Special Conditions: Pratt and Whitney Canada, PW220A; New Engine Rating: Idle-Cruise Regime

Issuing agencies

Abstract

This action proposes special conditions for the Pratt and Whitney Canada (P&WC) aircraft engine Model PW220A. This engine will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for engines. This design feature will incorporate an unusual power rating structure that includes an "idle cruise regime" (ICR). 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.

Full Text

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<title>Federal Register, Volume 91 Issue 163 (Tuesday, August 25, 2026)</title>
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[Federal Register Volume 91, Number 163 (Tuesday, August 25, 2026)]
[Proposed Rules]
[Pages 54839-54841]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-17298]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2026-3073; Notice No. 33-25-03-SC]


Special Conditions: Pratt and Whitney Canada, PW220A; New Engine 
Rating: Idle-Cruise Regime

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Pratt and 
Whitney Canada (P&WC) aircraft engine Model PW220A. This engine will 
have a novel or unusual design feature when compared to the state of 
technology envisioned in the airworthiness standards for engines. This 
design feature will incorporate an unusual power rating structure that 
includes an ``idle cruise regime'' (ICR). 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 October 9, 2026.

ADDRESSES: Send comments identified by Docket No. FAA-2026-3073 using 
any of the following methods:
    Federal eRegulations Portal: Go to <a href="http://www.regulations.gov">www.regulations.gov</a> 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 
<a href="http://www.regulations.gov">www.regulations.gov</a> 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: Philip Haberlen, Engine and 
Propulsion, AIR-625, Technical Policy Branch, Policy and Standards 
Division, Aircraft Certification Service, Federal Aviation 
Administration, FAA New England Regional Office, 1200 District Avenue, 
Burlington MA 01803; telephone (781) 238-7770; email 
<a href="/cdn-cgi/l/email-protection#3d6d555451544d13755c5f584f5158537d5b5c5c135a524b"><span class="__cf_email__" data-cfemail="32625a5b5e5b421c7a535057405e575c725453531c555d44">[email&#160;protected]</span></a>.

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 proposed 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 received without change to <a href="http://www.regulations.gov">www.regulations.gov</a>, including any 
personal information you provide. The FAA will also post a report 
summarizing each substantive verbal contact received about these 
special conditions.

Confidential Business Information

    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 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 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 above. Comments the FAA receives, which are 
not specifically designated as CBI, will be placed in the public docket 
for these proposed special conditions.

Background

    On November 16, 2021, P&WC applied for a type certificate for its 
new Model aircraft engine model PW220A. The PW220A is a turboshaft 
engine designed for transport category twin-engine helicopters.
    Under 14 CFR 21.17(c), an application for type certification is 
effective for three years, unless the FAA approves a longer period. 
Section 21.17(d) provides that, where a type certificate has not been 
issued within the time limit established under Sec.  21.17(c), the 
applicant may file for an extension and update the designated 
applicable regulations in the type certification

[[Page 54840]]

basis. Since the project was not certificated within the established 
time limit, the FAA approved a request for extension by P&WC, which 
reapplied on May 7, 2025. Their request was approved and the FAA 
determined the type certification basis established on November 19, 
2021 is unaffected.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, P&WC must show that the Model 
PW220A aircraft engine meets the applicable provisions of part 33, as 
amended by amendments 33-1 through 33-34.
    If the Administrator finds that the applicable airworthiness 
regulations (e.g., 14 CFR part 33) do not contain adequate or 
appropriate safety standards for the Model PW220A because of a novel or 
unusual design feature, special conditions are 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 novel or 
unusual design feature, these special conditions would also apply to 
the other model under Sec.  21.101.
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with 14 CFR 11.38, and they become part of the type 
certification basis under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The P&WC Model aircraft engine model PW220A will incorporate the 
following novel or unusual design feature:
    An unusual power rating structure that includes an ICR.

Discussion

    The PW220A engine is a new centerline turboshaft engine designed 
for a transport category, twin-engine helicopter. The applicant has 
requested that operation will include an ICR where the power from one 
engine will be reduced to a low idle condition while the other engine 
will provide 100% of the required power to the aircraft during cruise 
flight. The applicant is requesting a rating structure such that the 
PW220A engine in ICR will have different limits from the all-engines-
operating (AEO) or one-engine-inoperative (OEI) conditions.
    The applicable airworthiness requirements do not contain the ICR 
definition and do not contain adequate or appropriate safety standards 
for the type certification of these new and unusual engine ratings.
    The inclusion of the ICR will have implications on multiple 
regulatory sections affecting both engine operation and continued 
airworthiness which must be assessed by the FAA.
    The prime objective of ICR is to reduce total fuel consumption and 
increase the operating range of the helicopter. The fundamental concept 
of ICR stems from the fact that one engine is thermodynamically more 
efficient at providing a given total power than two engines sharing the 
load equally. As such, it is beneficial from a fuel savings point of 
view to bring one engine to minimum fuel flow (the stand-by engine) and 
use the other engine to provide 100% of the required power to the 
aircraft during the cruise phase of the flight (the active engine). The 
lower the stand-by condition, the higher the benefit in fuel 
consumption.
    The 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.

Applicability

    As discussed above, these proposed special conditions are 
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, these 
special conditions would apply to the other model as well.

Conclusion

    This action affects only a certain novel or unusual design feature 
on the PWC aircraft engine model PW220A. It is not a rule of general 
applicability.

List of Subjects in 14 CFR Part 33

    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), 40113, 44701, 44702, and 44704.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for Pratt and Whitney Canada Model PW220A engine.

