[Federal Register: December 2, 2002 (Volume 67, Number 231)]
[Proposed Rules]
[Page 71490-71493]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr02de02-27]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 23
[Docket No. CE191]; Notice No. 23-03-022-SC]
Special Conditions: Air Tractor Incorporated, Models AT-401, AT-
402, AT-502, AT-602, and AT-802; Seats With Goodrich Aircraft Interior
Products (AIP) Four-Point Inflatable Restraints
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This notice proposes special conditions for the following Air
Tractor AT series airplanes; AT-401, AT-402, AT-502, AT-602, and AT-
802. These airplanes, as modified by Goodrich Aircraft Interior
Products, will have novel and unusual design features associated with a
four-point inflatable (airbag) restraint. 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 January 2, 2003.
ADDRESSES: Comments on this proposal may be mailed in duplicate to:
Federal Aviation Administration (FAA), Regional Counsel, ACE-7,
Attention: Rules Docket, Docket No. CE191, 901 Locust, Room 506, Kansas
City, Missouri 64106, or delivered in duplicate to the Regional Counsel
at the above address. Comments must be marked: CE191. 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: Pat Mullen, Federal Aviation
Administration, Aircraft Certification Service, Small Airplane
Directorate, ACE-111, 901 Locust, Kansas City, Missouri, 816-329-4128,
fax 816-329-4090.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of
these proposed special conditions by submitting such written data,
views, or arguments, as they may desire. Communications should identify
the regulatory docket or notice number and be submitted in duplicate to
the address specified above. All communications received on or before
the closing date for comments will be considered by the Administrator.
The proposals described in this notice may be changed in light of the
comments received. All comments received will be available in the Rules
Docket for examination by interested persons, both before and after the
closing date for comments. A report summarizing each substantive public
contact with FAA personnel concerning this rulemaking will be filed in
the docket. Persons wishing the FAA to acknowledge receipt of their
comments submitted in response to this notice must include with those
comments a self-addressed, stamped postcard on which the following
statement is made:
[[Page 71491]]
``Comments to CE191.'' The postcard will be date stamped and returned
to the commenter.
Background
On March 8, 2002, Goodrich Aircraft Interior Products (GAIP), 1275
N. Newport Road, Colorado Springs, CO 80916-2779, applied for a
supplemental type certificate to install four-point inflatable
restraints in Air Tractor AT series airplanes AT-401, AT-402, AT-502,
AT-602, and AT-802. The Air Tractor AT series airplanes comprise a
group of agricultural aircraft certificated under 14 Code of Federal
Regulations (CFR) 21.25, Restricted Category. These airplanes are
intended for single pilot operation, sharing the same seating
environment and seat-to-aircraft attachments. Therefore, the inflatable
restraint system proposed by GAIP can be used with each Air Tractor
model listed. The inflatable restraint system limits occupant forward
excursion in case of an accident, while forming a protective cushion
around the sides of the occupant's head. This will reduce the potential
for head and torso injury. The inflatable four-point restraint behaves
in a manner that is similar to an automotive airbag, but in this case,
the airbags are integrated into each shoulder harness, inflating away
from the occupant. The lapbelt portion of this four-point restraint is
conventional and does not inflate. While airbags and inflatable
restraints are standard in the automotive industry, the use of an
inflatable four-point restraint is novel for agricultural operations.
Agricultural airplanes, like the Air Tractor AT series, contain
many elements of a cashworthy design first described in a 1949 Cornell
University study. These elements include a cockpit structure that
encases the pilot, crushable structure forward of and underneath the
pilot, a low-positioned instrument panel which the pilot's head would
not strike, required use of a helmet, and other features such as a
strong harness system and an energy absorbing seat. These design
features have contributed to the excellent safety record of
agricultural airplanes. The fatality rates experienced by the
agricultural airplane fleet are roughly half of that experienced by the
general aviation fleet. This lower fatality rate is in spite of a
higher overall accident rate with respect to that of general aviation.
In consideration of the excellent fatality record of agricultural
airplanes in general, and the Air Tractor AT series in particular, the
FAA has determined that installation of a four-point inflatable
restraint must be accomplished on the basis of not lowering the current
level of safety of the AT-401, AT-402, AT-502, AT-602, and AT-802.
Therefore, the FAA considers that installation of an inflatable
restraint as having two primary safety concerns:
[sbull] That it perform properly under foreseeable operating
conditions, and;
[sbull] That it not perform in a manner or at such times as would
constitute a hazard to the airplane or occupants.
