Federal Aviation Administration (FAA), DOT.
Notice of proposed rulemaking (NPRM).
This rulemaking would establish noise certification standards for issuing type and airworthiness certificates for a new civil, hybrid airplane-rotorcraft known as the tiltrotor. This rule proposes to adopt the same recommended guidelines for noise certification found in the International Civil Aviation Organization (ICAO) Annex 16, Volume 1, Chapter 13, Attachment F (Amendment 7) for tiltrotors certificated in the United States (U.S.). The ICAO recommended practices are already harmonized internationally, and the adoption as standards into our regulations would be consistent with the Federal Aviation Administration's (FAA) goal of harmonizing U.S. regulations with international standards.
The proposed standards would apply to the issuance of the original type certificate, changes to the type certificate, and standard airworthiness certificates for tiltrotors.
Send your comments on or before October 19, 2011.Start Printed Page 36002
You may send comments identified by Docket Number [Insert docket number, for example, FAA-2011-0629] using any of the following methods:
- Federal eRulemaking Portal: Go to http://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, 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.
Privacy: The FAA will post all comments it receives, without change, to http://www.regulations.gov, including any personal information the commenter provides. Using the search function of the docket Web site, anyone can find and read the electronic form of all comments received into any FAA dockets, including the name of the individual sending the comment (or signing the comment for an association, business, labor union, etc.). DOT's complete Privacy Act Statement can be found in the Federal Register published on April 11, 2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov.
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.Start Further Info
FOR FURTHER INFORMATION CONTACT:
For technical questions concerning this proposed rule contact Sandy Liu, AEE-100, Office of Environment and Energy, Federal Aviation Administration, 800 Independence Avenue, SW., Washington, DC 20591; telephone: (202) 493-4864; facsimile (202) 267-5594; e-mail: email@example.com. For legal questions concerning this proposed rule contact Karen Petronis, AGC-200, Office of the Chief Counsel, Regulations Division, Federal Aviation Administration, 800 Independence Avenue, SW., Washington, DC 20591; telephone: (202) 267-3073; e-mail: firstname.lastname@example.org.End Further Info End Preamble Start Supplemental Information
Authority for This Rulemaking
The FAA's authority to issue rules on aviation safety is found in Title 49 of the United States Code. Subtitle I, section 106 describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the agency's authority.
This rulemaking is promulgated under the authority described in subtitle VII, part A, subpart III, section 44715, Controlling aircraft noise and sonic boom. Under that section, the FAA is charged with prescribing regulations to measure and abate aircraft noise. This proposed regulation is within the scope of that authority since it would establish new noise certification test procedures and noise limits for a new class of aircraft. Applicants for type certificates, changes in type design, and airworthiness certificates for tiltrotors would be required to comply with these new regulations.
A new aircraft type known as a tiltrotor is currently in development after more than six decades. The aircraft uses a hybrid of propellers and helicopter rotors to provide both lift and propulsive force using rotating nacelles. The aircraft is designed to function as a helicopter for takeoff and landing and as an airplane during the en-route portion of flight operations.
The most recognizable tiltrotor operating today is the V-22 Osprey used by the U.S. Marines and the U.S. Air Force. The V-22 Osprey was tailored for the Department of Defense Special Operations Forces and can transport 24 fully equipped troops. The proposed civil version of the tiltrotor would carry up to nine passengers.
The tiltrotor concept was first explored for the U.S. Army in the mid-1950s as a convertiplane concept that incorporated mixed vertical and forward flight capabilities. In 1958, Bell Helicopter Textron Inc. (Bell) of Fort Worth, Texas developed the XV-3 tiltrotor for a joint research program between the U.S. Army and the U.S. Air Force. The Bell XV-3 completed a successful full conversion from vertical flight to forward cruise and demonstrated the feasibility of tiltrotor technology. Following the U.S. Army and National Aeronautics and Space Administration prototype development contract award to Bell in the mid-1970s, two Bell XV-15 tiltrotor demonstrator aircraft were built as predecessors to the V-22 Osprey to demonstrate mature tiltrotor technology and flight capabilities.
ICAO Noise Certification Standards
The ICAO is the international body with responsibility for the development of International Standards and Recommended Practices pursuant to the Convention on International Civil Aviation (the Chicago Convention). Consistent with their obligations under the Chicago Convention, Contracting States agree to implement ICAO standards in their national regulations to the extent practicable. The standards for aircraft noise are contained in Annex 16, Environmental Protection, Volume 1, Aircraft Noise.
In anticipation of civil tiltrotor production, ICAO's Committee on Aviation Environmental Protection (CAEP) chartered the Tiltrotor Task Group (TRTG) to develop noise certification guidelines for tiltrotors in 1997. The FAA participated in the TRTG and its development of the tiltrotor noise guidelines from 1997 to 2000. The ICAO tiltrotor guidelines used the same noise limits that the United States had incorporated into part 36, Appendix H for helicopter noise certification. The ICAO has included additional requirements that are unique to the design of tiltrotors.
