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

SUMMARY: This amendment establishes definitions for new one-engine

inoperative (OEI) ratings, and type certification standards for those

ratings. This amendment is the result of a petition for rulemaking from

Aerospace Industries Association of America, Inc. (AIA), and a

recognition by both the FAA, along with other civil airworthiness

authorities, and the aviation industry for a need for additional OEI

power rating standards. The maximum engine power rating for rotorcraft

available under current certification standards contained in the

Federal Aviation Regulations (FAR's) is the 2\1/2\-minute OEI rating.

This amendment establishes definitions and type certification standards

for the 30-second OEI and 2-minute OEI rating at higher power levels

than currently available. These new ratings will enhance rotorcraft

safety after an engine failure or precautionary shutdown by providing

the availability for higher OEI power. The benefits from this amendment

are enhanced safety through improved rotorcraft takeoff and landing

performances, and shorter field operations or higher payload with the

same degree of safety.

EFFECTIVE DATE: August 19, 1996.

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,

MA 01803-5229, telephone (617) 238-7115; fax (617) 238-7199.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a Notice of Proposed Rulemaking (NPRM) No. 89-27

that was published in the Federal Register on September 22, 1989 (54 FR

39080), and also issued Supplemental Notice of Proposed Rulemaking

(SNPRM) No. 89-27A that was published in the Federal Register on

February 7, 1995 (60 FR 7380). These notices proposed to define new

one-engine inoperative (OEI) ratings for rotorcraft engines and

establish type certification standards for these new OEI ratings. The

new OEI ratings will be applicable to turbine engines installed on

multiengine powered rotorcraft.

The payload for multiengine rotorcraft is limited by the power

available from the remaining operating engine(s) in the event one

engine fails during takeoff or landing. Currently, the maximum engine

power rating available for rotorcraft under part 33 is the 2\1/2\ OEI

rating. This amendment establishes 30-second OEI and 2-minute OEI

ratings at higher power level than currently available. The new rating

will allow rotorcraft to carry higher payloads from existing fields or

to takeoff from smaller fields with current payloads, without

decreasing the level of safety for these operations. Engine type

certification using these new ratings, however, as with other OEI

ratings, remains optional.

The Aerospace Industries Association of America, Inc., (AIA)

submitted a petition for rulemaking to the FAA on September 20, 1984,

requesting an amendment of the FAR's to permit type certification of

engines and rotorcraft with new OEI ratings. The FAA acknowledged

receipt of the AIA petition, by letter on November 26, 1984, and issued

a notice of that petition that was published in the Federal Register on

December 10, 1984 (49 FR 48759). The FAA subsequently held the petition

in abeyance pending AIA's submission of a revised petition for

rulemaking on April 1, 1987.

The AIA then sponsored a meeting with the Association European des

Constructeurs de Materiel d'Aerospatial (AECMA), the European

Helicopter Association (EHA), and the European Joint Airworthiness

Authorities (JAA) on April 9, 1987, and invited the FAA to attend. The

purpose of this meeting was to familiarize the European community with

the AIA petition. Thereafter, the FAA and the JAA convened their annual

harmonization meeting on May 19-21, 1987, to discuss, in part, the

status of programs of mutual interest. One result of the FAA/JAA

meeting was a recommendation that the FAA and the JAA should strive to

promulgate more harmonious rules and guidance material. Accordingly,

the FAA coordinated their reviews of the AIA petition directly with the

JAA. A meeting was held in late August 1987 between representatives of

the FAA and the JAA to discuss the JAA's concerns with the AIA

petition. The JAA provided many comments, most of which contained

significant deviations from specifies of the petition being considered.

On November 19, 1987, AIA, AECMA, and EHA jointly sponsored a

meeting at AIA Headquarters in Washington, DC, and invited the FAA and

the JAA to attend. The purpose of this meeting was for industry, AIA,

AECMA, and EHA, to jointly address and respond to the comments and

concerns previously expressed by the JAA. In follow-up to this meeting,

on June 8, 1988, the AIA submitted additional revisions to their

petition for rulemaking.

The FAA then issued a final rule from a previous proposal amending

parts 1 and 33 of the FAR's. Amendments 1-34 and 33-12 were issued and

published in the Federal Register on September 2, 1988 (53 FR 34196,

effective October 3, 1988), which redefined OEI ratings in part 1 and

added the Continuous OEI rating in both part 1 and part 33.

