[Federal Register Volume 62, Number 50 (Friday, March 14, 1997)]
[Proposed Rules]
[Pages 12119-12121]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-6528]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM-138, Notice No. SC-97-1-NM]


Special Conditions: Jetstream Aircraft Limited Model 4101 
Airplane; Continuous Power Reserve (CPR) System

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This notice proposes special conditions for the Jetstream 
Aircraft Limited Model 4101 airplane. This airplane will have a novel 
or unusual design feature associated with installation of the CPR 
system. This notice contains the additional safety standards that the 
Administrator considers necessary to establish a level of safety 
equivalent to that established by the airworthiness standards of part 
25 of the FAR.

DATES: Comments must be received on or before April 28, 1997.

ADDRESSES: Comments on this proposal may be mailed in duplicate to: 
Federal Aviation Administration, Office of the Assistant Chief Counsel, 
Attention: Rules Docket (ANM-7), Docket No. NM-138, 1601 Lind Avenue 
SW, Renton, Washington 98055-4056; or delivered in duplicate to the 
Office of the Assistant Chief Counsel at the above address. Comments 
must be marked: Docket No. NM-138. 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:
William Schroeder, FAA, Standardization Branch, ANM-113, Transport 
Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue 
SW, Renton, Washington 98055-4056; telephone 206-227-2148; fax 206-227-
1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of 
these proposed special conditions by submitting 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 
before futher rulemaking action on this proposal is taken. The 
proposals contained in this notice may be changed in light of the 
comments received. All comments received will be available, both before 
and after the closing date for comments, in the Rules Docket for 
examination by interested parties. 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:

[[Page 12120]]

``Comments to Docket No. NM-138.'' The postcard will be date stamped 
and returned to the commenter.

Background

    On June 7, 1994, Jetstream Aircraft Limited applied for approval of 
a design change (without a new airplane model designation) to Type 
Certificate No. A41NM for the installation of a CPR system on the 
Jetstream Model 4101 airplane. The Jetstream Model 4101 is a 30 
passenger, 23,000 pounds maximum take-off weight, transport category 
airplane with two Allied Signal TPE331-14GR/HR series turbopropeller 
engines. The CPR system makes a CPR power rating available for the 
final take-off climb and en route phases of flight after failure of one 
engine.
    The CPR power rating for this engine installation is equivalent to 
the maximum continuous power rating established for the engine under 
Part 33 of the Federal Aviation Regulations (FAR). Following engine 
failure, the CPR system automatically increases the engine maximum 
exhaust gas temperature (EGT) limit, which permits the operating 
engine's maximum continuous power rating to be obtained at higher 
ambient air temperatures. Increased engine hour and cycle maintenance 
factors apply for CPR power rating operation. Since the CPR power 
rating will only be available during engine-out conditions, the maximum 
power normally available with all engines operating will be less than 
the part 33 certified maximum continuous power rating at certain higher 
ambient temperature ranges.
    The CPR system is novel when compared to those systems envisaged 
when the applicable regulations in part 25 were promulgated. Therefore, 
the airworthiness regulations in part 25 do not contain adequate or 
appropriate safety standards for airplanes with CPR systems installed. 
Special conditions are therefore prescribed to supplement the 
certification basis of record for the Jetstream Model 4101 airplane 
with a CPR system installed.

Type Certification Basis

    Under the provisions of Sec. 21.101, Jetstream Aircraft Limited 
must show that the Jetstream Model 4101, as changed, continues to meet 
the applicable provisions of the regulations incorporated by reference 
in Type Certificate No. A41NM or the applicable regulations in effect 
on the date of application for the change. 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 No. A41NM are part 25 of the FAR dated 
February 1, 1965, as amended by Amendments 25-1 through 25-66. The 
regulations incorporated by reference also include certain special 
conditions, exemptions, and later amended sections of Part 25 that are 
not relevant to these proposed special conditions.
    If the regulations incorporated by reference do not provide 
adequate standards with respect to the change, the applicant must 
comply with certain regulations in effect on the date of application 
for the change. The FAA has determined that the areas of the Jetstream 
Model 4101 that are affected by the installation of the CPR system must 
also be shown to comply with all sections of part 25 as amended by 
Amendments 25-1 through 25-81 in effect on the date of application.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., part 25 as amended) do not contain adequate or 
appropriate safety standards for the Jetstream Model 4101 because of a 
novel or unusual design feature, special conditions are prescribed 
under the provisions of Sec. 21.16. When appropriate, special 
conditions are issued in accordance with Sec. 11.49 of the FAR after 
public notice, as required by Secs. 11.28 and 11.29(b), 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 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).
    In addition to the applicable airworthiness regulations and special 
conditions, the Jetstream Model 4101 must comply with the fuel vent and 
exhaust emission requirements of part 34 and the noise certification 
requirements of part 36.