On June 29, 2001, the TRTG's guidelines were adopted by the ICAO Council for incorporation into Annex 16, Volume 1, Chapter 13, Attachment F (Amendment 7). The ICAO guidelines became effective on October 29, 2001, with an applicability date of March 21, 2002.
Statement of the Problem
Current regulations in part 36 do not contain noise certification requirements specific to the tiltrotor and its unique flight capabilities. Since no standards for the tiltrotor currently exist, the FAA proposes to adopt the guidelines through rulemaking and add the new standards to part 36 and amend § 21.93 (Classification of Changes in Type Design) to accommodate certification of the tiltrotor. In order to harmonize the U.S. regulations with the international standards, this rulemaking proposes the adoption of the same noise certification guidelines used in ICAO Annex 16, Volume 1, Chapter 13, Attachment F (Amendment 7) for tiltrotors.
Application for Type Certification
As the tiltrotor concept and technology proved promising with the production of the V-22 Osprey, Bell and Agusta-Westland established a joint business venture in 1998 to co-develop the Bell/Agusta model BA609 civil tiltrotor.
In August 1996, Bell applied for a U.S. type certificate for the model Start Printed Page 36003BA609 tiltrotor. The BA609 would be type certificated as a “special class” of aircraft under §§ 21.17 and 21.21, using the applicable airworthiness provisions of part 25 (Airworthiness Standards: Transport Category Airplanes) and part 29 (Airworthiness Standards: Transport Category Rotorcraft). This is the first application for this class of aircraft. Bell is targeting existing helicopter operators as the primary civil market for the BA609, and has stated the BA609 could operate from existing heliports without the need for new infrastructure to accommodate the aircraft.
General Discussion of the Proposal
The standards proposed in this rulemaking would apply to the issuance of an original type certificate, changes to a type certificate, and the issuance of a standard airworthiness certificate for tiltrotors. This rulemaking proposes noise certification standards that would be applicable to all tiltrotors, including the Bell/Agusta Model BA609, which is currently under development. This rule proposes to incorporate the guidelines of ICAO Annex 16, Volume 1, Chapter 13, Attachment F (Amendment 7) for tiltrotors, consistent with the FAA goal of harmonization of regulations with international standards.
These proposed regulations would:
- Amend § 21.93 for acoustical changes in type design to add the tiltrotor as a class of aircraft;
- Amend § 36.1 noise certification standards for the issuance of type and airworthiness certificates for the new tiltrotor class of aircraft (including the definitions and applicability);
- Add a new § 36.13 acoustical change requirements for tiltrotors;
- Add a new subpart K to part 36 that includes noise measurement, evaluation and calculation criteria and maximum noise limits of tiltrotors;
- Add a new Appendix K to part 36 that includes noise certification standards (including the reference test conditions and reference test procedures) for tiltrotors certificated in the United States.
Paperwork Reduction Act
The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires the FAA consider the impact of paperwork and other information collection burdens imposed on the public. The FAA has determined there would be no new requirement for information collection associated with this proposed rule. The requirements are the same as for any other new aircraft type certification.
In keeping with U.S. obligations under the Convention on International Civil Aviation, it is FAA policy to conform our regulations to ICAO Standards and Recommended Practices to the maximum extent practicable. In 2001, ICAO adopted tiltrotor noise guidelines. This proposed regulation will harmonize U.S. noise standards with the international standards by adopting the same requirements, adapted for the U.S. regulatory format.
Regulatory Evaluation, Regulatory Flexibility Determination, International Trade Impact Assessment, and Unfunded Mandates Assessment
Changes to Federal regulations must undergo several economic analyses. First, Executive Order 12866 and Executive Order 13563 direct that each Federal agency shall propose or adopt a regulation only upon a reasoned determination that the benefits of the intended regulation justify its costs. Second, the Regulatory Flexibility Act of 1980 (Pub. L. 96-354) requires agencies to analyze the economic impact of regulatory changes on small entities. Third, the Trade Agreements Act (Public Law 96-39) prohibits agencies from setting standards that create unnecessary obstacles to the foreign commerce of the United States. In developing U.S. standards, this Trade Act requires agencies to consider international standards and, where appropriate, that they be the basis of U.S. standards. Fourth, the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires agencies to prepare a written assessment of the costs, benefits, and other effects of proposed or final rules that include a Federal mandate likely to result in the expenditure by State, local, or tribal governments, in the aggregate, or by the private sector, of $100 million or more annually (adjusted for inflation with base year of 1995). This portion of the preamble summarizes the FAA's analysis of the economic impacts of this proposed rule.