After reviewing the revised AIA petition, and coordinating with the

JAA, the FAA issued NPRM No. 89-27 (54 FR 39080), to address the part

33 engine certification aspects of 39-second and 2-minute OEI ratings,

and NPRM No. 89-26 (54 FR 39086), to address the part 27 and part 29

rotorcraft certification aspects of the OEI ratings. Both NPRM's were

published in the Federal Register on September 22, 1989. During the

comment period, the FAA held a joint public meeting to discuss the

proposals of both NPRM's in Fort Worth, Texas, on November 16, 1989

(see Notice of public meeting published on October 13, 1989, 54 FR

41986). The Final rules to part 27 and part 29 were published in the

Federal Register on September 16, 1994 (59 FR 47764).

Based on the comments received, the FAA determined that the

proposals contained in NPRM 89-27 warranted further consideration.

Substantive changes were made to the proposed rule, and SNPRM 89-27A

was published in the Federal Register on February 7, 1995 (60 FR 7380).

The SNPRM gave all interested parties an opportunity to comment on the

modified proposed rule.

All interested persons have been given an opportunity to

participate in this rulemaking, and due consideration has been given to

all matters presented. Some minor editorial changes have been made to

clarify the proposals as indicated herein. The changes are based on

comments received and further FAA review of the proposals. The FAA has

determined that certain technical issues associated with proposed

revisions to Sec. 33.27 have not been resolved. These

[[Page 31325]]

technical issues will be discussed in an Aviation Rulemaking Advisory

Committee (ARAC) working group (see Notice of establishment of

Propulsion Harmonization Working Group at 57 FR 58840, December 11,

1992). Except for the proposed revisions to Sec. 33.27 and other

changes as indicated herein, the proposals contained in SNPRM 89-27A

have been adopted without change.

Discussion of Comments

The commenters represent domestic and foreign engine manufacturers,

and foreign civil airworthiness authorities. Four commenters provided

the FAA with comments to NPRM 89-27, addressing numerous issues. The

FAA also received comments to SNPRM 89-27A from three commenters. This

discussion addresses all the comments made to SNPRM 89-27A, plus those

comments made to NPRM 89-27 that were not already addressed in the

discussion section of SNPRM 89-27A. Some comments presented orally at

the November 16, 1989, public meeting have not been addressed here,

since they have been withdrawn; other oral comments were submitted in

writing to the rules docket. The transcript of the public meeting is in

the Rules Docket. The comments are grouped according to the applicable

sections of the proposed amendment, with general comments discussed

first.

General Comments

One commenter recommends that the FAA should publish the proposals

as worded in the SNPRM as a final rule for all applicable 14 CFR part 1

and 33 sections, with the exception of the proposed revisions to

Sec. 33.27.

One commenter states that the new structure of helicopter engine

ratings as proposed creates a new certification scheme for helicopters

and, accordingly, all the pertinent regulatory and advisory matter must

be considered at the same time. The commenter points out that guidance

material for the proposed ratings, including the maintenance inspection

requirements under Sec. 33.90 and on the issue of power assurance, is

not available. Therefore, the commenter states that an acceptable level

of safety cannot be achieved until all advisory and regulatory material

can be reviewed at the same time.

The FAA disagrees. Even though specific advisory material that

addresses the new OEI ratings is not yet available, the FAA will not

delay issuing this Final rule. The existing guidance material on the

issue of power assurance, which is a certification requirement of the

helicopter under Secs. 27.45(f) and 29.45(f), may be of assistance to

applicants for type certification. A joint effort between the FAA's

Engine & Propeller Directorate and the Rotorcraft Directorate, and both

the engine and the helicopter industry, has resulted in a report

published by the Society of Automotive Engineers (SAE), Aerospace

Information Report AIR4083, ``Helicopter Power Assurance,'' dated July

13, 1989. Also, guidance material addressing the existing Sec. 33.90 is

provided in FAA Advisory Circular (AC) AC 33-2B, ``Aircraft Engine Type

Certification Handbook''. This AC will be revised to include guidance

material on power assurance and mandatory maintenance requirements for

the new OEI ratings following the adoption of this Final rule. The FAA

plans to issue advisory material for these new OEI ratings as soon as

practical.

The commenter also states that this rulemaking is based on an

assumption that the new OEI ratings will be used only during the

takeoff and landing phases of flight. The commenter speculates that it

would be possible that these new ratings be utilized under the

``External Load Operations'' provisions of Sec. 133.45(e)(1). The

commenter suggests that the Regulatory Evaluation section needs to

address whether this assumption will be invalidated if the enhanced OEI

performance is taken into account for other than takeoff and landing

purposes.

