[Federal Register Volume 68, Number 114 (Friday, June 13, 2003)]
[Proposed Rules]
[Pages 35335-35345]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-14992]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM81; Notice No. 25-03-04-SC]


Special Conditions: Boeing Model 777 Series Airplanes; Revision 
to Special Conditions 25-ANM-84

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes to revise Special Conditions 25-ANM-84, 
applicable to Boeing Model 777 series airplanes. The proposed special 
conditions revise the extended range operations with two-engine 
airplanes (referred to as ``ETOPS'') test requirements defined in the 
existing special conditions. These revisions include changing the 
airplane demonstration test requirement from a required 1000 flight 
cycles to a demonstration of capability in ETOPS flight conditions, and 
allowing more than one airplane to be used for the airplane 
demonstration test. In addition, the FAA proposes to add post-test 
inspection requirements for both the engine demonstration test and the 
airplane demonstration test articles.

DATES: Comments must be received on or before July 28, 2003.

ADDRESSES: Comments on this proposal may be mailed in duplicate to: 
Federal Aviation Administration, Transport Airplane Directorate, 
Attention: Rules Docket (ANM-113), Docket No. NM81, 1601 Lind Avenue, 
SW., Renton, Washington, 98055-4056; or delivered in duplicate to the 
Transport Airplane Directorate at the above address. Comments must be 
marked: Docket No. NM81. Comments may be inspected in the Rules Docket 
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Steve Clark, FAA, ETOPS Project 
Manager, Seattle Aircraft Certification Office, Propulsion Branch, ANM-
140S, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington, 98055-4056; telephone (425) 917-6496; facsimile (425) 227-
1180.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    The FAA invites interested persons to participate in this 
rulemaking by submitting written comments, data, or views. The most 
helpful comments reference a specific portion of the special 
conditions, explain the reason for any recommended change, and include 
supporting data. We ask that you send us two copies of written 
comments.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning these special conditions. The docket is available for public 
inspection before and after the comment closing date. If you wish to 
review the docket in person, go to the address in the ADDRESSES section 
of this preamble between 7:30 a.m. and 4 p.m., Monday through Friday, 
except Federal holidays.
    We will consider all comments we receive on or before the closing 
date for comments. We will consider comments filed late if it is 
possible to do so without incurring expense or delay. We may change 
these special conditions in light of the comments we receive.
    If you want the FAA to acknowledge receipt of your comments on this 
proposal, include with your comments a pre-addressed, stamped postcard 
on which the docket number appears. We will stamp the date on the 
postcard and mail it back to you.

Background

    Because of concerns over engine and airplane reliability, for many 
years, 14 CFR 121.161 has generally prohibited operations of two-engine 
airplanes on routes including segments that are more than one hour 
flight time from a suitable airport. This regulation contains an 
exception that allows such operations when specifically authorized by 
the Administrator. These extended range operations with two-engine 
airplanes are referred to as ETOPS. Advisory Circular (AC) 120-42A 
describes a method for obtaining ETOPS authorization if an operator can 
demonstrate sufficient engine and airplane reliability. This method is 
based on a combination of various design features and operational and 
maintenance procedures. The AC states that eligibility for 120-minute 
ETOPS authorization is normally based on a showing of reliable 
operation for a minimum of 250,000 engine hours of service in the world 
fleet. Eligibility for 180-minute ETOPS authorization is normally based 
on a showing of reliable operation for at least one year in 120-minute 
ETOPS. The AC also describes an option for reducing the number of hours 
of service if adequate compensating factors are identified to give a 
reasonably equivalent database.
    On May 18, 1994, the FAA issued Special Conditions Number 25-ANM-84 
for the Boeing Model 777 airplane (59 FR 28234). These special 
conditions define requirements for 180-minute ETOPS approval concurrent 
with basic type certification of the airplane without the service 
experience outlined in AC 120-42A that would normally be necessary. 
These special conditions define additional safety standards that the 
FAA considered necessary to establish a level of safety equivalent to 
that provided by the airworthiness standards for non-ETOPS airplanes.
    The current 777 ETOPS special conditions consist of five main 
elements needed to provide adequate compensation for the service 
experience normally required for 180-minute ETOPS eligibility described 
in AC 120-42A. No single element is considered sufficient by itself, 
but the FAA has found that the five elements combined provide an 
acceptable substitute for actual airline service experience. The five 
elements are:
    1. Design for reliability.
    2. Lessons learned.
    3. Test requirements.
    4. Demonstrated reliability.
    5. Problem tracking system.
    A description of each of these five elements is contained in the 
preamble to the 777 ETOPS special conditions.
    On December 13, 1999, Boeing Commercial Airplane Group applied for 
an amendment to Type Certificate No. T00001SE to include the new Model 
No. 777-200LR and 777-300ER airplanes. The Model No. 777-200LR, which 
is a derivative version of the existing Model 777-200 series airplanes, 
has the following differences from the 777-200:
    [sbull] The wingspan is increased from 199 feet, 11 inches to 212 
feet, 7 inches.
    [sbull] Maximum intended takeoff weight is 750,000 pounds.
    [sbull] It is capable of carrying from 301 to 440 passengers.
    [sbull] It has provisions for overhead crew and attendant rest 
areas.
    [sbull] Its range capability will be up to 8,800 nautical miles 
(16,298 kilometers).
    [sbull] It has 110,100 pounds thrust GE90 engines.
    [sbull] It has a supplemental electronic tail skid.
    [sbull] It has provisions for up to 3 auxiliary fuel tanks in the 
forward area of the aft cargo bay.

[[Page 35336]]

    The 777-300ER, which is a derivative of the Model 777-300 
airplanes, has the following differences from the Model 777-300:
    [sbull] The wingspan is increased from 199 feet, 11 inches to 212 
feet, 7 inches.
    [sbull] Maximum intended takeoff weight is 750,000 pounds.
    [sbull] It is capable of carrying from 359 to 550 passengers.
    [sbull] It has provisions for overhead crew and attendant rest 
areas.
    [sbull] Its range capability will be up to 7,250 nautical miles 
(13,427 kilometers).
    [sbull] It has 115,300 pound thrust GE90 engines.
    [sbull] It has a supplemental electronic tail skid.
    [sbull] It has a semi-levered main landing gear.

Both models are currently approved under Type Certificate No. T00001SE.
    For the Model 777-300ER and Model 777-200LR, Boeing has proposed 
certain changes to the ETOPS special conditions in order to take into 
account the experience from the original baseline Model 777 engine 
programs and to eliminate any unnecessary burden from the airplane 
demonstration testing required by paragraph (e)(7) of those special 
conditions.