Novel or Unusual Design Features

    The Jetstream Model 4101 will incorporate a CPR system that 
provides an engine power rating (as defined on the airplane) that is 
equivalent to the engine's part 33 certified maximum continuous power 
rating. Since the CPR power rating will only be available during 
engine-out conditions, the maximum power available with all engines 
operating will normally be less than the part 33 certified maximum 
continuous power rating at certain higher ambient temperatures. The CPR 
system is integrated into the existing approved Automatic Power Reserve 
(APR) system. On the Jetstream 4100 airplane, the APR system is 
equivalent to an Automatic Takeoff Thrust Control System (ATTCS) as 
defined in Appendix I of Part 25. The currently approved APR system 
automatically makes additional thermodynamic power and torque available 
on the operating engine after engine failure during takeoff and for 
approach climb (go-around). For certain ambient temperature ranges, the 
proposed CPR system automatically increases the engine's EGT limit and 
torque available on the operating engine for final take-off climb and 
en route flight phases after failure of one engine. The CPR-related 
increased EGT limit, which is above the two-engines-operating EGT 
maximum continuous power and take-off limits, enables the operating 
engine to achieve the flat-rated maximum continuous power (torque) 
level at higher outside air temperature (OAT). Engine operation in the 
APR and CPR modes requires application of engine hour and cycle 
maintenance factors as specified in engine Type C Certificate Data 
Sheet E18NE.
    As discussed above, these special conditions are applicable to the 
Jetstream Model 4101. Should Jetstream Aircraft Limited 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 one model of airplane. It is not a rule of general applicability, 
and it affects only the applicant who applied to the FAA for approval 
of these features on the airplane.

List of Subjects in 14 CFR Part 25

    Air transportation, Aircraft, Aviation safety, Safety.

    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, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for the Jetstream Model 4101 airplane.

[[Page 12121]]

Installation of a Continuous Power Reserve (CPR) System

    (a) General. With the CPR system functioning normally as designed, 
all applicable requirements of part 25 must be met without requiring 
any unusual action (other than arming the system prior to dispatch) by 
the crew to set power or thrust.
    (b) Performance and Reliability Requirements.
    (1) A CPR failure or combination of failures.
    (i) That prevents the automatic insertion of CPR thrust or power 
must be shown to be an improbable event;
    (ii) That prevents the automatic insertion of APR thrust or power 
during the critical time interval defined in Appendix I of Part 25 must 
be shown to be an improbable event; and
    (iii) Shall not result in the significant loss or reduction in 
thrust or power, or must be shown to be an extremely improbable event.
    (2) All applicable performance requirements of part 25 must be met 
with an engine failure occurring at the most critical time with the CPR 
system functioning.
    (c) Thrust Setting. The maximum continuous thrust or power setting 
specified for use with all engines operating may not be less than any 
of the following:
    (1) Ninety (90) percent of the thrust or power set by the CPR 
system for which AFM performance credit is approved;
    (2) That required to permit normal operation of all safety-related 
systems and equipment dependent upon engine thrust or power lever 
position; or
    (3) That shown to be free of hazardous engine response 
characteristics when thrust or power is advanced from the initial all-
engines-operating thrust or power setting to the maximum approved 
maximum continuous/CPR mode thrust or power setting.
    (d) Powerplant Controls.
    (1) In addition to the requirements of Sec. 25.1141, no single 
failure or malfunction, or probable combination thereof, of the CPR, 
including associated systems, may cause the failure of any powerplant 
function necessary for safety.
    (2) The CPR system must be designed to:
    (i) In the event of a CPR system failure, permit manual decrease or 
increase in thrust or power up to the highest maximum continuous thrust 
or power approved for the airplane under existing conditions through 
the use of the power lever. For airplanes equipped with limiters that 
automatically prevent engine operating limits from being exceeded under 
existing ambient conditions, other means may be used to increase the 
thrust or power in the event of a CFR failure provided the means is 
located on or forward of the power levers; is easily identified and 
operated under all operating conditions by a single action of either 
pilot with the hand that is normally used to actuate the power levels; 
and meets the requirements of Sec. 25.777 (a),(b), and (c).
    (ii) Provide a means for the flightcrew to deactivate the automatic 
CPR function. This means must be designed to prevent inadvertent 
deactivation.
    (iii) Provide a means for the flightcrew to verify that the CFR 
system is in a condition to operate.
    (e) Powerplant Instruments. In addition to the requirements of 
Sec. 25.1305, a means must be provided to indicate when the CPR is in 
the armed or ready condition.

    Issued in Renton, Washington, on March 6, 1997.
Neil D. Schalekamp,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 97-6528 Filed 3-13-97; 8:45 am]
BILLING CODE 4910-13-M