[Federal Register Volume 59, Number 179 (Friday, September 16, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-22970]


[[Page Unknown]]

[Federal Register: September 16, 1994]


_______________________________________________________________________

Part IV





Department of Transportation





_______________________________________________________________________



Federal Aviation Administration



_______________________________________________________________________



14 CFR Parts 27 and 29




Airworthiness Standards; New Rotorcraft 30-Second/2-Minute One-Engine-
Inoperative Power Ratings; Final Rule
DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 27 and 29

[Docket No. 26018, Amdts. 27-29 and 29-34]
RIN 2120-AB90

 
Airworthiness Standards; New Rotorcraft 30-Second/2-Minute One-
Engine-Inoperative Power Ratings

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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

SUMMARY: This rule adopts new and revised airworthiness standards by 
incorporating optional one-engine-inoperative (OEI) power ratings for 
multiengine, turbine-powered rotorcraft. These amendments result from a 
petition for rulemaking from Aerospace Industries Association of 
America (AIA) and the recognition by both government and industry that 
additional OEI power rating standards are needed. These amendments 
enhance rotorcraft safety after an engine failure or precautionary 
shutdown by providing higher OEI power, when necessary. These 
amendments also assure that the drive system will maintain its 
structural integrity and allow continued safe flight while operating at 
the new OEI power ratings with the operable engine(s).

EFFECTIVE DATE: October 17, 1994.

FOR FURTHER INFORMATION CONTACT:
Mr. Scott Horn, Rotorcraft Standards Staff, FAA, Fort Worth, Texas 
76193-0112, telephone number (817) 222-5125.

SUPPLEMENTARY INFORMATION:

Background

    By letter dated September 20, 1984, the AIA petitioned for 
rulemaking by requesting amendments to Parts 1, 27, 29, and 33 of the 
Federal Aviation Regulations (FAR) to establish new 30-second, 2-
minute, and continuous OEI power ratings.
    In the process of drafting the amendments, numerous meetings were 
held with the industry groups and airworthiness authorities of other 
countries in an attempt to identify and address all of the issues. As 
set forth in the AIA's petition, only multiengine rotorcraft, with 
turbine-powered engines, would be eligible for these new OEI power 
ratings which would be applicable to the remaining engine(s) only after 
an in-flight failure or precautionary engine shutdown. The rated 30-
second OEI power would be limited to periods of not more than 30 
seconds at any one time and would enhance the OEI performance of the 
rotorcraft during the transient phase of the takeoff and landing 
maneuvers. The rated 2-minute OEI power would be limited to periods of 
not more than 2 minutes at any one time and would achieve initial 
stabilized climb of at least 100 feet per minute following takeoff or 
balked landing flight with one engine inoperative. These ratings could 
be used instead of the existing 2\1/2\-minute OEI power rating or 
normal takeoff power.
    The continuous OEI power rating and all aspects of its definition, 
eligibility, qualification, and performance credit were adopted in 
Amendments 1-34, 27-23, 29-26, and 33-12, Rotorcraft Regulatory Review 
Program Amendment No. 3 (53 FR 34198, September 2, 1988).
    This final rule is based on Notice of Proposed Rulemaking (NPRM) 
No. 89-26 that was published in the Federal Register on September 22, 
1989 (54 FR 39086). A corresponding NPRM, Notice No. 89-27, that 
proposed changes to parts 1 and 33 for definitions and engines was also 
published in the same issue of the Federal Register (54 FR 39080). In 
addition, a joint public meeting was held on November 16, 1989, in 
Forth Worth, Texas, to discuss both notices (54 FR 41986).
    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. The changes are based on comments received and 
further FAA review of the proposals. Except as indicated herein, the 
proposals contained in the notice have been adopted without change.

Discussion of Comments

    The commenters represented airframe manufacturers, airworthiness 
authorities from other countries, rotorcraft owners and operators, and 
private individuals. The commenters generally agree with the substance 
of the proposal with certain recommended changes. The following 
discussion addresses these recommendations and their disposition.

