Proposed Special Conditions: Boeing Model 747-8/-8F Series Airplanes; Design Roll Maneuver Requirement
Federal Register: October 8, 2009 (Volume 74, Number 194)
Proposed Rules
Page 51813-51815
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
DOCID:fr08oc09-20
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration 14 CFR Part 25
Docket No. NM414 Special Conditions No. 25-09-10-SC
Special Conditions: Boeing Model 747-8/-8F Series Airplanes;
Design Roll Maneuver Requirement
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
SUMMARY: This notice proposes special conditions for the Boeing Model 747-8/-8F airplane. This airplane will have novel or unusual design features when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. These design features include an electronic flight control system that provides roll control of the airplane through pilot inputs to the flight computers.
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. Additional special conditions will be issued for other novel or unusual design features of the Boeing 747-8/-8F airplanes.
DATES: Comments must be received on or before November 9, 2009.
ADDRESSES: Comments on this proposal may be mailed in duplicate to:
Federal Aviation Administration, Transport Airplane Directorate,
Attention: Rules Docket (ANM-113), Docket No. NM414, 1601 Lind Avenue,
SW., Renton, Washington 98057-3356; or delivered in duplicate to the
Transport Airplane Directorate at the above address. All comments must be marked Docket No. NM414. Comments may be inspected in the Rules
Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT: Todd Martin, FAA, Airframe and Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue, SW., Renton, Washington 98057- 3356; telephone (425) 227-1178; facsimile (425) 227-1232.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites interested persons to participate in this rulemaking by submitting 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. We ask that you send us two copies of written comments.
We will file in the docket all comments we receive as well as a report summarizing each substantive public contact with FAA personnel concerning these proposed special conditions. The docket is available for public inspection before and after the comment closing date. If you wish to review the docket in person, go to the address in the ADDRESSES section of this notice between 7:30 a.m. and 4 p.m., Monday through
Friday, except Federal holidays.
We will consider all comments we receive on or before the closing date for comments. We will consider comments filed late if it is possible to do so without incurring expense or delay. We may change the proposed special conditions based on comments we receive.
If you want the FAA to acknowledge receipt of your comments on this proposal, include with your comments a pre-addressed, stamped postcard on which the docket number appears. We
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will stamp the date on the postcard and mail it back to you.
Background
On November 4, 2005, The Boeing Company, PO Box 3707, Seattle, WA, 98124, applied for an amendment to Type Certificate Number A20WE to include the new Model 747-8 series passenger airplane and the new Model 747-8F freighter airplane. The Model 747-8 and the Model 747-8F are derivatives of the 747-400 and the 747-400F, respectively. Both the
Model 747-8 and the Model 747-8F are four-engine jet transport airplanes that will have a maximum takeoff weight of 975,000 pounds and new General Electric GEnx -2B67 engines. The Model 747-8 will have two flight crew and the capacity to carry 660 passengers.
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.101, Boeing must show that the Model 747-8 and 747-8F
(hereafter referred as 747-8/-8F series) meet the applicable provisions of part 25, as amended by Amendments 25-1 through 25-117, except for earlier amendments as agreed upon by the FAA. These regulations will be incorporated into Type Certificate No. A20WE after type certification approval of the 747-8/-8F.
In addition, the certification basis includes other regulations, special conditions and exemptions that are not relevant to these proposed special conditions. Type Certificate No. A20WE will be updated to include a complete description of the certification basis for these airplanes.
If the Administrator finds that the applicable airworthiness regulations (i.e., 14 CFR part 25) do not contain adequate or appropriate safety standards for the 747-8/-8F because of a novel or unusual design feature, special conditions are prescribed under the provisions of Sec. 21.16.
In addition to the applicable airworthiness regulations and special conditions, the 747-8/-8F series must comply with the fuel vent and exhaust emission requirements of 14 CFR part 34 and the noise certification requirements of 14 CFR part 36.
Special conditions, as defined in Sec. 11.19, are issued under
Sec. 11.38, and become part of the type certification basis under
Sec. 21.101.
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 or series that incorporates the same or similar novel or unusual design feature, or should any other model or series already included on the same type certificate be modified to incorporate the same or similar novel or unusual design feature, the special conditions would also apply to the other model or series under
Sec. 21.101.
New or Unusual Design Features
The Boeing Model 747-8/-8F will incorporate the following novel or unusual design features: An electronic flight control system that provides roll control of the airplane through pilot inputs to the flight computers.
Discussion
The 747-8/-8F is equipped with an electronic flight control system that provides roll control of the airplane through pilot inputs to the flight computers. Current part 25 airworthiness regulations account for
``control laws,'' for which aileron deflection is proportional to control wheel deflection. They do not address any nonlinearities \1\ or other effects on aileron and spoiler actuation that may be caused by electronic flight controls. Therefore, the FAA considers the flight control system to be a novel and unusual feature compared to those envisioned when current regulations were adopted. Since this type of system may affect flight loads, and therefore the structural capability of the airplane, special conditions are needed to address these effects.
\1\ A nonlinearity is a situation where output does not change in the same proportion as input.
These proposed special conditions differ from current requirements in that the special conditions require that the roll maneuver result from defined movements of the cockpit roll control as opposed to defined aileron deflections. Also, these proposed special conditions require an additional load condition at design maneuvering speed
(VA), in which the cockpit roll control is returned to neutral following the initial roll input.
These proposed special conditions differ from similar special conditions applied to previous designs. These special conditions are limited to the roll axis only, whereas previous special conditions also included pitch and yaw axes. A special condition is no longer needed for the yaw axis because Sec. 25.351 was revised at Amendment 25-91 to take into account effects of an electronic flight control system. No special condition is needed for the pitch axis because the current requirement (Sec. 25.331(c)) is adequate.
Applicability
As discussed above, these proposed special conditions are applicable to Boeing Model 747-8/-8F airplanes. Should Boeing apply at a later date for a change to the type certificate to include another model incorporating the same novel or unusual design features, these proposed special conditions would apply to that model as well under the provisions of Sec. 21.101.
Conclusion
This action affects only certain novel or unusual design features of the Boeing Model 747-8/-8F airplanes. It is not a rule of general applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping requirements.
The authority citation for these Special Conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Proposed Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration (FAA) proposes the following special conditions as part of the type certification basis for the Boeing Model 747-8/-8F series airplanes.
In lieu of compliance with Sec. 25.349(a), the Boeing Model 747-8/
-8F must comply with the following special conditions.
The following conditions, speeds, and cockpit roll control motions
(except as the motions may be limited by pilot effort) must be considered in combination with an airplane load factor of zero, and separately, two-thirds of the positive maneuvering factor used in design. In determining the resulting control surface deflections, the torsional flexibility of the wing must be considered in accordance with
Sec. 25.301(b):
(a) Conditions corresponding to steady rolling velocities must be investigated. In addition, conditions corresponding to maximum angular acceleration must be investigated. For the angular acceleration conditions, zero rolling velocity may be assumed in the absence of a rational time history investigation of the maneuver.
(b) At VA, sudden movement of the cockpit roll control up to the limit is assumed. The position of the cockpit roll control must be maintained until a steady roll rate is achieved and then must be returned suddenly to the neutral position.
(c) At VC, the cockpit roll control must be moved suddenly and
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maintained so as to achieve a roll rate not less than that obtained in paragraph (b).
(d) At VD, the cockpit roll control must be moved suddenly and maintained so as to achieve a roll rate not less than one third of that obtained in paragraph (b).
Issued in Renton, Washington, on September 30, 2009.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
FR Doc. E9-24336 Filed 10-7-09; 8:45 am
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