[Federal Register Volume 76, Number 38 (Friday, February 25, 2011)]
[Rules and Regulations]
[Pages 10489-10492]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-4229]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 27
[Docket No. SW025; Special Conditions No. 27-025-SC]
Special Conditions: Bell Helicopter Textron Canada Limited Model
407 Helicopter, Installation of a Hoh Aeronautics, Inc. Autopilot/
Stabilization Augmentation System (AP/SAS)
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for the modification of
the Bell Helicopter Textron Canada Limited (Bell) model 407 helicopter.
This model helicopter will have novel or unusual design features when
modified by installing the Hoh Aeronautics, Inc. (Hoh) complex
Autopilot/Stabilization Augmentation System (AP/SAS) that has potential
failure conditions with more severe adverse consequences than those
envisioned by the existing applicable airworthiness regulations. These
special conditions contain the added safety standards the Administrator
considers necessary to ensure the failures and their effects are
sufficiently analyzed and contained.
DATES: The effective date of these special conditions is February 14,
2011. We must receive your comments by April 26, 2011.
ADDRESSES: You must mail your comments to: Federal Aviation
Administration, Rotorcraft Directorate, Attn: Rules Docket (ASW-111),
Docket No. SW025, 2601 Meacham Blvd., Fort Worth, Texas 76137. You may
deliver your comments to the Rotorcraft Directorate at the indicated
address. You must mark your comments: Docket No. SW025. You can inspect
comments in the Rules Docket weekdays, except Federal holidays, between
8:30 a.m. and 4 p.m., in the Rotorcraft Directorate.
FOR FURTHER INFORMATION CONTACT: Mark Wiley, Aviation Safety Engineer,
FAA, Rotorcraft Directorate, Regulations and Policy Group (ASW-111),
2601 Meacham Blvd., Fort Worth, Texas 76137; telephone (817) 222-5134;
facsimile (817) 222-5961.
SUPPLEMENTARY INFORMATION:
The FAA has determined that notice and opportunity for prior public
comment hereon are impracticable because these procedures would
significantly delay issuance of the design approval and thus delivery
of the affected aircraft. In addition, the substance of these special
conditions has been subject to the public comment process previously
with no substantive comments received. The FAA therefore finds that
good cause exists for making these special conditions effective on
issuance.
Comments Invited
While we did not precede this with a notice of proposed special
conditions, we invite interested people to take part in this action by
sending written comments, data, or views. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any
[[Page 10490]]
recommended change, and include supporting data.
We will file in the special conditions docket all comments we
receive, as well as a report summarizing each substantive public
contact with FAA personnel about these special conditions. You can
inspect the docket before and after the comment closing date. If you
wish to review the docket in person, go to the address in the ADDRESSES
section of this document between 8:30 a.m. and 4 p.m., Monday through
Friday, except Federal holidays.
We will consider all comments we receive by the closing date for
comments. We will consider comments filed late if it is possible to do
so without incurring expense or delay. We may change these special
conditions based on the comments we receive.
If you want us to let you know we received your mailed comments on
these special conditions, send us a pre-addressed, stamped postcard on
which the docket number appears. We will stamp the date on the postcard
and mail it back to you.
Background
On July 16, 2009, Hoh submitted an application to the FAA's Los
Angeles Aircraft Certification Office (LA ACO) for a supplemental type
certification (STC) to install an AP/SAS on a Bell model 407
helicopter. The Bell model 407 helicopter is a 14 CFR part 27 Normal
category, single turbine engine, conventional helicopter designed for
civil operation. This helicopter model is capable of carrying six
passengers with one pilot, and has a maximum gross weight of
approximately 5,250 pounds, depending on the configuration. The major
design features include a 4-blade, soft-in-plane main rotor, a 2-blade
anti-torque tail rotor, a skid landing gear, and a visual flight rule
(VFR) basic avionics configuration. Hoh proposes to modify a model 407
Bell helicopter by installing a two-axis AP/SAS.