Department of Transportation Order DOT 2100.5 prescribes policies and procedures for simplification, analysis, and review of regulations. If the expected cost impact is so minimal that a proposed or final rule does not warrant a full evaluation, this order permits that a statement to that effect and the basis for it be included in the preamble if a full regulatory evaluation of the cost and benefits is not prepared. Such a determination has been made for this proposed rule. The reasoning for this determination follows:
(1) Has benefits that justify its costs,
(2) Is not an economically “significant regulatory action” as defined in section 3(f) of Executive Order 12866;
(3) Would not have a significant economic impact on a substantial number of small entities;
(4) Would not have a significant effect on international trade; and
(5) Would not impose an unfunded mandate on state, local, or tribal governments, or on the private sector by exceeding the monetary threshold identified.
These analyses are summarized below.
The tiltrotor aircraft is a new class of aircraft. Currently there are no part 36 certification standards for tiltrotor aircraft. This proposed rule would provide for the part 36 certification requirements for this new class of aircraft. The benefit of this proposed rule is that it would allow the startup and development of a market for a new class of aircraft, the tiltrotor. The FAA believes that this would result in substantial benefits.
The potential size of the tiltrotor market can be estimated by the sales projections of the current developer, Bell/Agusta. In the next 10 years, only one model of tiltrotor is expected to be available, the BA609 currently in development. The price of a BA609 is expected to be $10 to $14 million, up from the original estimate of $7 million to the current $14 million. When first priced in 2000, the $7 million price was equivalent to the replacement value of a Bell 412 helicopter. The BA609 has unique capabilities, such as vertical takeoff and landing, combined with the speed and range of a turboprop airplane.
Bell estimates that it will sell approximately 100 BA609s, making the potential near-term tiltrotor market worth a nominal $1 billion to $1.4 billion. Table 1 shows the nominal and present value estimates of the tiltrotor market. The present value is based on a 7 percent discount rate, and a ten year production period with 10 tiltrotors being delivered each year. The present value of the tiltrotor market is estimated to be between $702,000,000 and $983,000,000.Start Printed Page 36004
|Year||Units produced||Unit price||Total market value||Unit price||Total market value|
|Nominal||Present value @ 7%||Nominal||Present value @ 7%|
Table 2 shows the incremental manufacturer costs for the noise certification of a civil tiltrotor aircraft. The costs consist of four major items: Acoustics; Flight Test; Aircraft; and Miscellaneous. For tiltrotor aircraft noise certification, as for any aircraft certification, the noise demonstration flight testing and reporting is the major incremental cost.
To meet the proposed requirements of noise control, acoustical measurements are used to quantify the characteristic noise levels of the aircraft. Almost half the expense ($250,000) is invested in the acoustics group equipment and analysis. This cost includes overall noise test planning and coordination, noise test site preparation and measurement set-up.
The next highest expense involves the support of the flight test group ($220,000). These expenses are needed to configure and prepare the aircraft to execute the required noise flight test procedures.
The last two major expense groups are aircraft and miscellaneous expenses. The aircraft expense ($50,000) involves costs associated with aircraft flight time, fuel, and flight crew support. Most other general expenses of test support are miscellaneous costs ($68,000).
Issuance of a type certificate requires compliance with the applicable noise certification requirements of part 36. Full noise certification testing is generally required for new aircraft types and for certain voluntary changes to type design that are classified as acoustical change under § 21.93(b). The incremental costs recur only when a new type certificate is issued, or when a change to a type design results when an acoustical change is made.
As shown in Table 2, the estimated total incremental cost of a single noise certification is $588,000. As the $588,000 would be incurred in the first year, the nominal value equals the present value. The cost estimates for noise certification were prepared by Bell Helicopter Textron. The cost of noise certification for the tiltrotor is comparable to that for a large helicopter (over 7,000 pounds). Since noise testing is required for new aircraft to gain U.S. certification, the cost burden is comparable and does not impose any unexpected burden on manufacturers.
The FAA may incur costs in this certification process, including the adoption of the new regulations. However, these costs are not expected to vary significantly from the agency's current costs to noise certificate any other new aircraft type.
