[Federal Register Volume 60, Number 25 (Tuesday, February 7, 1995)]
[Proposed Rules]
[Pages 7380-7384]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-2730]




[[Page 7379]]

_______________________________________________________________________

Part V





Department of Transportation





_______________________________________________________________________



Federal Aviation Administration



_______________________________________________________________________



14 CFR Parts 1 and 33



Airworthiness Standards: Aircraft Engines; New One-Engine-Inoperative 
Ratings, Definitions, and Type Certification Standards; Proposed Rule

  Federal Register / Vol. 60, No. 25 / Tuesday, February 7, 1995 / 
Proposed Rules   
[[Page 7380]] 

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

14 CFR Parts 1 and 33
[Docket No. 26019; Notice No. 89-27A]
RIN 2120-AD21

Airworthiness Standards: Aircraft Engines; New One-Engine-
Inoperative Ratings, Definitions, and Type Certification Standards

agency: Federal Aviation Administration, DOT.

action: Supplemental notice of proposed rulemaking.

-----------------------------------------------------------------------

summary: This document modifies Notice of Proposed Rulemaking (NPRM) 
No. 89-27, published in the Federal Register on September 22, 1989 (54 
FR 39080). In that document, the FAA proposed adoption of new 
definitions and airworthiness standards of new one-engine-inoperative 
(OEI) ratings for type certification of rotorcraft engines. The maximum 
engine power level available for a certificated rotorcraft engine under 
current part 33 rules is the 2\1/2\-minute OEI rating. The proposed 
rule would establish type certification standards for 30-second OEI and 
2-minute OEI ratings at higher power levels than the current OEI 
rating.
    Four commenters provided the FAA with comments to the NPRM, 
addressing numerous issues. The FAA has determined that the comments 
and recommended changes merit consideration. Substantive changes have 
been made to the proposed rule based upon the relevant comments 
received. Accordingly, the FAA is issuing this Supplemental Notice of 
Proposed Rulemaking (SNPRM) to give all interested parties an 
opportunity to comment on the modified proposed rule.

dates: Comments must be received on or before March 24, 1995.

addresses: Comments on this notice should be mailed in triplicate to: 
Federal Aviation Administration, Office of the Chief Counsel, Attn: 
Rules Docket (AGC-200), Docket No. 26019, 800 Independence Avenue SW., 
Washington, DC 20591. Comments delivered must be marked Docket No. 
26019. Comments may be examined in Room 915G weekdays between 9:00 a.m. 
and 5:00 p.m., except Federal holidays.

for further information contact: Chung C. Hsieh, Aerospace Engineer, 
Engine and Propeller Standards Staff, ANE-110, Engine and Propeller 
Directorate, Aircraft Certification Service, FAA, 12 New England 
Executive Park, Burlington, Massachusetts 01803-5299; telephone (617) 
238-7116; fax (617) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    This supplemental notice modifies Notice No. 89-27. Comments on the 
effect of this change to the proposed rule are invited. Comments should 
be limited to the changes proposed in this document. This notice does 
not serve to reopen the comment period on the remainder of the original 
proposal. Interested persons are invited to comment on this 
supplemental notice by submitting written data, views, or arguments as 
they may desire. Comments relating to the environmental, energy, or 
economic impact that might result from adopting the proposals, as 
modified in this document, are also invited. Communications should 
identify the regulatory docket number and be submitted in triplicate to 
the address specified above. All communications received on or before 
the closing date for comments will be considered by the Administrator 
before taking further rulemaking action. Commenters wishing the FAA to 
acknowledge receipt of their comments submitted in response to this 
proposed rule must submit with those comments a self-addressed stamped 
postcard on which the following statement is made: ``Comments to Docket 
No. 26019.'' The postcard will be date stamped and mailed to the 
commenter.

Availability of SNPRM

    Any person may obtain a copy of this notice by submitting a request 
to the Federal Aviation Administration Office of Public Affairs, Attn: 
Public Inquiry Center, (APA-200), 800 Independence Avenue, SW., 
Washington, DC 20591, or by calling (202) 267-3484. Communications must 
identify the notice number of this SNPRM.
    Persons interested in being placed on the mailing list for future 
NPRM's should request, from the above office, a copy of Advisory 
Circular No. 11-2A, Notice of Proposed Rulemaking Distribution System, 
which describes the application procedure.

