[Federal Register Volume 64, Number 238 (Monday, December 13, 1999)]
[Rules and Regulations]
[Pages 69383-69386]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-32111]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM166; Special Conditions No. 25-155-SC]
Special Conditions: CASA Model
C-295 Airplane; Automatic Takeoff Thrust Control System
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final Special Conditions; request for comments.
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SUMMARY: This notice proposes special conditions for the CASA Model C-
295 airplane. This airplane will have an unusual design feature
associated with an Automatic Takeoff Thrust Control System (ATTCS), for
which the applicable airworthiness regulations do not contain
appropriate safety standards for approach climb performance using an
ATTCS. 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: The effective date of these special conditions is November 30,
1999. Comments must be received on or before January 12, 2000.
ADDRESSES: Comments on these special conditions may be mailed in
duplicate to: Federal Aviation Administration, Transport Airplane
Directorate, Attn.: Rules Docket (ANM-114), Docket No. NM166, 1601 Lind
Avenue SW., Renton, Washington 98055-4056; or delivered in duplicate to
the Transport Airplane Directorate at the above address. Comments must
be marked ``Docket No. NM166.'' Comments may be inspected in the Rules
Docket weekdays, except Federal holidays, between 7:30 a.m. and 4:00
p.m.
FOR FURTHER INFORMATION CONTACT: Rosanne Ryburn, International Branch
(ANM-116), FAA Transport Airplane Directorate, 1601 Lind Avenue SW,
Renton, WA 98055-4056, telephone (425) 227-2139, or facsimile (425)
227-1149.
SUPPLEMENTARY INFORMATION: The FAA has determined that notice and
opportunity for prior public comment hereon are impracticable because
these procedures would significantly delay issuance of the approval
design and thus delivery of the affected aircraft. In addition, the
substance of these special conditions has been subject to the public
comment process in several prior instances with no substantive comments
received. The FAA therefore finds that good cause exists for making
these special conditions effective upon issuance.
Comments Invited
Interested persons are invited to submit such written data, views,
or arguments as they may desire. Communications should identify the
regulatory docket or notice number and be submitted in duplicate to the
address specified above. All communications received on or before the
closing date for comments will be considered by the Administrator. The
special conditions may be changed in light of the comments received.
All comments submitted will be available in the Rules Docket for
examination by interested persons, both before and after the closing
date for comments. A report summarizing each substantive public contact
with FAA personnel concerning this rulemaking will be filed in the
docket. Commenters wishing the FAA to acknowledge receipt of their
comments submitted in response to this notice must include a self-
addressed, stamped postcard on which the following statement is made:
``Comments to Docket No. NM166.'' The postcard will be date stamped and
returned to the commenter.
Background
On March 13, 1997, Construcciones Aeronauticas, S.A. (CASA),
located in Getafe, Spain, applied to the FAA for an amendment to Type
Certificate No. A21NM in the transport airplane category for the Model
C-295 airplane. CASA Model C-295 is a derivative of the Model CN-235
currently approved under Type Certificate No. A21NM. The CASA Model C-
295 is a medium-sized airplane powered by two Pratt & Whitney Canada
PW127G turbopropeller engines mounted on the wings. Each engine is
equipped with a Hamilton Standard Model 568F-5 six-blade propeller and
will be capable of delivering 2,645 shaft horsepower (SHP) at the
normal takeoff power setting. The airplane will be capable of operation
with a minimum of 2 flight crewmembers and cargo.
CASA Model C-295 will incorporate an unusual design feature, an
``Autofeather/Automatic Power Reserve'' (AF/APR) system, to show
compliance with the engine failure takeoff path requirements of part 25
and the approach climb requirements of Sec. 25.121(d). The functional
intent of this AF/APR system is the same as the Automatic Takeoff
Thrust Control System (ATTCS) described in Appendix I to part 25, which
limits the application of performance credit for such a system to
takeoff only. Since the airworthiness regulations do not contain
appropriate safety standards for approach climb performance using
ATTCS, special conditions are required to ensure a level of safety
equivalent to that established in the regulations.
Type Certification Basis
Under the provisions of 14 CFR 21.101, CASA must show that the
Model C-295 meets the applicable provisions incorporated by reference
in Type Certificate No. A21NM or the applicable regulations in effect
on the date of application for the change to the Model C-295.
The regulations incorporated by reference in the type certificate
are commonly referred to as the ``original type certification basis.''
