35648 Federal Register / Vol. 63, No. 125 /Tuesday, June 30, 1998 / Proposed Rules

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

RIN 2120–AD27

Airworthiness Standards; Occupant

Protection Standards for Commuter

Category Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM); withdrawal.

SUMMARY: The FAA is withdrawing a

previously published Notice of

Proposed Rulemaking (NPRM) that

proposed to amend the airworthiness

standards for normal, utility, acrobatic,

and commuter category airplanes. That

notice proposed an upgrade in the

requirements for both seat/restraint

systems and for flammability standards

for seat cushions used in commuter

category airplanes. It also proposed an

increase in the downward inertia load

factor for items of mass within the cabin

for all normal, utility, acrobatic, and

commuter category airplanes. The FAA

is developing a new proposal based on

information gathered subsequent to the

NPRM.

DATES: This proposed rule is withdrawn

as of June 30, 1998.

FOR FURTHER INFORMATION CONTACT:

Michael Downs, Standards Office (ACE–

111), Small Airplane Directorate,

Aircraft Certification Service, Federal

Aviation Administration, 601 East 12th

Street, Kansas City, Missouri 64106;

telephone (816) 426–5688.

SUPPLEMENTARY INFORMATION: On July

14, 1993, the FAA published Notice of

Proposed Rulemaking No. 93–71 (58 FR

38028) to propose an amendment to 14

CFR part 23 and invited public

comment. During the comment period,

the General Aviation Manufacturers

Association (GAMA) objected to the

proposed rule. GAMA’s September 17,

1993, letter to the docket stated the

following: ‘‘The docket for the rule did

not contain data on several recent

accidents of 10–19 passenger airplanes

operated under 14 CFR part 135 rules,

which indicated that those accidents

occurred at crash conditions

approaching those of a flat impact crash.

The FAA considered it necessary to

evaluate the flat impact crash condition

when conducting the analysis leading to

the proposals in this notice. Because

FAA bases certain of the criteria in this

proposal on these data and analyses

therefore, industry cannot appropriately

comment on this proposal until the

supporting data are made available for

public evaluation.’’ The report GAMA

referenced, ‘‘Commuter Airplane

Accident Data Analysis,’’ was published

in August 1994. The FAA reopened the

comment period on November 4, 1994;

it closed on March 4, 1995.

Many of the general comments

addressed the accuracy of the derived

safety benefits of the rule and

questioned how the safety benefits

could be evaluated independently from

the benefits expected of other recently

adopted rules. Several commenters

questioned the use of a 15-year life

expectancy for seats utilizing

fireblocking materials when their

commercial experience indicated an

average life expectancy of four years.

On March 29, 1995, Notice No. 95–5,

‘‘Commuter Operations and General

Certification and Operations

Requirements,’’ was published. This

rulemaking effort proposed, in part, to

move all scheduled part 135 operations

with ten passenger seats or more to 14

CFR part 121 operations and for newly

type certificated airplanes operating in

accordance with part 121 to be type

certificated under part 25. Since most

airplane manufacturers of part 23

commuter category airplanes design

their airplanes to be operated in

accordance with part 135, the proposed

rule affected the applicability of part 23

certification requirements for airplanes

operating in scheduled service with ten

or more passenger seats. On January 19,

1996, the ‘‘Commuter Operations and

General Certification and Operations

Requirements’’ final rule was adopted as

amendment 121–151. As a result, the

FAA re-evaluated the cost analysis for

Notice 93–71. With the removal of

scheduled part 135 aircraft, the

proposed amendment would no longer

be cost-beneficial. With the adoption of

amendment 121–151, the projected

benefits of the dynamic seat testing and

flammability requirements proposed in

Notice No. 93–71 have been negated.

Other commenters addressed the

stringency of the proposed rule when

compared to the existing requirements

for similarly sized small transport

category airplanes. The FAA cannot

agree that such a comparison is valid.

The 14 CFR part 25 transport category

airplane seat dynamic performance

standards were defined using data that

were representative of the impact

response characteristics of large (narrow

or wide body) transport category

airplanes. The structural depth under

the floor and impact energy absorption

characteristics of these airplanes is

considerably greater than that for

commuter category airplanes and small

transport category airplanes. In light of

these differences, the use of part 25

transport category airplane standards for

commuter category airplanes would not

provide adequate protection. The FAA

is considering amending both part 23

and part 25 standards to make them

consistent for commuter category and

small transport category airplanes.

Additional comments stated that the

maximum acceleration levels proposed

were unrealistically high and would

require excessive energy absorption

designs. The FAA disagrees. Energy

absorbing seats have been designed and

tested at the Civil Aeromedical Institute

(CAMI) to the combined longitudinal

and vertical test conditions found in

Notice No. 93–71, and those seats met

the requirements of the proposed rule.

Those tests demonstrated that the

minimum requirements for providing

occupant spinal column/pelvic load

protection can be provided with seats

that have four inches of seat stroke or

energy absorption capability. Full-scale

commuter category airplane impact tests

conducted with the CAMI energy

absorbing seats on board have

confirmed the above CAMI test lab

finding.

In consideration of those comments to

Notice No. 93–71 regarding the costbenefit analysis and the effect of

amendment 121–151, the Federal

Aviation Administration has decided to

withdraw Notice No. 93–71. Instead, the

FAA is planning to task the Aviation

Rulemaking Advisory Committee

(ARAC) to amend both part 25 transport

category airplane standards and part 23

to make them consistent for commuter

category and small transport category

airplanes.

In addition, the FAA plans to initiate

a new rulemaking project to propose

seat cushion fireblocking provisions for

new type certificated commuter

category airplanes. Accordingly, Notice

No. 93–71, published on July 14, 1993

(58 FR 32028), is withdrawn.

Issued in Washington, DC on June 22,

1998.

Thomas E. McSweeny,

Director, Aircraft Certification Service.

[FR Doc. 98–17291 Filed 6–29–98; 8:45 am]

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