Type Certification Basis

    Under the provisions of Sec.  21.101, Amendment 21-69, effective 
September 16, 1991, for a change to a type certificate Boeing must show 
that the Boeing Model 777 series airplane, as changed, continues to 
meet the applicable provisions of the regulations incorporated by 
reference in Type Certificate No. T00001SE or the applicable 
regulations in effect on the date of application for the change. The 
regulations incorporated by reference in the type certificate are 
commonly referred to as the ``original type certification basis.'' The 
regulations incorporated by reference in Type Certificate No. T00001SE 
for the Boeing Model 777 series airplanes include 14 CFR part 25, as 
amended by Amendments 25-1 through 25-82. The original type 
certification basis is listed in Type Certificate Data Sheet No. 
T00001SE.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 25) do not contain adequate or 
appropriate safety standards for the Model 777 series airplanes because 
of a novel or unusual design feature, special conditions are prescribed 
under the provisions of Sec.  21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, Boeing Model 777 series airplanes must comply with the fuel 
vent and exhaust emission requirements of 14 CFR part 34 and the noise 
certification requirements of 14 CFR part 36.
    Special conditions, as defined in Sec.  11.19, are issued in 
accordance with Sec.  11.38 and become part of the type certification 
basis in accordance with Sec.  21.101(b)(2), Amendment 21-69, effective 
September 16, 1991.
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate for that model be amended 
later to include any other model that incorporates the same novel or 
unusual design feature, or should any other model already included on 
the same type certificate be modified to incorporate the same novel or 
unusual design feature, the special conditions would also apply to the 
other model under the provisions of Sec.  21.101(a)(1).

ETOPS Certification

    All two-engine airplanes operating under 14 CFR part 121 are 
required to comply with Sec.  121.161, which states, in pertinent part, 
that ``Unless authorized by the Administrator * * * no certificate 
holder may operate two-engine airplanes * * * over a route that 
contains a point farther than one hour flying time * * * from an 
adequate airport.'' Advisory Circular (AC) 120-42A, ``Extended Range 
Operation With Two-Engine Airplanes (ETOPS),'' provides an acceptable 
means for obtaining FAA approval for two-engine airplanes to operate 
over a route that contains a point farther than one hour flying time 
from an adequate airport. The two basic objectives of this advisory 
circular are to establish that the airplane and its supporting systems 
are suitable for the extended range mission and that the maintenance 
and procedures to be employed in conducting ETOPS operations are 
adequate. This is accomplished by acquiring a substantial amount of 
service experience during non-ETOPS operation and then extensively 
evaluating this experience in the areas of systems reliability, 
maintenance tasks, and operating procedures. When it is determined that 
the appropriate reliabilities and capabilities have been achieved, the 
airplane is found eligible to be considered for use in ETOPS operation 
by an airline.
    When Boeing was developing the Model 777 series airplane, it 
proposed that the Model 777 be approved for ETOPS operation 
simultaneously with the issuance of the basic type certificate. At that 
time procedures did not exist for a finding of this type. The proposed 
issuance of ETOPS type design approval at certification would have 
precluded using accumulation of service experience, as outlined in AC 
120-42A, as a means to meet ETOPS approval requirements. So an 
alternative method was devised that provided an adequate level of 
inherent airplane reliability for ETOPS. It is important to note that 
the requirements for certification of the airplane regarding the 
design's suitability for ETOPS operation, as described in those special 
conditions, relate to type certification approval only. Advisory 
Circular 120-42A contains guidance regarding operational and 
maintenance practices criteria that must be met by the operator before 
ETOPS operations can be conducted. It is incumbent upon the operator to 
apply for operational approval in accordance with appropriate guidance 
issued by the FAA for such approvals. Satisfaction of the requirements 
of these special conditions does not constitute operational approval.
    Special Conditions 25-ANM-84 contained the additional safety 
standards that the Administrator considered necessary to establish a 
level of safety equivalent to that provided by the airworthiness 
standards for transport category airplanes for non-ETOPS airplanes. 
Experience with these special conditions since issuance has provided 
the FAA with additional data to justify a revision to those special 
conditions as described in this notice.

Discussion of the Proposed Special Conditions

    Boeing has requested the FAA to revise certain parts of the test 
requirements of Special Conditions 25-ANM-84 defined in paragraph (e). 
The FAA has concurred that some changes are justified based on an 
analysis of previous experience applying those special conditions to 
the original three engine types approved for installation on the Model 
777 airplane. The specific changes to those requirements and the 
justification for each proposed change are discussed below.

Paragraph (e)(6) Engine Demonstration Test

    The FAA has concluded from a review of in-service experience of the 
Model 777 series airplanes that the 3000-cycle engine and propulsion 
system test required by paragraph (e)(6) of Special Conditions 25-ANM-
84 provides an adequate opportunity to discover cyclic-related failure 
modes associated with the design, provided that an adequate post-test 
evaluation is conducted to find conditions that could result in an 
inflight shutdown, power

[[Page 35337]]

loss, or inability to control engine thrust. An FAA review of the test 
data from the 3000-cycle tests for the three original engine types 
installed on the Model 777 series airplanes has shown that most of the 
early in-service 777 engine failure modes could have been discovered 
had Boeing and the engine manufacturers conducted a more thorough 
teardown inspection and analysis of the 3000-cycle test engine and 
propulsion system hardware. Part conditions noted in the teardown 
inspection reports for the three baseline 777 engine types did later 
occur in service, and they resulted in engine inflight shutdowns or 
airplane diversions. Because the specific condition of those 3000-cycle 
test parts had been characterized as minor deviations from normal 
however, no specific investigations into how they might progress in 
service had been required as a prerequisite for ETOPS approval.
    Special Conditions 25-ANM-84 currently do not require a post-test 
teardown inspection. However, all three engine companies, in 
cooperation with Boeing, conducted post-test teardown inspections on 
the original baseline engines installed on the Model 777 series 
airplanes based on their own experience of what would constitute an 
adequate evaluation. In order to provide a consistent standard for a 
post-test evaluation of the 3000-cycle test hardware, the FAA is 
proposing a change to paragraph (e)(6) to require a complete teardown 
inspection of the engine and airplane nacelle test hardware after 
completion of the test. The inspection must include an analysis of any 
abnormal conditions found. The analysis must consider the possible 
consequences of similar occurrences in service to determine if they 
might become sources of engine inflight shutdowns, power loss, or 
inability to control engine thrust. The intent of this change to 
paragraph (e)(6) is to require further design analysis to catch 
potential sources of engine inflight shutdowns or diversions.
    For similar reasons, we are proposing to add a new subparagraph 
(e)(7)(v) to require a post-test external and internal visual 
inspection of the airplane demonstration test engines and propulsion 
system hardware. An analysis of the inspection results must identify 
any potential sources of engine inflight shutdown. Appropriate 
corrective actions must be performed in accordance with the provisions 
of the special conditions.
    Boeing proposed to delete the word complete from the description of 
the airplane nacelle package required for the 3000-cycle test. The 
rationale for this proposed change was that without the term complete, 
it is still understood that the test is intended to be a propulsion 
system test inclusive of the engine buildup items, but some allowance 
is made for configuration differences necessary to accommodate the test 
setup. The FAA is concerned that, without this qualifier, it is not 
clear what nacelle hardware must be installed for this test. It could 
be misinterpreted in such a way that, for instance, a functioning 
thrust reverser need not be installed. Therefore, the FAA has concluded 
that the word complete must remain in the requirement. However, we 
agree with Boeing that those configuration differences associated with 
test instrumentation and test stand interfaces with the engine nacelle 
package may be excluded, and we propose to add that qualification to 
the requirement in order to clarify this intent.

