[Federal Register Volume 90, Number 238 (Monday, December 15, 2025)]
[Rules and Regulations]
[Pages 57896-57898]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-22759]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 33
[Docket No. FAA-2025-0950; Special Conditions No. 33-029-SC]
Special Conditions: Pratt and Whitney Canada, PW220A; Flat 30-
Second and 2-Minute OEI Rating.
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
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SUMMARY: These special conditions are issued for the Pratt and Whitney
Canada (PWC) 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 is an additional one engine inoperative (OEI) power
rating that combines the 30-second and 2-minute OEI power ratings into
a single rating. 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: These special conditions are effective January 14, 2026.
FOR FURTHER INFORMATION CONTACT: Philip Haberlen, Engine and Propulsion
Section, AIR-625, Technical Policy Branch, Policy and Standards
Division, Aircraft Certification Service, Federal Aviation
Administration, 1200 District Avenue, Burlington, MA 01803; telephone
781-238-7770; email [email protected].
SUPPLEMENTARY INFORMATION:
Background
On November 16, 2021, Pratt and Whitney Canada applied for a type
certificate for the new engine model PW220A. The PW220A is a turboshaft
engine designed for transport category twin-engine helicopters.
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.17, Pratt and Whitney Canada must show that the model PW220A
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 Sec. 11.38, and they become part of the type
certification basis under Sec. 21.17(a)(2).
Novel or Unusual Design Features
The PW220A will incorporate the following novel or unusual design
feature:
A ``Flat 30-second and 2-minute'' one engine inoperative (OEI)
rating.
Discussion
These special conditions are necessary because current Part 33
regulations do not contain airworthiness standards for extending the 2-
minute OEI rating for 30 seconds. These special conditions extend the
time-dependent requirements in Sec. Sec. 33.87(f) and 33.88(b)
applicable to the 30-second OEI and 2-minute OEI to the 2.5-minute time
duration of the ``Flat 30-second and 2-minute OEI'' power. The 2.5-
minute time duration for the rating may affect the engine's structural
and operational characteristics that are time-dependent, such as the
values for transients, the time duration for stabilization to steady
state, and part growth due to deformation.
To address these aspects, the FAA proposed these special conditions
on August 7, 2025 (90 FR 38076) based on Sec. Sec. 33.7, 33.28(k),
33.29(c), 33.85(d), 33.87(a)(7), 33.87(f), 33.88(b), and A33.4(b).
In addition to Sec. 33.7, an engine rating and operating
limitation must be established for the flat 30-second and 2-minute OEI
power rating.
The 2.5-minute time duration for the rating necessitates extending
the time duration requirement of Sec. 33.28(k) applicable to the 30-
second OEI rating from 30 seconds to 2.5 minutes. This requirement is
for automatic availability and control of the engine for the entire
duration of the rating's usage.
The rating's 2.5-minute time duration also necessitates applying
the requirements of Sec. 33.29(c) to the flat 30-second and 2-minute
OEI power rating. These special conditions will be used to ensure that
the instrumentation requirements normally reserved for 30-second OEI
and 2-minute OEI ratings are applied to the flat 30-second and 2-minute
OEI power rating over its whole duration.
Paragraph (c)(3) of these special conditions states that the engine
must provide means or provision of means to alert maintenance personnel
of the use of the flat 30-second and 2-minute OEI power rating; the
retrieval of the recorded data must be available after the aircraft
lands, so any required maintenance actions can be completed before the
next flight.
A special condition regarding calibration tests for the flat 30-
second and 2-minute OEI power rating to mirror the requirements of
Sec. 33.85(d) is needed. This will permit the use of measurements
taken during the endurance test, required by the special condition
based on Sec. 33.87(f), to show compliance with Sec. 33.85(d).
The 2.5-minute time duration for the rating affects the endurance
test requirements of Sec. 33.87. For the flat 30-second and 2-minute
OEI power rating, a 2.5-minute time duration is needed to establish a
level of safety equivalent to that established by Sec. 33.87(f). For
the 30-second OEI and 2-minute OEI, the test
[[Page 57897]]
schedule of Sec. 33.87(f) is divided between the two ratings. The FAA
proposed these special conditions based on Sec. 33.87(f) to ensure the
test will be run for a duration of 2.5 minutes with no interruption.
A special condition to extend the time duration requirements
referenced in Section 33.88(b) from 4 to 5 minutes at the
overtemperature condition is also needed.
In addition, the FAA proposed these special conditions to ensure
that the requirements in Sec. A33.4(b) apply to this rating.
The 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.
Discussion of Comments
The FAA issued Notice of Proposed Special Conditions No. 33-25-01-
SC for the PWC aircraft engine model PW220A, which was published in the
Federal Register on August 7, 2025 (90 FR 38076).
No comments were received, and the special conditions are adopted
as proposed.
