Special Conditions: Sikorsky Aircraft Corporation Model S-92A Helicopter; Installation of a Search and Rescue (SAR) Automatic Flight Control System (AFCS), 77524-77528 [2010-31188]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 75, Number 238 (Monday, December 13, 2010)]
[Rules and Regulations]
[Pages 77524-77528]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-31188]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 29

[Docket No. SW023; Special Conditions No. 29-023-SC]


Special Conditions: Sikorsky Aircraft Corporation Model S-92A 
Helicopter; Installation of a Search and Rescue (SAR) Automatic Flight 
Control System (AFCS)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

-----------------------------------------------------------------------

SUMMARY: These special conditions are issued for the Sikorsky Aircraft 
Corporation (Sikorsky) model S-92A helicopter. This helicopter, as 
modified by Sikorsky, will have novel or unusual design features 
associated with installing an optional SAR AFCS. The applicable 
airworthiness standards do not contain adequate or appropriate safety 
standards for this design feature. These special conditions contain the 
additional safety standards the Administrator considers necessary to 
show a level of safety equivalent to that established by the existing 
airworthiness standards.

DATES: The effective date of these special conditions is December 3, 
2010. We must receive your comments by February 11, 2011.

ADDRESSES: You must mail or deliver two copies of your comments to: 
Federal

[[Page 77525]]

Aviation Administration, Rotorcraft Directorate, Attn: Special 
Conditions Docket (ASW-111), Docket No. SW023, 2601 Meacham Blvd., Fort 
Worth, Texas 76137. You must mark your comments: Docket No. SW023. You 
can inspect comments in the Docket on weekdays, except Federal 
holidays, between 8:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: FAA, Aircraft Certification Service, 
Rotorcraft Directorate, Regulations and Policy Group (ASW-111), Attn: 
John VanHoudt, 2601 Meacham Blvd., Fort Worth, Texas 76137; telephone 
(817) 222-5167, facsimile (817) 222-5961.

SUPPLEMENTARY INFORMATION:

Background and Discussion

    On July 30, 2007, Sikorsky applied for a change to Type Certificate 
(TC) No. R00024BO to install an optional SAR AFCS in the model S-92A 
helicopter. These special conditions were recently developed due to the 
intended function of the S-92A SAR AFCS not being completely defined 
until late in the certification program. The model S-92A is a transport 
category helicopter certified to Category A requirements when 
configured for more than nine passengers and Category A or B 
requirements when configured for nine or less passengers. This 
helicopter is also certified for instrument flight under the 
requirements of Appendix B of 14 CFR part 29, Amendment 29-47.
    The use of dedicated AFCS upper modes, in which a fully coupled 
autopilot provides operational SAR profiles, is needed for SAR 
operations conducted over water in offshore areas clear of 
obstructions. The SAR modes enable the helicopter pilot to fly fully 
coupled maneuvers, to include predefined search patterns during cruise 
flight, and to transition from cruise flight to a stabilized hover and 
departure (transition from hover to cruise flight). The SAR AFCS also 
includes an auxiliary crew control that allows another crewmember (such 
as a hoist operator) to have limited authority to control the 
helicopter's longitudinal and lateral position during hover operations.
    Flight operations conducted over water at night may have an 
extremely limited visual horizon with little visual reference to the 
surface even when conducted under Visual Meteorological Conditions 
(VMC). Consequently, the certification requirements for SAR modes must 
meet Appendix B to 14 CFR part 29. While Appendix B to 14 CFR part 29 
prescribes airworthiness criteria for instrument flight, it does not 
consider operations below instrument flight minimum speed 
(VMINI), whereas the SAR modes allow for coupled operations 
at low speed, all-azimuth flight to zero airspeed (hover).
    Since SAR operations have traditionally been a public use mission, 
the use of SAR modes in civil operations requires special airworthiness 
standards (special conditions) to ensure that a level of safety 
consistent with Category A and Instrument Flight Rule (IFR) 
certification is maintained. In this regard, 14 CFR part 29 lacks 
adequate airworthiness standards for AFCS SAR mode certification to 
include flight characteristics, performance, and installed equipment 
and systems.