Paragraph (e)(7) Airplane Demonstration Test

    Number of Test Airplanes: Boeing has proposed a change to paragraph 
(e)(7) to allow the use of more than one airplane to comply with the 
airplane demonstration test requirement (three test airplanes for the 
current Model 777-300ER program). Boeing's justification includes the 
argument that using multiple airplanes is an enhancement to the ETOPS 
validation program that takes into account airplane-to-airplane 
variation. The value of obtaining ETOPS data on multiple airplanes 
versus one is the increased sample size. The FAA agrees that increasing 
the number of test airplanes in the airplane demonstration test would 
provide a better evaluation of airplane-to-airplane variability. The 
limited experience obtained during the airplane demonstration test 
program is not really sufficient to evaluate end-of-life wear-out 
failure modes, so accumulating all of the time and cycles on one 
airplane is not really necessary. The main program schedule benefit 
from using multiple flight test airplanes is that testing can be 
completed in a shorter period. The FAA is proposing a change to 
paragraph (e)(7) to require that one or more airplanes must complete 
the airplane demonstration test required by that paragraph.
    Capability Demonstration vs. Reliability Demonstration: The 1000-
cycle airplane demonstration test requirement was developed with the 
intent of exposing the airplane to the conditions where the greatest 
numbers of inflight shutdowns occur. Most inflight shutdowns occur 
during takeoff and climb. The failure modes associated with these 
takeoff- and climb-related shutdowns tend to be cyclic in nature for a 
couple of reasons.\1\ For failure modes where the risk of failure 
increases with engine thrust, the takeoff portion of the flight is most 
critical. Failure modes that occur due to improper maintenance or 
engine servicing, for instance loss of engine oil due to improper 
assembly of an oil tube connection, also tend to occur early in the 
flight. A larger number of airplane flights increases the exposure to 
these types of failures. Therefore, the FAA considered a cyclic test to 
be the most appropriate airplane validation test for the original 777 
ETOPS special conditions. However, as stated above, we now consider 
that the 3000-cycle engine and propulsion system test required by 
paragraph (e)(6) provides an adequate opportunity to discover cyclic-
related failure modes associated with the design when the test hardware 
goes through an appropriate level of post-test teardown and inspection.
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    \1\ Data provided to the Aviation Rulemaking Advisory Committee 
(ARAC) ETOPS Working Group confirm that the inflight shutdown rate 
during the takeoff flight phase is on the order of 6 to 16 times the 
fleet average inflight shutdown rate and during the climb phase is 
2.5 to 4.5 times the fleet average.
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    For inflight shutdowns where improper maintenance is a main causal 
factor, the 1000-cycle airplane demonstration test provides multiple 
opportunities for these types of failures to occur. However, the 
maintenance procedure validation program required by paragraph (d)(2) 
is intended to minimize the probability of these occurrences. The 
airplane demonstration test airplane provides opportunities to 
demonstrate those maintenance tasks associated with the normal 
operation of the airplane. The FAA considers that these demonstrations 
can be accomplished in fewer than 1000 cycles.
    Although the fewest inflight shutdowns occur during cruise, this is 
the phase of flight that is most important to an ETOPS operation. 
Traditionally, the FAA and industry have avoided trying to 
differentiate between those inflight shutdowns that may occur during 
cruise from those that would only occur in a non-ETOPS environment. The 
main reason for this approach in existing ETOPS policy is that by 
correcting all causes of inflight shutdowns, the overall integrity of 
the propulsion system is assured. Since adequate cyclic exposure would 
be evaluated by an enhanced 3000-cycle engine demonstration test, as 
proposed for paragraph (e)(6) of these special

[[Page 35338]]

conditions, the FAA has concluded that the airplane validation program 
should emphasize exposure to the cruise phase of flight. During the 
three 1000-cycle tests conducted for the original 777 engine 
installation certification programs, only 91 of the total 1000 cycles 
were of durations of two hours or more. Since the intent of paragraph 
(e)(7) is to simulate an actual airline operation, this would better be 
accomplished through longer duration flight cycles. Long duration 
flight exposure provides additional confidence in the design against 
those cruise-related failure modes that cannot be evaluated in a cyclic 
test environment. Such failure modes could include freezing of 
entrapped water condensation or binding of propulsion system 
components, neither of which would likely occur in a sea level test 
facility.
    Based on these considerations, the FAA has determined that the 
airplane demonstration test requirement should be refocused on those 
conditions that are most prevalent in an ETOPS operating environment. 
Those conditions include long flights to a variety of airports with 
broad variations of airport elevation, temperature, and humidity. It is 
also important that these flights expose the airplane to several 
enroute climbs, such as may occur with a fully loaded 777-300ER on a 
long-range flight, and a number of single engine diversions. As such, 
the FAA proposes that the airplane demonstration test requirement of 
paragraph (e)(7) be revised to more clearly state the objectives of the 
test program. Those objectives include demonstrations that the 
aircraft, its components, and equipment are capable of and function 
properly during long-range operations and airplane diversions, 
including engine-inoperative diversions. This change in focus 
constitutes a significant departure from the original purpose of the 
1000-cycle airplane demonstration test requirement, as discussed in the 
preamble to special conditions 25-ANM-84.

Reliability of 777

    In order to further justify this change in philosophy for the 
airplane demonstration test requirement from being a demonstration of 
``reliability'' to a demonstration of ``capability,'' the FAA reviewed 
the original intent of Special Conditions 25-ANM-84, as documented in 
the preamble to those special conditions. The purpose of this review 
was to assess whether the assumptions we made in justifying the special 
conditions are still valid, or whether they should be revised based on 
ETOPS certification experience since their issuance in June 1994.

    In the preamble to Special Conditions 25-ANM-84, the FAA stated 
that: ``existing practices to achieve airplane certification safety 
objectives have involved definition of performance requirements, 
incorporation of safety margins, and prediction of failure 
probabilities through analysis and test. However, historical 
evidence, in general, indicates that a period of actual revenue 
service experience is necessary to identify and resolve problems not 
observed during the normal certification process. Successful 
achievement of this experience has been a prerequisite for granting 
ETOPS type design approval for a specific airplane engine 
combination. However, several recent airplane engine combinations 
incorporating new or substantially modified propulsion systems have 
demonstrated a high level of reliability consistent with ETOPS 
operation upon entry into revenue service. In addition, this high 
level of reliability was demonstrated by the small number of 
problems encountered during basic certification activity.'' Based on 
these successful airplane and engine development and certification 
programs, the special conditions were designed to ``result in a 
level of airplane reliability that is equivalent to the level of 
reliability previously found to be acceptable based upon service 
experience.''

