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

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]

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