[Federal Register Volume 76, Number 248 (Tuesday, December 27, 2011)]
[Proposed Rules]
[Pages 80829-80831]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-33049]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 23
[Docket No.FAA-2011-1387; Notice No. 23-11-02-SC]
Special Conditions: XtremeAir GmbH, XA42; Acrobatic Category
Aerodynamic Stability
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This action proposes special conditions for the XtremeAir GmbH
XA42 airplane. The XA42 airplane has a novel or unusual design feature
associated with its static stability. This airplane can perform at the
highest level of aerobatic competition. To be competitive, the aircraft
was designed with positive and, at some points, neutral stability
within its flight envelope. Its lateral and directional axes are also
decoupled from each other providing more precise maneuvering. The
applicable airworthiness regulations do not contain adequate or
appropriate safety standards for these design features. 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.
These special conditions are only applicable to aircraft certified
solely in the acrobatic category.
DATES: Send your comments on or before January 26, 2012.
ADDRESSES: Send comments identified by docket number FAA-2011-1387
using any of the following methods:
Federal eRegulations Portal: Go to
http:[sol][sol]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 of 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 8 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:[sol][sol]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 docket, 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:[sol][sol]DocketsInfo.dot.gov.
Docket: Background documents or comments received may be read at
http:[sol][sol]www.regulations.gov at any time. Follow the online
instructions for accessing the docket or go to the 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: Mr. Ross Schaller, Federal Aviation
Administration, Small Airplane Directorate, Aircraft Certification
Service, 901 Locust, Room 301, Kansas City, Missouri 64106; telephone
(816) 329-4162; facsimile (816) 329-4090.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite 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.
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
these special conditions based on the comments we receive.
Background
On May 3, 2011, XtremeAir GmbH applied for a type certificate for
their new XA42. The XA42 is certified under EASA authority as a dual
category (acrobatic/utility) airplane. It has a two-place tandem canopy
cockpit, and a single-engine. It also features a conventional landing
gear, conventional low-wing planform and is of composite construction.
The engine is a Lycoming AEIO-580-B1A with a rated power of 315 Hp at
2,700 rpm. The airplane is proposed to be approved for Day-VFR
operations with no icing approval.
The maximum takeoff weight is 2,200 pounds in utility category,
1,874 pounds in acrobatic category. VNE is 225 knots,
[[Page 80830]]
VNO is 185 knots and VA is 174 knots, indicated
airspeed. Maximum altitude is 15,000 feet.
Acrobatic airplanes previously type certificated by the FAA did
comply with the stability provisions of Subpart B of 14 CFR part 23.
However, airplanes like the XA42 are considered as ``unlimited''
acrobatic aircraft because they can perform at the highest level of
aerobatic competition and can perform any of the maneuvers listed in
the Aresti Catalog. Generally, the evolution of the ``unlimited'' types
of acrobatic airplanes, with very low mass, exceptional roll rates and
very high G capabilities, in addition to power to mass ratios that are
unique to this type of airplane, have led to airplanes that cannot
comply with the stability provisions of the regulations. These
airplanes can still be type-certificated, but in the acrobatic category
only and with an appropriate set of special conditions and associated
limitations.
The FAA will only consider certifying the XA42 in the acrobatic
category. XtremeAir GmbH will not be able to offer a utility category
operating envelope to accommodate the increased fuel load designed for
cross-country operations. The FAA does recognize that fuel exhaustion
is one of the top accident causes associated with this class of
aircraft. For this reason, the FAA proposes to allow XtremeAir to seek
certification of a limited acrobatic envelope at a higher weight that
will still meet the minimum load requirements of +6/-3 g associated
with 14 CFR, part 23, Sec. 23.337. The XA42 airplane would be approved
for unlimited maneuvers at or below its designed unlimited acrobatic
weight. The airplane would also be approved, at some higher weight (for
fuel), that would still meet the requirements of Sec. 23.337 for
acrobatic category and may have restrictions on the maneuvers allowed.
Type Certification Basis
Under the provisions of 14 CFR, part 21, Sec. 21.17, XtremeAir
GmbH must show that the XA42 meets the applicable provisions of part
23, as amended by Amendments 23-1 through 23-59 thereto.
Part 36 of Title 14 of the Code of Federal Regulations, effective
December 1, 1969, as amended by Amendments 36-1 through 36-28.
Not approved for ditching; compliance with provisions for ditching
equipment in accordance with 14 CFR 23.1415(a)(b) has not been
demonstrated.
Approved for VFR-day only. Flight in known icing prohibited.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 23) do not contain adequate or
appropriate safety standards for the XA42 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 or a
similar novel or unusual design feature, the special conditions would
also apply to the other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and special
conditions, the XA42 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 and the FAA must issue a finding of
regulatory adequacy under Sec. 611 of Public Law 92-574, the ``Noise
Control Act of 1972.''
The FAA issues special conditions, as defined in 14 CFR, part 11,
Sec. 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 XtremeAir GmbH XA42 will incorporate the following novel or
unusual design features:
For acrobatic category airplanes with unlimited acrobatic
capability:
Neutral longitudinal and lateral static stability characteristics.
Discussion
The Code of Federal Regulations states static stability criteria
for longitudinal, lateral, and directional axes of an airplane.
However, none of these criteria are adequate to address the specific
issues raised in the flight characteristics of an unlimited aerobatic
airplane. Therefore, the FAA has determined after a flight test
evaluation that, in addition to the requirements of part 21 and part
23, special conditions are needed to address these static stability
characteristics.