    The basic premise behind the engine and airplane demonstration 
tests required by paragraphs (e)(6) and (e)(7) of the special 
conditions was that those tests would provide a final validation of an 
``inherent'' level of reliability that was the product of an enhanced 
design and test process. This is similar to the purpose of the function 
and reliability testing required by Sec.  21.35(b)(2). The FAA's 
expectation for these tests was that no significant failures would 
occur. The probability of significant design failures occurring on a 
one-airplane flight test is so low that if any DO occur, that would be 
indicative of a design that is not suitable for ETOPS approval. This 
expectation is contained in the ``type and frequency'' requirement of 
special conditions paragraph (h)(1). Statistical reliability studies 
have shown that a much larger database would be required to validate a 
design's true reliability with a significant degree of confidence.
    No major engine failures occurred during the 1000-cycle airplane 
demonstration tests for any of the three engine types certified on the 
Model 777 series airplane, although several engine design problems were 
discovered during other certification testing that affected the start 
and conduct of those tests. The Reliability Assessment Board (RAB) 
evaluated each of these design problems in compliance with paragraph 
(g) of the special conditions, and found the 777 to be suitable for 
ETOPS type design approval with the incorporation of corrective actions 
identified in Appendix 1 of the RAB final recommendation reports for 
the three engine types. There were hardware similarities between 
engines with the original certified thrust ratings and follow-on 
higher-thrust-rated engines, and the FAA certified each of those 
follow-on engine derivatives for ETOPS in consideration of those 
hardware similarities. The FAA accepted the original baseline engine 
test programs as showing compliance to the 3000-cycle propulsion system 
ground test and 1000-cycle airplane demonstration test requirements for 
the follow-on derivative engines. Although the 3000-cycle and 1000-
cycle tests were not repeated for those follow-on derivative engines, 
Boeing and the engine companies completed reduced ground and flight 
test demonstrations tailored to the design changes being introduced in 
compliance with the ``Test Features'' requirement of special conditions 
paragraph (c)(4). Therefore, the follow-on engine derivatives are not 
included in this analysis of the 1000-cycle airplane demonstration test 
requirement.
    The Boeing Model 777-200 series airplane powered by Pratt & Whitney 
PW4077 engines was approved for ETOPS on May 30, 1995 and entered 
service in June 1995. By all accounts, it was a very successful new 
model introduction. This was followed by ETOPS approval of the 777-200 
powered by General Electric GE90-77B and Rolls-Royce RB211-Trent 877-17 
engines in October 1996. The inflight shutdown (IFSD) rate for all 
three engine types was zero for at least the first year in service. The 
Pratt & Whitney PW4000 reached a peak 12-month rolling average engine 
IFSD rate of .018/1000 hours in October 1996. The General Electric GE90 
reached a peak of .021 for one month in July 1998 and the Rolls-Royce 
Trent reached a peak of .016 in December 1997. Although the inflight 
shutdown rates stayed within the allowable .02/1000 hour standard for 
180-minute ETOPS, significant design problems were discovered on each 
engine type after ETOPS approval.
    During the first two years after ETOPS approval of each engine type 
on the Model 777 series airplanes, the FAA was concerned that the 
design problems being discovered may have indicated a failure of the 
early ETOPS process to identify those failure modes before they 
occurred in service. Some failure modes had the potential to result in 
inflight shutdowns had they occurred under different circumstances or 
had they not been detected during maintenance for

[[Page 35339]]

unassociated reasons. A summary of the actual problem reports for these 
inflight shutdowns and other events, which were submitted in compliance 
with paragraph (f) of these special conditions, is contained in Table 
1. Had every one of those events resulted in an engine inflight 
shutdown, the resulting IFSD rates for each engine type would have been 
significantly higher. Boeing, the engine manufacturers, the FAA, and 
other regulatory authorities worked together to prevent additional 
inflight occurrences of these failure types. The actual inflight 
shutdown rates prove that these early in-service problems were 
successfully managed to maintain the safety of 777 ETOPS operations 
worldwide.

