[Federal Register Volume 88, Number 92 (Friday, May 12, 2023)]
[Proposed Rules]
[Pages 30680-30682]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-10135]


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 Proposed Rules
                                                 Federal Register
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 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. 88, No. 92 / Friday, May 12, 2023 / Proposed 
Rules  

[[Page 30680]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 29

[Docket No. FAA-2021-1143; Notice No. 29-21-01-SC]


Special Conditions: Airbus Helicopters Model H160B Helicopter; 
Extended Duration of Flight After Loss of Main Gearbox Lubrication

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notification of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Airbus 
Helicopters (Airbus) Model H160B helicopter. This helicopter will have 
a novel or unusual design feature when compared to the state of 
technology envisioned in the airworthiness standards for helicopters. 
This design feature is the extended duration of safe flight beyond 30 
minutes after the loss of main gearbox lubrication. The applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards for this design feature. These proposed 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 comments on or before June 26, 2023.

ADDRESSES: Send comments identified by docket number FAA-2021-1143 
using any of the following methods:
    Federal eRegulations Portal: Go to https://www.regulations.gov/ and 
follow the online instructions for sending your comments 
electronically.
    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.
    Hand Delivery or 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 9 a.m. and 5 p.m., Monday through 
Friday, except Federal holidays.
    Fax: Fax comments to Docket Operations at (202) 493-2251.
    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 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: Kamron Dowlatabadi, Mechanical 
Systems, AIR-623, Technical Policy Branch, Policy and Standards 
Division, Aircraft Certification Service, 10101 Hillwood Parkway, Fort 
Worth, TX 76177; telephone (817) 222-5219; email 
[email protected].

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, and will consider comments filed late if it is possible to do 
so without incurring delay. The FAA may change these special conditions 
based on the comments received.

Privacy

    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in title 
14, Code of Federal Regulations (14 CFR) 11.35, the FAA will post all 
comments it receives, without change, to https://www.regulations.gov/, 
including any personal information the commenter provides. The FAA will 
also post a report summarizing each substantive verbal contact received 
about these special conditions.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to these proposed special 
conditions contain commercial or financial information that is 
customarily treated as private, that you actually treat as private, and 
that is relevant or responsive to these proposed special conditions, it 
is important that you clearly designate the submitted comments as CBI. 
Please mark each page of your submission containing CBI as ``PROPIN.'' 
The FAA will treat such marked submissions as confidential under the 
FOIA, and the indicated comments will not be placed in the public 
docket of these proposed special conditions. Send submissions 
containing CBI to the individual listed in the FOR FURTHER INFORMATION 
CONTACT section. Comments the FAA receives, which are not specifically 
designated as CBI will be placed in the public docket for this 
rulemaking.

Background

    On November 7, 2014, Airbus applied for FAA type certification for 
the Model H160B helicopter. On November 1, 2016, Airbus applied for an 
extension, which is also the date of the updated type certification 
basis.
    The Airbus Model H160B helicopter is a 14 CFR part 29 transport-
category, twin-turboshaft-engine helicopter. This helicopter has a 
maximum takeoff weight of 13,436 lbs. with seating for 12 passengers 
and 2 crewmembers. The Airbus Model H160B helicopter is a new part 29 
helicopter characterized by the integration of composite materials in 
its airframe, five main rotor blades (Blue EdgeTM 
technology), a FenestronTM tail rotor, and a 
HelionixTM avionics suite.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, Airbus must show that the 
Model H160B helicopter meets the applicable provisions of part 29 as 
amended by amendments 29-1 through 29-55. The date of the Airbus Model 
H160B helicopter type certification basis is November 1, 2016.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 29) do not contain adequate or 
appropriate safety standards for the Airbus Model H160B helicopter 
because of a novel or unusual design feature, special conditions are

[[Page 30681]]

prescribed under the provisions of Sec.  21.16.
    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 or similar 
novel or unusual design feature, the special conditions would also 
apply to the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the Airbus Model H160B helicopter must comply with the 
noise certification requirements of 14 CFR part 36.
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of the type-
certification basis under Sec.  21.17(a)(2).