Type Certification Basis

    Under 14 CFR 21.101, Sikorsky must show the S-92A, as changed, 
continues to meet the applicable provisions of the rules incorporated 
by reference in TC No. R00024BO or the applicable regulations in effect 
on the date of application for the change. The regulations incorporated 
by reference in the TC are commonly referred to as the ``original type 
certification basis.'' The regulations incorporated by reference in 
R00024BO are as follows:
    (a) 14 CFR part 29 Amendments 29-1 to 29-47, inclusive.
    (b) 14 CFR part 36 Amendment 20.
    (c) Equivalent Safety Findings:
    (1) Number TC0309BO-R/F-1.
    (i) 14 CFR 29.173 Static longitudinal stability.
    (ii) 14 CFR 29.175 Demonstration of static longitudinal stability.
    (2) Number TC0309BO-R/F-4.
    (i) 14 CFR 29.177 Static directional stability.
    (3) Number TC0309BO-R/P-1.
    (i) 14 CFR 29.1305(a)(24) Power Plant Instruments.
    (4) Number TC0309BO-R/P-5.
    (i) 14 CFR 29.1181(a)(4) Designated Fire Zones; Regions Included.
    (d) Special Conditions:
    (1) No. 29-011-SC for Dual-Engine 30 Minute Power.
    (2) No. 29-008-SC for High Intensity Radiated Frequency.
    (e) Noise Control Act of 1972.
    (f) Compliance with the following optional requirements has been 
established: Ditching provisions Sec.  29.563 including Sec. Sec.  
29.801 and 29.807(d), and excluding Sec. Sec.  29.1411, 29.1415, and 
29.1561 when emergency flotation system is installed. For extended 
over-water operations, compliance with the operating rules and 
Sec. Sec.  29.1411, 29.1415, and 29.1561 must be shown.
    In addition to the applicable airworthiness standards and special 
conditions, the Sikorsky model S-92A must comply with the noise 
certification requirements of 14 CFR part 36.

Regulatory Basis for Special Conditions

    If the Administrator finds the applicable airworthiness standards 
(that is, 14 CFR part 29) do not contain adequate or appropriate safety 
standards for the Sikorsky model S-92A helicopter because of a novel or 
unusual design feature, special conditions are prescribed under Sec.  
21.16.
    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.
    Special conditions are initially applicable to the model for which 
they are issued. Should the TC for that model be amended later to 
include any other model that incorporates the same novel or unusual 
design feature, or should any other model already included on the same 
TC be modified to incorporate the same novel or unusual design feature, 
these special conditions would also apply to the other model.

Novel or Unusual Design Features

    The Sikorsky model S-92A helicopter will incorporate the following 
novel or unusual design features:
    The SAR system is composed of a navigation computer with SAR modes, 
an AFCS that provides coupled SAR functions, hoist operator control, a 
hover speed reference system, and two radio altimeters. The AFCS 
coupled SAR functions include:
    (a) Hover hold at selected height above the surface.
    (b) Ground speed hold.
    (c) Transition down and hover to a waypoint under guidance from the 
navigation computer.
    (d) SAR pattern, transition down, and hover near a target over 
which the helicopter has flown.
    (e) Transition up, climb, and capture a cruise height.
    (f) Capture and track SAR search patterns generated by the 
navigation computer.
    (g) Monitor the preselected hover height with automatic increase in 
collective if the aircraft height drops below the safe minimum height.
    These SAR modes are intended to be used over large bodies of water 
in areas clear of obstructions. Further, use of the modes that 
transition down from cruise to hover will include operation at 
airspeeds below VMINI.
    The SAR system only entails navigation, flight control, and coupled 
AFCS operation of the helicopter. The system does not include the extra 
equipment that may be required for over

[[Page 77526]]

water flight or external loads to meet other operational requirements.