                                                     Table 1
----------------------------------------------------------------------------------------------------------------
                       EE-1            Engine type             Affected system            Event description
----------------------------------------------------------------------------------------------------------------
10/1/1995............          101  PW...................  ENGINE--OIL PUMP...........  Airplane diversion due
                                                                                         to low oil quantity.
                                                                                         Engine not shut down,
                                                                                         but oil quantity
                                                                                         indication went to
                                                                                         zero. Related to LP01
                                                                                         problem.
5/19/1996............          179  PW...................  ENGINE.....................  Takeoff aborted due to
                                                                                         EGT exceedance. A loose
                                                                                         B-nut was found on the
                                                                                         PS3 line to the 2.95
                                                                                         bleed valve, which
                                                                                         caused erratic
                                                                                         operation.
5/30/1996............          181  PW...................  ENGINE.....................  Air turnback due to high
                                                                                         oil consumption. Oil
                                                                                         wetness noted and
                                                                                         corrected from previous
                                                                                         flights. Consumption
                                                                                         continued to be high.
8/24/1996............          233  PW...................  ENGINE.....................  IFSD--Inflight shutdown
                                                                                         due to low oil pressure
                                                                                         indication. Plastic
                                                                                         shipping cap was left
                                                                                         in the LPO1 oil line
                                                                                         during installation as
                                                                                         part of fleet upgrade.
10/5/1996............          254  PW...................  ENGINE.....................  IFSD--Engine was shut
                                                                                         down due to low oil
                                                                                         quantity and low oil
                                                                                         pressure. Loose main
                                                                                         oil line at filter
                                                                                         housing. Repeat of oil
                                                                                         line shipping cap
                                                                                         problem.
10/11/1996...........          261  PW...................  ENGINE.....................  Air turnback. Engine
                                                                                         experienced high
                                                                                         vibration during
                                                                                         cruise. Vibration
                                                                                         indication exceeded
                                                                                         EICAS ``Pop-up'' level
                                                                                         at 4.06.
3/26/1997............          385  PW...................  ENGINE.....................  Twelve quarts of oil
                                                                                         lost after a series of
                                                                                         training flights due to
                                                                                         a leak of an oil line
                                                                                         to the fuel/oil cooler.
                                                                                         Oil loss took place
                                                                                         over approximately 3
                                                                                         hours of flight time.
2/24/1997............         G-65  GE...................  ENGINE GEARBOX.............  Air turnback due to loss
                                                                                         of right backup
                                                                                         generator followed by
                                                                                         engine oil filter EICAS
                                                                                         message. Root cause was
                                                                                         a failed gearbox backup
                                                                                         generator pad bearing.
11/4/1997............         G-84  GE...................  ENGINE.....................  IFSD--Engine experienced
                                                                                         a power loss during
                                                                                         approach. A restart
                                                                                         attempt was
                                                                                         unsuccessful. Root
                                                                                         cause was a sticking
                                                                                         bypass valve in the
                                                                                         hydromechanical unit
                                                                                         (HMU).
11/9/1997............         G-87  GE...................  ENGINE.....................  Flight crew heard a
                                                                                         surge toward the end of
                                                                                         the takeoff roll and
                                                                                         tower reported seeing
                                                                                         flames from the engine.
                                                                                         At 600 feet, the engine
                                                                                         surged again. The
                                                                                         flight crew reduced
                                                                                         power and returned to
                                                                                         the airport.
3/12/1998............         G-96  GE...................  ENGINE.....................  Pilot heard a bang and a
                                                                                         tower reported fire
                                                                                         from the tailpipe after
                                                                                         power was set for
                                                                                         takeoff. The takeoff
                                                                                         was aborted. Metal was
                                                                                         found in the tailpipe.
6/22/1998............        G-108  GE...................  ENGINE.....................  IFSD--After takeoff, the
                                                                                         pilot received low oil
                                                                                         pressure and low oil
                                                                                         quantity indications.
                                                                                         The pilot shut down the
                                                                                         engine. Two of four oil
                                                                                         filter cover bolts were
                                                                                         loose due to inserts
                                                                                         pulling out of the
                                                                                         filter housing casting.
7/1/1998.............        G-110  GE...................  ENGINE.....................  IFSD--Uncommanded engine
                                                                                         inflight shutdown
                                                                                         during cruise at flight
                                                                                         level 370. Flight crew
                                                                                         noted a rapid loss of
                                                                                         oil pressure and N2.
                                                                                         Root cause was a Number
                                                                                         3 bearing failure.
7/22/1998............        G-112  GE...................  ENGINE.....................  IFSD--During cruise,
                                                                                         EICAS indication of low
                                                                                         oil quantity. Pilot
                                                                                         shut down the engine.
                                                                                         Oil filter housing
                                                                                         cover bolts were over-
                                                                                         torqued resulting in
                                                                                         stripped threads in the
                                                                                         oil filter housing
                                                                                         inserts.
11/20/1998...........        G-120  GE...................  IDG installation...........  IFSD--Crew started
                                                                                         return to departure
                                                                                         airport due to
                                                                                         indication of complete
                                                                                         oil loss. Engine was
                                                                                         subsequently shut down
                                                                                         when oil pressure
                                                                                         dropped to 10 psi. The
                                                                                         integrated drive
                                                                                         generator (IDG) packing
                                                                                         was damaged during
                                                                                         installation.
10/11/1996...........         R-63  RR...................  ENGINE--RADIAL DRIVE SHROUD  Flight diverted after
                                                                                         crew observed right
                                                                                         engine oil quantity
                                                                                         loss approx. 5 hours
                                                                                         into flight. Found
                                                                                         cracked upper radial
                                                                                         drive shroud.
10/11/1996...........         R-64  RR...................  ENGINE--FUEL NOZZLE........  Fuel found leaking from
                                                                                         Zone 2 during
                                                                                         investigation of R-63
                                                                                         oil loss. Source of
                                                                                         fuel leak was a cracked
                                                                                         weld on the No. 24 fuel
                                                                                         nozzle (top dead
                                                                                         center).
10/25/1996...........         R-65  RR...................  ENGINE--RADIAL DRIVE SHROUD  After engine shutdown at
                                                                                         the gate, the right
                                                                                         engine oil quantity
                                                                                         indicated 9 qts. Upper
                                                                                         radial drive shroud
                                                                                         found cracked.
11/12/1996...........         R-67  RR...................  ENGINE.....................  ``ENGINE OIL PRESS R''
                                                                                         EICAS message displayed
                                                                                         after landing. Engine
                                                                                         shut down. Oil pump
                                                                                         drive shaft found
                                                                                         sheared.
1/26/1997............         R-91  RR...................  ENGINE--STEP ASIDE GEARBOX.  Low oil quantity caused
                                                                                         by crack in step aside
                                                                                         gearbox housing
                                                                                         approximately 4 to 5
                                                                                         inches long.
5/24/1997............        R-109  RR...................  ENGINE.....................  Engine was shut down on
                                                                                         takeoff following high
                                                                                         power surge. Subsequent
                                                                                         borescope inspection
                                                                                         revealed HPC rotor 1
                                                                                         blade failure caused by
                                                                                         foreign object damage
                                                                                         that was consistent
                                                                                         with blade damage noted
                                                                                         on 5/20/97 inspection.
7/7/1997.............        R-112  RR...................  ENGINE.....................  Aircraft diversion
                                                                                         caused by excessive oil
                                                                                         leakage due to
                                                                                         incorrectly installed
                                                                                         lower bevel box O-ring
                                                                                         seal following radial
                                                                                         drive shaft
                                                                                         replacement.
7/26/1997............           --  RR...................  ENGINE.....................  Aircraft diversion due
                                                                                         to high oil
                                                                                         consumption. Not
                                                                                         related to step aside
                                                                                         gearbox housing
                                                                                         cracking problem.

[[Page 35340]]

 
9/16/1997............        R-113  RR...................  ENGINE.....................  IFSD--Engine shutdown at
                                                                                         400 feet after takeoff
                                                                                         due to high- pressure
                                                                                         compressor failure.
----------------------------------------------------------------------------------------------------------------