Applicability
As discussed above, these special conditions are applicable to the
PWC aircraft engine model PW220A. Should PWC 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 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(g), 40113, 44701, 44702, 44704.
The Special Conditions
[squf] 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 engine model PW220A.
In addition to the general definitions in 14 CFR 1.1, the following
definition applies to these special conditions: ``Rated Flat 30-second
and 2-minute One Engine Inoperative (OEI) Power,'' with respect to
rotorcraft turbine engines, means (1) a single rating for which the
shaft horsepower and associated operating limitations of the 30-second
OEI and 2-minute OEI ratings are equal, and (2) the shaft horsepower is
that developed under static conditions for a specified altitude and
temperature and within the operating limitations established under Part
33. The rating is for continuation of flight operation after the
failure or shutdown of one engine in multiengine rotorcraft, for up to
three periods of use no longer than 2.5 minutes each in any one flight
and followed by mandatory inspection and prescribed maintenance action.
The airworthiness standards in Part 33 Amendment 34 for the 30-
second OEI and 2-minute OEI ratings are applicable to the flat 30-
second and 2-minute OEI power rating.
In addition to the airworthiness standards in Part 33, the
following special conditions apply:
(a) Section 33.7(c)(1) Engine ratings and operating limitations. In
addition to the requirements in Sec. 33.7(c)(1), the flat 30-second
and 2-minute OEI power rating and operating limitations must be
established for power, torque, rotational speed, gas temperature, and
time duration.
(b) Section 33.28 Engine controls systems. In addition to the
requirements in Sec. 33.28, rotorcraft engines having the flat 30-
second and 2-minute OEI power rating must incorporate a means, or a
provision for a means, for automatic availability and automatic control
of the flat 30-second and 2-minute OEI power within the declared
operating limitations.
(c) Section 33.29 Instrument Connection. In lieu of the
requirements of 33.29(c), the PW220A must incorporate a means or a
provision for a means to:
(1) Alert the pilot when the engine is at the flat 30-second and 2-
minute OEI power level, when the event begins, and when the time
interval expires;
(2) Automatically record each usage and duration of power at the
flat 30-second and 2-minute OEI power rating;
(3) Following each flight when the flat 30-second and 2-minute OEI
power rating is used, alert maintenance personnel in a positive manner
that the engine has been operated at the flat 30-second and 2-minute
OEI power level, and permit retrieval of the recorded data; and
(4) Enable routine verification of the proper operation of the
above means.
(d) Section 33.87 Endurance test. The requirements of Sec. 33.87
are applicable to the PW220A, except that for the flat 30-second and 2-
minute OEI power rating, the following requirements apply:
(1) The test of Sec. 33.87(a)(7), for the purposes of temperature
stabilization, must be run with a test period time of 2.5 minutes.
(2) The tests in Sec. 33.87(f)(2) and (3) must be run continuously
for the duration of 2.5 minutes, and
(3) The tests in Sec. 33.87(f)(6) and (7) must be run continuously
for the duration of 2.5 minutes.
(e) Section 33.85 Calibration tests. Test requirements of Sec.
33.85(d) are applicable to the PW220A except that any measurements
taken during the applicable endurance test prescribed in Sec.
33.87(f)(1) through (8) as modified per this special condition may be
used in showing compliance with the requirements of Sec. 33.85(d) for
the flat 30-second and 2-minute OEI power rating.
(f) Section 33.88 Engine overtemperature test. The requirements of
Sec. 33.88(b) apply, except that the test time is 5 minutes instead of
4 minutes. During the 5-minute time interval, the engine must be run at
the maximum power-on rpm with a gas temperature at least 35 [deg]F (19
[deg]C) higher than the maximum operating limit at the flat 30-second
and 2-minute OEI power rating.
(g) Section A33.4 Airworthiness Limitations Section. Additional
airworthiness requirements of Sec. A33.4(b) are applicable to the
PW220A as follows:
(1) The Airworthiness Limitations Section must also prescribe the
mandatory post-flight inspections and maintenance actions associated
with any use of the flat 30-second and 2-minute OEI power rating.
(2) The applicant must validate the adequacy of the inspections and
maintenance actions required with any use of the flat 30-second and 2-
minute OEI power rating.
(3) The applicant must establish an in-service engine evaluation
program to ensure the continued adequacy of the instructions for
mandatory post-flight inspections and maintenance actions prescribed
under paragraph (b)(1) of Sec. A33.4 and of the data for Sec.
33.5(b)(4) pertaining to power availability. The program must include
service engine tests or equivalent service engine test experience on
engines of similar design and evaluations of service usage of the flat
30-second and 2-minute OEI power rating.
[[Page 57898]]
Issued in Kansas City, Missouri, on December 2, 2025.
Patrick R. Mullen,
Manager, Technical Policy Branch, Policy and Standards Division,
Aircraft Certification Service.
[FR Doc. 2025-22759 Filed 12-12-25; 8:45 am]
BILLING CODE 4910-13-P