[Federal Register Volume 63, Number 125 (Tuesday, June 30, 1998)]
[Proposed Rules]
[Page 35648]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-17291]



[[Page 35647]]

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Part II





Department of Transportation





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Federal Aviation Administration



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14 CFR Part 23



Airworthiness Standards; Occupant Protection Standards for Commuter 
Category Airplanes; Proposed Rule

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

[[Page 35648]]



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.

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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DATES: This proposed rule is withdrawn as of June 30, 1998.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 cost-benefit 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]
BILLING CODE 4910-13-M