Comments Invited

    We invite 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.
    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 additional 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.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of helicopter. It is not a rule of general applicability.
    Normally, in adopting special conditions, the FAA provides notice 
and an opportunity for comment before issuing the final special 
conditions. However, because the delivery date of the Sikorsky model S-
92A helicopter is imminent, we find that it is impracticable to provide 
prior notice because a delay would be contrary to the public interest. 
The FAA therefore finds that good cause exists for making these special 
conditions effective upon issuance.

Applicability

    These special conditions apply to the Sikorsky model S-92A 
helicopters. Should Sikorsky apply at a later date for a change to the 
TC to include another model incorporating the same novel or unusual 
design feature, these special conditions would apply to that model as 
well.

List of Subjects in 14 CFR Part 29

    Aircraft, Aviation safety.

0
The authority citation for these special conditions is as follows:

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

The Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for Sikorsky Aircraft Corporation model S-
92A helicopters when the optional Search and Rescue (SAR) Automatic 
Flight Control System (AFCS) is installed:
    In addition to the part 29 certification requirements for Category 
A and helicopter instrument flight (Appendix B), the following 
additional requirements must be met for certification of the SAR AFCS:
    (a) SAR Flight Modes. The coupled SAR flight modes must provide:
    (1) Safe and controlled flight in three axes (lateral and 
longitudinal position/speed and height/vertical speed) at all airspeeds 
from instrument flight minimum speed (VMINI) to a hover 
(within the maximum demonstrated wind envelope).
    (2) Automatic transition to the helicopter instrument flight 
(Appendix B) envelope as part of the normal SAR mode sequencing.
    (3) A pilot-selectable Go-Around mode that safely interrupts any 
other coupled mode and automatically transitions to the helicopter 
instrument flight (Appendix B) envelope.
    (4) A means to prevent unintended flight below a safe minimum 
height. Pilot-commanded descent below the safe minimum height is 
acceptable provided the alerting requirements in (b)(7)(i) are 
sufficient to alert the pilot of this descent below safe minimum 
height.
    (b) SAR Mode System Architecture. To support the integrity of the 
SAR modes, the following system architecture is required:
    (1) A system for limiting the engine power demanded by the AFCS 
when any of the automatic piloting modes are engaged, so FADEC power 
limitations, such as torque and temperature, are not exceeded.
    (2) A system providing the aircraft height above the surface and 
final pilot-selected height at a location on the instrument panel in a 
position acceptable to the FAA that will make it plainly visible to and 
usable by any pilot at their station.
    (3) A system providing the aircraft heading and the pilot-selected 
heading at a location on the instrument panel in a position acceptable 
to the FAA that will make it plainly visible to and usable by any pilot 
at their station.
    (4) A system providing the aircraft longitudinal and lateral ground 
speeds and the pilot-selected longitudinal and lateral ground speeds 
when used by the AFCS in the flight envelope where airspeed indications 
become unreliable. This information must be presented at a location on 
the instrument panel in a position acceptable to the FAA that is 
plainly visible to and usable by any pilot at their station.
    (5) A system providing wind speed and wind direction when automatic 
piloting modes are engaged or transitioning from one mode to another.
    (6) A system that monitors for flight guidance deviations and 
failures with an appropriate alerting function that enables the flight 
crew to take appropriate corrective action.
    (7) The alerting system must provide visual or aural alerts, or 
both, to the flight crew under any of the following conditions:
    (i) When the stored or pilot-selected safe minimum height is 
reached.
    (ii) When a SAR mode system malfunction occurs.
    (iii) When the AFCS changes modes automatically from one SAR mode 
to another.

    Note:  For normal transitions from one SAR mode to another, a 
single visual or aural alert may suffice. For a SAR mode malfunction 
or a mode having a time-critical component, the flight crew alerting 
system must activate early enough to allow the flight crew to take 
timely and appropriate action. The alerting system means must be 
designed to alert the flight crew in order to minimize crew errors 
that could create an additional hazard.