Accordingly, these special conditions are for the XtremeAir GmbH
XA42 static stability characteristics to be certified solely as an
acrobatic category airplane. Other conditions may be developed, as
needed, based on further FAA review and discussions with the
manufacturer and civil aviation authorities.
Applicability
As discussed above, these special conditions are applicable to the
XA42. Should XtremeAir GmbH apply at a later date for a change to the
type certificate to include another model incorporating the same novel
or unusual design feature, the special conditions would apply to that
model as well.
Conclusion
This action affects only certain novel or unusual design features
on one model of airplanes. It is not a rule of general applicability
and affects only the applicant who applied to the FAA for approval of
these flight characteristics on the airplane.
List of Subjects in 14 CFR Part 23
Aircraft, Aviation safety, Signs and symbols.
Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, and 44701; 14 CFR 21.16 and
21.17; and 14 CFR 11.38 and 11.19.
The Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for XtremeAir GmbH XA42 airplanes.
1. Unlimited Acrobatic-Only Category Static Stability Requirements
For unlimited, acrobatic-only category aircraft, the FAA proposes
that the XtremeAir GmbH XA42 comply with the following stability
special conditions in lieu of the existing Sec. Sec. 23.171, 23.173,
23.175, and 23.177:
A. In place of 14 CFR part 23, Sec. 23.171 Flight--General
(stability) requirement, comply with the following:
SC23.171 Flight--General: The airplane must be neutrally or
positively stable in the longitudinal, directional, and lateral axes
under sections SC23.173 through SC23.181. In addition, the airplane
must show suitable stability and control ``feel'' (static stability) in
any condition normally encountered in service, if flight tests show it
is necessary for safe operation.
B. In place of 14 CFR part 23, Sec. 23.173, Static longitudinal
stability requirement, comply with the following:
SC23.173 Static longitudinal stability: Under the conditions
specified in SC23.175 and with the airplane trimmed as indicated, the
characteristics of the elevator control forces and the friction within
the control system must be as follows:
(a) A pull must be required to obtain and maintain speeds below the
specified trim speed and a push required to obtain and maintain speeds
[[Page 80831]]
above the specified trim speed. This must be shown at any speed that
can be obtained, except that speeds requiring a control force in excess
of 40 pounds or speeds above the maximum allowable speed or below the
minimum speed for steady unstalled flight need not be considered.
(b) The stick force or position must vary with speed so that any
substantial speed change results in a stick force or position clearly
perceptible to the pilot.
C. In place of 14 CFR part 23, Sec. 23.175, Demonstration of
static longitudinal stability requirement, comply with the following:
SC23.175 Demonstration of static longitudinal stability:
(a) Climb. The stick force curve must have, at a minimum, a
neutrally stable to stable slope at speeds between 85 and 115 percent
of the trim speed, with--
(1) Maximum continuous power; and
(2) The airplane trimmed at the speed used in determining the climb
performance required by section 23.69(a).
(b) Cruise. With the airplane in trim with power for level flight
at representative cruising speeds at high and low altitudes, including
speeds up to VNO, except that the speed need not exceed
VH--
(1) The stick force curve must, at a minimum, have a neutrally
stable to stable slope at all speeds within a range that is the greater
of 15 percent of the trim speed plus the resulting free return speed
range, or 40 knots plus the resulting free return speed range, above
and below the trim speed, except that the slope need not be stable--
(i) At speeds less than 1.3 VS1; or
(ii) For airplanes with VNE established under section
23.1505(a), at speeds greater than VNE.
(c) Landing. The stick force curve must, at a minimum, have a
neutrally stable to stable slope at speeds between 1.1 VS1
and 1.8 VS1 with--
(1) Landing gear extended; and
(2) The airplane trimmed at--
(i) VREF, or the minimum trim speed if higher, with
power off; and
(ii) VREF with enough power to maintain a 3 degree angle
of descent.
D. In place of 14 CFR part 23, Sec. 23.177, Static directional and
lateral stability requirement, comply with the following:
SC23.177 Static directional and lateral stability:
(a) The static directional stability, as shown by the tendency to
recover from a wings level sideslip with the rudder free, must be
positive for any landing gear and flap position appropriate to the
takeoff, climb, cruise, approach, and landing configurations. This must
be shown with symmetrical power up to maximum continuous power, and at
speeds from 1.2 VS1 up to the maximum allowable speed for
the condition being investigated. The angle of sideslip for these tests
must be appropriate to the type of airplane. At larger angles of
sideslip, up to that at which full rudder is used or a control force
limit in section 23.143 is reached, whichever occurs first, and at
speeds from 1.2 VS1 to VO, the rudder pedal force
must not reverse.
(b) In straight, steady slips at 1.2 VS1 for any landing
gear and flap positions, and for any symmetrical power conditions up to
50 percent of maximum continuous power, the rudder control movements
and forces must increase steadily, but not necessarily in constant
proportion, as the angle of sideslip is increased up to the maximum
appropriate to the type of airplane. The aileron control movements and
forces may increase steadily, but not necessarily in constant
proportion, as the angle of sideslip is increased up to the maximum
appropriate to the type of airplane. At larger slip angles, up to the
angle at which the full rudder or aileron control is used or a control
force limit contained in section 23.143 is reached, the aileron and
rudder control movements and forces must not reverse as the angle of
sideslip is increased. Rapid entry into, and recovery from, a maximum
sideslip considered appropriate for the airplane must not result in
uncontrollable flight characteristics.
Issued in Kansas City, Missouri, on December 16, 2011.
Earl Lawrence,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 2011-33049 Filed 12-23-11; 8:45 am]
BILLING CODE 4910-13-P