Sections 27.923 and 29.923  Rotor Drive System and Control Mechanism 
Tests

    The notice proposed changes to Secs. 27.923(e) and 29.923 (a) and 
(b) that add the special tests to the rotor drive system endurance test 
schedule, which are necessary to qualify the rotor drive system for the 
new 30-second/2-minute OEI power ratings.
    One commenter, referring to Secs. 27.923(e)(2)(i) and 
29.923(e)(3)(i), states that if the 5-minute takeoff power run to 
qualify the drive system is conducted as part of the endurance run, and 
the 30-second/2-minute OEI requirements are conducted on a bench test, 
then the takeoff power 5-minute run will be conducted twice on the same 
set of gears. The commenter proposes that the wording for the bench 
testing requirements be changed to state ``* * * following 
stabilization at takeoff power.'' The FAA does not intend to duplicate 
the takeoff power 5-minute run and agrees that clarification is needed; 
therefore, the recommended change has been incorporated.
    Another commenter recommends doubling the test time in 
Sec. 29.923(b)(3)(i) because the drive system, at the higher and 
potentially more damaging 30-second/2-minute OEI power ratings, will be 
substantiated by less endurance testing at these new powers. This 
recommendation is beyond the scope of the notice. Further, the FAA 
disagrees with the recommendation to double the test time for drive 
system substantiation because the test time proposed for the new 30-
second/2-minute OEI power ratings is more severe than the current OEI 
ratings, when considering expected usage. The test time was established 
based upon the proportionate duration of load applications during these 
test runs when compared with the expected service life of the rotor 
drive system. In addition, the test time was also based upon the 
statistical failure rate of turboshaft engines and three applications 
of 30-second/2-minute OEI power during the expected life of the drive 
system. The relationship between test time and anticipated OEI exposure 
in service is more severe by a factor of 2.64 for the new OEI ratings.
    Another commenter proposes removing the words `` * * * when engine 
limitations either preclude repeated use of this power or would result 
in premature engine removal * * *'' from Secs. 27.923(e)(2)(iii) and 
29.923(b)(3)(iii). The FAA disagrees because the preferred method of 
conducting the tests is on the rotorcraft where the entire drive system 
is subjected to the OEI powers. Since the FAA recognizes that in some 
cases it may not be possible to conduct these tests on the rotorcraft, 
a bench test, which is representative of the aircraft, is included as 
an acceptable alternative.
    Another commenter proposes to clarify Secs. 27.923(e)(2)(iii) and 
29.923(b)(3)(iii) by inserting the word ``vibration'' between the words 
``the'' and ``frequency.'' The FAA agrees, and the change has been 
made.
    Other than some minor editorial changes, these amendments are 
adopted as discussed.

Sections 27.1143 and 29.1143  Engine Controls

    The notice proposed to include the requirement for automatic 
control of the 30-second OEI power in Secs. 27.1143(e) and 29.1143(f). 
One commenter suggests that Sec. 29.1143(f) is ambiguous in that it 
does not adequately define the meaning of ``control.'' The FAA agrees 
that additional clarification is necessary. The amendment now states 
``* * * automatically activate and control the 30-second OEI power and 
prevent * * *.'' Other than this clarification, the amendments are 
adopted as proposed.

Sections 27.1305 and 29.1305  Powerplant Instruments

    The notice proposed to include the requirements for a pilot alert 
and a recording device when 30-second/2-minute OEI powers are used by 
adding paragraphs (t) and (u) to Sec. 27.1305 and paragraphs (a) (24) 
and (25) to Sec. 29.1305.
    One commenter proposes to add the words ``* * * for use by ground 
personnel * * *'' between the words ``provided'' and ``which'' in 
Secs. 27.1305(u) and 29.1305(a)(25). The FAA agrees, and the change has 
been made.
    Another commenter states that because of the number of warnings 
being introduced by Sec. 29.1305(a)(24), some guidance material is 
needed. The FAA agrees and will address these concerns with forthcoming 
advisory material.
    A third commenter suggests adding the word ``automatically'' before 
the word ``records'' in Sec. 29.1305(a)(25)(i). The FAA agrees, and the 
amendments are adopted with the changes.