The regulations incorporated by reference in Type Certificate A21NM are
as follows: part 25, effective February 1, 1965, including Amendments
25-1 through 25-89. The certification basis may also include later
amendments to part 25 that are not relevant to these special
conditions. In addition, the certification basis for the Model C-295
includes part 34, effective September 10, 1990, including
[[Page 69384]]
Amendment 34-3 effective February 3, 1999, plus any amendments in
effect at the time of certification; and part 36, effective December 1,
1969, including Amendments 36-1 through 36-21 and any subsequent
amendments that may be applicable on the date the type certificate is
issued. These special conditions form an additional part of the type
certification basis. In addition, the certification basis may include
other special conditions that are not relevant to these special
conditions.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25, as amended) do not contain adequate
or appropriate safety standards for the CASA Model C-295 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 Model C-295 must comply with the part 25 fuel vent and
exhaust emission requirements of 14 CFR part 34 and the part 25 noise
certification requirements of 14 CFR part 36.
Special conditions, as appropriate, are issued in accordance with
Sec. 11.49, as required by Secs. 11.28 and 11.29, and become part of
the type certification basis in accordance with Sec. 21.101(b)(2).
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, or should any other model already included on
the same type certificate be modified to incorporate the same novel or
unusual design feature, the special conditions would also apply to the
other model under the provisions of Sec. 21.101(a)(1).
Novel or Unusual Design Features
The Model C-295 will incorporate the following novel or unusual
design feature: the ATTCS (referred to by CASA as ``Autofeather/APR''),
to show compliance with the approach climb requirements of
Sec. 25.121(d). The Model C-295 is a medium-sized airplane powered by
two Pratt & Whitney Canada PW127G turbopropeller engines equipped with
Electronic Engine Controls (EEC) that, in part, protect against
exceeding engine limits. The Model C-295 is also equipped with Hamilton
Standard 568F-5 six-blade propellers as part of the propulsion package.
The Model C-295 engine and propeller control system allows the pilot to
select an Autofeather/APR control position on the overhead panel that
will, in the result of an engine failure, automatically feather the
propeller on the failed engine and increase the power output of the
operating engine to the Maximum Takeoff Power (MTOP) setting (2,920 SHP
at sea level).
The Model C-295 incorporates a power setting system that includes a
center pedestal-mounted rotary switch, referred to as the Power Rating
Selector (PRS), that allows the pilot to select the desired torque and
propeller speed combination for the phase of flight. After selecting
the appropriate position on the PRS, the corresponding level of thrust
is obtained by moving a single Power Lever (PL) for each engine to a
detent position that is referred to as MAX AUTO.
With the PRS set to the takeoff and go-around (TOGA) position, the
power levers in the MAX AUTO position, and the AF/APR selected to the
ON position, the applicable one-engine-inoperative performance
requirements of part 25 will be met without requiring any action by the
crew to increase power.
For takeoff, the PRS is set to TOGA and the power levers are
advanced to MAX AUTO, resulting in Normal Takeoff Power (NTOP) being
obtained, which is 90 percent of the Maximum Takeoff Power (MTOP)
available. In the event of an engine failure during takeoff, operation
of the Model C-295 AF/APR system will result in the EEC automatically
increasing the power on the operating engine to Maximum Takeoff Power
(MTOP). (Note that for this engine installation, the MTOP level of
power automatically obtained with AF/APR operation may be manually
obtained by placing the PRS in the Maximum Continuous Power (MCT)
position and the power levers at MAX AUTO (maximum takeoff and maximum
continuous power ratings and limits are the same)). Similarly, if both
engines are operating when the approach is initiated, the AF/APR and
power setting controls must be set to the same positions as for takeoff
to ensure obtaining the approach climb (ref. Sec. 25.121(d))
performance presented in the Airplane Flight Manual (AFM) in the event
of an engine failure during the approach or go-around.
For both the takeoff and go-around case, the operating procedures
require the flightcrew to turn the system on by pressing the ``ARM/ON''
button on the overhead panel; this will result in the ``ON'' portion of
the button remaining illuminated. When Autofeather/APR is selected ON,
the PRS is set to TOGA, and both power levers are beyond 49 degrees
with both engines producing power above the 48 percent Torque (%TQ)
level, the ``ARM'' portion of the button will illuminate. This will
indicate to the pilot that the system is ``armed'' and will perform
autofeather and power increase functions without any further action by
the crew if an engine fails. If one engine fails after initiating a go-
around, before the 48 percent TQ level is reached, the APR/Autofeather
system will not function.
The engine operating limits Torque (%TQ), Inter-Turbine Temperature
(ITT), Engine RPM (%NH), and Propeller RPMs (%NP) are set such that the
engine red line limits are not exceeded when the APR system operates.