The FAA disagrees. While the proposed new OEI ratings are intended

to be used only after the failure of one engine on a multiengine

rotorcraft during takeoff, climb, or landing, it is entirely possible

that these new ratings might be utilized to meet the provisions of

current Sec. 133.45(e)(1), if the rotorcraft and the operator fulfill

those criteria. Therefore, the Regulatory Evaluation does not depend on

how the higher power levels associated with the new OEI ratings may be

used in showing compliance with an existing regulation. In addition the

commenter does not suggest any changes to the regulatory language of

the proposed amendment to part 1 or part 33 to address that concern.

These new ratings are intended to supplement the existing OEI rating

structure for the type certification of engines and rotorcraft.

Existing rotorcraft operating rules with respect to OEI conditions

should not be impacted by the addition of the 30-second and the 2-

minute OEI ratings.

Section 1.1 Definitions

One commenter recommends that the existing Sec. 1.1 definition of

rated 30-minute OEI power should be amended to clarify that the period

of use must not exceed a total of 30 minutes during any flight. The

commenter further states that many authorities are aware of instances

of misinterpretations, not precluded by Flight Manuals, whereby more

than 30 minutes of 30-minute OEI power could have been accumulated

during one flight. This commenter also recommends that the common

aspects of all existing and proposed definitions of rated power/thrust

be expressed in identical language to eliminate differences as much as

possible.

The FAA disagrees. The existing Sec. 1.1 definition of rated 30-

minute OEI power states that the engine power at this rating is limited

in use to a period of not more than 30 minutes after the failure of one

engine of a multiengine rotorcraft. The language used to define the new

30-second OEI and 2-minute OEI ratings is consistent with this and

other OEI definitions. The recommendations on the existing definitions

of rated power and thrust are beyond the scope of this rulemaking. Such

a change may be considered, however, as part of the Engine & Propeller

Directorate's ongoing study on engine ratings.

Section 33.14 Start-Stop Cyclic Stress

One commenter states that the proposal should also include a change

to existing Sec. 33.14 that would exclude OEI ratings from the meaning

of the term ``maximum rated power'' as it appears in Sec. 33.14. The

commenter bases the need for this change on an interpretation of the

existing Sec. 33.14 using the preambles to two previous amendments to

the FAR's, both pre-dating the most recent changes to parts 1 and 33

relating to OEI ratings. The commenter concludes that the suggested

changes would make Sec. 33.14 more rational and provide clarity to

promote consistent application. The commenter also states that

Sec. 33.14 should address rotational speed operating limits and rotor

temperatures in addition to rated powers/thrusts.

The FAA disagrees. No changes to Sec. 33.14 were proposed in either

NPRM No. 89-27 or SNPRM 89-27A. The FAA finds that the existing

Sec. 33.14 is adequate to address the new 30-second OEI and 2-minute

OEI ratings.

Section 33.27 Turbine, Compressor, Fan and Turbosupercharger Rotors

Several commenters state that proposed revisions to Sec. 33.27,

rotor integrity, are not consistent with the status of the discussions

on rotor integrity requirements currently ongoing in an ARAC working

group.

The FAA agrees that proposed Sec. 33.27 is not harmonized with JAR-

E. The proposed revision to Sec. 33.27 has been

[[Page 31326]]

removed from the Final rule as the proposal has not been completely

harmonized by the FAA (part 33) and the JAA (JAR-E). However, the FAA

will consider additional amendments to Sec. 33.27, and ARAC

harmonization is anticipated. In the interim the FAA will address each

application for type certification that requests 30-second OEI and 2-

minute OEI ratings on a case by case basis.

Section 33.29 Instrument Connection

One commenter states that Sec. 29.1305(a)(24) requires an

indication to the pilot when the use of OEI rating begins and when the

allowed time of this rating has expired, and the proposed 33.29(c)(1)

should have consistent requirements.

The FAA agrees. New Sec. 33.29(c)(1) is changed accordingly. In

addition, new Sec. 33.29(c)(3) is changed to clarify the FAA's intent

to require that each usage of a power level at one of the new OEI

ratings is limited in duration. Therefore, for example, as the

definition of the rating provides, 30-second OEI power is limited to

three periods of use in any one flight following an engine failure, and

each period of use is limited to no more than 30 seconds. Unused time

from one period of use may not be accumulated for use during a

subsequent period. Accordingly, new Sec. 33.29(c)(3) is changed to

provide for a means to record each use and the duration of each use of

power at each rating.