Sections 27.1521 and 29.1521  Powerplant Limitations

    The notice proposed to add paragraphs (j) and (k) to Sec. 27.1521 
and paragraphs (i) and (j) to Sec. 29.1521 to include the 30-second/2-
minute OEI power limitations, along with rotorcraft applicability and 
the conditions for their use. One commenter supports this proposal if 
the amendments to Parts 1 and 33 ensure mandatory maintenance of the 
engine following use of the 30-second OEI power rating. In addition, 
the commenter further states that the transmission and gearbox should 
not be subject to mandatory maintenance. The testing requirements 
proposed in Secs. 27.923 and 29.923 for the 30-second/2-minute OEI 
power ratings will minimize the need for mandatory maintenance of the 
transmission and gearbox following application of the 30-second/2-
minute OEI power in service. The amendments, which concern the airframe 
requirements, are adopted without change.

Sections 27.1549 and 29.1549  Powerplant Instruments

    The notice proposed to revise Secs. 27.1549(e) and 29.1549(e) by 
defining the instrument markings associated with the 30-second/2-minute 
OEI power ratings. One commenter supports the proposal and suggests 
that some guidance material is needed. The FAA agrees, and guidance 
material will be developed. These amendments are adopted as proposed.

Section 29.67  Climb: One Engine Inoperative

    The notice proposed to revise paragraph (a)(1)(i) to specify that 
for rotorcraft certificated for the 30-second/2-minute OEI power, only 
2-minute OEI power may be used to comply with the 100-foot-per-minute 
rate of climb required by this section.
    One commenter supports the proposal. Another comment concerns 
paragraphs (a)(2) and (b), which are not changed by this rulemaking. It 
is noted that OEI climb performance required by the current rules can 
be determined by using either 30-minute or continuous OEI power. There 
are no restrictions on which long duration OEI power rating may be used 
with the short duration 30-second/2-minute OEI power ratings. OEI climb 
performance will be based upon the highest long duration OEI power for 
which certification is requested.
    The amendment is adopted without change.

Additional Discussion

Training

    Although outside the scope of this rulemaking, the FAA has 
recognized the need for additional training for flight crewmembers in 
the correct procedures and use of these new OEI power ratings. A 
commenter notes that the use of these new ratings could result in 
serious damage to the operating engine and that additional training 
must be available to satisfy the operational and airworthiness needs. 
The FAA agrees, and these training procedures will be considered by 
operations specialists during the certification process.

Power Assurance

    A commenter notes that power assurance requirements, as given in 
Secs. 27.45(f) and 29.45(f), will be affected by these amendments and 
recommends the issuance of guidance material. The FAA recognizes the 
importance of the power assurance requirement for approval and use of 
these new OEI power ratings, and appropriate guidance material will be 
developed.

Limiting Height-Speed Envelope

    One commenter asks whether the 30-second power is the ``greatest 
power for which certification is requested'' as currently contained in 
Secs. 27.79(b)(2) and 29.79(b)(1). For these amendments, 30-second 
power is the greatest power for which certification could be 
accomplished.

Airworthiness Limitations Section

    One commenter addressed the need for changes to Appendix A33.4, 
Airworthiness Limitations Section. Since this comment addresses part 
33, it will be handled in the rulemaking effort underway addressing 
that part.