Based on the above analyses, this proposed rule is considered to be a minimal cost rule.
|Item||Hours||Cost per hour||Total cost|
|Acoustics Group Items|
|Hours & Costs Acoustic Group||2,000||$125||$250,000|
|Flight Test Groups|
|Statement of Conformity|
|TSPI pilot guidance and off-site ground station development|
|Aircraft mods to production-representation configuration|
|Aircraft instrumentation buildup special to noise tests|
|Start Printed Page 36005|
|Aircraft data archiving|
|Hours & Costs Flight Test Groups||2,000||110||220,000|
|(Flight time: Instrumentation check out; ferry; & test)|
|Miscellaneous flight time||2||5,000||10,000|
|Test flight time||8||5,000||40,000|
|Hours & Costs—Aircraft||10||50,000|
|Test site lease||10,000|
|Off-site equipment rental & supplies||10,000|
|Equipment shipping & local transportation costs (cars, pickups)||15,000|
|Travel, food, and hotel costs (10 people* 14 days* $200/day + $500 airfare per person)||33,000|
|Total Hours & Costs||4,010||N.A.||588,000|
|Source: Bell Helicopter Textron, 04/01/2011.|
Since the tiltrotor industry is still developing, the costs and benefits discussed are based on a single tiltrotor program. The proposed rule would require the noise certification of a tiltrotor aircraft type. While the estimated benefits and costs are based on a single tiltrotor type, we believe the benefits will exceed the costs for any future designs. Bell Agusta anticipates selling 100 tiltrotor aircraft, allowing a $1 to $1.4 billion ($700 million to $1billion in present value) new market to start up and develop.
The present value cost of the proposed rule is $588,000 for the certification of one aircraft type. The estimated 100 tiltrotor aircraft that would be sold would be covered under this type certificate, unless major modifications were made that would change the original certification. Therefore, the total present value cost of the proposed rule is $588,000, which the FAA considers to be minimal.
Although the FAA cannot quantify the benefits of the proposed rule, the FAA believes that the benefits would be substantial. Because of this and the minimal cost nature of the proposed rule the FAA believes that the proposed rule would be cost beneficial.
Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 (RFA) establishes “as a principle of regulatory issuance that agencies shall endeavor, consistent with the objective of the rule and of applicable statutes, to fit regulatory and informational requirements to the scale of the businesses, organizations, and governmental jurisdictions subject to regulation.” To achieve that principle, the RFA requires agencies to solicit and consider flexible regulatory proposals and to explain the rationale for their actions. The RFA covers a wide-range of small entities, including small businesses, not-for-profit organizations and small governmental jurisdictions.
Agencies must perform a review to determine whether a proposed or final rule will have a significant economic impact on a substantial number of small entities. If the agency determines that it will, the agency must prepare a regulatory flexibility analysis as described in the Act.
However, if an agency determines that a proposed or final rule is not expected to have a significant economic impact on a substantial number of small entities, section 605(b) of the 1980 RFA provides that the head of the agency may so certify and a regulatory flexibility analysis is not required. The certification must include a statement providing the factual basis for this determination, and the reasoning should be clear.
Size standards for small entities are published by the Small Business Administration (SBA) on their Web site at http://www.sba.gov/size. The size standards used herein are from “SBA U.S. Small Business Administration, Table of Small Business Size Standards, Matched to North American Industry Classification System Codes”. The Table is effective November 5, 2010, and uses the 2007 NAICS codes. All aircraft manufacturers are listed in Sector 31-33—Manufacturing; Subsector 336—Transportation Equipment Manufacturing; NAICS Code 336411—Aircraft Manufacturing. The small entity size standard is 1,500 employees.
Bell Helicopter is a wholly owned subsidiary of Textron Inc. Bell Helicopter employed approximately 9,800 employees at the end of 2009 while Textron employed approximately 32,000 employees. (Textron Fact Book 2009). Agusta-Westland is a wholly owned subsidiary of Finmeccanica. Agusta-Westland employed 13,886 employees at September 30, 2010 while Finmeccanica employed 75,733 employees. (Finmeccanica Press Release, Rome, 3 November 2010) Since the only tiltrotor manufacturer, Bell Helicopter, employs more than 1,500 employees, there are no small-entity tiltrotor manufacturers.
Consequently, the FAA certifies that this proposed rule would not have a significant economic impact on a substantial number of small tiltrotor manufacturers.
International Trade Impact Assessment
The Trade Agreements Act of 1979 (Pub. L. 96-39), as amended by the Uruguay Round Agreements Act (Pub. L. 103-465), prohibits Federal agencies from establishing standards or engaging in related activities that create Start Printed Page 36006unnecessary obstacles to the foreign commerce of the United States. Pursuant to these Acts, the establishment of standards is not considered an unnecessary obstacle to the foreign commerce of the United States, so long as the standard has a legitimate domestic objective, such as the protection of safety, and does not operate in a manner that excludes imports that meet this objective. The statute also requires consideration of international standards and, where appropriate, that they be the basis for U.S. standards.
The FAA has assessed the potential effect of this proposed rule and determined that it would encourage international trade by using international standards as the basis for a rule for the noise certification of tiltrotors.
