[Federal Register Volume 61, Number 73 (Monday, April 15, 1996)]
[Rules and Regulations]
[Pages 16375-16377]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-9252]



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  Federal Register / Vol. 61, No. 73 / Monday, April 15, 1996 / Rules 
and Regulations  

[[Page 16375]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. 95-ANE-46; 33-ANE-05]


Special Conditions: Turbomeca Model Arriel 2S1 Turboshaft Engine

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Turbomeca Model 
Arriel 2S1 turboshaft engine. This engine will have novel or unique 
engine ratings that are not defined by the applicable airworthiness 
regulations. These special conditions contain the additional safety 
standards which the Administrator considers necessary to establish a 
level of safety equivalent to that established by the airworthiness 
standards of part 33 of the Federal Aviation Regulations (FAR).

EFFECTIVE DATE: May 15, 1996.

FOR FURTHER INFORMATION CONTACT:
Chung Hsieh, Engine and Propeller Standards Staff, ANE-110, Engine and 
Propeller Directorate, Aircraft Certification Service, FAA, New England 
Region, 12 New England Executive Park, Burlington, Massachusetts 01803-
5229; (617) 238-7115; Fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: 

Background

    On February 25, 1994, Turbomeca applied for an amendment to type 
certificate E19EU to include a new Model Arriel 2S1 turboshaft engine. 
The Model Arriel 2S1 turboshaft engine will be rated at 30-Second and 
2-Minute one engine inoperative (OEI), 30-Minute OEI, Continuous OEI, 
Takeoff, and Maximum Continuous ratings.
    The applicable airworthiness requirements do not contain 30-Second 
OEI and 2-Minute OEI rating definitions, and do not contain adequate or 
appropriate safety standards for the type certification of these new 
and unusual engine ratings.

Type Certification Basis

    Under the provisions of section 21.101 of the Federal Aviation 
Regulations (FAR), Turbomeca must show that the Model Arriel 2S1 
turboshaft engine meets the applicable provisions of the regulations as 
referenced in Type Certificate No. E19EU or the applicable regulations 
in effect on the date of the application. The regulations incorporated 
by reference in Type Certificate No. E19EU are Section 21.29 and part 
33, effective February 1, 1965, as amended by Amendments 33-1 through 
33-5, Turbomeca, however, has elected, under section 21.17, to comply 
with Amendments 33-1 through 33-14. The FAA has determined that the use 
of the airworthiness standards as amended by the later amendments for 
type certification of this derivative engine will enhance safety and 
therefore accepts the Turbomeca's proposal.
    The Administrator finds that the applicable airworthiness 
regulations in part 33, as amended, do not contain adequate or 
appropriate safety standards for the Turbomeca Model Arriel 2S1 
turboshaft engine because of the new and unique engine ratings. 
Therefore, the Administrator prescribes special conditions under the 
provisions of section 21.16 to establish a level of safety equivalent 
to that established in the regulations.
    Special conditions, as appropriate, are issued in accordance with 
section 11.49 of the FAR after public notice and opportunity for 
comment, as required by sections 11.28 and 11.29(b), and become part of 
the type certification basis in accordance with section 21.101(b)(2).

Discussion of Comments

    Interested persons have been afforded the opportunity to 
participate in the making of these special conditions. No comments were 
received on the special conditions as proposed. However, comments 
addressing numerous issues were received in response to proposed 
special conditions for a similar engine program, Allison Engine Company 
(AE) Model 250 turboshaft engine. These comments were discussed in 
Notice No. SC-95-04-NE published in the Federal Register on November 
27, 1995 (FR 60 58204). As a result of those comments, changes to the 
proposals and for clarification in certain sections of the special 
conditions were made. The FAA has determined that those changes made to 
the special conditions for AE Model 250 engine are also applicable to 
Turbomeca Arriel Model 2S1 engine and therefore they are adopted in 
this Final special conditions. In addition, some editorial changes have 
also been made to section 33.27 of this Final special condition for 
clarification.
    After careful review of the available data, the FAA determined that 
air safety and the public interest require the adoption of the special 
conditions with the changes described previously.