Background

    On September 14, 1989, the FAA issued two NPRM's, Notice Nos. 89-27 
(54 FR 39080 and 54 FR 39085). The Notice associated with this SNRPM is 
No. 89-27, which proposed to define and establish type certification 
standards for new OEI ratings for rotorcraft engines. The companion 
NPRM, No. 89-26, addressed the usage of the 30-second OEI and 2-minute 
OEI ratings by rotorcraft. A final rule based on Notice No. 89-26 was 
published in the Federal Register on September 16, 1994 (59 FR 47764).
    These new OEI ratings are applicable to turbine engines installed 
on multiengine powered rotorcraft. In a Category A operation, a 
multiengine turbine-powered rotorcraft must have the ability to either 
continue flight or land within a demonstrated field size in the event 
of failure of an engine. In a Category B operation, the rotorcraft 
would not have sufficient residual power if one engine failed to 
continue its flight and would, therefore, a need safe landing areas 
throughout its flight path. Category A rotorcraft mission payloads are 
limited by the power available from the remaining operating engine(s) 
in the event one engine fails during takeoff or landing. The maximum 
engine power level available under current part 33 rules is the 2\1/2\-
minute OEI rating.
    This proposal would establish 30-second OEI and 2-minute OEI 
ratings at higher power levels than the current 2\1/2\-minute OEI 
rating. Engine type certification to these ratings, as with other OEI 
ratings, would be optional.
    The comment period for Notice 89-27 closed on March 27, 1990. On 
November 16, 1989, a public meeting to hear comments on the proposals 
was convened in Fort Worth, Texas. In addition, the minutes of a 
meeting between the FAA and the Aerospace Industries Association of 
America, Inc., inspected, in the Rules Docket No. 26019. The FAA has 
determined that the comments and recommended changes merit 
consideration. Substantive changes have been made to the proposed rule 
based upon the relevant comments received. Accordingly, the FAA is 
issuing this SNPRM to give all interested parties an opportunity to 
comment on the modified proposed rule.

Discussion

    Four commenters provided the FAA with comments to the NPRM, 
addressing numerous issues. This discussion describes only those 
changes made to the proposal of Notice 89-27 and the comments 
associated with those changes. However, for the convenience of the 
public, the proposed rule is being reprinted in its entirety.

Section 1.1  Definitions and Abbreviations

    One commenter states that the definitions of 30-second OEI and 2-
minute OEI ratings should contain a specific limit as to the number of 
items these power levels could be used during [[Page 7381]] 
any one flight. The commenter noted that the lack of a specific limit 
in the proposed definitions leaves the issue ambiguous. The commenter 
also noted that a number of a specific limit in the proposed 
definitions leaves the issue ambiguous. The commenter also noted that a 
number of people at the public meeting expressed differing views on the 
intended maximum number of allowable applications of 30-second OEI or 
2-minute OEI power on a single flight.
    The FAA agrees. The rated 30-second OEI power and rated 2-minute 
OEI power for section 1.1 are therefore revised to limit the use of 
these new power levels to a maximum of three periods. The definitions 
retain requirements of mandatory inspection and prescribed maintenance 
following any use of 30-second OEI or 2-minute OEI power, and the limit 
of use of these new power levels to continue operation, in order to 
complete the flight during which engine failure occurred.

Section 33.27  Turbine, Compressor, Fan, and Turbosupercharger Rotors

    One commenter states that post-test acceptance criteria after the 
overspeed test for the 30-second OEI rating should be less severe since 
a mandatory inspection of the engine will be required after the engine 
is used at the 30-second OEI rating. The commenter suggests that since 
the inspection would result in replacement of parts unsuitable for 
continuous use, more specific acceptable criteria are not considered 
practical in view of the wide variety of designs in use and yet to 
come. The commenter also suggests that the last paragraph of 
Sec. 33.27(c) be changed as follows:

    Following the testing, each rotor must be within approved 
dimensional limits for an overspeed condition and may not be 
cracked; except that following the test based on the 30-second OEI 
rating condition, growth and distress beyond the dimensional limits 
for an overspeed condition and cracks will be permitted, provided 
there is no evidence of imminent failure. The applicant may show by 
analysis or test, as found necessary by the Administrator, that 
there is no evidence of imminent failure.

