[Federal Register: October 14, 2003 (Volume 68, Number 198)]
[Rules and Regulations]
[Page 59095-59097]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr14oc03-5]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 23
[Docket No. CE197; Special Conditions No. 23-138-SC]
Special Conditions: AMSAFE, Incorporated, Zenair Model CH2000,
Inflatable Three-Point Self-Adjusting Restraint Safety Belt With an
Integrated Inflatable Airbag Device
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
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SUMMARY: These special conditions are issued for the installation of an
AMSAFE, Inc. Inflatable Three-Point Self-Adjusting Restraint Safety
Belt with an Integrated Inflatable Airbag Device on the Zenair model
CH2000. This airplane, as modified by AMSAFE, Inc. will have novel and
unusual design features associated with the lap belt portion of the
safety belt, which contains an integrated airbag device. The applicable
airworthiness regulations do not contain adequate or appropriate safety
standards for this design feature. These 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.
EFFECTIVE DATE: October 2, 2003.
FOR FURTHER INFORMATION CONTACT: Mr. 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:
Background
On March 8, 2003, AMSAFE, Inc. Inflatable Restraints Division, 5456
East McDowell Road, Mesa, AZ, 85215, applied for a supplemental type
certificate to install an inflatable lapbelt restraint with a standard
upper torso restraint (or shoulder harness) in the Zenair model CH2000.
The model CH2000 is a single-engine, two-place airplane with a stall
speed in the landing configuration that is below 45 knots.
The inflatable restraint system is a three-point restraint system
consisting of a shoulder harness and an inflatable airbag lap belt, and
will be installed on both the pilot and co-pilot seats. In the event of
an emergency landing, the airbag will inflate and provide a protective
cushion between the occupant's head and the airplane's yoke and
instrument panel. This will reduce the potential for head and torso
injury. The inflatable restraint behaves in a manner that is similar to
an automotive airbag, but in this case, the airbags are integrated into
the lapbelt. The shoulder harness is conventional and does not inflate.
While airbags and inflatable restraints are standard in the automotive
industry, the use of an inflatable three-point restraint is novel for
general aviation operations.
The FAA has determined that this project will be accomplished on
the basis of providing the same current level of safety of the model
CH2000 occupant restraint design. The FAA has considered the
installation of airbags as having two primary safety concerns:
[sbull] That they perform properly under foreseeable operating
conditions; and
[sbull] That they do not perform in a manner or at such times as to
impede the pilot's ability to maintain control of the airplane or
constitute a hazard to the airplane or occupants.
The latter point has the potential to be the more rigorous of the
requirements. An unexpected deployment while conducting the takeoff and
landing phases of flight may result in an unsafe condition. The
unexpected deployment may either startle the pilot, or generate a force
sufficient to cause a sudden movement of the control yoke. Either
action could result in a loss of control of the airplane, the
consequences of which are magnified due to the low operating altitudes
during these phases of flight. The FAA has considered this when
establishing the special conditions.
The inflatable airbag is integrated into the lap belt and relies on
sensors to electronically activate the inflator for deployment. 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. AMSAFE, Inc. must show that the effects of
an inadvertent deployment in flight are not a hazard to the airplane or
that an inadvertent deployment is extremely improbable. In addition,
any general aviation aircraft can generate a large amount of cumulative
wear and tear on a 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
appropriate system components in the restraint system design.
There are additional factors to be considered to minimize the
chances of inadvertent deployment. General aviation airplanes are
exposed to a unique operating environment, since the same airplane may
be used by both experienced and student pilots. The effect of this
environment on inadvertent deployment of the restraint must be
understood. Therefore, qualification testing of the firing hardware/
software must consider the following:
[sbull] The airplane vibration levels appropriate for a general
aviation airplane; 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) and lightning. Since the sensors that
trigger deployment are electronic, they must be protected from the
effects of these threats. To comply with HIRF and lightning
requirements, the AMSAFE, Inc. inflatable restraint system is
considered a critical system, since its inadvertent deployment could
have a hazardous effect on the airplane.
Given the level of safety of the current Zenair model CH2000 lap
belt and shoulder harness restraint, the inflatable restraint must show
that it will offer an equivalent level of protection in the event of an
emergency landing. In the event of an inadvertent deployment, the
restraint must still be at least as strong as a Technical Standard
Order certificated belt and shoulder harness. 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
for each occupant under a crash condition where it is necessary to
prevent serious head injury. However, the Zenair CH2000 seats are not
certificated to the requirements specified in Sec. 23.562 and it is
not known if they would remain intact following exposure to the crash
pulse identified in Sec. 23.562. Therefore, the test crash pulse used
to satisfy this requirement may have a peak longitudinal deceleration
lower than that required by Sec. 23.562. However, the test pulse must
have an onset rate (deceleration divided by time) equal to or greater
than the onset rate of the
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pulse described in Sec. 23.562. This will demonstrate that the crash
sensor will trigger when exposed to a rapidly applied deceleration,
like an actual crash event.