Unfunded Mandates Assessment
Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires each Federal agency to prepare a written statement assessing the effects of any Federal mandate in a proposed or final agency rule that may result in an expenditure of $100 million or more (adjusted annually for inflation) in any one year by State, local, and tribal governments, in the aggregate, or by the private sector; such a mandate is deemed to be a “significant regulatory action”. The FAA currently uses an inflation-adjusted value of $140.8 million in lieu of $100 million. This proposed rule does not contain such a mandate; therefore, the requirements of Title II do not apply.
Executive Order 13132, Federalism
The FAA has analyzed this proposed rule under the principles and criteria of Executive Order 13132, Federalism. The agency determined that this action would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government, and, therefore, would not have federalism implications.
FAA Order 1050.1E identifies FAA actions that are categorically excluded from preparation of an environmental assessment or environmental impact statement under the National Environmental Policy Act in the absence of extraordinary circumstances. This rule adopts internationally established noise guidelines for a new civil, hybrid airplane-rotorcraft known as the tiltrotor. Based on the dual helicopter and propeller airplane characteristics inherit in the tiltrotor, the noise guidelines utilize preexisting helicopter noise certification limits and procedures. This rule adopts these noise limits to control the harshest (maximum) noise levels when the tiltrotor operates in its noisiest configuration—helicopter mode. In airplane mode, the tiltrotor is significantly quieter given its low cruise RPM design. The FAA finds the applicability of the noise guidelines to be technologically and environmentally consistent for this new class of aircraft. The tiltrotor will function as a helicopter and will follow the same helicopter noise certification requirements, thus maintaining a comparable level of environmental protection.
The FAA has determined this rulemaking action qualifies for the categorical exclusion identified in paragraph 312f and involves no extraordinary circumstances.
Regulations That Significantly Affect Energy Supply, Distribution, or Use
The FAA has analyzed this NPRM under Executive Order 13211, Actions Concerning Regulations that Significantly Affect Energy Supply, Distribution, or Use (May 18, 2001). The agency determined that it is not a “significant energy action” under the executive order, it is not a “significant regulatory action” under Executive Order 12866 and DOT's Regulatory Policies and Procedures, and it is not likely to have a significant adverse effect on the supply, distribution, or use of energy.
The FAA invites interested persons to participate in this rulemaking by submitting written comments, data, or views. We also invite comments relating to the economic, environmental, energy, or federalism impacts that might result from adopting the proposals in this document. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. To ensure the docket does not contain duplicate comments, please send only one copy of written comments, or if you are filing comments electronically, please submit your comments only one time.
We will file in the docket all comments we receive, as well as a report summarizing each substantive public contact with FAA personnel concerning this proposed rulemaking. Before acting on this proposal, we will consider all comments we receive on or before the closing date for comments. We will consider comments filed after the comment period has closed if it is possible to do so without incurring expense or delay. We may change this proposal in light of the comments we receive.
Availability of Rulemaking Documents
You can get an electronic copy of rulemaking documents using the Internet by—
1. Searching the Federal eRulemaking Portal (http://www.regulations.gov);
2. Visiting the FAA's Regulations and Policies Web page at http://www.faa.gov/regulations_policies or
3. Accessing the Government Printing Office's Web page at http://www.gpoaccess.gov/fr/index.html.
You can also get a copy by sending a request to the Federal Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence Avenue, SW., Washington, DC 20591, or by calling (202) 267-9680. Make sure to identify the docket or notice number of this rulemaking.
You may access all documents the FAA considered in developing this proposed rule, including economic analyses and technical reports, from the internet through the Federal eRulemaking Portal referenced in paragraph (1).Start List of Subjects
List of SubjectsEnd List of Subjects
The Proposed Amendment
In consideration of the foregoing, the Federal Aviation Administration proposes to amend chapter I of title 14, Code of Federal Regulations, as follows:Start Part
PART 21—CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS
1. The authority citation for part 21 continues to read as follows:
2. Amend § 21.93 by adding paragraph (b)(5) to read as follows:
(b) * * *Start Printed Page 36007
PART 36—NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION
3. The authority citation for part 36 continues to read as follows:
4. Amend § 36.1 as follows:
A. Add paragraph (a)(5);
B. Amend paragraph (c) by removing the phrase “or 36.11” and adding the phrase “36.11 or 36.13” in its place; and
C. Add paragraph (i).
The additions and revisions read as follows:
(a) * * *
(5) Type certificates, changes to those certificates, and standard airworthiness certificates, for tiltrotors.
(i) For the purpose of showing compliance with this part for tiltrotors, the following terms have the specified meanings:
Airplane mode means a configuration with nacelles on the down stops (axis aligned horizontally) and rotor speed set to cruise revolutions per minute (RPM).
Airplane mode RPM means the lower range of rotor rotational speed in RPM defined for the airplane mode cruise flight condition.