Regulatory Evaluation Summary

Regulatory Evaluation

    This section summarizes the full regulatory evaluation prepared by 
the FAA that provides more detailed estimates of the economic 
consequences of this regulatory action. This summary and the full 
evaluation quantify, to the extent practicable, estimated costs to the 
private sector, consumers, and Federal, State and local governments, as 
well as anticipated benefits.
    Executive Order 12866 dated September 30, 1993, directs Federal 
agencies to promulgate new regulations and maintain current regulations 
only if they are required by law, are necessary to interpret the law, 
or are made necessary by a ``compelling public need.'' The order also 
requires that agencies assess all costs and benefits of available 
regulatory alternatives and select the alternative that maximizes the 
net benefits and imposes the least burden on society.
    Additionally, the order requires agencies to submit a list of all 
rules, except those specifically exempted by the Office of Information 
and Regulatory Affairs (OIRA) because they respond to emergency 
situations or other narrowly defined exigencies, to determine if the 
rules constitute ``significant regulatory action.'' ``Significant 
regulatory action'' means an action that is likely to result in a rule 
that may (1) have an annual effect on the economy of $100 million or 
more or adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or state, local, or tribal governments or 
communities; (2) create a serious inconsistency or otherwise interfere 
with an action taken or planned by another agency; (3) materially alter 
the budgetary impact of entitlements, grants, user fees, or loan 
programs or the rights and obligations of recipients thereof; or (4) 
raise novel legal or policy issues arising out of legal mandates, the 
President's priorities, or the principles set forth in the Executive 
Order. ``Significant regulatory action'' is submitted to centralized 
regulatory review by OIRA.
    OIRA and the FAA have determined that this rule is not ``a 
significant regulatory action.'' However, a cost-benefit analysis, 
including evaluation of cost-reducing alternatives to this rule has 
been prepared. This analysis also contains the regulatory flexibility 
determination required by the Regulatory Flexibility Act and a Trade 
Impact Assessment. If more detailed economic information is desired, 
the reader may refer to the full evaluation contained in the docket.