Type Certification Basis
Under 14 CFR 21.115, Hoh must show that the Bell model 407
helicopter, as modified by the installed AP/SAS, continues to meet the
14 CFR 21.101 standards. The baseline of the certification basis for
the unmodified Bell model 407 helicopter is listed in Type Certificate
Number H2SW. Additionally, compliance must be shown to any applicable
equivalent level of safety findings, exemptions, and special
conditions, prescribed by the Administrator as part of the
certification basis.
If the Administrator finds the applicable airworthiness regulations
(that is, 14 CFR part 27), as they pertain to this STC, do not contain
adequate or appropriate safety standards for the Bell model 407
helicopter because of a novel or unusual design feature, special
conditions are prescribed under Sec. 21.101(d).
In addition to the applicable airworthiness regulations and special
conditions, Hoh must show compliance of the AP/SAS STC-altered Bell
model 407 helicopter with the noise certification requirements of 14
CFR part 36.
The FAA issues special conditions, as defined in Sec. 11.19, under
Sec. 11.38 and they become part of the type certification basis under
Sec. 21.101.
Novel or Unusual Design Features
The Hoh AP/SAS incorporates novel or unusual design features, for
installation in a Bell model 407 helicopter, Type Certificate Number
H2SW. This AP/SAS performs non-critical control functions, since this
model helicopter has been certificated to meet the applicable
requirements independent of this system. However, the possible failure
conditions for this system, and their effect on continued safe flight
and landing of the helicopter, are more severe than those envisioned by
the present rules.
Discussion
The effect on safety is not adequately covered under Sec. 27.1309
for the application of new technology and new application of standard
technology. Specifically, the present provisions of Sec. 27.1309(c) do
not adequately address the safety requirements for systems whose
failures could result in catastrophic or hazardous/severe-major failure
conditions, or for complex systems whose failures could result in major
failure conditions.
To comply with the provisions of the special conditions, we require
that Hoh provide the FAA with a systems safety assessment (SSA) for the
final AP/SAS installation configuration that will adequately address
the safety objectives established by the functional hazard assessment
(FHA) and the preliminary system safety assessment (PSSA), including
the fault tree analysis (FTA). This must ensure that all failure
conditions and their resulting effects are adequately addressed for the
installed AP/SAS. The SSA process, FHA, PSSA, and FTA are all parts of
the overall safety assessment (SA) process discussed in FAA Advisory
Circular (AC) 27-1B (Certification of Normal Category Rotorcraft) and
Society of Automotive Engineers (SAE) document Aerospace Recommended
Practice (ARP) 4761 (Guidelines and Methods for Conducting the Safety
Assessment Process on Civil Airborne Systems and Equipment).
These special conditions require that the AP/SAS installed on a
Bell model 407 helicopter meet the requirements to adequately address
the failure effects identified by the FHA, and subsequently verified by
the SSA, within the defined design integrity requirements.
Applicability
These special conditions are applicable to the Hoh AP/SAS installed
as an STC approval, in Bell model 407 helicopter, Type Certificate
Number H2SW.
Conclusion
This action affects only certain novel or unusual design features
for a Hoh AP/SAS STC installed on one model helicopter. It is not a
rule of general applicability and affects only the applicant who
applied to the FAA for approval of these features on the helicopter.
The substance of these special conditions has been subjected to the
notice and comment period previously and has been derived without
substantive change from those previously issued. It is unlikely that
prior public comment would result in a significant change from the
substance contained herein. Therefore, because a delay would
significantly affect the certification of the helicopter, which is
imminent, the FAA has determined that prior public notice and comment
are unnecessary and impracticable, and good cause exists for adopting
these special conditions upon issuance. The FAA is requesting comments
to allow interested persons to submit views that may not have been
submitted in response to the prior opportunities for comment.
List of Subjects in 14 CFR Part 27
Aircraft, Aviation safety.
The authority citation for these special conditions is as follows:
Authority: 42 U.S.C. 7572, 49 U.S.C. 106(g), 40105, 40113,
44701-44702, 44704, 44709, 44711, 44713, 44715, 45303.
The Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the Hoh Aeronautics, Inc. (Hoh) supplemental type certificate basis for
the installation of an autopilot/stability augmentation system (AP/SAS)
on the Bell Helicopter Textron Canada Limited (Bell) model
[[Page 10491]]
407 helicopter, Type Certificate Number H2SW.
The AP/SAS must be designed and installed so that the failure
conditions identified in the Functional Hazard Assessment and verified
by the System Safety Assessment, after design completion, are
adequately addressed in accordance with the ``failure condition
categories'' and ``requirements'' sections (including the system design
integrity, design environmental, and test and analysis requirements) of
these special conditions.
Failure Condition Categories Failure conditions are classified,
according to the severity of their effects on the rotorcraft, into one
of the following categories:
1. No Effect--Failure conditions that would have no effect on
safety; for example, failure conditions that would not affect the
operational capability of the rotorcraft or increase crew workload;
however, could result in an inconvenience to the occupants, excluding
the flight crew.
2. Minor--Failure conditions which would not significantly reduce
rotorcraft safety, and which would involve crew actions that are well
within their capabilities. Minor failure conditions would include, for
example, a slight reduction in safety margins or functional
capabilities, a slight increase in crew workload, such as, routine
flight plan changes, or result in some physical discomfort to
occupants.
3. Major--Failure conditions which would reduce the capability of
the rotorcraft or the ability of the crew to cope with adverse
operating conditions to the extent that there would be, for example, a
significant reduction in safety margins or functional capabilities, a
significant increase in crew workload or result in impairing crew
efficiency, physical distress to occupants, including injuries, or
physical discomfort to the flight crew.
4. Hazardous/Severe-Major--Failure conditions which would reduce
the capability of the rotorcraft or the ability of the crew to cope
with adverse operating conditions to the extent that there would be:
A large reduction in safety margins or functional
capabilities;
Physical distress or excessive workload that would impair
the flight crew's ability to the extent that they could not be relied
on to perform their tasks accurately or completely; or,
Possible serious or fatal injury to a passenger or a cabin
crewmember, excluding the flight crew.
Note 1: ``Hazardous/severe-major'' failure conditions can
include events that are manageable by the crew by the use of proper
procedures, which, if not implemented correctly or in a timely
manner, may result in a catastrophic event.
5. Catastrophic--Failure conditions which would result in multiple
fatalities to occupants, fatalities or incapacitation to the flight
crew, or result in loss of the rotorcraft.
The present Sec. Sec. 27.1309(b) and (c) regulations do not
adequately address the safety requirements for systems whose failures
could result in ``catastrophic'' or ``hazardous/severe-major'' failure
conditions, or for complex systems whose failures could result in
``major'' failure conditions. The current regulations are inadequate
because when Sec. Sec. 27.1309(b) and (c) were promulgated, it was not
envisioned that this type of rotorcraft would use systems that are
complex or whose failure could result in ``catastrophic'' or
``hazardous/severe-major'' effects on the rotorcraft. This is
particularly true with the application of new technology, new
application of standard technology, or other applications not
envisioned by the rule that affect safety.
Hoh must provide the FAA with a systems safety assessment (SSA) for
the final AP/SAS installation configuration that will adequately
address the safety objectives established by the functional hazard
assessment (FHA) and the preliminary system safety assessment (PSSA),
including the fault tree analysis (FTA). This will show that all
failure conditions and their resulting effects are adequately addressed
for the installed AP/SAS.
Note 2: The SSA process, FHA, PSSA, and FTA are all parts of the
overall safety assessment (SA) process discussed in FAA Advisory
Circular (AC) 27-1B (Certification of Normal Category Rotorcraft)
and Society of Automotive Engineers (SAE) document Aerospace
Recommended Practice (ARP) 4761 (Guidelines and Methods for
Conducting the Safety Assessment Process on Civil Airborne Systems
and Equipment).
Requirements
Hoh must comply with the existing requirements of Sec. 27.1309 for
all applicable design and operational aspects of the AP/SAS with the
failure condition categories of ``no effect,'' and ``minor,'' and for
non-complex systems whose failure condition category is classified as
``major.'' Hoh must comply with the requirements of these special
conditions for all applicable design and operational aspects of the AP/
SAS with the failure condition categories of ``catastrophic'' and
``hazardous severe/major,'' and for complex systems whose failure
condition category is classified as ``major.''
