[Federal Register Volume 68, Number 198 (Tuesday, October 14, 2003)]
[Rules and Regulations]
[Pages 59095-59097]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-25950]



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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]
BILLING CODE 4910-13-P