Economic Evaluation

    The use of the new optional rating structure will provide 
significant benefits to operators of Category A helicopters. Category A 
helicopters are multiengine, can withstand any single engine becoming 
inoperative, and can continue safe flight or landing within a 
demonstrated field size. In addition to increased payloads, the 
amendments will enable rotorcraft operators to operate from 
significantly smaller heliports with the same degree of safety because 
of the decrease in the minimum required rejected takeoff distance for 
Category A operations. The rejected takeoff distance is the distance 
from the start of the takeoff to the stopping point after landing. The 
current regulation puts operators using shorter fields at a 
disadvantage because of the inability to satisfy Category A operational 
requirements. This increased operational flexibility should enable them 
to fly Category A operations and possibly use more efficient and 
profitable route structures (where larger fields are not available).
    The rule establishes OEI ratings for periods of shorter duration 
than previously allowed and will provide an additional optional 
capability to manufacturers. The testing costs associated with 
obtaining these ratings should be viewed as the price of an additional 
capability and will be evaluated by the individual rotorcraft 
manufacturers based on market potential. The principal operational 
benefit of these new optional ratings is the ability to carry higher 
payloads from existing fields or to takeoff from smaller fields with 
current payloads. The AIA estimates that the use of the new rating 
structure for a given Category A mission could result in an increase in 
productivity of 48 percent for a 37,000-pound design gross weight (DGW) 
helicopter, and up to 125 percent for a 7,500-pound DGW helicopter if 
operators who fly only Category A missions choose to take full 
advantage of the increase in payload that will be permitted. The AIA 
further notes that the public will also benefit from these changes 
because the availability of viable, short-field performance should 
encourage the development of downtown heliports, thereby enhancing 
convenience.
    For a manufacturer considering a new design, the issue of whether 
to design a helicopter to accommodate engines capable of satisfying the 
new OEI rating scheme (use of the new ratings will affect helicopter 
performance standards as well as the structural and drive system 
requirements) will be influenced by the following factors:
     The availability of appropriately sized engines (larger 
helicopters designed for Category A use will be able to use a smaller 
engine).
     The OEI capability of competitive products.
     The operator mission requirements.
     The cost (for increased testing and increased engine 
performance) of obtaining the new OEI capability compared to the 
benefit derived from the increase in payload or flexibility of route 
structures afforded by this capability.
    The availability of the new OEI capability could provide 
substantial benefits to rotorcraft manufacturers and operators. 
However, such benefits are difficult to quantify because the number of 
products certificated to this standard cannot be estimated. In 
addition, the specific increase in dispatch payload cannot be estimated 
because it will depend on the specific rotorcraft design in relation to 
the engines that will be available. These optional ratings should 
enhance the ability of operators who are limited by current regulations 
to Category B operations, because of the small size fields they use to 
fly more Category A operations, which should improve their 
profitability. The extent of these benefits cannot be predicted since 
they will depend, to a large degree, on the mix of Category A and B 
operations that are chosen. The FAA has not been able to quantify these 
potential benefits either on a per-unit or industry-wide scale due to 
the changes in rotorcraft design and performance that these optional 
ratings could promote and the large number of highly variable factors 
that would influence the magnitude of the overall benefits. The FAA 
concludes that the optional OEI ratings will not have a negative impact 
on manufacturers or operators. Since these ratings are optional, 
manufacturers will provide this capability only if the additional costs 
can be recovered in the market place.
    The FAA maintains that, after an engine failure under the revised 
regulations for limited-use ratings, safety will be at least equivalent 
to operational safety under the previous regulations. This condition is 
supported by the fact that these 30-second and 2-minute OEI ratings are 
``limited use/mandatory inspection ratings.'' Following one mission 
cycle of rating use, specific requirements for inspection will have to 
be met to verify continued airworthiness of the engine. Under current 
regulations, there is no requirement for an inspection following an OEI 
power application. Any rotorcraft parts found to be unsuitable for 
further use must be replaced after application of these ratings. As a 
result of new test and analysis requirements, a high level of safety 
will be maintained.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) was enacted by 
Congress to ensure that small entities are not unnecessarily and 
disproportionately burdened by government regulations. The RFA requires 
agencies to review rules that may have ``a significant economic impact 
on a substantial number of small entities.'' The FAA's criteria for a 
small aircraft manufacturer is one employing fewer than 75 employees. A 
substantial number is a number that is not fewer than 11 and is more 
than one-third of the small entities subject to the rule. A significant 
impact is one having an annual cost of more than $14,900 (1987 dollars) 
per manufacturer.
    A review of domestic helicopter manufacturing companies indicates 
that there are fewer than eleven small helicopter manufacturers. 
Therefore, the amendments to Parts 27 and 29 will not affect a 
substantial number of small entities.

Trade Impact Analysis

    The 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 certificate 
their rotorcraft to U.S. rules, which will limit any competitive 
advantage U.S. manufacturers might gain in foreign markets.

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 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule 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 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 CFR 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 in 14 CFR Parts 27 and 29

    Air transportation, Aircraft, Aviation safety, Rotorcraft, Safety.

Adoption of the Amendments

    Accordingly, Parts 27 and 29 of the Federal Aviation Regulations 
(14 CFR Parts 27 and 29) are amended as follows:

PART 27--AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT

    1. The authority citation for Part 27 continues to read as follows:

    Authority: 49 U.S.C. 1344, 1354(a), 1355, 1421, 1423, 1425, 
1428, 1429, and 1430; 49 U.S.C. 106(g).

    2. Section 27.923 is amended by revising paragraph (e) to read as 
follows:


Sec. 27.923  Rotor drive system and control mechanism tests.