Fixed operation points mean designated nacelle angle positions selected for airworthiness reference. These are default positions used to refer to normal nacelle positioning operation of the aircraft. The nacelle angle is controlled by a self-centering switch. When the nacelle angle is 0 degrees (airplane mode) and the pilot moves the nacelle switch upwards, the nacelles are programmed to automatically turn to the first default position (for example, 60 degrees) where they will stop. A second upward move of the switch will tilt the nacelle to the second default position (for example, 75 degrees). Above the last default position, the nacelle angle can be set to any angle up to approximately 95 degrees by moving the switch in the up or down direction. The number and position of the fixed operation points may vary on different tiltrotor configurations.
Nacelle angle is defined as the angle between the rotor shaft centerline and the longitudinal axis of the aircraft fuselage.
Tiltrotor means a class of aircraft capable of vertical take-off and landing, within the powered-lift category, with rotors mounted at or near the wing tips that vary in pitch from near vertical to near horizontal configuration relative to the wing and fuselage.
Vertical takeoff and landing (VTOL) mode means the aircraft state or configuration having the rotors orientated with the axis of rotation in a vertical manner (i.e., nacelle angle of approximately 90 degrees) for vertical takeoff and landing operations.
VCON is defined as the maximum authorized speed for any nacelle angle in VTOL/Conversion mode.
VMCP is defined as the maximum level flight airspeed for airplane mode corresponding to minimum specification engine power corresponding to maximum continuous power available for sea level pressure of 2,116 pounds per square foot (1,013.25 hPa), at 77° Fahrenheit (25° Celsius) ambient conditions at the relevant maximum certificated weight (mass).
VMO is defined as the maximum airspeed in airplane mode that may not be deliberately exceeded.
VTOL/Conversion mode is all approved nacelle positions where the design operating rotor speed is used for hover operations.
VTOL mode RPM means highest range of RPM that occur for takeoff, approach, hover, and conversion conditions.
5. Add § 36.13 to subpart A to read as follows:
The following requirements apply to tiltrotors in any category for which an acoustical change approval is applied for under § 21.93(b) of this chapter on or after [effective date of final rule]:
(a) In showing compliance with Appendix K of this part, noise levels must be measured, evaluated, and calculated in accordance with the applicable procedures and conditions prescribed in Appendix K of this part.
(b) Compliance with the noise limits prescribed in section 4 of Appendix K of this part must be shown in accordance with the applicable provisions of sections K2 (Noise Evaluation Measure), K3 (Noise Measurement Reference Points), K6 (Noise Certification Reference Procedures), and K7 (Test Procedures) of Appendix K of this part.
(c) After a change in type design, tiltrotor noise levels may not exceed the limits specified in § 36.1103.
6. Add Subpart K of part 36 to read as follows:
For tiltrotors, the noise generated must be measured and evaluated under Appendix K of this part, or under an approved equivalent procedure.
(a) Compliance with the maximum noise levels prescribed in Appendix K of this part must be shown for a tiltrotor for which the application for the issuance of a type certificate is made on or after [effective date of the final rule].
(b) To demonstrate compliance with this part, noise levels may not exceed the noise limits listed in section K4 of Appendix K of this part. Appendix K of this part (or an approved equivalent procedure) must also be used to evaluate and demonstrate compliance with the approved test procedures, and at the applicable noise measurement points.
7. Add Appendix K of part 36 to read as follows:
Appendix K to Part 36—Noise Requirements for Tiltrotors Under Subpart K
K2 Noise Evaluation Measure
K3 Noise Measurement Reference Points
K4 Noise Limits
K6 Noise Certification Reference Procedures
K7 Test Procedures
Section K1 General
This appendix prescribes noise limits and procedures for measuring noise and adjusting the data to standard conditions for tiltrotors as specified in § 36.1 of this part.
Section K2 Noise Evaluation Measure
The noise evaluation measure is the effective perceived noise level in EPNdB, to be calculated in accordance with section A36.4 of Appendix A of this part, except corrections for spectral irregularities must be determined using the 50 Hertz sound pressure level found in section H36.201 of Appendix H of this part.
Section K3 Noise Measurement Reference Points
The following noise reference points must be used when demonstrating tiltrotor compliance with section K6 (Noise Certification Reference Procedures) and section K7 (Test Procedures) of this appendix:
(a) Takeoff reference noise measurement points—
As shown in Figure K1 below:
(1) The centerline noise measurement flight path reference point, designated A, is located on the ground vertically below the reference takeoff flight path. The Start Printed Page 36008measurement point is located 1,640 feet (500 m) in the horizontal direction of flight from the point Cr where transition to climbing flight is initiated, as described in section K6.2 of this appendix;
(2) Two sideline noise measurement points, designated as S(starboard) and S(port), are located on the ground perpendicular to and symmetrically stationed at 492 feet (150 m) on both sides of the takeoff reference flight path. The measurement points bisect the centerline flight path reference point A.
