[Federal Register Volume 74, Number 114 (Tuesday, June 16, 2009)]
[Proposed Rules]
[Pages 28449-28451]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-14103]


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Proposed Rules
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of 
the proposed issuance of rules and regulations. The purpose of these 
notices is to give interested persons an opportunity to participate in 
the rule making prior to the adoption of the final rules.

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Federal Register / Vol. 74, No. 114 / Tuesday, June 16, 2009 / 
Proposed Rules

[[Page 28449]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 21 and 27

[Docket No. SW021; Notice No. 27-021-SC]


Special Conditions: Robinson Helicopter Company R66 Helicopters, 
14 CFR 27.1309, Installation of an Autopilot (AP) Stabilization 
Augmentation System (SAS)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for installing an 
Autopilot Stabilization Augmentation System (AP/SAS) in the Robinson 
Helicopter Company (Robinson) Model R66 helicopter. This helicopter 
will have novel or unusual design features associated with installing a 
complex AP/SAS that has potential failure modes with more severe 
adverse results than those envisioned by the existing applicable 
airworthiness standards. The applicable airworthiness standards do not 
contain adequate or appropriate safety standards for this design 
feature. This proposed special condition contains the added safety 
standards the Administrator considers necessary to establish a level of 
safety equivalent to the existing airworthiness standards.

DATES: We must receive your comments by July 31, 2009.

ADDRESSES: Mail two copies of your comments to: Federal Aviation 
Administration, Rotorcraft Directorate, Attn: Rules Docket (ASW-111), 
Docket No. SW021, 2601 Meacham Blvd., Fort Worth, Texas 76137. You may 
deliver two copies to the Rotorcraft Directorate at this address. You 
must mark your comments for: Docket No. SW021. You may inspect comments 
in the Rules Docket weekdays, except Federal holidays, between 8:30 
a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: George Schwab, Aviation Safety 
Engineer, FAA, Rotorcraft Directorate (ASW-112), Aircraft Certification 
Service, 2601 Meacham Blvd., Fort Worth, Texas, 76137; telephone (817) 
222-5114; facsimile (817) 222-5961.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to take part in this rulemaking by sending written 
comments, data, or views. The most helpful comments reference a 
specific portion of the special conditions, explain the reason for any 
recommended change, and include supporting data. We ask that you send 
us two copies of written comments.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
on 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 on or before the closing 
date for comments. We will consider comments filed late if it is 
possible to do so without incurring additional expense or delay. We may 
change these special conditions based on the comments we receive.
    If you want the FAA to acknowledge receipt of your comments on this 
proposal, include with your comments 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 November 1, 2006, Robinson proposed a change to the 
certification basis, through the FAA's Los Angeles Aircraft 
Certification Office (LA ACO), that would include installing an AP/SAS 
as part of the application for type certification for the Robinson 
Model R66 helicopter. The Robinson Model R66 helicopter is a part 27 
Normal category, single turbine engine, conventional helicopter 
designed for civil operation. The helicopter is capable of carrying 
four passengers with one pilot, and has a maximum gross weight of 
approximately 2,650 pounds. The major design features include a 2-
blade, fully articulated main rotor, a 2-blade anti-torque tail rotor, 
a skid landing gear, and a visual flight rule (VFR) basic avionics 
configuration. Robinson proposes offering the Hoh Aeronautics, Inc. 
two-axis AP/SAS as a factory installed option.

Type Certification Basis

    Under 14 CFR 21.17, Robinson must show that the Model R66 
helicopter meets the applicable provisions of 14 CFR part 27, as 
amended by Amendments 27-1 through 27-40.
    If the Administrator finds the applicable airworthiness standards, 
as they apply to the type certification, do not contain adequate or 
appropriate safety standards because of a novel or unusual design 
feature, special conditions are prescribed under Sec.  21.16.
    Special conditions, as appropriate, are defined in Sec.  11.19, and 
issued by following the procedures in Sec.  11.38 and become part of 
the type certification basis under Sec.  21.17(a)(2).
    Special conditions are initially applicable to the model for which 
they are issued. Should the Type Certificate for that model be amended 
later to include any other model that incorporates the same novel or 
unusual design feature, the special condition would also apply to the 
other model under Sec.  21.101.

Novel or Unusual Design Features

    The Robinson Model R66 helicopter will be required to show 
compliance with the current applicable requirements without the 
optional AP/SAS system. The Hoh Aeronautics, Inc. AP/SAS system will 
constitute a novel or unusual design feature when installed in the 
Model R66 helicopter. Although this AP/SAS system performs non-critical 
control functions, the possible failure modes for this system and their 
effects on the ability of the helicopter to continue safe flight and 
landing are more severe than those envisioned when the present safety 
standards were promulgated. Therefore, additional safety standards are 
necessary.

Discussion

Failure Condition Categories

    The effect on safety is not adequately covered under Sec.  27.1309 
for the application of new technology and new application of standard 
technology.

[[Page 28450]]

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 provision of the special condition, we propose 
to require that Robinson provide the FAA with a Systems Safety 
Assessment (SSA) for the final Hoh Aeronautics Inc. 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 modes 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 SAE document ARP 4761 
(Guidelines and Methods for Conducting the Safety Assessment Process on 
civil airborne Systems and Equipment).
    This special condition requires that the AP/SAS system installed on 
a Robinson Model R66 helicopter meet these requirements to adequately 
address the failure effects identified by the FHA, and subsequently 
verified by the SSA, within the defined design integrity requirements.