If the torque on one engine drops below 19 percent, the Autofeather
Unit (AFU) on the failed engine sends a signal to increase the power to
the MTOP/MCT level on the remaining engine. The power levers will
continue to function normally should the ATTCS fail. The MTOP can also
be obtained by selecting the MCT position at the Power Rating Selector.
To deactivate the power increase provided by operation of the APR
system, the power levers should be moved out of the MAX AUTO detent to
a position less than 49 degrees (PL angle not high) or the Autofeather/
APR should be selected OFF.
For both the takeoff and approach power setting cases, the power
levers may be pushed forward beyond the MAX AUTO position to the MAX
MANUAL position. This will result in the engines producing slightly
more power than MTOP/MCT levels. This power setting is limited to 20
seconds of application in the AFM limitations; operation for periods
slightly beyond 20 seconds will result in a maintenance (NEW
EXCEEDENCE) message being recorded on the Integrated Engine Display
System (IEDS), which requires a maintenance check, but will not result
in an engine failure. In the extremely improbable event that the APR
system fails to operate in combination with an engine failure, the all-
engines operating approach and go-around procedures in the Model C-295
AFM instruct the pilot to both feather the propeller on the operating
engine using the Fuel Feather Levers (FFL), immediately adjacent to (on
the pilot side) the aft end of the power levers, and advance the power
levers to the MAX MANUAL position. This provides a subsequent level of
performance greater than that presented in the AFM for the approach
climb configuration of Sec. 25.121(d). Following this action, as
cockpit workload permits, MCT may be selected on the PRS followed by
retarding the power levers to the MAX AUTO position, which will
[[Page 69385]]
provide the APR level of power for the extent of time required.
The part 25 standards for ATTCS, contained in Sec. 25.904 and
Appendix I, specifically restrict performance credit for ATTCS to
takeoff. Expanding the scope of the standards to include other phases
of flight, including go-around, was considered at the time the
standards were issued, but flightcrew workload issues precluded further
consideration. The preamble to Amendment 25-62 states:
``In regard to ATTCS credit for approach climb and go-around
maneuvers, current regulations preclude a higher thrust for the
approach climb (Sec. 25.121(d)) than for the landing climb
(Sec. 25.119). The workload required for the flightcrew to monitor and
select from multiple in-flight thrust settings in the event of an
engine failure during a critical point in the approach, landing, or go-
around operations is excessive. Therefore, the FAA does not agree that
the scope of the amendment should be changed to include the use of
ATTCS for anything except the takeoff phase.'' (52 FR 43153, November
9, 1987)
The ATTCS incorporated on the Model C-295 allows the pilot to use
the same power setting procedure during an all-engines operating
approach and go-around, regardless of whether or not an engine fails.
In either case, the pilot obtains go-around power by moving the power
levers into the MAX AUTO detent. Since the ATTCS is armed, it will
function automatically following an engine failure, and increase the
power on the remaining engine to the ATTCS thrust level. Therefore,
this design adequately addresses the pilot workload concerns identified
in the preamble to Amendment 25-62. Accordingly, these special
conditions will require a showing of compliance with those provisions
of Sec. 25.904 and Appendix I that are applicable to the approach climb
and go-around maneuvers.
The definition of a critical time interval for the approach climb
case, during which time it must be extremely improbable to violate a
flight path based on the Sec. 25.121(d) gradient requirement, is of
primary importance. The Sec. 25.121(d) gradient requirement implies a
minimum one-engine-inoperative flight path capability with the airplane
in the approach configuration. There are three engine failure cases
that must be considered for the approach climb: (1) The engine may have
been inoperative before initiating the go-around, (2) the engine may
become inoperative at the point of go-around initiation, or (3) the
engine may become inoperative during the go-around. For the Model C-
295, the definition of a critical time interval for the first case is
not relevant since the operating procedures require selection of the
MCT position on the PRS, thus enabling the pilot to manually obtain the
APR level of power by advancing the power levers to the MAX AUTO
position. The definition of the critical time interval must, however,
be defined in accordance with the following special conditions for the
second and third cases.
Applicability
As discussed above, these special conditions are applicable to the
CASA Model C-295. Should CASA 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 under the provisions of Sec. 21.101(a)(1).
Conclusion
This action affects only certain novel or unusual design features
on the CASA Model C-295 airplane. It is not a rule of general
applicability and affects only the manufacturer who applied to the FAA
for approval of these features on the airplane.
