[Federal Register Volume 62, Number 113 (Thursday, June 12, 1997)]
[Rules and Regulations]
[Pages 32021-32023]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-15433]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM-138, Special Conditions No. 25-ANM-129]


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued 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. 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 airworthiness standards of 14 CFR 
Part 25.

EFFECTIVE DATE: July 14, 1997.

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 425-227-2148; fax 425-227-
1149.

SUPPLEMENTARY INFORMATION:

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 14 
CFR Part 33. 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 14 CFR Sec. 21.101, Jetstream Aircraft 
Limited must show that the Jetstream Model 4101, as changed, continues 
to meet the applicable provisions of the regulations

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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 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 final 
special conditions.
    In addition, 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 14 CFR Sec. 21.16. 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 14 CFR Part 34 and the noise certification 
requirements of 14 CFR Part 36.
    Special conditions, as appropriate, are issued in accordance with 
14 CFR Sec. 11.49 after public notice, as required by 14 CFR 
Secs. 11.28 and 11.29(b), and become part of the type certification 
basis in accordance with 14 CFR 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, 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 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 Certificate Data Sheet 
E18NE.

Discussion of Comments

    Notice of Proposed Special Conditions No. SC-97-1-NM for the 
Jetstream Aircraft Limited Model 4101 airplane, was published in the 
Federal Register on March 14, 1997. No comments were received.

Applicability

    As discussed above, these special conditions are applicable to the 
Jetstream Aircraft Limited Model 4101 airplane. 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, the special conditions would apply to that 
model as well under the provisions of 14 CFR 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 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 Jetstream Model 4101 airplane.

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 of 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

[[Page 32023]]

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 or a CPR 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 levers; and meets the requirements of Sec. 25.777 
(a), (b), and (c);
    (ii) Provide a means for the flightcrew to deactivate the 
automatice CPR function. This means must be designed to prevent 
inadvertent deactivation.
    (iii) Provide a means for the flightcrew to verify that the CPR 
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 June 5, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 97-15433 Filed 6-11-97; 8:45 am]
BILLING CODE 4910-13-M