2024-27041. Special Conditions: Pratt and Whitney Canada Model PW220A Engine; 30-Minute All Engine Operating Power Rating

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Department of Transportation

Federal Aviation Administration

1. 14 CFR Part 33
2. [Docket No. FAA-2024-2164; Special Conditions No. 33-025-SC]

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final special conditions; request for comments.

SUMMARY:

These special conditions are issued for the Pratt and Whitney Canada (P&WC) Model PW220A engine. This engine will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for aircraft engines. This design feature is a 30-minute all engine operating (AEO) power rating. This rating will be used for hovering at increased power for search and rescue missions. 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:

This action is effective on P&WC on November 20, 2024. Send comments on or before January 6, 2025.

ADDRESSES:

Send comments identified by Docket No. FAA-2024-2164 using any of the following methods:

• Federal eRegulations Portal: Go to 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 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:

Alberto Hernandez, Engine and Propulsion Section, AIR-625, Technical Policy Branch, Policy and Standards Division, Aircraft Certification Service, Federal Aviation Administration, 107 Charles W. Grant Parkway, Atlanta, GA 30354; telephone [phone]; email [e-mail].

SUPPLEMENTARY INFORMATION:

The substance of these special conditions has been published in the Federal Register for public comment in several prior instances with no substantive comments received. Therefore, the FAA finds, pursuant to title 14, Code of Federal Regulations (14 CFR) 11.38(b), that new comments are unlikely, and notice and comment prior to this publication are unnecessary.

Privacy

Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in § 11.35, the FAA will post all comments received without change to www.regulations.gov, 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 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 ( print page 91540) public docket for these special conditions.

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 may change these special conditions based on the comments received.

Background

On November 16, 2021, P&WC applied for a type certificate for its new Model PW220A engine. The Model PW220A engine is a new centerline free-turbine turboshaft engine design intended to be used on transport category twin-engine helicopters. The engine architecture is a split compression system that incorporates the latest generation design methodology of a high-pressure ratio compressor, providing significant improvements in specific fuel consumption (SFC) and power.

A single low pressure compressor (LPC) is driven by a two-stage uncooled power turbine, which also provides mechanical power through an output shaft to the helicopter rotor system. The high pressure compressor (HPC) is a two-stage compressor system driven by a single-stage cooled high pressure turbine (HPT).

Type Certification Basis

Under the provisions of 14 CFR 21.17, P&WC must show that the Model PW220A engine meets the applicable provisions of part 33, dated February 1, 1965, 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 P&WC Model PW220A engine because of a novel or unusual design feature, special conditions are prescribed under the provisions of § 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 § 21.101.

The FAA issues special conditions, as defined in § 11.19, in accordance with § 11.38, and they become part of the type certification basis under § 21.17(a)(2).

Novel or Unusual Design Feature

The P&WC Model PW220A engine will incorporate the following novel or unusual design feature:

A 30-minute all engine operating (AEO) power rating.

Discussion

The type certification basis for the Model PW220A engine does not contain adequate or appropriate airworthiness standards to address a 30-minute AEO power rating. Therefore, special conditions are necessary to provide additional requirements for rating definition, instructions for continued airworthiness (ICA), and endurance testing.

The 30-minute time limit applies to each instance the rating is used; however, there is no limit to the number of times the rating can be used during any one flight, and there is no cumulative time limitation. The ICA requirement in these special conditions is intended to address the unknown nature of actual usage of the 30-minute AEO power rating and any associated engine deterioration. The applicant is expected to make an assessment of the expected usage and publish ICA's and airworthiness limitations section (ALS) limits in accordance with those assumptions, such that engine deterioration is not excessive. The endurance test requirement of 25 hours of operation at a 30-minute AEO rating is similar to several special conditions issued over the past 20 years addressing the same subject. Because the PWC Model PW220A turboshaft engine has a continuous one engine inoperative (OEI) rating and limits equal to or higher than the 30-minute AEO rating, the test time performed at the continuous OEI rating may be credited toward the 25-hour requirement. However, test time spent at other rating elements of the § 33.87 endurance test, such as takeoff or other OEI ratings (that may be equal to or higher values), may not be counted toward the 25 hours of required running. 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.

Applicability

As discussed above, these special conditions are applicable to the P&WC Model PW220A engine. Should PW&C 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 engine model. 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), 106(g), 40113, 44701, 44702, and 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 the Pratt and Whitney Canada Model PW220A engine.

In addition to the general definitions in 14 CFR 1.1, the following definition applies to these special conditions: “Rated 30-Minute All Engine Operating (AEO) Power,” means the approved shaft horsepower developed under static conditions at the specified altitude and temperature, and within the operating limitations established under part 33, and limited in use to periods not exceeding 30-minutes each.

In addition to the airworthiness standards in part 33, the following special conditions apply:

(a) Sections 33.1 Applicability and 33.3 General: As applicable, all documentation, testing, and analysis required to comply with the part 33 certification basis, must account for the 30-minute AEO rating, limits, and usage.

(b) Section 33.4, Instructions for Continued Airworthiness (ICA). In addition to the requirements of § 33.4, the ICA must:

(1) Include instructions to ensure that in-service engine deterioration due to rated 30-minute AEO power usage will not be excessive, meaning that all other approved ratings are available within associated limits and assumed usage, for successive flights; and that deterioration will not exceed that assumed for declaring a time between overhaul (TBO) period.

(i) The applicant must validate the adequacy of the maintenance actions required under paragraph (b)(1) above. ( print page 91541)

(2) Include in the airworthiness limitations section (ALS), any mandatory inspections and serviceability limits related to the use of the 30-minute AEO rating.

(c) Section 33.87, Endurance Test. In addition to the requirements of §§ 33.87(a) and 33.87(d), the overall test run must include a minimum of 25 hours of operation at 30-minute AEO power and limits, divided into periods of 30-minutes AEO power with alternate periods at maximum continuous power or less.

(1) Modification of the § 33.87 test requirements to include the 25 hours of operation at 30-minute AEO power rating must be proposed by the Applicant and accepted by the FAA.

(2) Each § 33.87(d) continuous one-engine-inoperative (OEI) rating test period of 30-minutes or longer, run at power and limits equal to or higher than the 30-minutes AEO rating, may be credited toward this requirement. Note that the test time required for the takeoff or other OEI ratings may not be counted toward the 25 hours of operation required at the 30-minute AEO rating.

Issued in Seattle, Washington, on November 13, 2024.

Paul R. Siegmund,

Acting Manager, Technical Policy Branch, Policy and Standards Division, Aircraft Certification Service.