* * * * *
    (e) A 10-hour part of the test prescribed in paragraph (b) of this 
section must be run at not less than takeoff torque and the maximum 
speed for use with takeoff torque. The main and auxiliary rotor 
controls must be in the normal position for vertical ascent.
    (1) For multiengine rotorcraft for which the use of 2\1/2\ minute 
OEI power is requested, 12 runs during the 10-hour test must be 
conducted as follows:
    (i) Each run must consist of at least one period of 2\1/2\ minutes 
with takeoff torque and the maximum speed for use with takeoff torque 
on all engines.
    (ii) Each run must consist of at least one period for each engine 
in sequence, during which that engine simulates a power failure and the 
remaining engines are run at 2\1/2\ minute OEI torque and the maximum 
speed for use with 2\1/2\ minute OEI torque for 2\1/2\ minutes.
    (2) For multiengine turbine-powered rotorcraft for which the use of 
30-second and 2-minute OEI power is requested, 10 runs must be 
conducted as follows:
    (i) Immediately following a takeoff run of at least 5 minutes, each 
power source must simulate a failure, in turn, and apply the maximum 
torque and the maximum speed for use with 30-second OEI power to the 
remaining affected drive system power inputs for not less than 30 
seconds, followed by application of the maximum torque and the maximum 
speed for use with 2-minute OEI power for not less than 2 minutes. At 
least one run sequence must be conducted from a simulated ``flight 
idle'' condition. When conducted on a bench test, the test sequence 
must be conducted following stabilization at takeoff power.
    (ii) For the purpose of this paragraph, an affected power input 
includes all parts of the rotor drive system which can be adversely 
affected by the application of higher or asymmetric torque and speed 
prescribed by the test.
    (iii) This test may be conducted on a representative bench test 
facility when engine limitations either preclude repeated use of this 
power or would result in premature engine removal during the test. The 
loads, the vibration frequency, and the methods of application to the 
affected rotor drive system components must be representative of 
rotorcraft conditions. Test components must be those used to show 
compliance with the remainder of this section.
* * * * *
    3. Section 27.1143 is amended by adding paragraph (e) to read as 
follows:


Sec. 27.1143  Engine controls.

* * * * *
    (e) For rotorcraft to be certificated for a 30-second OEI power 
rating, a means must be provided to automatically activate and control 
the 30-second OEI power and prevent any engine from exceeding the 
installed engine limits associated with the 30-second OEI power rating 
approved for the rotorcraft.
    4. Section 27.1305 is amended by adding paragraphs (t) and (u) to 
read as follows:


Sec. 27.1305  Powerplant instruments.

* * * * *
    (t) For rotorcraft for which a 30-second/2-minute OEI power rating 
is requested, a means must be provided to alert the pilot when the 
engine is at the 30-second and the 2-minute OEI power levels, when the 
event begins, and when the time interval expires.
    (u) For each turbine engine utilizing 30-second/2-minute OEI power, 
a device or system must be provided for use by ground personnel which--
    (1) Automatically records each usage and duration of power at the 
30-second and 2-minute OEI levels;
    (2) Permits retrieval of the recorded data;
    (3) Can be reset only by ground maintenance personnel; and
    (4) Has a means to verify proper operation of the system or device.
    5. Section 27.1521 is amended by adding paragraphs (j) and (k) to 
read as follows:


Sec. 27.1521  Powerplant limitations.

* * * * *
    (j) Rated 30-second OEI power operation. Rated 30-second OEI power 
is permitted only on multiengine, turbine-powered rotorcraft, also 
certificated for the use of rated 2-minute OEI power, and can only be 
used for continued operation of the remaining engine(s) after a failure 
or precautionary shutdown of an engine. It must be shown that following 
application of 30-second OEI power, any damage will be readily 
detectable by the applicable inspections and other related procedures 
furnished in accordance with Section A27.4 of Appendix A of this part 
and Section A33.4 of Appendix A of part 33. The use of 30-second OEI 
power must be limited to not more than 30 seconds for any period in 
which that power is used, and by--
    (1) The maximum rotational speed, which may not be greater than--
    (i) The maximum value determined by the rotor design; or
    (ii) The maximum value demonstrated during the type tests;
    (2) The maximum allowable gas temperature; and
    (3) The maximum allowable torque.
    (k) Rated 2-minute OEI power operation. Rated 2-minute OEI power is 
permitted only on multiengine, turbine-powered rotorcraft, also 
certificated for the use of rated 30-second OEI power, and can only be 
used for continued operation of the remaining engine(s) after a failure 
or precautionary shutdown of an engine. It must be shown that following 
application of 2-minute OEI power, any damage will be readily 
detectable by the applicable inspections and other related procedures 
furnished in accordance with Section A27.4 of Appendix A of this part 
and Section A33.4 of Appendix A of part 33. The use of 2-minute OEI 
power must be limited to not more than 2 minutes for any period in 
which that power is used, and by--
    (1) The maximum rotational speed, which may not be greater than--
    (i) The maximum value determined by the rotor design; or
    (ii) The maximum value demonstrated during the type tests;
    (2) The maximum allowable gas temperature; and
    (3) The maximum allowable torque.
    6. Section 27.1549 is amended by revising paragraph (e) to read as 
follows:


Sec. 27.1549  Powerplant instruments.

* * * * *
    (e) Each OEI limit or approved operating range must be marked to be 
clearly differentiated from the markings of paragraphs (a) through (d) 
of this section except that no marking is normally required for the 30-
second OEI limit.

PART 29--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT

    7. The authority citation for Part 29 continues to read as follows:

    Authority: 49 U.S.C. 1344, 1354(a), 1355, 1421, 1423, 1424, 
1425, 1428, 1429, and 1430; 49 U.S.C. 106(g).

    8. Section 29.67 is amended by revising paragraph (a)(1)(i) to read 
as follows:


Sec. 29.67  Climb: one engine inoperative.

    (a) * * *
    (1) * * *
    (i) The critical engine inoperative and the remaining engines 
within approved operating limitations, except that for rotorcraft for 
which the use of 30-second/2-minute OEI power is requested, only the 2-
minute OEI power may be used in showing compliance with this paragraph;
* * * * *
    9. Section 29.923 is amended by revising paragraphs (a) 
introductory text and (b)(1); and by adding paragraph (b)(3) to read as 
follows:


Sec. 29.923   Rotor drive system and control mechanism tests.

    (a) Endurance tests, general. Each rotor drive system and rotor 
control mechanism must be tested, as prescribed in paragraphs (b) 
through (n) of this section, for at least 200 hours plus the time 
required to meet the requirements of paragraphs (b)(2), (b)(3), and (k) 
of this section. These tests must be conducted as follows:
* * * * *
    (b) * * *
    (1) Except as prescribed in paragraphs (b)(2) and (b)(3) of this 
section, the takeoff torque run must consist of 1 hour of alternate 
runs of 5 minutes at takeoff torque and the maximum speed for use with 
takeoff torque, and 5 minutes at as low an engine idle speed as 
practicable. The engine must be declutched from the rotor drive system, 
and the rotor brake, if furnished and so intended, must be applied 
during the first minute of the idle run. During the remaining 4 minutes 
of the idle run, the clutch must be engaged so that the engine drives 
the rotors at the minimum practical r.p.m. The engine and the rotor 
drive system must be accelerated at the maximum rate. When declutching 
the engine, it must be decelerated rapidly enough to allow the 
operation of the overrunning clutch.
* * * * *
    (3) For multiengine, turbine-powered rotorcraft for which the use 
of 30-second/2-minute OEI power is requested, the takeoff run must be 
conducted as prescribed in paragraph (b)(1) of this section except for 
the following:
    (i) Immediately following any one 5-minute power-on run required by 
paragraph (b)(1) of this section, each power source must simulate a 
failure, in turn, and apply the maximum torque and the maximum speed 
for use with 30-second OEI power to the remaining affected drive system 
power inputs for not less than 30 seconds, followed by application of 
the maximum torque and the maximum speed for use with 2-minute OEI 
power for not less than 2 minutes. At least one run sequence must be 
conducted from a simulated ``flight idle'' condition. When conducted on 
a bench test, the test sequence must be conducted following 
stabilization at takeoff power.
    (ii) For the purpose of this paragraph, an affected power input 
includes all parts of the rotor drive system which can be adversely 
affected by the application of higher or asymmetric torque and speed 
prescribed by the test.
    (iii) This test may be conducted on a representative bench test 
facility when engine limitations either preclude repeated use of this 
power or would result in premature engine removals during the test. The 
loads, the vibration frequency, and the methods of application to the 
affected rotor drive system components must be representative of 
rotorcraft conditions. Test components must be those used to show 
compliance with the remainder of this section.
* * * * *
    10. Section 29.1143 is amended by adding paragraph (f) to read as 
follows:


Sec. 29.1143   Engine controls.