Section 1.1 General Definitions

    The following definitions are added to Sec.  1.1:
    ICR mode of operation means one engine is providing 100% of the 
required power to the rotorcraft for cruise flight, and the other 
engine is in Rated ICR stand-by power for a two-engine rotorcraft.
    Rated ICR stand-by power means, with respect to rotorcraft turbine 
engines, the approved lowest engine rpm at which the engine can safely 
operate while in the ICR mode of operation.
    Rated ICR active maximum continuous power means, with respect to 
rotorcraft turbine engines, the approved brake horsepower developed 
statically or in flight in standard atmosphere at a specified altitude 
within the engine operating limitations established under 14 CFR, part 
33 and approved for unrestricted periods of use while in the ICR mode 
of operation.
    Rated ICR 2 minute power means, with respect to rotorcraft turbine 
engines, the approved brake horsepower developed under static 
conditions at specified altitudes and temperatures within the engine 
operating limitations established under 14 CFR, part 33 for periods not 
longer than 2 minutes while in the ICR mode of operation. There is no 
mandatory inspection or prescribed maintenance action required after 
reaching this power level.

Section 33.7 Engine Ratings and Operating Limitations

    In addition to the requirements of section 33.7(c), ratings and 
limitations are established for horsepower, torque, r.p.m., gas 
temperature, time duration, and number of occurrences for rated ICR 
active maximum continuous power and rated ICR 2 minute power.

Section 33.28 Engine Control Systems

    The requirements of Sec.  33.28 except that Sec.  33.28(i)(2) 
should read as follows:
    When an engine dedicated electrical power source is required for 
compliance with paragraph (i)(1) of this section, its capacity should 
provide sufficient margin to account for engine operation below the 
rated ICR stand-by power, where the engine control system is designed 
and expected to recover engine operation automatically.

Section 33.68 Induction System Icing

    The requirements of Sec.  33.68, except that ``minimum descent idle 
rotor speeds'' is replaced with the ``rated ICR stand-by power rotor 
speeds'' in Sec.  33.68(a) and Sec.  33.68(b).

Section 33.73 Power or Thrust Response

    The requirements of Sec.  33.73, except Sec.  33.73(b) should read 
as follows:
    The design and construction of the engine must enable an increase 
from the

[[Page 54841]]

rated ICR stand-by power lever position to 95 percent rated takeoff 
power in not over 5 seconds. The 5-second power response must occur 
from a stabilized static condition using only the bleed air and 
accessories loads necessary to run the engine.

Section 33.78 Rain and Hail Ingestion

    The requirements of Sec.  33.78, except Sec. Sec.  33.78(b)(1) 
through 33.78(b)(4) should read as follows:
    (1) A normal stabilization period of three minutes at rated maximum 
continuous power without rain ingestion, followed immediately by the 
suddenly commencing ingestion of rain for three minutes at rated 
maximum continuous power, then
    (2) Continuation of the rain ingestion during subsequent rapid 
deceleration to the rated ICR stand-by power, then
    (3) Continuation of the rain ingestion during three minutes at the 
rated ICR stand-by power, then
    (4) Continuation of the rain ingestion during subsequent rapid 
acceleration to rated ICR 2 minute power.

Section 33.87 Endurance Test

    The requirements of Sec.  33.87, except as follows:
    (1) The requirements of Sec.  33.87(d)(1) except that instead of 
alternating between rated takeoff power and idling power:
    (i) The higher condition must be rated takeoff power during the 
first, second and fourth periods and rated ICR 2 minute power during 
the third, fifth and sixth periods.
    (ii) The lower condition must be the rated ICR stand-by power 
condition or lower.
    (iii) During the sixth period, lower condition must be kept for 10 
minutes instead of 5 minutes.
    (2) The requirements of Sec.  33.87(d)(2) through Sec.  
33.87(d)(7), except as follows:
    (i) The first 15 of the twenty-five 6-hour test cycles required by 
Sec.  33.87(d)(2) must be conducted at the rated ICR active maximum 
continuous power instead of the rated maximum continuous power.
    (ii) In the last 10 of the twenty-five 6-hour test cycles, the last 
5 minutes of the 1 hour at the rated continuous OEI power required by 
Sec.  33.87(d)(3), must be run at the rated ICR 2 minute power instead 
of the rated continuous OEI power.
    (iii) The test required by Sec.  33.87(d)(4) must be performed for 
55 minutes instead of 60 minutes and must be performed as follows: 
rated maximum continuous power for 30 minutes, followed by the rated 
ICR active maximum continuous power for 25 minutes.
    (iv) The two hours of incremental cruise power required by Sec.  
33.87(d)(5) must be conducted between the rated ICR active maximum 
continuous power and the ground or minimum idle rotational speed.
    (v) The thirty minutes of accelerations and decelerations required 
by Sec.  33.87(d)(6) must be conducted as follows:
    a. The higher condition must be the rated takeoff power during the 
first and fourth period and the rated ICR 2 minute power during the 
second, third, fifth and sixth periods.
    b. The lower condition must be the rated ICR stand-by power 
condition or lower.

Section 33.89 Operation Test

    The requirements of Sec.  33.89, except Sec.  33.89(a)(3) should be 
as follows:
    The minimum power response time to 95% rated takeoff power, from 
power lever positions representative of rated ICR stand-by power 
condition and of minimum flight idle, starting from stabilized idle 
operation, under the following engine load conditions:
    i. No bleed air and power extraction for aircraft use.
    ii. Maximum allowable bleed air and power extraction for aircraft 
use.
    iii. An intermediate value for bleed air and power extraction 
representative of that which might be used as a maximum for aircraft 
during approach to a landing.

    Issued in Des Moines, WA, on August 19, 2026.
Paul Siegmund,
Branch Manager, Technical Policy, Policy and Standards Division, 
Aircraft Certification Service.
[FR Doc. 2026-17298 Filed 8-24-26; 8:45 am]
BILLING CODE 4910-13-P


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