Section 33.85 Calibration Tests

One commenter states that the reference in proposed Sec. 33.85(d)

to Secs. 33.87(f) (1) through (8) should read Sec. 33.87, because

paragraphs (1) through (8) of proposed Sec. 33.87(f) relate only to the

new 30-second OEI and 2-minute OEI ratings where proposed Sec. 33.85(d)

is also applicable to the 2\1/2\-minute OEI rating.

The FAA disagrees. New Sec. 33.85(d) is intended for 30-second OEI

and 2-minute OEI ratings only, and reference to the 2\1/2\-minute OEI

rating was accidentally included in the SNPRM. Therefore, the reference

to the 2\1/2\- minute OEI rating is removed from new Sec. 33.85(d).

Section 33.87 Endurance Test

One commenter questions whether, during the additional endurance

testing introduced by proposed Sec. 33.87 (f)(1) through (f)(8), at

least 100 percent of 30-second OEI and 2-minute OEI rated powers must

be produced during all such operations. The commenter states that it

appears to be the intent because Sec. 33.87(a)(3) remains applicable to

the proposed Sec. 33.87(f), yet the commenter states that 100 percent

power may only be required for the first sequence of proposed

Sec. 33.87(f), and not for all the sequences.

The FAA disagrees. The 100 percent rule of Sec. 33.87(a)(3) applies

to new Sec. 33.87(f) for all sequences; no exceptions are intended or

implied.

One commenter suggests the following for proposed Sec. 33.87 (f)(1)

through (f)(8):

1. The test sequence described by Sec. 33.87 (f)(1) through (f)(8)

would be required to be repeated eight times for a total time of not

less than 180 minutes and would be required to be conducted in a

prescribed sequence and without stopping during the 180 minutes total

test period.

2. The sequence during which the length of the particular test

condition defined by Sec. 33.87(f)(4) is increased to sixty-five

minutes would need to be re-defined as: ``except that during the fourth

or fifth test sequence this period shall be sixty-five minutes.''

The FAA disagrees. The two hour supplementary test is to simulate a

flight scenario using 30-second and 2-minute OEI ratings. After the

initial 30-second and 2-minute applications to complete the takeoff or

effect a rejected takeoff and the climb out to a safe altitude and

airspeed, the engine is run at the 30-minute or continuous OEI rating

power to maintain a safe altitude enroute and to complete a landing of

the aircraft. The two hour cyclic test defined in this section

demonstrates the ability of the engine to complete a safe flight with

up to three applications of the 30-second and 2-minute OEI ratings

during one flight. The proposed changes from the commenter are not

supported by reasonable technical justification.

Section 33.88 Engine Overtemperature Test

One commenter suggests that the words ``steady state'' be inserted

before the words ``power-on r.p.m.'' in proposed Sec. 33.88(c). The

commenter states that the words are necessary since the test is

conducted at maximum steady state rpm limit rather than maximum

transient rpm limit. In addition, the proposed change to ``steady

state'' rpm limit and to the post test acceptance criteria is also

applicable to engines not having automatic temperature limiting which

are tested at 75 deg.F above the maximum temperature limit.

The FAA disagrees. The overtemperature condition associated with

usage of the 30-second OEI rating is normally expected from over-

fueling and consequently is accompanied by an excess rpm, not a steady

state level associated with a non-overtemperature or a non-overboost

condition.

One commenter states that use of the words ``provides an exception

from the existing requirements'' in the preamble for Proposal No. 10 of

NPRM 89-27, published September 22, 1989, concerning proposed

Sec. 33.88, could be misconstrued, and that it would have been better

to state `` * * * provides for an alleviation from the rotational speed

and the gas temperature prescribed by the existing requirements* * *.''

The FAA disagrees. The commenter does not suggest any changes to

proposed Sec. 33.88 and the editorial comment addresses the wording

preference in the preamble only.

One commenter states that the last sentence of proposed

Sec. 33.88(c) should read as follows: ``Following this run, the turbine

assembly may exceed serviceable limits, provided there is no evidence

of imminent failure. The applicant may be required to show there is no

evidence of imminent failure by analysis or test''. Another commenter

states that current JAR-E has no direct equivalent to the 5 minute

tests of either the existing Sec. 33.88 or proposed Sec. 33.88(a).