The latter point has the potential to be the more rigorous of the
requirements. Agricultural operations typically occur at very low
altitudes. An unexpected deployment while conducting these operations
may result in an unsafe condition in flight. The unexpected deployment
may either startle the pilot, or generate a force sufficient to cause a
sudden movement of the control stick. Either action could result in a
loss of control of the airplane, the consequences of which are
magnified due to the low operating altitude. The FAA has considered
this when establishing the special conditions.
GAIP has developed a ``Smartbelt'' Four-Point Manually Adjusting
Restraint seatbelt with an integrated inflatable airbag device. This
inflatable restraint will rely on electronic sensors for firing and
pyrotechnic charges for activation. These sensors could be susceptible
to inadvertent activation, causing deployment in a potentially unsafe
manner. The consequences of an inadvertent deployment must be
considered in establishing the reliability of the system. GAIP must
substantiate that the effects of an inadvertent deployment in flight
are not a hazard to the airplane. In addition, the operating conditions
of agricultural aircraft can generate a large amount of cumulative wear
and tear on the restraint system. It is likely that the potential for
inadvertent deployment increases as a result of this cumulative damage.
Therefore, the impact of wear and tear on inadvertent deployment must
be considered. Ultimately, because of the effects of this cumulative
damage, a life limit must be established for the restraint system
design.
There are additional factors to be considered to minimize the
chances of inadvertent deployment. Agricultural airplanes are exposed
to an extreme operating environment. The effect of this environment on
inadvertent deployment of the restraint must be understood. The
qualification testing of the firing hardware/software must consider the
following:
[sbull] The airplane vibration levels appropriate for agricultural
airplanes, and
[sbull] The inertial loads that result from typical flight or
ground maneuvers, including gusts and hard landings.
Any tendency for the firing mechanism to activate as a result of these
loads or acceleration levels is unacceptable.
Other influences on inadvertent deployment include high intensity
electromagnetic fields (HIRF). Since the sensors that trigger
deployment are electronic, they must be protected from the effects of
this threat. For complying with HIRF requirements, the inflatable
system is considered a critical system if its deployment could have a
hazardous effect on the airplane; otherwise, it is considered an
essential system. Finally, the inflatable restraint should be protected
from the effects of fire, so that an additional hazard is not created
by, for example, a rupture of the pyrotechnic squib.
While restricted category aircraft need not demonstrate compliance
to 14 CFR part 23, Sec. 23.562, there are many elements of Sec.
23.562 that can be used to ensure an adequate level of protection
during an emergency landing. These elements include an appropriate
crash pulse and various injury pass/fail criteria. Therefore, the
inflatable seatbelt must undergo qualification tests of the firing
hardware/software for the 26 G deceleration pulse defined under Sec.
23.562(b)(2). When the inflatable portion of the restraint is subjected
to, and operates as a result of the 26 G deceleration pulse, it must be
shown that deployment of the device will not be a hazard to the
occupant. This can be accomplished by assuring that the 4-point
restraint does not ride above the pelvis into the abdomen, as required
by Sec. 23.562(c)(4). This also includes satisfying the maximum
harness loads permitted by Sec. 23.562(c)(6).
Given the level of safety of the current Air Tractor harness, the
inflatable restraint must show that it will offer an equivalent level
of protection in the event the inflatable portion fails to deploy. In
the event of an inadvertent deployment, the restraint must still have
the same strength capability after the inflatable portion of the
restraint has been deployed. There is no requirement for the inflatable
portion of the restraint to offer protection during multiple impacts,
where more than one impact would require protection.
The inflatable seatbelt system must deploy and provide protection
under crash conditions where it is necessary to prevent serious injury.
In support of this operational capability, there must be a means to
verify the integrity of this system before each flight. As an option,
GAIP can establish inspection intervals
[[Page 71492]]
where they have demonstrated the system to be reliable between these
intervals.
It is possible a wide range of occupants will use the inflatable
restraint. Thus, the protection offered by this restraint should be
effective for occupants that range from the fifth percentile female to
the ninety-fifth percentile male. In addition, the operation of this
restraint must be transparent to the user. Therefore, the design must
prevent the inflatable seatbelt from being incorrectly buckled and/or
installed such that the airbag would not properly deploy. In addition,
when deployment does occur, there must not be a release of hazardous
quantities of gas or particulate matter into the cockpit area.
