42278 Federal Register / Vol
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42278 Federal Register / Vol. 65, No. 132 / Monday, July 10, 2000 / Rules and Regulations shipments; and (5) this rule provides a FOR FURTHER INFORMATION CONTACT: Jay materials introduce fatigue 60-day comment period, and any Turnberg, FAA, Engine and Propeller characteristics and failure modes that comments received will be considered Standards Staff, Engine and Propeller differ from metallic materials. prior to finalization of this rule. Directorate, Aircraft Certification The requirements of part 35 were Service, ANE±110, 12 New England established to address the airworthiness List of Subjects in 7 CFR Part 947 Executive Park, Burlington, considerations associated with metal Marketing agreements, Potatoes, Massachusetts, 01803±5229; telephone propeller blades. Propeller blades Reporting and recordkeeping (781) 238±7116; fax (781) 238±7199. constructed using composite material requirements. SUPPLEMENTARY INFORMATION: may be subject to damage due to the For the reasons set forth in the high impact forces associated with a preamble, 7 CFR Part 947 is amended as Background bird strike. Thus, composite propellers follows: On February 9, 1999, Hamilton must demonstrate propeller integrity Sundstrand applied for type following a bird strike. PART 947ÐIRISH POTATOES GROWN certification for a new model NP2000 Part 35 does not require a IN MODOC AND SISKIYOU COUNTIES, propeller. The NP2000 propeller uses a demonstration of propeller integrity CALIFORNIA, AND IN ALL COUNTIES digital electro-hydraulic control system following a lightning strike. Composite IN OREGON, EXCEPT MALHEUR and blades that are constructed of blades may not safely conduct or COUNTY composite material. dissipate the electrical current from a Conventional propellers on turboprop lightning strike. Severe damage can 1. The authority citation for 7 CFR aircraft use a mechanical governor in result if the propellers are not properly Part 947 continues to read as follows: the propeller control system that senses protected. Therefore, composite blades Authority: 7 U.S.C. 601±674. propeller speed and adjusts the pitch by must demonstrate propeller integrity 2. In Part 947, §§ 947.120, 947.123, directing hydraulic oil to the propeller following a lightning strike. 947.125, 947.130, 947.132, 947.133, actuator to increase or decrease pitch to The existing certification 947.134, 947.141, 947.180, 947.247, and maintain the propeller at the correct requirements only address structural 947.340 are suspended in their entirety revolutions per minute (RPM). When and fatigue evaluation of metal effective July 1, 2000. the mechanical governor fails, the propeller blades or hubs, and those metal components of non-metallic blade Dated: July 5, 2000. propeller pitch is controlled by a backup mechanical overspeed governor. assemblies. Allowable design stress Robert C. Keeney, The Hamilton Sundstrand model limits for composite blades must Deputy Administrator, Fruit and Vegetable NP2000 propeller uses a digital consider the deteriorating effects of the Programs. electronic governor in the propeller environment and in-service use, [FR Doc. 00±17415 Filed 7±6±00; 9:48 am] control system. The digital electronic particularly those effects from BILLING CODE 3410±02±P governor is designed to operate a hydro- temperature, moisture, erosion and mechanical interface to direct hydraulic chemical attack. Composite blades also oil to the propeller actuator to increase present new and different DEPARTMENT OF TRANSPORTATION or decrease pitch. The digital electronic considerations for retention of the governor logic commands speed blades in the propeller hub. Federal Aviation Administration governing, synchrophasing, failure The applicable airworthiness monitoring and provides beta requirements do not contain adequate or 14 CFR Part 35 scheduling. The digital electronic appropriate safety standards for these [Docket No. NE±120; Special Conditions No. governor introduces potential failures novel and unusual design features. 35±001±SC] associated with electrical power, Type Certification Basis software commands, data, and Special Conditions: Hamilton environmental effects that can result in Under § 21.17, Hamilton Sundstrand Sundstrand, Model NP2000 Propeller hazardous propeller effects. In addition must show that the model NP2000 to these features, the system has a propeller meets the applicable AGENCY: Federal Aviation provisions of § 21.21 and part 35. Administration (FAA), DOT. backup mechanical overspeed governor. The special conditions address the If the Administrator finds that the ACTION: Final special conditions. following airworthiness issues for the applicable airworthiness regulations (i.e. part 35), do not contain adequate or SUMMARY: These special conditions are Hamilton Sundstrand model NP2000 propeller: appropriate safety standards for the issued for the Hamilton Sundstrand model NP2000 propeller because of a model NP2000 constant speed propeller. 