Applicability

    As discussed, this special condition is applicable to the Robinson 
Model R66 helicopter with the Hoh Aeronautics, Inc. AP/SAS installed as 
a factory option under the pending application for the Robinson Model 
R66 type certificate. Should Robinson Helicopter Company apply at a 
later date for a change to the type certificate to include another 
model incorporating this same factory installed option Hoh Aeronautics, 
Inc. AP/SAS novel or unusual design feature, this special condition 
would also apply to that model, under the provisions of Sec.  
21.101(b)(1).

Conclusion

    This action affects only the Robinson R66 model series of 
helicopter with the novel or unusual design features of a Hoh 
Aeronautics, Inc. AP/SAS installed. It is not a rule of general 
applicability.

List of Subjects in 14 CFR Parts 21 and 27

    Aircraft, Aviation safety, Exports, Imports, Reporting and 
recordkeeping requirements.

    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 Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes 
the following special conditions as part of the type certification 
basis for Robinson Model R66 helicopters:
    For installation of a Hoh Aeronautics, Inc. Autopilot/Stability 
Augmentation System on a Robinson Model R66 helicopter, the system 
must be designed and installed so that the failure conditions 
identified in the Functional Hazard Assessment and addressed by the 
System Safety Assessment, after design completion, are adequately 
addressed in accordance with the Definitions for the Failure 
Condition Categories and the Requirements (including the design 
integrity, design environmental, and test and analysis requirements) 
of this special condition.

Definitions

    Failure Conditions are conditions that result from a failure and 
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 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 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 that would reduce 
the capability of the rotorcraft or the ability of the crew to cope 
with adverse operating conditions to the extent there would be:
    (i) A large reduction in safety margins or functional 
capabilities;
    (ii) 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
    (iii) Possible serious or fatal injury to a passenger or a cabin 
crewmember, excluding the flight crew.

    Note:  Hazardous/Severe-Major failure conditions can include 
events that are manageable by the crew by use of proper procedures, 
which, if not carried out 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 the inability of the rotorcraft to 
continue safe flight and landing.

Requirements

    Robinson 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, Minor, and 
for non-complex systems whose failure condition category is 
classified as Major. Robinson must also comply with the requirements 
of this special condition 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 
classified as a Major failure condition category.
    A complex system is a system whose operations, failure modes, or 
failure effects are difficult to understand without the aid of 
analytical methods (for example, Fault Tree Analysis, Failure Modes 
and Effect Analysis, Functional Hazard Assessment, etc.).

a. Design Integrity Requirements

    Each of the failure condition categories defined in this special 
condition relate to the corresponding aircraft system integrity 
requirements. The design integrity requirements for the Hoh 
Aeronautics, Inc. 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--Condition classified as a ``Major failure condition'' and 
resulting in Major effects must be shown to be improbable, or at or 
less than 1 x 10<SUP>-5</SUP> failures/hour, and associated software 
must be developed to the RTCA/DO-178B (Software Considerations in 
Airborne Systems And Equipment Certification) software design 
assurance Level C.
    Hazardous/Severe-Major--Condition classified as a ``Hazardous/
Severe-Major failure condition'' and resulting in Hazardous/Severe-
Major effects must be shown to be extremely remote or at or less 
than 1 x 10<SUP>-7</SUP> failures/hour, and associated software must 
be developed to the RTCA/DO-178B (Software Considerations in 
Airborne Systems And Equipment Certification) software design 
assurance Level B.
    Catastrophic--Condition classified as a ``Catastrophic failure 
condition'' and resulting in Catastrophic effects must be shown to 
be extremely improbable or at or less than 1 x 10<SUP>-9</SUP> 
failures/hour, and associated software must be developed to the

[[Page 28451]]

RTCA/DO-178B (Software Considerations in Airborne Systems And 
Equipment Certification) Level A software design assurance level.

b. Design Environmental Requirements

    Robinson must qualify the AP/SAS system equipment to the 
appropriate environmental level in the RTCA document DO-160F 
(Environmental Conditions and Test Procedures for Airborne 
Equipment), for all relevant aspects. This must show that the AP/SAS 
system performs its intended function under any foreseeable 
operating condition, which includes the expected environment in 
which the AP/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 condition and 
effects on the aircraft.

c. Test & Analysis Requirements

    Compliance with these requirements 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 
partly related to the associated failure condition category. If the 
AP/SAS is a complex system, compliance with the requirements for 
aspects of the AP/SAS that can result in failure conditions 
classified as Major may be shown by analysis, in combination with 
appropriate testing to validate the analysis. Compliance with the 
requirements for aspects of the AP/SAS that can result in 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 this classification of failures due to safety 
considerations.
    Compliance with the requirements for aspects of the AP/SAS that 
can result in failure conditions classified as Catastrophic may be 
shown by analysis and validated by appropriate testing in 
combination with simulation. Very limited flight tests in 
combination with simulation may be used as a part of a showing of 
compliance for failures in this classification. Flight tests are 
performed only in circumstances that use operational variations or 
extrapolations from other flight performance aspects to address 
flight safety.

    Issued in Fort Worth, Texas, on June 11, 2009.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. E9-14103 Filed 6-15-09; 8:45 am]
BILLING CODE 4910-13-P