    Another commenter suggests that the severity of the rotor test 
requirement needs to be clearly specified, consistent with the worst 
case rationale identified in the NPRM. The commenter suggests that the 
second paragraph of Sec. 33.27(c) should be extended by the addition of 
the following: ``* * * including two subsequent uses of both 30-second 
OEI and 2-minute OEI conditions.''
    The FAA does not agree that section 33.27 should be revised as the 
commenters suggested. The FAA would require that, based on the 
condition of the rotor following the test, the engine would have 
sufficient safety margin for continued operation and the capability of 
completing up to three uses of both 30-second OEI power and 2-minute 
OEI power. It is inappropriate to specify in the rule that all cracks 
would be acceptable, since a rotor with cracks may not be in airworthy 
condition in all engines affected by the rule. The same argument 
applies concerning the ``dimensional'' and ``imminent failure'' 
statements. The standard that growth and distress beyond the limits for 
an overspeed condition will be permitted provided the engine is shown 
by analysis or test, as found necessary by the Administrator, that the 
structural integrity of each rotor is maintained will permit the FAA to 
apply the best engineering judgment for each specific engine type 
design tested. Therefore, the FAA proposes to revise the paragraph at 
the end of section 33.27(c) by incorporating that standard; the revised 
paragraph is proposed as a new paragraph (d) to section 33.27. In 
addition to these revisions other editorial changes have been made in 
the proposed Sec. 33.27.

Section 33.29  Instrument Connection

    One commenter states that Proposal No. 6 of the NPRM corresponds to 
only one of the two aspects covered by Proposal No. 11 for Sec. 29.1305 
in Notice No. 89-26. The commenter states that it corresponds only with 
Sec. 29.1305(a)(25), whereas, it should also be concerned with 
Sec. 29.1305(a)(24) because the engine manufacturer will need to 
provide some means, incorporated in the engine, in order to enable the 
complete helicopter to comply with both of these two part 29 sections. 
Therefore, the engine certification standards must address all issues 
that could be considered as engine requirements.
    The FAA agrees. The proposed section 33.29 is changed to require a 
provision for a means to alert the pilot when the engine is at the 30-
second OEI and 2-minute OEI levels; and is reorganized. The proposed 
section 33.29(c)(1) corresponds to section 29.1305(a)(24); the proposed 
sections 33.29(c)(2) and (c)(3) correspond to section 29.1305(a)(25).

Section 33.67  Fuel System

    One commenter states that the FAA proposal is somewhat meager when 
compared with existing requirements in Joint Airworthiness Requirement 
Engines (JAR-E) for engines in which power output and associated 
conditions are controlled by automatic devices. The commenter, 
therefore, suggests changing the wording from ``* * * means for 
automatic control of 30-second power'' to ``* * * means for automatic 
availability and automatic control of 30-second OEI power.''
    The FAA concurs with the suggested wording and the proposed 
Sec. 33.67 is changed accordingly.

Section 33.85  Calibration Tests

    One commenter states that Proposal No. 8 of the NPRM contains 
cross-referencing errors in the first sentence of the proposed 
Sec. 33.85(c). It should state that ``* * * measurements taken during 
the endurance test described in Sec. 33.87(f)(1) through (8) may be 
used * * *''
    The FAA agrees, and the changes have been made to the proposal.
    One commenter states that, in the absence of any provision in the 
existing Sec. 33.85 concerning the minimum period of stabilized 
conditions before taking measurements, it is not clear why the proposed 
Sec. 33.85(c) is required. Alternatively, if this aspect needs to be 
included under Sec. 33.85, it should address all engines, regardless of 
their power ratings.
    The commenter further suggests that the following language would be 
more appropriate for Sec. 33.85 (c) and (d):

    (c) In showing compliance with the section, each condition must 
be allowed to stabilize before measurements are taken, except as 
permitted by (d) of this section.
    (d) In the case of engines having 30-second, 2-minute, or 2\1/
2\-minute OEI ratings, measurements taken during the applicable 
endurance test prescribed in Sec. 33.87 may be used in showing 
compliance with the requirements of this section for these OEI 
ratings.

