Document ID: FAA-2019-0546-0001
Agency: faa
Document Type: Proposed Rule
Title: Special Conditions: Bell Helicopter Textron Canada Limited, Model Bell 505, Visual Flight Rules Autopilot and Stability Augmentation System
Posted Date: 2019-11-21T05:00Z

[Federal Register Volume 84, Number 225 (Thursday, November 21, 2019)]
[Proposed Rules]
[Pages 64233-64234]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-25291]

[[Page 64233]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 27

[Docket No. FAA-2019-0546; Notice No. 27-048-SC]

Special Conditions: Bell Helicopter Textron Canada Limited, Model 
Bell 505, Visual Flight Rules Autopilot and Stability Augmentation 
System (AP/SAS System)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: These special conditions are proposed for the Bell Helicopter 
Textron Canada Limited (BHTCL) Bell Model 505 helicopter. This 
helicopter as modified by S-TEC will have a novel or unusual design 
feature associated with installation of the autopilot and stability 
augmentation system (AP/SAS system). 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.

DATES: Send your comments on or before December 23, 2019.

ADDRESSES: Send comments identified by docket number [FAA-2019-0546] 
using any of the following methods:
    [squ] Federal eRegulations Portal: Go to http://www.regulations.gov 
and follow the online instructions for sending your comments 
electronically.
    [squ] Mail: Send comments to Docket Operations, M-30, U.S. 
Department of Transportation (DOT), 1200 New Jersey Avenue SE, Room 
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
    [squ] Hand Delivery of Courier: Take comments to Docket Operations 
in Room W12-140 of the West Building Ground Floor at 1200 New Jersey 
Avenue SE, Washington, DC, between 8 a.m., and 5 p.m., Monday through 
Friday, except Federal holidays.
    [squ] Fax: Fax comments to Docket Operations at 202-493-2251.
    Privacy: The FAA will post all comments it receives, without 
change, to http://www.regulations.gov, including any personal 
information the commenter provides. Using the search function of the 
docket website, anyone can find and read the electronic form of all 
comments received into any FAA docket, including the name of the 
individual sending the comment (or signing the comment for an 
association, business, labor union, etc.). DOT's complete Privacy Act 
Statement can be found in the Federal Register published on April 11, 
2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov.
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov at any time. Follow the online instructions 
for accessing the docket or go to the Docket Operations in Room W12-140 
of the West Building Ground Floor at 1200 New Jersey Avenue SE, 
Washington, DC, between 9 a.m., and 5 p.m., Monday through Friday, 
except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Andy Shaw, Aerospace Engineer, FAA, 
Rotorcraft Standards Branch, Policy and Innovation Division, 10101 
Hillwood Pkwy., Fort Worth, TX 76177; telephone (817) 222-5384; email 
Andy.Shaw@faa.gov.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    The FAA invites interested people 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.
    The FAA will consider all comments received by the closing date for 
comments. The FAA will consider comments filed late if it is possible 
to do so without incurring expense or delay. The FAA may change these 
special conditions based on the comments received.

Background

    On January 21, 2019, S-TEC applied for a supplemental type 
certificate (STC) to install an AP/SAS system on the Bell Model 505 
helicopter. The Bell Model 505 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 up to 
four passengers with one pilot and has a maximum gross weight of up to 
4,475 pounds, depending on the model configuration. The major design 
features include a 2-blade main rotor, an anti-torque tail rotor 
system, a skid landing gear, and a visual flight rule basic avionics 
configuration. S-TEC proposes to modify this model helicopter by 
installing an AP/SAS system.
    The AP/SAS system provides attitude stabilization in two or three 
axes (pitch and roll with optional yaw) as well as higher-level 
autopilot functions such as altitude hold, heading command and 
navigation tracking. However, the possible failure conditions for this 
system, and their effect on the continued safe flight and landing of 
the helicopter, are more severe than those envisioned by the present 
rules.
    The effect on safety is not adequately covered under 14 CFR 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. The current regulations are inadequate because when 
Sec.  27.1309(c) was promulgated, it was not envisioned that a normal 
category 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. Possible 
failure modes exhibited by the S-TEC AP/SAS system could result in a 
catastrophic event.