Finally, the inflatable restraint is likely to have a large volume
displacement, where the inflated bag could impede the egress of an
occupant. Since the bag deflates to absorb energy, it is likely that
the inflatable restraint would be deflated at the time an occupant
would attempt egress. However, it is appropriate to specify a time
interval after which the inflatable restrain may not impede rapid
egress. Ten seconds has been chosen as reasonable time. This time limit
will offer a level of protection throughout the impact event.
Type Certification Basis
Under the provisions of Sec. 21.101, Goodrich Aircraft Interior
Products must show that the Air Tractor AT series airplanes AT-401, AT-
402, AT-502, AT-602, and AT-802, as changed, continue to meet the
applicable provisions of the regulations incorporated by reference in
Type Certificate No. A17SW (for AT-401, AT-402, and AT-502) and Type
Certificate No. A19SW (for AT-602 and AT-802) or the applicable
regulations in effect on the date of application for the change. The
regulations incorporated by reference in the type certificate are
commonly referred to as the ``original type certification basis.'' The
regulations incorporated by reference in Type Certificate No. A17SW are
as follows:
[sbull] For models AT-401, AT-401A, and AT-401B, Sec. 21.25(a)(1),
14 CFR part 23 through 23-9, and Appendix B, CAM 8. For models AT-402,
AT-402A, AT-402B, AT-502, AT-502A, and AT-502B, Sec. 21.25(a), (b)(1),
(b)(2), Amendments 23-1 through 23-9, Appendix B, CAM 8, and additional
turbine engine requirements that are of no relevance to the special
conditions.
The regulations incorporated by reference in Type Certificate No.
A19SW are as follows:
[sbull] For model AT-602, 14 CFR part 23 through Amendment 23-42.
For model AT-802, 14 CFR part 23 through Amendment 23-42, plus Sec.
21.25(b)(1), (b)(2), and (b)(7). For model AT-802A, 14 CFR part 23
through Amendment 42, plus Sec. 21.25(b)(1), (b)(2), and (b)(7).
For each model listed above, the certification basis also includes all
exemptions, if any; equivalent level of safety findings, if any; and
the special conditions adopted by this rulemaking action.
The Administrator has determined that the applicable airworthiness
regulations (i.e., part 23 as amended) do not contain adequate or
appropriate safety standards for the GAIP inflatable restraint as
installed on Air Tractor models AT-401, AT-402, AT-502, AT-602, and AT-
802 because of a novel or unusual design feature. Therefore, special
conditions are prescribed under the provisions of Sec. 21.6.
In addition to the applicable airworthiness regulations and special
conditions, Air Tractor models equipped with the GAIP inflatable
restraint must comply with the fuel vent and exhaust emission
requirements of 14 CFR part 34.
Special conditions, as appropriate, as defined in Sec. 11.19, are
issued in accordance with Sec. 11.38, and become part of the type
certification basis in accordance with Sec. 21.101(b)(2).
Special conditions are initially applicable to the model for which
they are issued. Should the applicant apply for a supplemental type
certificate to modify any other model included on the same type
certificate to incorporate the same novel or unusual design feature,
the special conditions would also apply to that model under the
provisions of Sec. 21.101(a)(1).
Novel or Unusual Design Features
Air Tractor Models AT-401, AT-402, AT-502, AT-601, and AT-802 will
incorporate the following novel or unusual design features.
The Goodrich Aircraft Interior Products ``Smartbelt'' Four-Point
Manually Adjusting Restraint Seatbelt
The purpose of the inflatable airbag seatbelt is to reduce the
potential for injury in the event of an accident. In a severe impact,
airbags will deploy out of the shoulder harnesses portion of the
restraint, in a manner similar to an automotive airbag. These airbags
will restrain the motion of the occupant during a severe impact and
offer some protection to the head of the occupant. The restraint will
rely on electronic sensors for firing, and pyrotechnic charges for
activation.
The CFR states performance criteria for seats and restraints in an
objective manner. However, none of these criteria are adequate to
address the specific issues raised concerning inflatable restraints in
agricultural airplanes. Therefore, the FAA has determined that, in
addition to the requirements of part 21 and part 23, special conditions
are needed to address the installation of inflatable four-point
restraints.