Novel or Unusual Design Feature

    The Airbus Model H160B helicopter will incorporate the following 
novel or unusual design feature:
    Extended duration of safe flight beyond 30 minutes after indication 
to the crew of the loss of main gearbox lubrication.

Discussion

    Current regulations do not prescribe a duration for continued safe 
flight and landing to be specifically called out in the rotorcraft 
flight manual when a loss of main gearbox lubrication warning is 
activated. Although Sec.  29.927(c)(1) requires a loss of main gearbox 
lubrication bench test for 30 minutes to show that the main gearbox is 
operational for 30 minutes following a loss of main gearbox lubrication 
event, the bench test conditions may not be representative of aircraft 
flight conditions because a 30-minute main gearbox bench test may not 
translate to 30 minutes of continued safe flight and landing.
    The novel or unusual design feature of the Airbus Model H160B 
helicopter is intended to enable the helicopter to continue safe 
flight, for a minimum of 30 minutes, to the intended destination or to 
a safe landing location after the loss of main gearbox lubrication. To 
meet this minimum 30 minutes of continued safe flight, the Airbus Model 
H160B helicopter main gearbox is designed with a redundant lubrication 
system. This main gearbox redundant lubrication system would allow 
operation after the failure of a single lubrication system. Current 
regulations do not address a redundant lubrication system that allows 
operation after the failure of a single lubrication system because at 
the time the existing regulations were issued, the agency did not 
envision that a flight duration of more than 30 minutes, after the loss 
of main gearbox lubrication, was needed. Accordingly, these proposed 
special conditions would provide testing criteria to ensure the 
reliability of the redundant lubrication system to provide safe flight 
beyond 30 minutes after annunciation of the loss of the main gearbox 
lubrication.
    These proposed special conditions would add requirements in lieu of 
the existing airworthiness standards in Sec.  29.917(a) and (c), and 
would add a new requirement to Sec.  29.1585.
    The FAA did not envision the standards for the lubrication system 
components to be a critical failure point at the time of the issuance 
of the existing regulations, and the standards were not included in the 
design assessment of the drive system. Accordingly, these proposed 
special conditions would include ``any associated lubrication system 
components including oil coolers.''
    These proposed special conditions would add a safety margin over 
the current 30-minute main gearbox bench test by requiring a test 
duration of more than 30 minutes to ensure that the rotor-drive gearbox 
system has an in-flight operational endurance capability of at least 30 
minutes following a failure of any one pressurized, normal-use 
lubrication system. The 30-minute test interval starts when the 
lubrication-failure indication to the flight crew is triggered and the 
engine is at maximum continuous power. These proposed special 
conditions would require a bench test of the main gearbox for at least 
60 minutes in some cases, depending on reduction factors, which are 
applied to correlate the test duration with the maximum period of in-
flight operation following loss of lubrication, and to ensure that the 
main gearbox operates for 30 minutes after a loss-of-lubrication 
situation.
    The degree of confidence specified in Category A and B in these 
proposed special conditions would require the applicant to establish a 
reduction factor to correlate the test duration with the maximum period 
of in-flight operation following loss of lubrication. The factor 
assigned by the applicant is directly dependent on the availably of 
supporting data with respect to the mechanical behavior of the gearbox, 
and must reflect the applicant's confidence in the repeatability of the 
certification test data. Test loading, in the context of these special 
conditions, refers to the engine, gearbox, clutch system, and rotors 
(or similar test apparatus) interconnected and operating in unison, as 
this combination of mechanical elements pertains to power input 
transmitted to the gearbox and subsequent reaction torques simulating 
operating conditions.
    These proposed special conditions would add a requirement that the 
maximum duration of operation after a failure, which results in a loss 
of main gearbox lubrication and an associated oil pressure warning, 
must be furnished in the rotorcraft flight manual, a duration that must 
not exceed the maximum period substantiated.

