts of wing fuel tanks 

near the fuselage or near the engines, 

the greater of the fuel pressures 

resulting from paragraphs (d)(2)(i) and 

(d)(2)(ii) of this section must be used: 

(i) The fuel pressures resulting from 

paragraph (d)(1) of this section, and 

(ii) The lesser of the two following 

conditions: 

(A) Fuel pressures resulting from the 

accelerations as specified in 

§ 25.561(b)(3) considering the fuel tank 

full of fuel at maximum fuel density. 

Fuel pressures based on the 9.0g 

forward acceleration may be calculated 

using the fuel static head equal to the 

streamwise local chord of the tank. For 

inboard and outboard conditions, an 

acceleration of 1.5g may be used in lieu 

of 3.0g as specified in § 25.561(b)(3), 

and 

(B) Fuel pressures resulting from the 

accelerations as specified in 

§ 25.561(b)(3) considering a fuel volume 

beyond 85% of the maximum 

permissible volume in each tank using 

the static head associated with the 85% 

fuel level. A typical density of the 

appropriate fuel may be used. For 

inboard and outboard conditions, an 

acceleration of 1.5g may be used in lieu 

of 3.0g as specified in § 25.561(b)(3). 

(3) Fuel tank internal barriers and 

baffles may be considered as solid 

boundaries if shown to be effective in 

limiting fuel flow. 

(4) For each fuel tank and 

surrounding airframe structure, the 

effects of crushing and scraping actions 

with the ground should not cause the 

spillage of enough fuel, or generate 

temperatures that would constitute a 

fire hazard under the conditions 

specified in § 25.721(b). 

(5) Fuel tank installations must be 

such that the tanks will not rupture as 

a result of an engine pylon or engine 

mount or landing gear, tearing away as 

specified in § 25.721(a) and (c). 

* * * * * 

■ 8. Revise § 25.994 to read as follows: 

§ 25.994 Fuel system components. 

Fuel system components in an engine 

nacelle or in the fuselage must be 

protected from damage that could result 

in spillage of enough fuel to constitute 

a fire hazard as a result of a wheels-up 

landing on a paved runway under each 

of the conditions prescribed in 

§ 25.721(b). 

Issued in Washington, DC, on February 14, 

2013. 

Dorenda D. Baker, 

Director, Aircraft Certification Service. 

[FR Doc. 2013–04812 Filed 2–28–13; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 71 

[Docket No. FAA–2013–0026; Airspace 

Docket No. 13–ANM–3] 

Proposed Amendment of Class E 

Airspace; Bend, OR 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: This action proposes to 

modify Class E airspace at Bend, OR to 

accommodate aircraft departing and 

arriving under Instrument Flight Rules 

(IFR) at Bend Municipal Airport. This 

action would enhance the safety and 

management of aircraft operations. The 

geographic coordinates of the airport 

would also be updated. 

DATES: Comments must be received on 

or before April 15, 2013. 

ADDRESSES: Send comments on this 

proposal to the U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–140, 1200 New Jersey Avenue SE., 

Washington, DC 20590; telephone (202) 

366–9826. You must identify FAA 

Docket No. FAA–2013–0026; Airspace 

Docket No. 13–ANM–3, at the beginning 

of your comments. You may also submit 

comments through the Internet at 

http://www.regulations.gov. 

FOR FURTHER INFORMATION CONTACT: 

Richard Roberts, Federal Aviation 

Administration, Operations Support 

Group, Western Service Center, 1601 

Lind Avenue SW., Renton, WA 98057; 

telephone (425) 203–4517. 

SUPPLEMENTARY INFORMATION:

Comments Invited 

Interested parties are invited to 

participate in this proposed rulemaking 

by submitting such written data, views, 

or arguments, as they may desire. 

Comments that provide the factual basis 

supporting the views and suggestions 

presented are particularly helpful in 

developing reasoned regulatory 

decisions on the proposal. Comments 

are specifically invited on the overall 

regulatory, aeronautical, economic, 

environmental, and energy-related 

aspects of the proposal. 

Communications should identify both 

docket numbers (FAA Docket No. FAA– 

2013–0026 and Airspace Docket No. 13– 

ANM–3) and be submitted in triplicate 

to the Docket Management System (see 

ADDRESSES section for address and 

phone number). You may also submit 

comments through the Internet at 

http://www.regulations.gov. 

Commenters wishing the FAA to 

acknowledge receipt of their comments 

on this action must submit with those 

comments a self-addressed stamped 

postcard on which the following 

statement is made: ‘‘Comments to FAA 

Docket No. FAA–2013–0026 and 

Airspace Docket No. 13–ANM–3’’. The 

postcard will be date/time stamped and 

returned to the commenter. 

All communications received on or 

before the specified closing date for 

comments will be considered before 

taking action on the proposed rule. The 

proposal contained in this action may 

be changed in light of comments 

received. All comments submitted will 

be available for examination in the 

public docket both before and after the 

closing date for comments. A report 

summarizing each substantive public 

contact with FAA personnel concerned 

with this rulemaking will be filed in the 

docket. 

Availability of NPRM’s 

An electronic copy of this document 

may be downloaded through the 

Internet at http://www.regulations.gov. 

Recently published rulemaking 

documents can also be accessed through 

the FAA’s Web page at http:// 

www.faa.gov/airports_airtraffic/ 

air_traffic/publications/ 

airspace_amendments/. 

You may review the public docket 

containing the proposal, any comments 

received, and any final disposition in 

person in the Dockets Office (see the 

ADDRESSES section for the address and 


emcdonald on DSK67QTVN1PROD with PROPOSALS