Reliability of 737NG

    As part of the process of reviewing existing methods for ETOPS 
approval, the FAA also analyzed data from the initial in-service period 
for Boeing Models 737-600, 737-700, and 737-800 powered by CFM56-7 
engines. As a group, these variants of the 737 were referred to as the 
737 Next Generation, or ``737NG.'' Even though early ETOPS special 
conditions were not issued, the 737NG was chosen for this analysis 
because it followed an ETOPS approval process program that was very 
similar to what Boeing is proposing for the 777-300ER. Several months 
after entry into service, however, the 737NG did not exhibit an 
acceptable level of propulsion system reliability for ETOPS approval. 
Early ETOPS special conditions were intended to identify a design not 
suitable for ETOPS approval prior to type certification.
    Boeing proposed in 1994, prior to the 777's type certification, 
that the 737NG be certified as an early ETOPS airplane in a manner 
similar to the 777, but without all of the testing required in the 777 
special conditions. Since the success of the 777 program was still an 
unknown at the time of Boeing's request for the 737NG, the FAA did not 
agree to Boeing's proposed changes to the airplane demonstration test 
requirement. Early ETOPS special conditions for the 737NG were never 
issued. Even so, Boeing proceeded with those elements of the 777 
special conditions that the company had proposed to accomplish. These 
included the relevant experience assessment, design requirements 
assessment, 3000-cycle propulsion system ground test, and enhanced 
problem reporting and resolution.
    Although the FAA never issued special conditions for the 737NG 
program, we agreed that the elements from the 777 special conditions 
that Boeing did accomplish justified a reduction in the service 
experience normally required for ETOPS type design approval, as 
outlined in AC 120-42A. Boeing presented the following information in 
support of its request for a reduction in service experience required 
for ETOPS certification.
    [sbull] ``Design involved lessons learned, similar to 777 Early 
ETOPS process.
    [sbull] ``APU most thoroughly tested in Allied Signal history--more 
than 3000-cycle ground test, including hot/cold exposure.
    [sbull] ``Propulsion system subjected to 3000-cycle ground test, 
intentionally unbalanced, with three 180-minute diversion cycles.
    [sbull] ``Flight testing included a Southwest Airlines 50-cycle 
demonstration, using airline crews and maintenance. During the Function 
and Reliability testing, 61 ETOPS cycles were conducted with three 
single engine 180-minute diversions.
    [sbull] ``A proposed ETOPS problem tracking and resolution system, 
similar to that used on the 777 that will remain in effect until the 
fleet attains 250,000 engine fleet hours.''
    In its analysis of the 737NG approval process, the FAA noted that 
these program elements, at the time, had been accomplished with good 
results. The engines and airplane system had performed well during the 
test programs, with results comparable to the 777 test fleet (all 
engines). The in-service 737NG airplanes had achieved a 98.96% dispatch 
reliability rate after 45 days in service, better than any previous 
Boeing airplane. Boeing's proposal included an accumulation of 15,000 
fleet engine hours of service experience before requesting ETOPS 
approval. At that time, there would be three airplanes with more than 
1000 flight cycles, the total 737NG fleet would have accumulated more 
than 20,000 flight cycles, and the high-time airplane/engines would 
have more than 2000 flight cycles. During the 737 NG approval process, 
the FAA concurred with Boeing's proposal to require 15,000 hours of 
service experience based on the following:
    [sbull] ``The FAA has agreed to the concept that ETOPS at entry 
into service can be achieved by appropriate design and testing as 
evidenced by the 777 special conditions, which have now been validated 
through actual service experience,
    [sbull] ``The 737NG/CFM56-7B airframe/engine configuration is a 
derivative/evolution of the existing 737-300/400/500 which through 
extensive service experience has demonstrated exceptional reliability, 
and, is approved for 120-minute ETOPS,
    [sbull] ``Except for the lack of a dedicated 1000-cycle ETOPS test 
program, design and testing of the 737NG/CFM56-7B mirrors what was done 
on the 777 to satisfy Early-ETOPS approval.
    [sbull] ``The additional 15,000 engine hour in-service evaluation 
plus the fact that three 180-minute single engine diversions were 
performed during Function and Reliability testing more than compensates 
for the omission of a 1000-cycle test,
    [sbull] ``The satisfactory performance of the 737NG/CFM56-7B 
airframe/engine configuration during the certification testing, and
    [sbull] ``The proven ability of Boeing to satisfactorily manage 
ETOPS airworthiness of the 777 fleet in the face of problems 
encountered in service. The 737NG proposal includes a problem tracking 
and resolution system that will remain in effect for a full 250,000 
engine hours.''
    The Model 737-700 was the first variant of the 737NG to enter 
service, in December 1997. Section 4.2 of the FAA-approved 120-minute 
ETOPS Airplane Assessment Report for the 737-700, Boeing Document 
Number D033A003, Revision B, states that the Model 737-700 was 
designed, manufactured, and tested for extended range operations at 
entry into service. The following additional supporting statements were 
also made.
    a. ``The 737-700 airplanes have been designed and manufactured 
based on regimented application of lessons learned from other ETOPS 
program experience as well as the in-service experience of earlier 737 
models.
    b.``The 737-700 airplane was subjected to a rigorous test program 
as described in following paragraphs. Production equivalent equipment 
where appropriate, was used to support test objectives. Equipment was 
production equivalent as defined at the time of the test.''
    No significant propulsion system design problems occurred during 
any of the testing described above. Two inflight shutdowns did occur 
during certification flight testing. One was caused by an indication 
fault within the electronic engine control that was corrected with a 
simple software change. The other was caused by an inappropriate flight 
test condition.

[[Page 35341]]

    Boeing stated in the 737-700's 120-minute ETOPS Airplane Assessment 
Report that the fleet reached the 15,000-hour mark during the month of 
April 1998. At that time, there had been no inflight shutdowns in 
service. However, on May 9, 1998, before the FAA had completed its 
assessment of the airplane for ETOPS approval, the first inflight 
shutdown occurred. A second inflight shutdown occurred during the month 
of May, and the fleet exceeded the accepted 120-minute ETOPS standard 
of .05 inflight shutdowns per 1000 engine hours. Three inflight 
shutdowns occurred in June 1998, and one in July 1998. The peak 
inflight shutdown rate during this period was .085/1000 hours at the 
end of June 1998, which clearly did not meet the minimum standard for 
ETOPS type design approval.
    The six engine inflight shutdowns were caused by three different 
failure root causes. Boeing and CFMI, the engine manufacturer, 
undertook aggressive actions to correct each of these design problems 
as they occurred. The high rate of fleet hourly accumulation during 
this period, however, resulted in new ETOPS reportable events occurring 
faster than the known problems could be corrected. This delayed FAA 
consideration of the 737-700 for ETOPS approval until the problems were 
brought under control. A consequence of the high rate of fleet hourly 
accumulation was that, with no additional inflight shutdowns, the 
inflight shutdown rate decreased rapidly and was within the ETOPS type 
design approval standard by the end of 1998. The FAA approved the 737-
600/-700/-800 (737NG) for 120-minute ETOPS approximately one year after 
entry into service with over 300,000 engine-hours of service experience 
and an inflight shutdown rate of .020/1000 hours.