1. Safety assessment; 2. Propeller control system; novel or unusual design feature, special This eight-bladed propeller uses a dual 3. Centrifugal load tests; conditions are prescribed under the acting digital electro-hydraulic propeller 4. Fatigue limits and evaluation; provisions of § 21.16. control system and has blades 5. Bird impact; and Special conditions, as appropriate, are constructed of composite materials. 6. Lightning strike. issued in accordance with § 11.49 after These design features are novel and The Hamilton Sundstrand model public notice, as required by §§ 11.28 unusual. The applicable airworthiness NP2000 propeller incorporates propeller and 11.29(b), and become part of the regulations do not contain adequate or blades constructed of composite type certification basis in accordance appropriate safety standards for these material. This material has fibers that with § 21.17(a)(2). design features. These special are woven or aligned in specific Special conditions are initially conditions contain the additional safety directions to give the material applicable to the model for which they standards that the Administrator directional strength properties. These are issued. Should the type certificate considers necessary to establish a level properties depend on the type of fiber, for that model be amended later to of safety equivalent to that established the orientation and concentration of include any other model that by the existing airworthiness standards. fiber, and the resin matrix material that incorporates the same novel or unusual DATES: Effective date August 9, 2000. binds the fibers together. Composite design features, the special conditions VerDate 11<MAY>2000 16:51 Jul 07, 2000 Jkt 190000 PO 00000 Frm 00004 Fmt 4700 Sfmt 4700 E:\FR\FM\10JYR1.SGM pfrm02 PsN: 10JYR1 Federal Register / Vol. 65, No. 132 / Monday, July 10, 2000 / Rules and Regulations 42279 would also apply to the other model electronic control components perform Propeller blade and spinner under the provisions of § 21.101(a)(1). the same basic function but use construction now use composite software, electronic circuitry, and materials that have a higher potential for Novel or Unusual Design Features electro-hydraulic actuators. The damage from bird impact. The NP2000 propeller will electronic control systems may also The need for bird impact incorporate the following novel and incorporate additional functions such as requirements was recognized when unusual design features: dual acting failure monitoring, synchrophasing and composite blades were introduced in digital electro-hydraulic propeller beta scheduling. This addition of the 1970's; the safety issue has been control system and blades constructed electronics to the control system may addressed by special tests and special of composite materials. Special introduce new failure modes that can conditions for composite blade conditions for a safety assessment, the result in hazardous propeller effects. certifications. These special conditions propeller control system, centrifugal Centrifugal Load Tests were unique for each propeller and load tests, fatigue limits and evaluation, effectively stated that the propeller will bird impact, and lightning strike address Section 35.35 currently requires that withstand a four-pound bird impact the novel and unusual design features. the hub and blade retention without contributing to a hazardous The special conditions are discussed arrangement of propellers with propeller effect. These special tests and below. detachable blades be tested to a special conditions have been effective centrifugal load of twice the maximum Safety Assessment for over four million flight hours. There centrifugal force to which the propeller have not been any accidents attributed The special conditions require the would be subjected during operation. applicant to conduct a safety assessment to bird impact on composite propellers. This requirement is limited to the blade The selection of a four-pound bird has of the propeller in conjunction with the and hub retention capacity and does not requirements for evaluating the digital been substantiated by the extensive address composite materials and service history of blades that have been electro-hydraulic control system. A composite construction of the propeller safety assessment is necessary due to designed using the four-pound bird assembly or changes in materials due to criteria. the increased complexity of these service degradation and environmental propeller designs and related control factors. Lightning Strike systems. The ultimate objective