    The FAA agrees, and has made the suggested changes to proposed 
Sec. 33.85 (c) and (d). This proposal is required to provide an 
acceptable and viable approach for obtaining meaningful calibration 
data in the briefest time possible, consistent with the practical 
limits of the 30-second OEI and 2-minute OEI power ratings. The 
proposed Sec. 33.85(c), which requires engine parameters to stabilize 
before recording measurements, is consistent with current Sec. 33.85(a) 
requirements.

Section 33.87  Endurance Test

    One commenter suggests that Sec. 33.87(f)(5) be changed to read as 
follows: ``50 percent takeoff power. One minute at 50 percent takeoff 
power.'' The commenter reasons that the power level for a one-minute 
run at 50 percent takeoff power realistically represents the minimum 
OEI flight power and engine [[Page 7382]] thermal condition preceding 
reapplication of 30-second OEI power.
    The FAA agrees. The proposed wording for Sec. 33.87(f)(5) is 
modified accordingly. Actual operations could realistically be expected 
to have a power setting of 50 to 60 percent takeoff power in an 
approach descent from a continuous OEI power setting toward a landing 
spot. The flight scenario would likely include and follow one use of 
takeoff power to the takeoff path's critical decision point (CDP), then 
from one to three applications of 30-second OEI power, and one or two 
applications of 2-minute OEI power.
    One commenter states that Proposal 9 of the NPRM is inaccurate in 
stating that existing Sec. 33.87(f) will be redesignated as paragraph 
(g) without text change.The commenter claims that a number of cross-
references in the existing subparagraphs of the newly redesignated 
Sec. 33.87(g) are incorrectly designated as (e) instead of (f). The 
commenter suggests changing those cross-references from (e) to (g) if 
Sec. 33.87(f) is redesignated as Sec. 33.87(g).
    The FAA agrees. Editorial changes have been made in the proposed 
Sec. 33.87.

Section 33.88  Engine Overtemperature Test

    One commenter suggests that the wording ``or equivalent device'' be 
inserted after ``temperature limiter'' in Sec. 33.88(c) and that 
language allowing ``equivalent limiting device'' be added as an 
alternative to the direct temperature limiting control system.
    The FAA agrees. The proposed wording is changed from ``a 
temperature limiter'' to ``a means to limit temperature.'' The means to 
limit the temperature is intended for limiting the maximum engine gas 
temperature.

Section 33.93  Teardown Inspection

    One commenter states that in Sec. 33.93, an ``and'' in the first 
sentence of Sec. 33.93(c) should read ``or'', making the fifth and 
sixth lines read as follows: ``* * * the endurance testing of 
Sec. 33.87 (b), or (c), or (d), or (e) of this part and followed * * 
*.'' The commenter states this change is needed because in Proposal No. 
9, revised Sec. 33.87(a) states: ``* * * for engines tested under 
paragraphs (b), (c), (d), or (e) of this section * * *,'' and the new 
Sec. 33.87(f) reads: ``* * * and following completion of the tests 
under paragraphs (b), (c), (d), or (e) of this section * * *.''
    The FAA agrees, and editorial changes in proposed Sec. 33.93 are 
made.

Supplemental Regulatory Evaluation Summary

    The FAA has determined that the changes made to the NPRM do not 
increase the scope of the proposed rule or the original economic 
analysis. Therefore, the FAA has determined that this is not a 
significant rulemaking as defined in Executive Order 12866.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) was enacted to ensure 
that small entities are not unnecessarily or disproportionately 
burdened by Government regulations. The RFA requires a Regulatory 
Flexibility Analysis if a proposed rule would have ``a significant 
economic impact, on a substantial number of small entities.'' FAA Order 
2100.14A outlines FAA's procedures and criteria for implementing the 
RFA.
    The proposed modification of Notice No. 89-27 will neither 
eliminate any present regulations, nor impose any new regulations and, 
thus, will not have a significant economic impact on a substantial 
number of small entities. Consequently, the FAA has determined that, 
under the criteria of the Regulatory Flexibility Act of 1980, a 
regulatory flexibility analysis of this supplemental notice of proposed 
rulemaking is not required.

International Trade Impact Assessment

    The proposed modification of Notice No. 89-27 will neither 
eliminate any present regulations, nor impose any new ones. As a 
result, affected manufacturers and operators will not incur additional 
costs, or realize significant savings. Thus, the proposed modification 
of Notice No. 89-27 will not have any impact on trade opportunities for 
either U.S. firms doing business overseas, or foreign firms doing 
business in the United States.