Conclusion

    This action affects only certain novel or unusual design features 
on one model engine. 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 engine.

List of Subjects in 14 CFR Part 33

    Air transportation, Aircraft, Aviation safety, Safety.

PART 33--[AMENDED]

    The authority citation for these special conditions continues to 
read 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 Turbomeca Model 2S1 turboshaft 
engine:


Sec. 33.4  Instructions for Continued Airworthiness.

    In addition to the requirements of section 33.4, the mandatory 
inspection and maintenance actions required following the use of the 
30-Second or 2-Minute OEI rating must be included in the airworthiness 
limitations section of the appropriate engine manuals.


Sec. 33.7  Engine Ratings and Operating Limitations.

    In addition to the requirements of section 33.7, the following 
ratings are defined as:

[[Page 16376]]

    (a) Rated 30-Second one engine inoperative (OEI) power: The 
approved brake horsepower developed under static conditions at 
specified altitudes and temperatures within the operating limitations 
established for the engine under part 33 and this special conditions, 
for continued one-flight operation after the failure of one engine in 
multi-engine rotorcraft, limited to three periods of use, no longer 
than 30 seconds each, in any one flight, and followed by mandatory 
inspection and prescribed maintenance action.
    (b) Rated 2-Minute OEI power: The approved brake horsepower, 
developed under static conditions at specified altitudes and 
temperatures, within the operating limitations established for the 
engine under part 33 and this special conditions, for continued one-
flight operation after the failure of one engine in multi-engine 
rotorcraft, limited to three periods of use, of no longer than 2 
minutes each in any one flight, and followed by mandatory inspection 
and prescribed maintenance action.


Sec. 33.27  Turbine, Compressor, Fan, and Turbo-supercharger Rotors.

    For 2-minute and 30-second OEI ratings, in addition to the 
requirements of section 33.27(b), turbine and compressor rotors must 
have sufficient strength to withstand the conditions specified in one 
of the following tests for the most critically stressed rotor component 
of each turbine and compressor including integral drum rotors and 
centrifugal compressor, as determined by analysis or other acceptable 
means. The selection of the test from the following paragraph (a) or 
(b) of this section is determined by the speed defined in paragraph 
(a)(2) or (b)(2), whichever is higher.
    (a) Test for a period of two and one-half minutes--
    (1) At its maximum operating temperature except as provided in 
paragraph 33.27(c)(2)(iv); and
    (2) At the highest speed determined, in accordance with section 
33.27(c)(2) (i) through (iv).
    (3) This test may be performed using a separate test vehicle as 
desired.
    (b) Test for a period of 5 minutes--
    (1) At its maximum operating temperature except as provided in 
paragraph 33.27(c)(2)(iv); and
    (2) At 100 percent of the highest speed that would result from 
failure of the most critical component of each turbine and compressor 
or system in a representative installation of the engine when operating 
at 30-Second and 2-Minute OEI rating conditions, and
    (3) The test speed must take into account minimum material 
properties, maximum operating temperature, and the most adverse 
dimensional tolerances.
    (4) This test may be performed using a separate test vehicle as 
desired.
    Following the test, rotor growth and distress beyond dimensional 
limits for an overspeed condition is permitted for 30-Second and 2-
Minute OEI rating only, provided the structural integrity of the rotor 
is maintained, as shown by a procedure acceptable to the Administrator.


Sec. 33.29  Instrument Connection.

    In addition to the requirements of section 33.29, the engine must 
have a provision for a means to:
    (a) Alert the pilot when the engine is at the 30-Second OEI and a 
2-Minute OEI power levels;
    (b) Determine, in a positive manner, that the engine has been 
operated at each rating; and
    (c) Determine the elapsed time of operation of each rating.


Sec. 33.67  Fuel System.