Conclusions From Comparison of 777 and 737NG

    In comparing the 737NG experience with that of the 777, the FAA 
observes that there is a fleet hourly accumulation rate above which 
aggressive problem management to qualify for early ETOPS certification 
may become resource prohibitive. Therefore, when certifying an 
airplane/engine combination that will be entering service with a high 
production rate resulting in a rapid accumulation of engine hours, 
manufacturers may find it more cost-effective to use the service 
experience criteria of AC 120-42A than to follow the rigorous 
requirements of the early ETOPS process.
    As stated earlier, the 777 ETOPS special conditions were designed 
to ``result in a level of airplane reliability that is equivalent to 
the level of reliability previously found to be acceptable based upon 
service experience.'' As previously noted, the current 777 ETOPS 
special conditions consist of five main elements needed to provide 
adequate compensation for the service experience normally required for 
180-minute ETOPS eligibility described in AC 120-42A. No single element 
is considered sufficient by itself, but the FAA has found that the five 
elements combined provide an acceptable substitute for actual airline 
service experience. The five elements are:
    1. Design for reliability.
    2. Lessons learned.
    3. Test requirements.
    4. Demonstrated reliability.
    5. Problem tracking system.
    Even though the overall objective is a level of airplane and 
propulsion system reliability that is equivalent to that achieved 
through service experience, we considered the uncertainty of actually 
achieving that goal in the development of these special conditions. The 
first three elements focus on designing an airplane to eliminate 
sources of engine inflight shutdowns and diversions to the greatest 
practical extent. This is accomplished by an overall design philosophy 
to preclude sources of engine inflight shutdowns and diversions using 
the manufacturer's experience with earlier designs to identify 
successful and unsuccessful design features. The additional testing 
required by the special conditions focuses on exposing the design to 
conditions that in the past have contributed to engine failures, such 
as high engine vibration or repeated exposure to humid and inclement 
weather on the ground followed by long-range operation at the extreme 
cold temperatures at high altitude. These design and test elements do 
not assure a level of reliability that is equivalent to that based on 
service experience. Instead, they result in an acceptable level of 
inherent design reliability from which we can successfully manage ETOPS 
fleet safety once the airplane enters service.
    The fourth element, ``demonstrated reliability,'' provides the FAA 
with a standard by which to judge a design against existing ETOPS-
approved airplanes. This gives the FAA a standard from which to 
withhold ETOPS approval from airplanes that experience significant 
failures during certification testing, demonstrating that they are not 
suitable for ETOPS. However, it does not by itself guarantee that 
designs showing no significant failures during flight testing will have 
adequate reliability for ETOPS.
    To manage fleet safety after ETOPS approval, we rely on the fifth 
element of the ETOPS special conditions. Paragraph (f) of the special 
conditions requires a problem tracking system for the prompt 
identification of those problems that could impact ETOPS safety. The 
FAA uses this enhanced problem reporting system to work with the 
airplane and engine manufacturers to aggressively manage and correct 
significant design problems identified after ETOPS approval. This 
requirement is the ``catch-all'' for those design flaws that are not 
caught by the other special conditions elements during airplane design 
and testing.
    The first in-service inflight shutdown of the 737-700 variant of 
the 737NG did not occur until the fleet had accumulated approximately 
30,000 engine-hours. The FAA could not have expected that a complete 
1000-cycle airplane demonstration test would have had a better chance 
of discovering the types of problems that occurred in service on the 
737NG than the nearly 30,000 hours accumulated on multiple airplanes 
and engines prior to the first inflight engine shutdown. While 
significant propulsion system failures occurring during type 
certification testing, including the additional testing required by the 
ETOPS special conditions, may indicate that a design is not yet ready 
to enter ETOPS service, the 737NG experience shows that the reverse 
cannot be stated with a significant degree of confidence. A lack of 
significant failures during certification testing does not in itself 
assure an ETOPS-suitable design at entry into service.
    The 777 experience shows that a relatively small fleet can be 
managed successfully during the initial service period based on the 
data provided by the enhanced problem tracking system required by 
special conditions paragraph (f). The 737NG experience shows that a 
larger fleet may require a much more resource-intensive fleet 
management program. However, had the 737NG received its ETOPS approval 
as originally proposed prior to its first inflight shutdown in service, 
the problem reporting system that Boeing had in place gave the FAA 
timely identification of the problems causing inflight shutdowns so 
that we could have required appropriate corrective action through the 
airworthiness directive process to maintain ETOPS safety. Such 
airworthiness directives could have required the operators to 
incorporate design changes prior to

[[Page 35342]]

further ETOPS flight or withdrawn ETOPS approval.
    Since we cannot be certain that an airplane approved for ETOPS 
under the special conditions will have the same maturity at original 
type certification as an airplane that we have approved based on 
service experience, our experience with the 777 and 737NG confirms that 
the five elements of the special conditions, in conjunction with the 
FAA's normal safety oversight processes, adequately compensate for that 
uncertainty.
    The changes we propose for the engine demonstration test and the 
airplane demonstration test, including enhanced post-test inspection 
requirements, are intended to address our experience with the existing 
ETOPS special conditions, which identified several shortcomings in the 
original test requirements. We are proposing these changes to more 
clearly focus the testing on the objective of exposing the engines and 
airplane to those operating conditions that give us the best chance of 
identifying underlying major design flaws that could jeopardize ETOPS 
safety in service. These proposed changes would provide a better 
evaluation of the design than the existing requirements, including the 
1000-cycle airplane flight test as previously conducted.
    The FAA therefore proposes to change the purpose of the airplane 
demonstration test requirement of paragraph (e)(7) from being a 
demonstration of reliability to a demonstration of airplane capability 
under the types of ETOPS operational and diversion scenarios being 
proposed in this notice. The requirements of that airplane 
demonstration test have been changed accordingly.

Aged Engine Requirement

    In response to Boeing's request, the FAA is proposing to delete 
paragraph (e)(7)(ii), which currently requires the installation of the 
engine and propulsion system from the 3000-cycle engine demonstration 
test required by paragraph (e)(6), or another suitable aged engine, on 
the 1000-cycle demonstration test airplane for a minimum of 500 cycles. 
Boeing provided the following information in support of its request for 
deleting the aged engine requirement:
    Review of the aged engine data from the baseline 777 program showed 
that the nature of the findings, which occurred on the aged engines, 
was not related to the aging of the engines. The findings were related 
to the variation that occurs during manufacturing, assembly, etc. This 
lesson learned on the aged engines is consistent for each engine 
manufacturers' baseline 777 ETOPS test program.
    The lack of findings related to the aging of an engine in the ETOPS 
flight test program has been demonstrated three times. Based on this 
consistent demonstration, there is no further need to maintain the 
requirement for an aged engine in the flight test program. 
Additionally, flying more airplane/engine combinations will provide 
increased opportunities for evaluating potential problem areas.
    Boeing reported nine events (EE-1 Reports) which occurred during 
the ``aged'' engine portions of the 1000-cycle tests for the three 
baseline engine types, with an explanation of why the aged engine 
requirement was not necessary in order to identify each failure. Boeing 
stated that the lack of any EE-1 reports from the post-test inspections 
is an indication that there were no significant findings from the aged 
engine testing.
    FAA Analysis of Boeing's Proposal: The original intent of the aged 
engine requirement was to expose the 3000-cycle test engine, or 
equivalent, to inflight conditions that cannot be simulated in a ground 
test environment. This would further validate the propulsion system 
design out to an age beyond 3000 cycles. Boeing data available at the 
time the ETOPS special conditions were developed indicated that 95% of 
all new significant failure modes occur on airplane propulsion systems 
with 3000 cycles or less. That concept is still valid. The lack of 
specific findings on the aged engine during the 1000-cycle airplane 
validation test only confirms the validity of the Reliability 
Assessment Board's conclusion that those baseline 777 engine 
installations were suitable for 180-minute ETOPS. A number of 
significant events during the 1000-cycle test program would have 
jeopardized that conclusion.
    The question that the FAA considers to be more relevant is whether 
or not a greater benefit would come from a more thorough teardown 
inspection and analysis of the 3000-cycle test engine and propulsion 
system hardware than from this additional level of validation. In this 
regard, the FAA agrees with Boeing that other test articles may provide 
sufficient experience to uncover the majority of age-related problems 
independent of the additional exposure provided by the 1000-cycle test 
inflight exposure.
    In consideration of the need to perform a detailed analysis of the 
3000-cycle test engine and the extra expense of using a parallel 3000-
cycle test engine as ``another suitable aged engine,'' the FAA agrees 
that the requirement for installation of an aged engine on the ETOPS 
test airplane can be eliminated provided significantly improved 
processes are used to analyze the condition of the 3000-cycle test and 
airplane demonstration test engines at the conclusion of these tests, 
as being proposed for paragraph (e)(6).