Applicability

    As discussed above, these proposed special conditions would be 
applicable to the Airbus Model H160B helicopter. Should Airbus apply at 
a later date for a change to the type certificate to include another 
model incorporating the same novel or unusual design feature, these 
special conditions would apply to that model as well.

Conclusion

    This action affects only a certain novel or unusual design feature 
on one model of helicopter. It is not a rule of general applicability.

List of Subjects in 14 CFR Part 29

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

Authority Citation

    The authority citation for these special conditions is as follows:

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

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for the Airbus Helicopters Model H160B helicopter. Unless stated 
otherwise, all requirements in Sec. Sec.  29.917, 29.927, and 29.1585 
would still apply.
    In lieu of Sec.  29.917(a), the following special condition 
applies:
    (a) Design: General. The rotor-drive gearbox system includes any 
part necessary to transmit power from the engines to the rotor hubs. 
This includes gearboxes, shafting, universal joints, couplings, rotor-
brake assemblies, clutches, supporting bearings for shafting, any 
attendant accessory pads or drives, any cooling fans, and any 
associated lubrication-system components including oil coolers that are 
a part of, attached to, or mounted on the rotor-drive gearbox system.
    In lieu of Sec.  29.927(c), the following special condition 
applies:

[[Page 30682]]

    (c) Lubrication system failure. For rotor-drive gearbox systems 
featuring a pressurized normal-use lubrication system, the following 
requirements for continued safe flight and landing apply:
    (1) Category A. Confidence must be established that the rotor-drive 
gearbox system has an in-flight operational endurance capability of at 
least 30 minutes following a failure of any one pressurized, normal-use 
lubrication system.
    (i) For each rotor-drive gearbox system necessary for continued 
safe flight or safe landing, the applicant must conduct a test that 
simulates the effect of the most severe failure mode of the normal-use 
lubrication system, as determined by the failure analysis of Sec.  
29.917(b). The duration of the test must be dependent on the number of 
tests and the component condition after each test.
    (ii) The test must begin when the indication to the flight crew 
shows a lubrication failure has occurred, and its loading must be 
consistent with 1 minute at maximum continuous power, followed by the 
minimum power needed for continued flight at the rotorcraft maximum 
gross weight.
    (iii) The test must end with a 45-second out-of-ground-effect (OGE) 
hover to simulate a landing phase. Test results must substantiate the 
maximum period of operation following a loss of lubrication by means of 
an extended test duration or multiple test specimens, or another 
approach prescribed by the applicant and accepted by the FAA.
    (2) Category B. Confidence must be established that the rotor-drive 
gearbox system has an in-flight operational endurance capability to 
complete an autorotation descent and landing following a failure of any 
one pressurized, normal-use lubrication system.
    (i) For each rotor-drive gearbox system necessary for safe 
autorotation descent or safe landing, the applicant must conduct a test 
of at least 16 minutes and 15 seconds, following the most severe 
failure mode of the normal-use lubrication system, as determined by the 
failure analysis of Sec.  29.917(b).
    (ii) The test must begin when the indication to the flight crew 
shows that a lubrication failure has occurred, and its loading must be 
consistent with 1 minute at maximum continuous power. Thereafter, the 
input torque should be reduced to simulate autorotation for a minimum 
of 15 minutes.
    (iii) The test must be conducted using an input torque to simulate 
a minimum power landing for approximately 15 seconds.
    In addition to Sec.  29.1585, the following special condition 
applies:
    (h) Power Plant limitations. The maximum duration of operation 
after a failure, resulting in any loss of lubrication of a rotor-drive-
system gearbox and an associated oil-pressure warning, must be 
furnished in the rotorcraft flight manual, and must not exceed the 
maximum period substantiated in accordance with Sec.  29.927(c) of 
these special conditions.

    Issued in Des Moines, Washington, on May 8, 2023.
Suzanne A. Masterson,
Acting Manager, Technical Policy Branch, Policy and Standards Division, 
Aircraft Certification Service.
[FR Doc. 2023-10135 Filed 5-11-23; 8:45 am]
BILLING CODE 4910-13-P