Proposed Sec. 33.88 (b) and (c), which make provision for 5 minute or 4

minute over-temperature test for 30-second OEI ratings, will be

considered by the JAA as a possible basis for a revision to JAR-E.

However, this will be in addition to complying with the existing

turbine rotor overtemperature requirement of JAR-E, C4-6, paragraph 22.

The commenter also suggests that proposed Sec. 33.88 (b) and (c) should

include a requirement that the worst case intended flight profile must

be assumed to include at least a further two applications of 30-second

OEI power, each followed by an application of 2 minute OEI power for

consistency of interpretation and compatibility with usage rational for

these particular OEI ratings, as stated in the ``Background'' of NPRM

89-27.

The FAA disagrees. The intent of the post-test requirements is to

assure that after the overtemperature test, the engine is suitable for

continued service use to complete the worst case intended flight

profile associated with the application of the 30-second OEI power

rating. Although the worst case scenario may include at lease two

additional applications of both 30-second OEI power and 2-minute OEI

power, the last sentence of revised Sec. 33.88(b) and revised

Sec. 33.88(c) will permit the FAA, on a case by case assessment, to

apply the best engineering judgment for each given engine type design

tested.

[[Page 31327]]

Two commenters state that the FAA is proposing a certification

standard for rotorcraft engines with a temperature limiter that differs

from the standard for all other type engines. The commenters conclude

that if a temperature limiter principle is acceptable for rotorcraft

engines, it should also be acceptable for other gas turbine engines and

for other engine ratings. Therefore, the proposal should be changed to

apply generally and not just to 30-second and 2-minute OEI ratings.

The FAA disagrees. The FAA considers that this comment is beyond

the scope of this rulemaking, which addresses only certification

standards for rotorcraft engines. The FAA may consider further

rulemaking to revise Sec. 33.88 for other gas turbine engine

certifications.

One commenter states that the overtemperature subject has been

incorporated into the harmonization effort and requests that the FAA

clearly indicate the intent to harmonize certification standards

related to overtemperature.

The FAA agrees. The FAA will continue to support the ongoing

harmonization effort toward the overtemperature test rule with the JAA

through the ARAC. However, the proposed overtemperature test

requirements in the SNPRM for 30-second and 2-minute OEI ratings are

published as an addition to the existing rule based on the comments

received. It is anticipated that the ARAC will recommend the adoption

of the overtemperature test for these new ratings in their draft

proposals.

Section 33.90 Initial Maintenance Inspection

One commenter suggests that the interpretation of the current

Sec. 33.90 needs to clearly define the requirements in that section for

engines that incorporate the new OEI rated power levels, and that an

advisory circular must be published together with this Final rule.

The FAA disagrees. The FAA should not delay publication of this

Final rule pending the development of new advisory material. The FAA

plans to issue to the advisory material as soon as practical.

Section 33.93 Teardown Inspection

One commenter states that in proposed Sec. 33.93, there is an

``and'' which they believe should be an ``or'' in the first sentence of

proposed Sec. 33.93(c), so that the fifth and sixth lines would read:

``the endurance testing of Sec. 33.87 (b) or (c) or (d) or (e) or this

part and followed * * *''. This change is needed because proposed

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. The changes to revised Sec. 33.93 are made.

Regulatory Evaluation Summary

Changes to the federal regulations must undergo several economic

analyses. First, Executive Order 12866 directs Federal agencies to

promulgate new regulations or modify existing regulations only if the

potential benefits to society outweigh the potential costs. Second, the

Regulatory Flexibility Act of 1980 requires agencies to analyze the

economic impact of regulatory changes on small entities. Finally, the

Office of Management and Budget directs agencies to assess the effects

of regulatory changes on international trade. In conducting these

assessments, the FAA has determined that this rule: (1) Will generate

benefits exceeding its costs and is not ``significant'' as defined in

Executive Order 12866; (2) is not ``significant'' as defined in DOT's

Policies and Procedures; (3) will not have a significant impact on a

substantial number of small entities; and (4) will not restrain

international trade. These analyses are available in the docket.

The new OEI power ratings will afford rotorcraft manufacturers the

opportunity to install higher rated engines in their products. The

principal operational benefits will be the ability to carry higher

payloads from existing fields or to takeoff from smaller fields with

current payloads, which should enable more Category B operators to use

their rotorcraft for Category A operations, and also increase the

potential for all operators to use more efficient and profitable

routes.