Accordingly, these special conditions are adopted for Air Tractor
Models AT-401, AT-402, AT-502, AT-602, and AT-802 equipped with the
Goodrich Aircraft Interior Products four-point inflatable restraint.
Other conditions may be developed, as needed, based on further FAA
review and discussions with the manufacturer and civil aviation
authorities.
The FAA has determined that this project will be accomplished on
the basis of not lowering the current level of safety for these Air
Tractor models. The FAA recognizes that the current Air Tractor
occupant restraint system has an excellent safety record. The FAA has
considered the installation of inflatable restraints as having two
primary safety concerns: (1) That they perform properly under
foreseeable operating conditions; (2) that they not perform in a manner
or at such times as would constitute a hazard to the airplane or
occupants.
Applicability
As discussed above, these special conditions are applicable to the
Air Tractor model series AT-401, AT-402, AT-502, AT-602, and AT-802
equipped with the GAIP four-point inflatable restraint. Should GAIP
apply at a later date for a supplemental type certificate to modify any
other model on Type Certificate numbers A17SW or AW19SW to incorporate
the same novel or unusual design feature, the special conditions would
apply to that model as well under the provisions of Sec. 21.101(a)(1).
Conclusion
This action affects only certain novel or unusual design features
on Air Tractor model series AT-401, AT-402, AT-502, AT-602, and AT-802
airplanes. It is not a rule of general applicability, and it affects
only the applicant who applied to the FAA for approval of these
features on the airplane.
List of Subjects in 14 CFR Part 23
Aircraft, Aviation safety, Signs and symbols.
[[Page 71493]]
Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113 and 44701; 14 CFR 21.16 and
21.101 for STC or 21.17 for TC; and 14 CFR 11.38 and 11.19.
The Proposed Special Conditions
The FAA has determined that this project will be accomplished on
the basis of not lowering the current level of safety for the Air
Tractor Model AT-401, -402, -502, -602, and -802 series occupant
restraint design. Accordingly, the (FAA) proposes the following special
conditions as part of the type certification basis for Air Tractor
series airplanes AT-401, AT-402, AT-502, AT-602, and AT-802 modified by
Goodrich Aircraft Interior Products.
4-Point Inflatable Restraints for Agricultural Airplanes
1. It must be shown that the inflatable seatbelt will deploy and
provide protection under crash conditions where it is necessary to
prevent serious injury. A dynamic test is required to verify that the
system operates as intended when subjected to the 26 G deceleration
pulse described in Sec. 23.562(b)(2). The dynamic test need only be
performed using a 50 percentile male ATD.
2. The means of protection must take into consideration a range of
stature from a 5 percentile female to a 95 percentile male. The
inflatable seatbelt must provide a consistent level of energy
absorption throughout that range.
3. The design must prevent the inflatable seatbelt from either
being incorrectly buckled or incorrectly installed, or both, such that
the airbag would not properly deploy.
4. It must be shown that an inadvertent deployment does not cause
an unsafe condition (or hazard to the airplane). Consideration needs to
be given as a result of wear and tear, or inertial loads resulting from
in-flight or ground maneuvers (including gusts and hard landings),
likely to be experienced in service. The seat belt must have the same
strength capability after the inflatable portion of the restraint has
been deployed.
5. It must be shown that deployment of the device is not hazardous
to the occupant. In addition, the seated occupant must not be injured
as established by criteria in Sec. 23.562 as a result of the
inflatable seatbelt deployment, including keeping the lap belt located
on the pelvis.
6. It must be shown that the inflatable seatbelt will not impede
rapid egress of the occupant 10 seconds after its deployment.
7. For the purpose of complying with HIRF and lightning
requirements, the inflatable seatbelt system is considered a ``critical
system'' if its deployment could have a hazardous effect on the
airplane; otherwise, it is considered an ``essential'' system.
8. It must be shown that the inflatable seatbelt will not release
hazardous quantities of gas or particulate matter into the cabin.
9. The inflatable seatbelt installation must be protected from the
effects of fire such that no hazard to occupants will result.
10. There must be a means to verify the integrity of the inflatable
seatbelt activation system before each flight or it must be
demonstrated to reliably operate between inspection intervals.
11. A life limit needs to be established for appropriate system
designs.
12. Qualification testing of the internal firing mechanism must be
accomplished using the vibration levels appropriate for an agricultural
airplane.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 02-30325 Filed 11-29-02; 8:45 am]
BILLING CODE 4910-13-M