[Federal Register Volume 60, Number 163 (Wednesday, August 23, 1995)]
[Proposed Rules]
[Pages 43727-43728]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-20876]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 33
[Docket No. 95-ANE-46; Notice No. 33-ANE-05]


Special Conditions: Turbomeca Model Arriel 2S1 Turboshaft Engine

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This notice proposes special conditions 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. This notice proposes the safety standards 
for those novel or unique ratings that 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).

DATES: Comments must be submitted on or before September 22, 1995.

ADDRESSES: Comments on this proposal may be submitted in triplicate to: 
Federal Aviation Administration (FAA), New England Region, Office of 
the Assistant Chief Counsel, Attn: Rules Docket No. 95-ANE-46, 12 New 
England Executive Park, Burlington, Massachusetts 01803-5299. Comments 
must be marked: Docket No. 95-ANE-46. Comments may be inspected at this 
location between 8 a.m. and 4:30 p.m., Monday through Friday, except 
Federal holidays.

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: 

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed special conditions by submitting such written data, views, or 
arguments as they may desire. Communications should identify the Rules 
Docket number and be submitted in triplicate to the address specified 
under ADDRESSES. All communications received on or before the closing 
date for comments, specified under DATES, will be considered by the 
Administrator before taking action on the proposal. The proposal 
contained in this notice may be changed in light of the comments 
received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed special 
conditions. 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 proposal will be filed in 
the docket.
    Comments wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit with those comments a 
self addressed, stamped postcard on which the following statement is 
made: ``Comments to Docket No. 95-ANE-46.'' The postcard will be date 
stamped and returned to the commenter.

Background

    On February 25, 1994, Turbomeca applied for an amendment to Type 
Certificate No. E19EU to add a new Model Arriel 2S1 turboshaft engine. 
The Model Arriel 2S1 turboshaft engine, a derivative of the Arriel 1 
turboshaft engine will be rated at 30-Second OEI, 2-Minute one engine 
inoparative (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's) Turbomeca must show that the new Model Arriel 2S1 
turboshaft engine meets the applicable provisions of the regulations 
incorporated by reference in Type Certificate No. E19EU or the 
applicable regulations in effect on the date of application. The FAR's 
incorporated by reference in type Certificate No. E19EU are: Section 
21.29 and part 33, effective February 1, 1965, as amended.
    The Administrator finds that the applicable airworthiness 
regulations in part 33, as amended, do not contain adequate or 
appropriate safety standards for the Turbomeca Arriel 2S1 turboshaft 
engine because of the new and unique engine ratings. Therefore, the 
Administrator proposes 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 21.17(a)(2).
Conclusion

    This action affects only certain novel or unusual design features 
on one model engine. It is not a rule of general 

[[Page 43728]]
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.

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421, 1423; 49 U.S.C. 106(g).

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for the Turbomeca Arriel 2S1 turboshaft engine:
    (a) In addition to the requirements of section 33.7, the following 
ratings are defined as:

    (1) RATED 30-SECOND ONE-ENGINE-INOPERATIVE (OEI) POWER: The 
approved brake horsepower developed statically in standard 
atmosphere at sea level, or at a specified altitude and temperature, 
for continued one-flight operation after the failure of one engine 
in multi-engine rotorcraft, limited to three periods of use, no 
greater than 30 seconds each, at rotor shaft rotation speed and gas 
temperature established for this rating by part 33 or this special 
condition.
    (2) RATED 2-MINUTE OEI POWER: The approved brake horsepower, 
developed statically in standard atmosphere at sea level, or at a 
specified altitude and temperature, for continued one-flight 
operation, after failure of one engine in multi-engine rotorcraft, 
limited to three periods of use, of up to two minutes each, at rotor 
shaft rotation speed and gas temperature established for this rating 
by part 33 or this special condition.
    (b) 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.
    (c) In addition to the requirements of section 33.27, the 
following additional test requirements must be considered. For 30-
Second and 2-Minute OEI conditions, test for a period of 5 minutes--
    (1) 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.
    (2) The test speed must take into account minimum material 
properties, maximum operating temperature, and the most adverse 
dimensional tolerances.
    (3) 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.
    (d) In addition to the requirements of section 33.29, the engine 
must provide for a means:
    (1) To indicate when the engine is at either 30-Second and 2-
Minute OEI-rated power level; and
    (2) To determine the elapsed time of operation at 2-Minute OEI 
and 30-Second OEI-rated power levels.
    (e) 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 switching to a 30-Second OEI 
rating condition.
    (f) In addition to the requirements of section 33.83, the 
following additional test requirements must be considered under 
section 33.83(a):
    (1) 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 minumum 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 high physical or corrected rotational 
speeds, the surveys shall be extended in order to quantify the 
phenomenon and to ensure compliance with the requirements of section 
33.63.
    (g) In addition to the requirements of section 33.85, tests 
performed at the 30-Second and 2-Minute OEI ratings, during the 
applicable endurance test prescribed in section 33.87, may be used 
to show compliance with the requirements of section 33.85.
    (h) 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:
    (1) Takeoff Power--three minutes at rated takeoff power.
    (2) 30-Second OEI power--thirty seconds at rated 30-Second OEI 
power.
    (3) 2-Minute OEI power--two minutes at rated 2-Minute OEI power.
    (4) 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.
    (5) 50 percent takeoff power--one minute at 50 percent takeoff 
power.
    (6) 30-second OEI power--thirty seconds at rated 30-Second OEI 
power.
    (7) 2-minute OEI power--two minutes at rated 2-Minute OEI power.
    (8) Idle power--one minute at Idle power.
    (i) In addition to the requirements of section 33.88, the 
following must be performed:
    (1) 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.
    (2) 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.
    (3) A separate test engine may be used for each test.
    (4) 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.
    (j) In addition to the requirements of section 33.93, this 
special condition requires that the engine be completely 
disassembled after completing the additional testing of section 
33.87. The engine 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 August 14, 1995.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 95-20876 Filed 8-22-95; 8:45 am]
BILLING CODE 4910-13-M