(b) Flyover reference noise measurement points—
As shown in Figure K2 below:
(1) The centerline noise measurement flight path reference point, designated A, is located on the ground 492 feet (150 m) vertically below the reference flyover flight path. The measurement point is defined by the flyover reference procedure in section K6.3 of this appendix;
(2) Two sideline noise measurement points, designated as S(starboard) and S(port), are located on the ground perpendicular to and symmetrically stationed at 492 feet (150 m) on both sides of the flyover reference flight path. The measurement points bisect the centerline flight path reference point A.Start Printed Page 36009
(c) Approach reference noise measurement points—
As shown in Figure K3 below:
(1) The centerline noise measurement flight path reference point, designated A, is located on the ground 394 feet (120 m) vertically below the reference approach flight path. The measurement point is defined by the approach reference procedure in section K6.4 of this appendix. On level ground, the measurement point corresponds to a position 3,740 feet (1,140 m) from the intersection of the 6.0 degree approach path with the ground plane;
(2) Two sideline noise measurement points, designated as S(starboard) and S(port), are located on the ground perpendicular to and symmetrically stationed at 492 feet (150 m) on both sides of the approach reference flight path. The measurement points bisect the centerline flight path reference point A.Start Printed Page 36010
Section K4 Noise Limits
For a tiltrotor, the maximum noise levels, as determined in accordance with the noise evaluation in EPNdB and calculation method described in section H36.201 of Appendix H of this part, must not exceed the noise limits as follows:
(a) At the takeoff flight path reference point: For a tiltrotor having a maximum certificated takeoff weight (mass) of 176,370 pounds (80,000 kg) or more, in VTOL/Conversion mode, 109 EPNdB, decreasing linearly with the logarithm of the tiltrotor weight (mass) at a rate of 3 EPNdB per halving of weight (mass) down to 89 EPNdB, after which the limit is constant. Figure K4 illustrates the takeoff noise limit as a solid line.
(b) At the Flyover path reference point: For a tiltrotor having a maximum certificated takeoff weight (mass) of 176,370 pounds (80,000 kg) or more, in VTOL/Conversion mode, 108 EPNdB, decreasing linearly with the logarithm of the tiltrotor weight (mass) at a rate of 3 EPNdB per halving of weight (mass) down to 88 EPNdB, after which the limit is constant. Figure K4 illustrates the flyover noise limit as a dashed line.
(c) At the approach flight path reference point: For a tiltrotor having a maximum certificated takeoff weight (mass) of 176,370 pounds (80,000 kg) or more, in VTOL/Conversion mode, 110 EPNdB, decreasing linearly with the logarithm of the tiltrotors weight (mass) at a rate of 3 EPNdB per halving of weight (mass) down to 90 EPNdB, after which the limit is constant. Figure K4 illustrates the approach noise limit as a dash-dot line.
Section K5 Trade-Offs
If the noise evaluation measurement exceeds the noise limits described in K4 of this appendix at one or two measurement points:
(a) The sum of excesses must not be greater than 4 EPNdB;
(b) The excess at any single point must not be greater than 3 EPNdB; and
(c) Any excess must be offset by the remaining noise margin at the other point or points.
Section K6 Noise Certification Reference Procedures
K6.1 General Conditions
(c) The takeoff, flyover and approach reference procedures must be established in accordance with sections K6.2, K6.3 and K6.4 of this appendix, except as specified in section K6.1(d) of this appendix.
(d) When the design characteristics of the tiltrotor prevent test flights to be conducted in accordance with section K6.2, K6.3 or K6.4 of this appendix, the applicant must revise Start Printed Page 36011the test procedures and resubmit the procedures for approval.
(e) The following reference atmospheric conditions must be used to establish the reference procedures:
(1) Sea level atmospheric pressure of 2,116 pounds per square foot (1,013.25 hPa);
(2) Ambient air temperature of 77° Fahrenheit (25° Celsius, i.e., ISA + 10 °C);
(3) Relative humidity of 70 percent; and
(4) Zero wind.
(f) For tests conducted in accordance with sections K6.2, K6.3, and K6.4 of this appendix, use the maximum normal operating RPM corresponding to the airworthiness limit imposed by the manufacturer. For configurations for which the rotor speed automatically links with the flight condition, use the maximum normal operating rotor speed corresponding for that flight condition. For configurations for which the rotor speed can change by pilot action, use the highest normal rotor speed specified in the flight manual limitation section for power-on conditions.