The substance of these special conditions has been subjected to the
notice and comment period in several prior instances and has been
derived without substantive change from those previously issued. It is
unlikely that prior public comment would result in a significant change
from the substance contained herein. For this reason, and because a
delay would significantly affect the certification of the airplane,
which is imminent, the FAA has determined that prior public notice and
comment are unnecessary and impracticable, and good cause exists for
adopting these special conditions upon issuance. The FAA is requesting
comments to allow interested persons to submit views that may not have
been submitted in response to the prior opportunities for comment
described above.
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 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 CASA Model C-295 airplane.
1. General. An Automatic takeoff thrust control system (ATTCS) is
defined as the entire automatic system, including all devices, both
mechanical and electrical, that sense engine failure, transmit signals,
actuate fuel controls or power levers, or increase engine power by
other means on operating engines to achieve scheduled thrust or power
increases and furnish cockpit information on system operation.
2. ATTCS. The engine power control system that automatically resets
the power or thrust on the operating engine (following engine failure
during the approach for landing) must comply with the following
requirements:
a. Performance and System Reliability Requirements. The concurrent
existence of an ATTCS failure and an engine failure between the time at
which the flightcrew last verifies that the ATTCS is in a condition to
operate until the end of the critical time interval must be shown to be
extremely improbable.
b. Thrust Setting. The ATTCS thrust or power level for go-around
must be obtained in accordance with the following criteria:
(1) The maximum thrust or power attainable on each engine prior to
ATTCS operation may not be less than 90 percent of the thrust or power
level set by the ATTCS (the maximum takeoff thrust or power approved
for the airplane under existing ambient conditions);
(2) It must be shown that the operating engine will be free of
hazardous engine response characteristics when the thrust or power is
increased from any level between flight idle and the maximum level
attainable without ATTCS to the maximum approved takeoff thrust or
power.
c. Powerplant Controls. In addition to the requirements of
Sec. 25.1141, no single failure or malfunction, or probable combination
thereof, of the ATTCS, including associated systems, may cause the
failure of any powerplant function necessary for safety. The ATTCS must
be designed to:
(1) Apply thrust or power on the operating engine(s), following any
one engine failure during go-around, to achieve the maximum approved
takeoff thrust or power without exceeding engine operating limits; and
(2) Provide a means to verify to the flightcrew before beginning an
approach for landing that the ATTCS is in a condition to operate.
3. Critical Time Interval. The definition of the Critical Time
Interval
[[Page 69386]]
in Appendix I, Section I25.2(b) shall be expanded to include the
following:
a. When conducting an approach for landing using ATTCS, the
critical time interval is defined as follows:
(1) The critical time interval begins at a point on a 2.5 degree
approach glide path from which, assuming a simultaneous engine and
ATTCS failure, the resulting approach climb flight path intersects a
flight path originating at a later point on the same approach path
corresponding to the part 25 one-engine-inoperative approach climb
gradient. The period of time from the point of simultaneous engine and
ATTCS failure to the intersection of these flight paths must be no
shorter than the time interval used in evaluating the critical time
interval for takeoff beginning from the point of simultaneous engine
and ATTCS failure and ending upon reaching a height of 400 feet.
(2) The critical time interval ends at the point on a minimum
performance, all-engines-operating go-around flight path from which,
assuming a simultaneous engine and ATTCS failure, the resulting minimum
approach climb flight path intersects a flight path corresponding to
the part 25 minimum one-engine-inoperative approach climb gradient. The
all-engines-operating go-around flight path and the part 25 one-engine-
inoperative approach climb gradient flight path originate from a common
point on a 2.5 degree approach path. The period of time from the point
of simultaneous engine and ATTCS failure to the intersection of these
flight paths must be no shorter than the time interval used in
evaluating the critical time interval for the takeoff beginning from
the point of simultaneous engine and ATTCS failure and ending upon
reaching a height of 400 feet.
b. The critical time interval must be determined at the altitude
resulting in the longest critical time interval for which one-engine-
inoperative approach climb performance data are presented in the
Airplane Flight Manual.
c. The critical time interval is illustrated in the following
figure:
BILLING CODE 4910-13-P
[GRAPHIC] [TIFF OMITTED] TR13DE99.001
BILLING CODE 4910-13-C
* The engine and ATTCS failed time interval must be no shorter
than the time interval from the point of simultaneous engine and
ATTCS failure to a height of 400 feet used to comply with I25.2(b)
for ATTCS use during takeoff.
BILLING CODE 4910-13-C
Issued in Renton, Washington, on November 30, 1999.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 99-32111 Filed 12-10-99; 8:45 am]
BILLING CODE 4910-13-P