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. Energy absorption must be performed
in a consistent manner for this occupant range.
In support of this operational capability, there must be a means to
verify the integrity of this system before each flight. As an option,
AMSAFE, Inc. can establish inspection intervals where they have
demonstrated the system to be reliable between these intervals.
It is possible that an inflatable restraint will be ``armed'' even
though no occupant is using the seat. While there will be means to
verify the integrity of the system before flight, it's also prudent to
require that unoccupied seats with active restraints not constitute a
hazard to any occupant. This will protect any individual performing
maintenance items inside the cockpit while the aircraft is on the
ground and includes protection against inadvertent deployment.
In addition, the use and 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. As an alternative,
AMSAFE, Inc. may show that such deployment is not hazardous to the
occupant, and will still provide the required protection.
The cockpit of the model CH2000 is a confined area, and the FAA is
concerned that noxious gasses may accumulate in the event the
inflatable restraint deploys. When deployment does occur, either by
design or inadvertently, there must not be a release of hazardous
quantities of gas or particulate matter into the cockpit area.
Fire is a concern for any airplane, regardless of the size or class
of the airplane. An inflatable restraint should not increase the risk
already associated with fire. Therefore, 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 inflator.
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 restraint 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, AMSAFE, Inc. must show that
the Zenair model CH2000, as changed, continues to meet the applicable
provisions of the regulations incorporated by reference in Type
Certificate No. TA5CH 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. TA5CH are as follows:
FAR 21.29 and FAR 23 effective February 1, 1965, as amended by 23-1
through 23-42.
JAR-VLA effective April 26, 1990, through Amendment VLA/92/1 effective
January 1, 1992, used as a safety equivalence to FAR 23, as provided by
AC 23-11.
FAR 36 dated December 1, 1969, as amended by current amendment as of
date of type certification.
For the 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 AMSAFE, Inc. inflatable restraint
as installed on Zenair model CH2000 because of a novel or unusual
design feature. Therefore, special conditions are prescribed under the
provisions of Sec. 21.16.
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.
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.
Novel or Unusual Design Features
The Zenair model CH2000 will incorporate the following novel or
unusual design feature:
The AMSAFE, Inc. Inflatable Three-Point Self-Adjusting Restraint
safety belt with an integrated inflatable airbag device. The purpose of
the inflatable airbag seatbelt is to reduce the potential for injury in
the event of an accident. In a severe impact, an airbag will deploy
from the lapbelt portion of the restraint, in a manner similar to an
automotive airbag. The airbag will deploy between the head of the
occupant and the airplane's yoke and instrument panel. This will,
therefore, provide some protection to the head of the occupant. The
restraint will rely on sensors to electronically activate the inflator
for deployment.
Title 14 of the Code of Federal Regulations, parts 21 and 23,
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. 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
this inflatable restraint.
Accordingly, these special conditions are adopted for the Zenair
model CH2000 equipped with the AMSAFE, Inc. Three-Point Self-Adjusting
Restraint safety belt with an integrated inflatable airbag device.
Other conditions may be developed, as needed, based on further FAA
review and discussions with the manufacturer and civil aviation
authorities.
Discussion of Comments
Notice of proposed special conditions No. 23-03-01-SC for the
Zenair model CH2000 equipped with the AMSAFE, Inc. Three-Point Self-
Adjusting Restraint safety belt with an integrated airbag device was
published on July 17, 2003 (68 FR 42315). One comment was received,
regarding the requirement that the lapbelt must deploy and provide
protection under the crash conditions specified in Sec. 23.562
(proposed Special Condition No. 1).
The commenter is in general agreement with the special conditions
proposed for this particular program. In addition, the commenter is in
agreement that a dynamic test is necessary to demonstrate the
deployment timing and positioning of the inflatable lapbelt. However,
the commenter states that proposed SC No. 1, as written, requires the
inflatable restraint to operate only when subjected to the crash pulse
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identified in Sec. 23.562. In addition, since the seats installed in
the Zenair CH2000 do not meet the requirements of Sec. 23.562, an
inflatable restraint that operates only after being exposed to this
pulse may offer little benefit.
The commenter suggests that reference to Sec. 23.562 be retained,
but allow for the following:
[sbull] The test pulse may have a reduction in the peak
longitudinal deceleration but the onset rate (deceleration divided by
time) must be equal to or greater than the pulse specified in Sec.