K6.2 Takeoff Reference Procedure. The takeoff reference flight procedure is as follows:
(a) A constant takeoff configuration must be maintained, including the nacelle angle selected by the applicant;
(b) The tiltrotor power must be stabilized at the maximum takeoff power corresponding to the minimum installed engine(s) specification power available for the reference ambient conditions or gearbox torque limit, whichever is lower. The tiltrotor power must also be stabilized along a path starting from a point located 1,640 feet (500 m) before the flight path reference point, at 65 ft (20 m) above ground level;
(c) The nacelle angle and the corresponding best rate of climb speed, or the lowest approved speed for the climb after takeoff, whichever is the greater, must be maintained throughout the takeoff reference procedure;
(d) The rotor speed must be stabilized at the maximum normal operating RPM certificated for takeoff;
(e) The weight (mass) of the tiltrotors must be the maximum takeoff weight (mass) as requested for noise certification; and
(f) The reference takeoff flight profile is a straight line segment inclined from the starting point 1,640 feet (500 m) before to the center noise measurement point and 65 ft (20 m) above ground level at an angle defined by best rate of climb and the speed corresponding to the selected nacelle angle and for minimum specification engine performance.
K6.3 Flyover Reference Procedure. The flyover reference flight procedure is as follows:
(a) The tiltrotor must stabilize for level flight along the centerline flyover flight path and over the noise measurement reference point at an altitude of 492 ft (150 m) above ground level;
(b) A constant flyover configuration must be maintained;
(c) The weight (mass) of the tiltrotor must be the maximum takeoff weight (mass) as requested for noise certification;
(d) In the VTOL/Conversion mode:
(1) The nacelle angle must be at the authorized fixed operation point that is closest to the shallow nacelle angle certificated for zero airspeed;
(2) The airspeed must be 0.9VCON; and
(3) The rotor speed must be stabilized at the maximum normal operating RPM certificated for level flight.
K6.4 Approach Reference Procedure. The approach reference procedure is as follows:
(a) The tiltrotor must be stabilized to follow a 6.0 degree approach path;
(b) An approved airworthiness configuration in which maximum noise occurs must be maintained;
(1) An airspeed equal to the best rate of climb speed corresponding to the nacelle angle, or the lowest approved airspeed for the approach, whichever is greater, must be stabilized and maintained; and
(2) The tiltrotor power during the approach must be stabilized over the flight path reference point, and continue to a landing;
(c) The rotor speed must stabilize at the maximum normal operating RPM certificated for approach;
(d) The constant approach configuration used in airworthiness certification tests, with the landing gear extended, must be maintained; and
(e) The weight (mass) of the tiltrotor at landing must be the maximum landing weight (mass) as requested for noise certification.
Section K7 Test Procedures
K7.2 The test procedures and noise measurements must be conducted and processed to yield the noise evaluation measure designated in section K2 of this appendix.
K7.3 If either the test conditions or test procedures do not conform to the applicable noise certification reference conditions or procedures prescribed by this part, the applicant must apply the correction methods described in section H36.205 of Appendix H of this part to the acoustic test data measured.
K7.4 Adjustments for differences between test and reference flight procedures must not exceed:
(a) For takeoff: 4.0 EPNdB, of which the arithmetic sum of delta 1 and the term −7.5 log (QK/QrKr) from delta 2 must not in total exceed 2.0 EPNdB;
(b) For flyover or approach: 2.0 EPNdB.
K7.5 The average rotor RPM must not vary from the normal maximum operating RPM by more than +/-1.0 percent during the 10 dB-down time interval.
K7.6 The tiltrotor airspeed must not vary from the reference airspeed appropriate to the flight demonstration by more than +/−9 km/h (5 kts) throughout the 10 dB-down time interval.
K7.7 The number of level flyovers made with a head wind component must be equal to the number of level flyovers made with a tail wind component.
K7.8 The tiltrotor must operate between +/−10 degrees from the vertical or between +/−65 feet (+/−20 m) lateral deviation tolerance, whichever is greater, above the reference track and throughout the 10 dB-down time interval.
K7.9 The tiltrotor altitude must not vary during each flight by more than +/−30 ft (+/−9 m) from the reference altitude at the overhead point.
K7.10 During the approach procedure, the tiltrotor must establish a stabilized constant speed approach and fly between approach angles of 5.5 degrees and 6.5 degrees.
K7.11 During all test procedures, the tiltrotor weight (mass) must not be less than 90 percent and not more than 105 percent of the maximum certificated weight (mass). For each of the test procedures, complete at least one test at or above this maximum certificated weight (mass).
K7.12 A tiltrotor capable of carrying external loads or external equipment must be noise certificated without such loads or equipment fitted.
K7.13 The values of VCON and VMCP or VMO used for noise certification must be included in the approved Flight Manual.Start Signature
Issued in Washington, DC, on June 10, 2011.
Director, Office of Environment and Energy.
[FR Doc. 2011-15276 Filed 6-20-11; 8:45 am]
BILLING CODE 4910-13-P