    (8) The SAR system hoist operator control is considered a flight 
control with limited authority and must comply with the following:
    (i) The hoist operator control must be designed and located to 
provide for convenient operation and to prevent confusion and 
inadvertent operation.
    (ii) The helicopter must be safely controllable by the hoist 
operator control throughout the range of that control.
    (iii) The hoist operator control may not interfere with the safe 
operation of the helicopter.
    (iv) Pilot and copilot flight controls must be able to smoothly 
override the control authority of the hoist operator control, without 
exceptional piloting skill, alertness, or strength, and without the 
danger of exceeding any other limitation because of the override.
    (9) The reliability of the AFCS must be related to the effects of 
its failure.

[[Page 77527]]

The occurrence of any failure condition that would prevent continued 
safe flight and landing must be extremely improbable. For any failure 
condition of the AFCS which is not shown to be extremely improbable:
    (i) The helicopter must be safely controllable and capable of 
continued safe flight without exceptional piloting skill, alertness, or 
strength. Additional unrelated probable failures affecting the control 
system must be evaluated.
    (ii) The AFCS must be designed so that it cannot create a hazardous 
deviation in the flight path or produce hazardous loads on the 
helicopter during normal operation or in the event of a malfunction or 
failure, assuming corrective action begins within an appropriate period 
of time. Where multiple systems are installed, subsequent malfunction 
conditions must be evaluated in sequence unless their occurrence is 
shown to be improbable.
    (10) A functional hazard assessment (FHA) and a system safety 
assessment must be provided to address the failure conditions 
associated with SAR operations. For SAR catastrophic failure 
conditions, changes may be required to the following:
    (i) System architecture.
    (ii) Software and complex electronic hardware design assurance 
levels.
    (iii) HIRF test levels.
    (iv) Instructions for continued airworthiness.
    The assessments must consider all the systems required for SAR 
operations to include the AFCS, all associated AFCS sensors (for 
example, radio altimeter), and primary flight displays. Electrical and 
electronic systems with SAR catastrophic failure conditions (for 
example, AFCS) must comply with the Sec.  29.1317(a)(4) High Intensity 
Radiated Field (HIRF) requirements.
    (c) SAR Mode Performance Requirements.
    (1) The SAR modes must be demonstrated in the requested flight 
envelope for the following minimum sea-state and wind conditions:
    (i) Sea State: Wave height of 2.5 meters (8.2 feet), considering 
both short and long swells.
    (ii) Wind: 25 knots headwind; 17 knots for all other azimuths.
    (2) The selected hover height and hover velocity must be captured 
(to include the transition from one captured mode to another captured 
mode) accurately and smoothly and not exhibit any significant overshoot 
or oscillation.
    (3) For any single failure or any combination of failures of the 
AFCS that is not shown to be extremely improbable, the recovery must 
not result in a loss of height greater than half of the minimum use 
height (MUH) with a minimum margin of 15 feet above the surface. MUH is 
the minimum height at which any SAR AFCS mode can be engaged.
    (4) The SAR mode system must be usable up to the maximum certified 
gross weight of the aircraft or to the lower of the following weights:
    (i) Maximum emergency flotation weight.
    (ii) Maximum hover Out-of-Ground Effect (OGE) weight.
    (iii) Maximum demonstrated weight.
    (d) Flight Characteristics.
    (1) The basic aircraft must meet all the part 29 airworthiness 
criteria for helicopter instrument flight (Appendix B).
    (2) For SAR mode coupled flight below VMINI, at the 
maximum demonstrated winds, the helicopter must be able to maintain any 
required flight condition and make a smooth transition from any flight 
condition to any other flight condition without requiring exceptional 
piloting skill, alertness, or strength, and without exceeding the limit 
load factor. This requirement also includes aircraft control through 
the hoist operator's control.
    (3) For SAR modes at airspeeds below VMINI the following 
requirements of Appendix B to part 29 must be met and will be used as 
an extension to the IFR certification envelope of the basic aircraft:
    (i) Static Longitudinal Stability: the requirements of paragraph IV 
of Appendix B are not applicable.
    (ii) Static Lateral-Directional Stability: The requirements of 
paragraph V of Appendix B are not applicable.
    (iii) Dynamic Stability: The requirements of paragraph VI of 
Appendix B are replaced with the following two paragraphs:
    (A) Any oscillation must be damped and any aperiodic response must 
not double in amplitude in less than 10 seconds. This requirement must 
also be met with degraded upper mode(s) of the AFCS. An ``upper mode'' 
is a mode that utilizes a fully coupled autopilot to provide an 
operational SAR profile.
    (B) After any upset, the AFCS must return the aircraft to the last 
commanded position within 10 seconds or less.
    (4) With any of the upper mode(s) of the AFCS engaged the pilot 
must be able to manually recover the aircraft and transition to the 
normal (Appendix B) IFR flight profile envelope without exceptional 
skill, alertness, or strength.
    (e) One-Engine Inoperative (OEI) Performance Information.
    (1) The following performance information must be provided in the 
Rotorcraft Flight Manual Supplement (RFMS):
    (i) OEI performance information and emergency procedures, providing 
the maximum weight that will provide a minimum clearance of 15 feet 
above the surface, following failure of the critical engine in a hover. 
The maximum weight must be presented as a function of the hover height 
for the temperature and pressure altitude range requested for 
certification. The effects of wind must be reflected in the hover 
performance information.
    (ii) Hover OGE performance with the critical engine inoperative for 
OEI continuous and time-limited power ratings for those weights, 
altitudes, and temperatures for which certification is requested.