Type Certification Basis

    Under 14 CFR 21.101, S-TEC must show that the Bell Model 505 
helicopter, as modified by the installed AP/SAS, continues to meet the 
applicable regulations incorporated by reference in the Type 
Certificate Number R00008RD. 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 Number R00008RD are as follows:

14 CFR part 27, dated October 2, 1964, amendment 27-1 through 27-47
14 CFR part 36, amendment 36-1 through 36-30

    In addition, the certification basis includes certain equivalent 
level of safety findings that are not relevant to these special 
conditions.
    The Administrator has determined 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 
505 helicopter because of a novel or unusual design feature. Therefore, 
special conditions are prescribed under Sec.  21.16.
    Special conditions are initially applicable to the model for which 
they

[[Page 64234]]

are issued. Should S-TEC apply for an STC 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 the 
other model.
    The FAA issues special conditions, as defined in Sec.  11.19, in 
accordance with Sec.  11.38 and they become part of the type 
certification basis under Sec.  21.101(d).

Novel or Unusual Design Features

    The Bell Model 505 helicopter will incorporate the following novel 
or unusual design features: AP/SAS. An autopilot (AP) is a system used 
to control the trajectory of an aircraft without constant input from 
the pilot. This allows the pilot to focus on other aspects of 
operations such as weather and systems. A stability augmentation system 
(SAS) is another type of automatic flight control system; however, 
instead of maintaining the aircraft on a predetermined attitude or 
flight path, the SAS will reduce pilot workload by dampening aircraft 
buffeting regardless of the attitude or flight path.

Discussion

    To comply with the provisions of the special conditions, the FAA 
proposes to require that S-TEC 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 a 
functional hazard assessment (FHA). This process will ensure that all 
failure conditions and their resulting effects are adequately addressed 
for the installed AP/SAS. The SSA process is part of the overall safety 
assessment process discussed in FAA Advisory Circular 27-1B, 
Certification of Normal Category Rotorcraft, and Society of Automotive 
Engineers document Aerospace Recommended Practice 4761, Guidelines and 
Methods for Conducting the Safety Assessment Process on Civil Airborne 
Systems and Equipment.
    These proposed special conditions would require that the AP/SAS 
installed on a Bell Model 505 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.
    Failure conditions are classified according to the severity of 
their effects on the rotorcraft. Radio Technical Commission for 
Aeronautics, Inc. (RTCA) Document DO-178C, Software Considerations in 
Airborne Systems and Equipment Certification, provides software design 
assurance levels most commonly used for the major, hazardous/severe-
major, and catastrophic failure condition categories. The AP/SAS system 
equipment must be qualified for the expected installation environment. 
The test procedures prescribed in RTCA Document DO-160G, Environmental 
Conditions and Test Procedures for Airborne Equipment, are recognized 
by the FAA as acceptable methodologies for finding compliance with the 
environmental requirements. Equivalent environment test standards may 
also be acceptable. Environmental qualification provides data to show 
that the AP/SAS system can perform its intended function under the 
expected operating condition. 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 also 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.

Applicability

    These special conditions are applicable to the S-TEC AP/SAS 
installed as an STC approval in Bell Model 505 helicopters, Type 
Certificate Number R00008RD.

Conclusion

    This action affects only certain novel or unusual design features 
for an S-TEC 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.

List of Subjects in 14 CFR Part 27

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Proposed Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are proposed as part of 
the S-TEC supplemental type certification basis for installation of an 
autopilot/stabilization augmentation system (AP/SAS) system on Bell 
Model 505 helicopters.
    Instead of the requirements of 14 CFR 27.1309(b) and (c), the 
following must be met for certification of the AP/SAS system installed 
on Bell Model 505 helicopters:
    a. The equipment and systems must be designed and installed so that 
any equipment and systems do not adversely affect the safety of the 
rotorcraft or its occupants.
    b. The rotorcraft systems and associated components considered 
separately and in relation to others systems, must be designed and 
installed so that:
    (1) The occurrence of any catastrophic failure condition is 
extremely improbable;
    (2) The occurrence of any hazardous failure condition is extremely 
remote; and
    (3) The occurrence of any major failure condition is remote.
    c. Information concerning an unsafe system operating condition must 
be provided in a timely manner to the crew to enable them to take 
appropriate corrective action. An appropriate alert must be provided if 
immediate pilot awareness and immediate or subsequent corrective action 
is required. Systems and controls, including indications and 
annunciations, must be designed to minimize crew errors which could 
create additional hazards.

    Issued in Fort Worth, Texas, on November 13, 2019.
Jorge Castillo,
Manager, Rotorcraft Standards Branch, Policy and Innovation Division, 
Aircraft Certification Service.
[FR Doc. 2019-25291 Filed 11-20-19; 8:45 am]
 BILLING CODE 4910-13-P