23.562.
[sbull] The peak longitudinal deceleration must be greater than the
deployment threshold of the crash sensor.
[sbull] The peak longitudinal deceleration must be equal to or
greater than the forward static design load factors required by the
original certification basis of the airplane.
The FAA concurs. The seats installed in the Zenair CH2000 may not
satisfy the requirements of Sec. 23.562, so it is not appropriate to
install an inflatable restraint that will deploy only when subjected to
the crash pulse specified in Sec. 23.562. The FAA agrees that the test
pulse used to satisfy the dynamic test requirements must be less severe
than that specified in Sec. 23.562. In addition, we agree with the
commenter that the onset rate of the test pulse should be equal to or
greater than the onset rate of the pulse required by Sec. 23.562. This
will show that the crash sensor will trigger when exposed to a high
deceleration that builds up in rapid time, like a real crash event.
The FAA will incorporate the commenter's input into Special
Condition No. 1.
Applicability
As discussed above, these special conditions are applicable to the
Zenair model CH2000 equipped with the AMSAFE, Inc. Three-Point Self-
Adjusting Restraint safety belt with an integrated inflatable airbag
device. Should AMSAFE, Inc. apply at a later date for a supplemental
type certificate to modify any other model on Type Certificate number
TA5CH 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.
Conclusion
This action affects only certain novel or unusual design features
on the Zenair model CH2000. 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.
Citation
0
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; and 14 CFR 11.38 and 11.19.
The Special Conditions
0
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the typ certification basis for the Zenair model CH2000, as modified by
AMSAFE, Inc.
Three-Point Self-Adjusting Restraint Safety Belt With an Integrated
Airbag Device
1. It must be shown that the inflatable lapbelt will deploy and
provide protection under crash conditions where it is necessary to
prevent serious head injuries. Compliance will be demonstrated using
the dynamic test condition specified in Sec. 23.562, which may be
modified as follows:
a. The peak longitudinal deceleration may be reduced, however the
onset rate of the deceleration must be equal to or greater then the
crash pulse identified in Sec. 23.562.
b. The peak longitudinal deceleration must be above the deployment
threshold of the crash sensor, and equal to or greater than the forward
static design longitudinal load factor required by the original
certification basis of the airplane.
The means of protection must take into consideration a range of
stature from a 5th percentile female to a 95th percentile male. The
inflatable lapbelt must provide a consistent approach to energy
absorption throughout that range.
2. The inflatable lapbelt must provide adequate protection for each
occupant. In addition, unoccupied seats that have active seat belts
must not constitute a hazard to any occupant.
3. The design must prevent the inflatable safety belt from being
incorrectly buckled and/or incorrectly installed such that the airbag
would not properly deploy. Alternatively, it must be shown that such
deployment is not hazardous to the occupant and will provide the
required protection.
4. It must be shown that the inflatable lapbelt system is not
susceptible to inadvertent deployment as a result of wear and tear or
inertial loads resulting from in-flight or ground maneuvers (including
gusts and hard landings) that are likely to be experienced in service.
5. It must be shown (or be extremely improbable) that an
inadvertent deployment of the restraint system during the most critical
part of the flight does not impede the pilot's ability to maintain
control of the airplane or cause an unsafe condition (or hazard to the
airplane). In addition, a deployed inflatable restraint must be at
least as strong as a Technical Standard Order certificated belt and
shoulder harness.
6. It must be shown that deployment of the restraint system is not
hazardous to the occupant or result in injuries that could impede rapid
egress. This assessment should include occupants whose belt is loosely
fastened.
7. It must be shown that an inadvertent deployment that could cause
injury to a standing or sitting person is improbable.
8. It must be shown that the inflatable safety belt will not impede
rapid egress of the occupants 10 seconds after its deployment.
9. For the purposes of complying with HIRF and lightning
requirements, the inflatable safety belt system is considered a
critical system since its deployment could have a hazardous effect on
the airplane.
10. It must be shown that the inflatable safety belt will not
release hazardous quantities of gas or particulate matter into the
cabin.
11. The inflatable safety belt installation must be protected from
the effects of fire such that no hazard to occupants will result.
12. There must be a means to verify the integrity of the inflatable
safety belt activation system prior to each flight or it must be
demonstrated to reliably operate between inspection intervals.
13. A life limit must be established for appropriate system
components.
14. Qualification testing of the internal firing mechanism must be
performed at vibration levels appropriate for a general aviation
airplane.
Issued in Kansas City, Missouri, on October 2, 2003.
Dorenda D. Baker,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 03-25950 Filed 10-10-03; 8:45 am]
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