    Note:  These OEI performance requirements do not replace 
performance requirements that may be needed to comply with the 
airworthiness or operational standards (Sec.  29.865 or 14 CFR part 
133) for external loads or human external cargo.

    (f) RFMS.
    (1) The RFMS must contain, at a minimum:
    (i) Limitations necessary for safe operation of the SAR system to 
include:
    (A) Minimum crew requirements.
    (B) Maximum SAR weight.
    (C) Engagement criteria for each of the SAR modes to include MUH 
(as determined in subparagraph (c)(3)).
    (ii) Normal and emergency procedures for operation of the SAR 
system (to include operation of the hoist operator control), with AFCS 
failure modes, AFCS degraded modes, and engine failures.
    (iii) Performance information:
    (A) OEI performance and height-loss.
    (B) Hover OGE performance information, utilizing OEI continuous and 
time-limited power ratings.
    (C) The maximum wind envelope demonstrated in flight test.
    (g) Flight Demonstration.
    (1) Before approval of the SAR system, an acceptable flight 
demonstration of all the coupled SAR modes is required.
    (2) The AFCS must provide fail-safe operations during coupled 
maneuvers. The demonstration of fail-safe operations must include a 
pilot workload assessment associated with manually flying the aircraft 
to an altitude greater than 200 feet above the surface and an airspeed 
of at least the best rate of climb airspeed (Vy).
    (3) For any failure condition of the SAR system not shown to be 
extremely improbable, the pilot must be able to

[[Page 77528]]

make a smooth transition from one flight mode to another without 
exceptional piloting skill, alertness, or strength.
    (4) Failure conditions that are not shown to be extremely 
improbable must be demonstrated by analysis, ground testing, or flight 
testing. For failures demonstrated in flight, the following normal 
pilot recovery times are acceptable:
    (i) Transition modes (Cruise-to-Hover/Hover-to-Cruise) and Hover 
modes: Normal pilot recognition plus 1 second.
    (ii) Cruise modes: Normal pilot recognition plus 3 seconds.
    (5) All AFCS malfunctions must include evaluation at the low-speed 
and high-power flight conditions typical of SAR operations. 
Additionally, AFCS hard-over, slow-over, and oscillatory malfunctions, 
particularly in yaw, require evaluation. AFCS malfunction testing must 
include a single or a combination of failures (for example, erroneous 
data from and loss of the radio altimeter, attitude, heading, and 
altitude sensors) which are not shown to be extremely improbable.
    (6) The flight demonstration must include the following 
environmental conditions:
    (i) Swell into wind.
    (ii) Swell and wind from different directions.
    (iii) Cross swell.
    (iv) Swell of different lengths (short and long swell).

    Issued in Fort Worth, Texas, on December 3, 2010.
Kimberly K. Smith,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 2010-31188 Filed 12-10-10; 8:45 am]
BILLING CODE 4910-13-P