Federalism Implications

    The revised regulations proposed herein would not have substantial 
direct effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.

Conclusion

    This SNPRM changes certain sections of the proposed rule based on 
comments received. For the reasons discussed in the Notice No. 89-27 
and this supplemental notice, and based on the findings in the 
Regulatory Flexibility Determination and the International Trade Impact 
Analysis, the FAA has determined that this proposed regulation is not a 
significant regulation as defined in Executive Order 12866. In 
addition, it is certified this SNPRM will not have a significant 
economic impact, positive or negative, on a substantial number of small 
entities under the criteria of the Regulatory Flexibility Act. This 
proposal, including this supplemental notice, is not considered 
significant under DOT Regulatory Policies and Procedures (44 FR 11034, 
February 26, 1979). A draft regulatory evaluation of the proposal, 
including a supplement relating to the modifications in this notice, 
has been placed in the regulatory docket. A copy may be obtained by 
contacting the person identified under the caption FOR FURTHER 
INFORMATION CONTACT.

List of Subjects

14 CFR Part 1

    Airmen, Flights, Balloons, Parachutes, Aircraft pilots, Pilots, 
Transportation, Agreements, Kites, Air safety, Safety, Aviation safety, 
Air transportation, Air carriers, Aircraft, Airports, Airplanes, 
Helicopters, Rotorcraft, Heliports, Engines, and Ratings.

14 CFR Part 33

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, the Federal Aviation Administration proposes to amend 
14 CFR part 1 and part 33 as follows:

PART 1--DEFINITIONS AND ABBREVIATIONS

    1. The authority citation for Part 1 continues to read as follows:

    Authority: 49 U.S.C. app. 1347, 1348, 1354(a), 1357(d)(2), 1372, 
1421 through 1430, 1432, 1442, 1443, 1472, 1510, 1522, 1652(e), 
1655(c), 1567(f); 49 U.S.C. 106(g).

    2. Section 1.1 is amended by adding the definitions in alphabetical 
order of ``Rated 30-second OEI power'' and ``Rated 2-minute OEI power'' 
to read as follows:


Sec. 1.1  General definitions.

* * * * *
    Rated 30-second OEI power, with respect to rotorcraft turbine 
engines, means the approved brake horsepower developed under static 
conditions at specified altitudes and temperatures within the operating 
limitations established for the engine under part 33 of this chapter, 
for continued one-flight [[Page 7383]] operation after the failure of 
one engine in multiengine 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.
    Rated 2-minute OEI power, with respect to rotorcraft turbine 
engines, means the approved brake horsepower developed under static 
conditions at specified altitudes and temperatures within the operating 
limitations established for the engine under part 33 of this chapter, 
for continued one-flight operation after the failure of one engine in 
multiengine rotorcraft, limited to three periods of use no longer than 
2 minutes each in any one flight, and followed by mandatory inspection 
and prescribed maintenance action.
* * * * *

PART 33--AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES

    3. The authority citation for Part 33 continues to read as follows:

    Authority: 49 U.S.C. 1344, 1354(a), 1355, 1421, 1423, 1424, 
1425; 49 U.S.C. 106(g).

    4. Section 33.7 is amended by redesignating paragraph (c)(1)(viii) 
as paragraph (c)(1)(x); and by adding new paragraphs (c)(1)(viii) and 
(c)(1)(ix) to read as follows:


Sec. 33.7  Engine ratings and operating limitations.

* * * * *
    (c) * * *
    (1) * * *
    (viii) Rated 2-minute OEI power;
    (ix) Rated 30-second OEI power; and
* * * * *
    5. Section 33.27 is amended by revising the introductory text of 
paragraph (c) and paragraph (c)(1), and by designating the undesignated 
paragraph following paragraph (c)(2)(vi) as paragraph (d) and revising 
it to read as follows:


Sec. 33.27  Turbine, compressor, fan, and turbosupercharger rotors.