* * * * *
    (f) For rotorcraft to be certificated for a 30-second OEI power 
rating, a means must be provided to automatically activate and control 
the 30-second OEI power and prevent any engine from exceeding the 
installed engine limits associated with the 30-second OEI power rating 
approved for the rotorcraft.
    11. Section 29.1305 is amended by adding paragraphs (a)(24) and 
(25) to read as follows:


Sec. 29.1305   Powerplant instruments.

* * * * *
    (a) * * *
    (24) For rotorcraft for which a 30-second/2-minute OEI power rating 
is requested, a means must be provided to alert the pilot when the 
engine is at the 30-second and 2-minute OEI power levels, when the 
event begins, and when the time interval expires.
    (25) For each turbine engine utilizing 30-second/2-minute OEI 
power, a device or system must be provided for use by ground personnel 
which--
    (i) Automatically records each usage and duration of power at the 
30-second and 2-minute OEI levels;
    (ii) Permits retrieval of the recorded data;
    (iii) Can be reset only by ground maintenance personnel; and
    (iv) Has a means to verify proper operation of the system or 
device.
* * * * *
    12. Section 29.1521 is amended by adding paragraphs (i) and (j) to 
read as follows:


Sec. 29.1521  Powerplant limitations.

* * * * *
    (i) Rated 30-second OEI power operation. Rated 30-second OEI power 
is permitted only on multiengine, turbine-powered rotorcraft, also 
certificated for the use of rated 2-minute OEI power, and can only be 
used for continued operation of the remaining engine(s) after a failure 
or precautionary shutdown of an engine. It must be shown that following 
application of 30-second OEI power, any damage will be readily 
detectable by the applicable inspections and other related procedures 
furnished in accordance with Section A29.4 of Appendix A of this part 
and Section A33.4 of Appendix A of part 33. The use of 30-second OEI 
power must be limited to not more than 30 seconds for any period in 
which that power is used, and by--
    (1) The maximum rotational speed which may not be greater than--
    (i) The maximum value determined by the rotor design; or
    (ii) The maximum value demonstrated during the type tests;
    (2) The maximum allowable gas temperature; and
    (3) The maximum allowable torque.
    (j) Rated 2-minute OEI power operation. Rated 2-minute OEI power is 
permitted only on multiengine, turbine-powered rotorcraft, also 
certificated for the use of rated 30-second OEI power, and can only be 
used for continued operation of the remaining engine(s) after a failure 
or precautionary shutdown of an engine. It must be shown that following 
application of 2-minute OEI power, any damage will be readily 
detectable by the applicable inspections and other related procedures 
furnished in accordance with Section A29.4 of Appendix a of this part 
and Section A33.4 of Appendix A of part 33. The use of 2-minute OEI 
power must be limited to not more than 2 minutes for any period in 
which that power is used, and by--
    (1) The maximum rotational speed, which may not be greater than--
    (i) The maximum value determined by the rotor design; or
    (ii) The maximum value demonstrated during the type tests;
    (2) The maximum allowable gas temperature; and
    (3) The maximum allowable torque.
    13. Section 29.1549 is amended by revising paragraph (e) to read as 
follows:


Sec. 29.1549  Powerplant instruments.

* * * * *
    (e) Each OEI limit or approved operating range must be marked to be 
clearly differentiated from the markings of paragraphs (a) through (d) 
of this section except that no marking is normally required for the 30-
second OEI limit.

    Issued in Washington, D.C., on September 9, 1994.
David R. Hinson,
Administrator.
[FR Doc. 94-22970 Filed 9-15-94; 8:45 am]
BILLING CODE 4910-13-M