    In addition to the requirements of section 33.67, the engine must 
provide for a means for automatic availability and automatic control of 
the 30-Second OEI power; and engine test runs must be performed to 
demonstrate automatic functioning of both of these means.


Sec. 33.83  Vibration Test.

    In addition to the requirements of section 33.83, the following 
additional test requirements must be considered under 33.83(a): For 30-
Second and 2-Minute OEI rating conditions, the vibration survey shall 
cover the ranges of power, and both the physical and corrected 
rotational speeds for each rotor system, corresponding to operations 
throughout the range of ambient conditions in the declared flight 
envelope, from the minimum rotor speed up to 103 percent of the maximum 
rotor speed permitted for 2-Minute OEI rating, and up to 100 percent of 
the maximum rotor speed permitted for 30-Second OEI rating speed. If 
there is any indication of a stress peak arising at the highest 
physical or corrected rotational speeds, the surveys shall be extended 
sufficiently to reveal the maximum stress values present except that 
the extension needs not cover more than a further 2 percent beyond 
those speed.


Sec. 33.85  Calibration Test.

    In addition to the requirements of section 33.85, tests performed 
at the 30-Second and 2-Minute OEI ratings, during the applicable 
additional endurance test prescribed in section 33.87 as amended by 
these special conditions, may be used to show compliance with the 
requirements of section 33.85.


Sec. 33.87  Endurance Test.

    In addition to the requirements of section 33.87, an engine test 
must be conducted four times, using the following test sequence, for a 
total of not less than 120 minutes:
    (a) Takeoff Power--three minutes at rated takeoff power.
    (b) 30-Second OEI power--thirty seconds at rated 30-Second OEI 
power.
    (c) 2-Minute OEI power--two minutes at rated 2-Minute OEI power.
    (d) 30-Minute OEI, Continuous OEI, or Maximum Continuous power--
five minutes at rated 30-Minute OEI power, or rated Continuous OEI 
power, or rated Maximum Continuous power, whichever is greatest, except 
that during the first test sequence this period shall be 65 minutes.
    (e) 50 Percent takeoff power--one minute at 50 percent takeoff 
power.
    (f) 30-Second OEI power--thirty seconds at rated 30-Second OEI 
power.
    (g) 2-Minute OEI power--two minutes at rated 2-Minute OEI power.
    (h) Idle power--one minute at idle power.


Sec. 33.88  Engine Overtemperature Test.

    In addition to the requirements of section 33.88, the following 
must be performed:
    (a) For engines that do not provide a means for temperature 
limiting; conduct a test for a period of five minutes at the maximum 
permissible power-on RPM, with the gas temperature at least 75 degrees 
Fahrenheit higher than the 30-Second OEI rating operating temperature 
limit.
    (b) For engines that provide a means for temperature limiting; 
conduct a test for a period of four minutes at the maximum permissible 
power-on RPM, with the gas temperature at least 35 degrees Fahrenheit 
higher than the 30-Second OEI rating operating temperature limit.
    (c) A separate test engine may be used for each test.
    (d) Following the test, rotor assembly growth and distress beyond 
serviceable limits for an overtemperature condition is permitted, 
provided the structural integrity of the rotor assembly is maintained, 
as shown by a procedure that is acceptable to the Administrator.


Sec. 33.93  Teardown Inspection.

    In addition to the requirements of section 33.93, this special 
condition requires that the engine be completely disassembled after 
completing the

[[Page 16377]]

additional testing of section 33.87. The engine must comply with 
section 33.93(a), but it may exhibit deterioration in excess of that 
permitted in section 33.93(b), and may include some engine parts and 
components that may be unsuitable for further use. It must be shown by 
procedures approved by the Administrator that the structural integrity 
of the engine, including mounts, cases, bearing supports, shafts and 
rotors, is maintained.

    Issued in Burlington, Massachusetts, on April 3, 1996.
James C. Jones,
Acting Manager, Engine & Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 96-9252 Filed 4-12-96; 8:45 am]
BILLING CODE 4910-13-M