The testing costs associated with obtaining these ratings should be

viewed as the price of an additional capability and would be evaluated

by the manufacturer based on market potential. It is not possible to

quantify the extent of the net operational benefits that will be

realized by the operators because the number of products that will be

certificated to this standard cannot be predicted. The FAA is able to

conclude, however, that the rule will not have a negative economic

impact on manufacturers or operators. Because these are optional

ratings, manufacturers will provide this capability only if the

additional costs can be recovered in the marketplace.

Safety after an engine failure under the provisions of this rule

will be as test equivalent to operational safety under the previous

regulations. This assessment is based on the requirement for an engine

inspection following one mission cycle of either the 30-second or 2-

minute OEI power levels. All engine parts that may not be suitable for

further use must be discarded and replaced in order to maintain the

continued airworthiness of the engine. The existing minimum level of

engine airworthiness will be maintained under this rule by virtue of

new and existing design, analysis, and test certification requirements.

In summary, the FAA finds that the benefits of this rule will exceed

the costs.

International Trade Impact Analysis

These rule changes will have little or no impact on trade for both

U.S. firms doing business in foreign countries and foreign firms doing

business in the United States. In the U.S. market, foreign

manufacturers will have the option of designing engines and helicopters

capable of satisfying the new OEI ratings and therefore will not be at

a competitive disadvantage with U.S. manufacturers. Because of the

large U.S. market, foreign manufacturers are likely to certify their

rotorcraft to U.S. rules, which will limit any competitive advantage

U.S. manufacturers might gain in foreign markets.

Regulatory Flexibility Determination

The Regulatory Flexibility Act of 1980 (RFA) was enacted by

Congress to ensure that small entities are not unnecessarily or

disproportionately burdened by Government regulations. The RFA requires

a Regulatory Flexibility Analysis if a rule would have a significant

economic impact, either detrimental or beneficial, on a substantial

number of small entities. FAA order 2100.14A, Regulatory Flexibility

Criteria and Guidance, establishes threshold cost values and small

entity size standards for complying with RFA review requirements in FAA

rulemaking actions. A review of domestic engine manufacturers indicates

that none meets the minimum size threshold. As such, the FAA has

determined that this rule will not have significant economic impact on

a substantial number of small entities.

Federalism Implications

The regulations adopted herein will 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

[[Page 31328]]

responsibilities among the various levels of government. Therefore, in

accordance with Executive Order 12612, it is determined that this

regulation does not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

Conclusion

For the reasons discussed in the preamble, and based on the

findings in the Regulatory Flexibility Determination and the

International Trade Impact Analysis, the FAA has determined that this

regulation is not a significant regulatory action under Executive Order

12866. In addition, the FAA certifies that these amendments do not have

a significant economic impact, positive or negative, on a substantial

number of small entities under the criteria of the Regulatory

Flexibility Act. These amendments are considered nonsignificant under

DOT Regulatory Policies and Procedures (44 FR 11034, February 26,

1979). A regulatory evaluation of the amendments, including a

Regulatory Flexibility Determination and Trade Impact Analysis, has

been placed in the docket. A copy may be obtained by contacting the

person identified under 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, Ratings.

14 CFR Part 33

Engines, Rotorcraft, Air Transportation, Aircraft, Aviation safety,

Safety.

Adoption of the Amendments

Accordingly, The Federal Aviation Administration (FAA) amends 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 106(g), 40113, 44701.

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 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. 106(g), 40113, 44701, 44702, 44704.

4. Section 33.7 is amended by redesignating paragraph (c)(1)(viii)

as (c)(1)(x); by revising newly redesignated (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

(x) Auxiliary power unit (APU) mode of operation.

* * * * *

5. Section 33.29 is amended by adding new paragraph (c) as follows:

Sec. 33.29 Instrument connection.

* * * * *

(c) Each rotorcraft turbine engine having a 30-second OEI rating

and a 2-minute OEI 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, when the event begins, and when the time

interval expires;

(2) Determine, in a positive manner, that the engine has been

operated at each rating; and

(3) Automatically record each usage and duration of power at each

rating.

6. Section 33.67 is amended by adding new paragraph (d) 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 a 30-second OEI

power.

7. Section 33.85 is amended by adding new paragraphs (c) and (d) 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, and 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.

8. 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), (e) or (g) 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

[[Page 31329]]

(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

the 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:

(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 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. One minute at idle.

* * * * *

9. 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 rating 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.

10. 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) of this part, 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 Secs. 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 May 30, 1996.

David R. Hinson,

Administrator.

[FR Doc. 96-14083 Filed 6-18-96; 8:45 am]

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