* * * * *
    (c) The most critically stressed rotor component (except blades) of 
each turbine, compressor, and fan, including integral drum rotors and 
centrifugal compressors in an engine or turbosupercharge, as determined 
by analysis or other acceptable means, must be tested:
    (1) For a period of 5 minutes at the maximum rating's steady-state 
operating temperature limit, excluding the maximum operating 
temperature limits of the 30-second OEI and 2-minute OEI ratings, 
except as provided in paragraph (c)(2)(iv) of this section; for engines 
with 30-second OEI and 2-minute OEI ratings, using a separate test 
vehicle if desired, for a period of 2-1/2 minutes at the maximum 
operating temperature limit of the 30-second OEI rating, except as 
provided in paragraph (c)(2)(iv) of this section; and
* * * * *
    (d) Following the test, each rotor must be within approved 
dimensional limits for an overspeed condition and may not be cracked, 
except that following the test based on the maximum operating 
temperature limit of the 30-second OEI rating, growth and distress 
beyond the limits for an overspeed condition will be permitted, 
provided the engine is shown by analysis or test, as found necessary by 
the Administrator, to maintain the structural integrity of each rotor.
    6. Section 33.29 is amended by adding a new paragraph (c) to read 
as follows:


Sec. 33.29  Instrument connection.

* * * * *
    (c) Each rotorcraft turbine engine having a 30-second OEI and a 2-
minute OEI power rating must have a provision for a means to:
    (1) Alert the pilot when the engine is at the 30-second OEI and the 
2-minute OEI power levels;
    (2) Determine, in a positive manner, that the engine has been 
operated at each rating; and
    (3) Determine the elapsed time of operation at each rating.
    7. Section 33.67 is amended by adding a new paragraph (d) to read 
as follows:


Sec. 33.67  Fuel system.

* * * * *
    (d) Engines having a 30-second OEI rating must incorporate means 
for automatic availability and automatic control of 30-second OEI 
power.
    8. Section 33.85 is amended by adding new paragraphs (c) and (d) to 
read as follows:


Sec. 33.85 Calibration tests.

    (c) In showing compliance with this section, each condition must 
stabilize before measurements are taken, except as permitted by 
paragraph (d) of this section.
    (d) In the case of engines having 30-second, OEI, 2-minute OEI, or 
2\1/2\-minute OEI ratings, measurements taken during the applicable 
endurance test prescribed in Sec. 33.87 (f)(1) through (8) may be used 
in showing compliance with the requirements of this section for these 
OEI ratings.
    9. Section 33.87 is amended by revising the introductory text of 
paragraph (a) and paragraph (a)(8); by redesignating paragraph (f) as 
paragraph (g); by revising the reference ``(e)(2) (ii) through (iv)'' 
to read ``(g)(2) (ii) through (iv)'' in newly designated paragraph 
(g)(2)(i); by revising the reference ``(e)(2)(i)'' to read 
``(g)(2)(i)'' in newly designated paragraph (g)(2)(ii); by revising the 
reference ``(e)(2)(i)'' to read ``(g)(2)(i)'' in newly designated 
paragraph (g)(2)(iii); by revising the reference ``(e)(2) (i) and 
(ii)'' to read ``(g)(2)(i) and (ii)'' in newly designated paragraph 
(g)(2)(iv); and by adding a new paragraph (f) to read as follows:


Sec. 33.87  Endurance test.

    (a) General. Each engine must be subjected to an endurance test 
that includes a total of at least 150 hours of operation and, depending 
upon the type and contemplated use of the engine, consists of one of 
the series of runs specified in paragraphs (b) through (g) of this 
section, as applicable. For engines tested under paragraphs (b), (c), 
(d), or (e) of this section, the prescribed 6-hour test sequence must 
be conducted 25 times to complete the required 150 hours of operation. 
Engines for which the 30-second OEI and 2-minute OEI ratings are 
desired must be further tested under paragraph (f) of this section. The 
following test requirements apply:
* * * * *
    (8) If the number of occurrences of either transient rotor shaft 
overspeed or transient gas overtemperature is limited, that number of 
accelerations required by paragraphs (b) through (g) of this section 
must be made at the limiting overspeed or overtemperature. If the 
number of occurrences is not limited, half the required accelerations 
must be made at the limiting overspeed or overtemperature.
* * * * *
    (f) Rotorcraft engines for which 30-second OEI and 2-minute OEI 
ratings are desired. For each rotorcraft engine for which 30-second OEI 
and 2-minute OEI power ratings are desired, and following completion of 
the tests under paragraphs (b), (c), (d), or (e) of this section, the 
applicant may disassemble the tested engine, to the extent necessary to 
show compliance with the requirements of Sec. 33.93(a). The tested 
engine must then be reassembled using the same parts used during the 
test runs of paragraphs (b), (c), (d), or (e) of this section, except 
those parts described as consumables in the Instructions for Continued 
Airworthiness. The applicant must then conduct the following test 
sequence four times, for a total time of not less than 120 
minutes: [[Page 7384]] 
    (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 power, continuous OEI power, or maximum 
continuous power. Five minutes at rated 30-minute OEI power, rated 
continuous OEI power, or rated maximum continuous power, whichever is 
greatest, except that, during the first test sequence, this period 
shall be sixty-five 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. One minute at idle.
* * * * *
    10. Section 33.88 is revised to read as follows:


Sec. 33.88  Engine overtemperature test.

    (a) Each engine must run for 5 minutes at maximum permissible rpm 
with the gas temperature at least 75  deg.F (42  deg.C) higher than the 
maximum rating's steady-state operating limit, excluding maximum values 
of rpm and gas temperature associated with the 30-second OEI and 2-
minute OEI ratings. Following this run, the turbine assembly must be 
within serviceable limits.
    (b) Each engine for which 30-second OEI and 2-minute OEI ratings 
are desired, that does not incorporate a means to limit temperature, 
must be run for a period of 5 minutes at the maximum power-on rpm with 
the gas temperature at least 75  deg.F (42  deg.C) higher than the 30-
second OEI ratings operating limit. Following this run, the turbine 
assembly may exhibit distress beyond the limits for an overtemperature 
condition provided the engine is shown by analysis or test, as found 
necessary by the Administrator, to maintain the integrity of the 
turbine assembly.
    (c) Each engine for which 30-second OEI and 2-minute OEI ratings 
are desired, that incorporates a means to limit temperature, must be 
run for a period of 4 minutes at the maximum power-on rpm with the gas 
temperature at least 35  deg.F (20  deg.C) higher than the maximum 
operating limit. Following this run, the turbine assembly may exhibit 
distress beyond the limits for an overtemperature condition provided 
the engine is shown by analysis or test, as found necessary by the 
Administrator, to maintain the integrity of the turbine assembly.
    (d) A separate test vehicle may be used for each test condition.
    11. Section 33.93 is revised to read as follows:


Sec. 33.93  Teardown inspection.

    (a) After completing the endurance testing of Sec. 33.87 (b), (c), 
(d), (e), or (g), each engine must be completely disassembled; and--
    (1) Each component having an adjustment setting and a functioning 
characteristic that can be established independent of installation on 
the engine must retain each setting and functioning characteristic 
within the limits that were established and recorded at the beginning 
of the test; and
    (2) Each engine part must conform to the type design and be 
eligible for incorporation into an engine for continued operation, in 
accordance with information submitted in compliance with Sec. 33.4.
    (b) After completing the endurance testing of Sec. 33.87(f), each 
engine must be completely disassembled; and
    (1) Each component having an adjustment setting and a functioning 
characteristic that can be established independent of installation on 
the engine must retain each setting and functioning characteristic 
within the limits that were established and recorded at the beginning 
of the test; and
    (2) Each engine may exhibit deterioration in excess of that 
permitted in paragraph (a)(2) of this section, including some engine 
parts or components that may be unsuitable for further use. The 
applicant must show by analysis and/or test, as found necessary by the 
Administrator, that structural integrity of the engine including 
mounts, cases, bearing supports, shafts, and rotors, is maintained; or
    (c) In lieu of compliance with paragraph (b) of this section, each 
engine for which the 30-second OEI and 2-minute OEI ratings are 
desired, may be subjected to the endurance testing of Sec. 33.87 (b), 
(c), (d), or (e) of this part, and followed by the testing of 
Sec. 33.87(f), without intervening disassembly and inspection. However, 
the engine must comply with paragraph (a) of this section after 
completing the endurance testing of Sec. 33.87(f). Issued in 
Washington, DC, on January 24, 1995.
Elizabeth Yoest,
Acting Director, Aircraft Certification Service.
[FR Doc. 95-2730 Filed 2-6-95; 8:45 am]
BILLING CODE 4910-13-M