A complex system is a system whose operations, failure conditions,
or failure effects are difficult to comprehend without the aid of
analytical methods (for example, FTA, Failure Modes and Effect
Analysis, FHA).
System Design Integrity Requirements
Each of the failure condition categories defined in these special
conditions relate to the corresponding aircraft system integrity
requirements. The system design integrity requirements, for the Hoh AP/
SAS, as they relate to the allowed probability of occurrence for each
failure condition category, and the proposed software design assurance
level, are as follows:
``Major''--For systems with ``major'' failure conditions,
failures resulting in these major effects must be shown to be remote, a
probability of occurrence on the order of between 1 x 10 -5
to 1 x 10 -7 failures/hour, and associated software must be
developed to the RTCA/DO-178B (Software Considerations in Airborne
Systems And Equipment Certification) Level C software design assurance
level.
``Hazardous/Severe-Major''--For systems with ``hazardous/
severe-major'' failure conditions, failures resulting in these
hazardous/severe-major effects must be shown to be extremely remote, a
probability of occurrence on the order of between 1 x 10 -7
to 1 x 10 -9 failures/hour, and associated software must be
developed to the RTCA/DO-178B (Software Considerations in Airborne
Systems and Equipment Certification) Level B software assurance level.
``Catastrophic''--For systems with ``catastrophic''
failure conditions, failures resulting in these catastrophic effects
must be shown to be extremely improbable, a probability of occurrence
on the order of 1 x 10 -9 failures/hour or less, and
associated software must be developed to the RTCA/DO-178B (Software
Considerations in Airborne Systems and Equipment Certification) Level A
design assurance level.
System Design Environmental Requirements
The AP/SAS system equipment must be qualified to the appropriate
environmental level per RTCA document DO-160F (Environmental Conditions
and Test Procedures for Airborne Equipment), for all relevant aspects.
This is to show that the AP/SAS system performs its intended function
under any foreseeable operating condition, which includes the expected
environment in which the AP/
[[Page 10492]]
SAS is intended to operate. Some of the main considerations for
environmental concerns are installation locations and the resulting
exposure to environmental conditions for the AP/SAS system equipment,
including considerations for other equipment that may be affected
environmentally by the AP/SAS equipment installation.The level of
environmental qualification must be related to the severity of the
considered failure conditions and effects on the rotorcraft.
Test & Analysis Requirements
Compliance with the requirements of these special conditions may be
shown by a variety of methods, which typically consist of analysis,
flight tests, ground tests, and simulation, as a minimum. Compliance
methodology is related to the associated failure condition category. If
the AP/SAS is a complex system, compliance with the requirements for
failure conditions classified as ``major'' may be shown by analysis, in
combination with appropriate testing to validate the analysis.
Compliance with the requirements for failure conditions classified as
``hazardous/severe-major'' may be shown by flight-testing in
combination with analysis and simulation, and the appropriate testing
to validate the analysis. Flight tests may be limited for ``hazardous/
severe-major'' failure conditions and effects due to safety
considerations. Compliance with the requirements for failure conditions
classified as ``catastrophic'' may be shown by analysis, and
appropriate testing in combination with simulation to validate the
analysis. Very limited flight tests in combination with simulation are
used as a part of a showing of compliance for ``catastrophic'' failure
conditions. Flight tests are performed only in circumstances that use
operational variations, or extrapolations from other flight performance
aspects to address flight safety.
These special conditions require that the Hoh AP/SAS system
installed on a Bell model 407 helicopter, Type Certificate Number H2SW,
meet these requirements to adequately address the failure effects
identified by the FHA, and subsequently verified by the SSA, within the
defined system design integrity requirements.
Issued in Fort Worth, Texas, on February 14, 2011.
Kimberly K. Smith,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 2011-4229 Filed 2-24-11; 8:45 am]
BILLING CODE 4910-13-P