Miscellaneous Amendments

    We are also proposing the following revisions.
    Re-identification of paragraph (e)(7)(iii) as (e)(7)(iv) and 
revision of the requirement that the 1000-cycle test airplane be 
operated and maintained using the recommended operations and 
maintenance procedures to recognize that more than one test airplane 
may be used.
    Replacement of the reference to the ``1000-cycle ETOPS test'' with 
``Airplane Demonstration Test'' in paragraph (g)(2) in order to be 
consistent with the changes being proposed for paragraph (e)(7).
    Replacement of the reference to the ``1000-flight-cycle ETOPS 
test'' with ``Airplane Demonstration Test'' in paragraph (h)(1) in 
order to be consistent with the changes being proposed for paragraph 
(e)(7).

Applicability

    As discussed above, these special conditions are applicable to 
Boeing Model 777 series airplanes. Should The Boeing Company apply at a 
later date for a change to the type certificate to modify any model 
included on Type Certificate No. T00001SE to incorporate the same novel 
or unusual design feature, the special conditions would apply to that 
model as well under the provisions of Sec.  21.101(a)(1), Amendment 21-
69, effective September 16, 1991.

Conclusion

    This action affects only certain novel or unusual design features 
on Boeing Model 777 series airplanes. It is not a rule of general 
applicability, and it affects only the applicant who applied to the FAA 
for approval of these features on the airplane.

List of Subjects in CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.
    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

[[Page 35343]]

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following revisions to Special Conditions 25-ANM-84 as part of the type 
certification basis for Boeing Model 777 series airplanes. The existing 
special conditions are printed in their entirety for clarity. Your 
comments are invited on the proposed revisions: Sections (e)(6), 
(e)(7), and the word substitutions in sections (g)(2) and (h)(1).
    In addition to the airworthiness requirements of 14 CFR part 25, 
the Model 777 airplane must comply with the following requirements in 
order to be eligible for Extended Range Operation with Two-Engine 
Airplanes (ETOPS) without the requisite operating experience specified 
in Advisory Circular (AC) 120-42A:
    (a) Introduction. An approved ETOPS Type Design Assessment Plan 
covering the engine and each applicable airplane system must be 
established. The specific methods that will be used to substantiate 
compliance with the requirements of these special conditions must be 
defined in the plan. Specific systems that will undergo the complete 
analysis, testing, and development program tracking defined in 
paragraph (c) of these special conditions must be identified. Other 
airplane systems that may contribute to the overall safety of an ETOPS 
operation, but that do not warrant the rigorous type design 
requirements and relevant experience assessments defined in paragraph 
(c) of these special conditions, must be identified and agreed to by 
the FAA. Compliance must be shown for these other systems with all 
provisions of these special conditions, except paragraph (c). In 
showing compliance with these special conditions, tests and analyses 
conducted to substantiate compliance with the basic airworthiness 
standards of part 25 may be referenced, if applicable.
    (b) Engine Assessment.
    (1) The ETOPS eligibility of the engine must be determined 
specifically for the airplane installation for which early ETOPS type 
design approval is requested.
    (2) Procedures for an engine condition monitoring program must be 
defined and validated at the time of ETOPS type design approval. The 
engine condition monitoring program must be able to predict when an 
engine is no longer capable of providing, within certified engine 
operating limits, the maximum thrust required for a single engine 
diversion.
    (c) ETOPS Type Design Assessment.
    (1) Design Requirements Assessment. 14 CFR part 25, including 
applicable amendments, defines most of the requirements necessary to 
design an airplane that is suitable for ETOPS operation, as long as the 
ETOPS mission is considered in applying these requirements for all 
anticipated dispatch configurations. In addition to these requirements, 
the propulsion system must be designed to preclude failures or 
malfunctions that could result in an engine inflight shutdown. The 
applicant must identify and list methods of compliance for each of the 
applicable ETOPS requirements, including those specific part 25 
requirements for which methods of compliance relative to the ETOPS 
mission are different from those traditionally used for two-engine 
airplanes. Paragraph (c)(3) of these special conditions lists certain 
design feature categories that may be affected by a consideration of 
the ETOPS mission in the design of these systems. The effects of the 
applicable ETOPS requirements on the design of any of those design 
feature categories listed in paragraph (c)(3) must be specifically 
addressed by this assessment.
    (2) Relevant Experience Assessment. For each system covered by the 
ETOPS Type Design Assessment, there must be an assessment of the 
relevant design, manufacturing, and operational problems experienced on 
previous airplanes built by the applicant. The assessment must include 
the applicable relevant service experience of vendor supplied systems 
or, to the extent possible, the service experience of components on 
aircraft built by other manufacturers. Specific corrective actions 
taken to preclude similar problems from occurring on the new airplane 
must be identified.
    (3) Design Features.
    (i) The applicant must define any design features implemented to 
comply with the design requirements listed in paragraph (c)(1). 
Consideration of the following design feature categories must be 
specifically addressed:
    (A) Airplane capabilities and capacities of the ETOPS mission;
    (B) Fuel system integrity, including consideration of uncontained 
main engine rotor burst and fuel availability as affected by cross-feed 
capability and electrical power to pumps and other components;
    (C) Fuel quantity indication to the flightcrew, including alerts 
that consider the fuel required to complete the mission, abnormal fuel 
management or transfer between tanks, and possible fuel leaks between 
the tanks and the main engines;
    (D) Communication systems for the ETOPS environment;
    (E) Navigation systems for the ETOPS environment;
    (F) Minimum single engine cruise altitude capability; and
    (G) Failure tolerant designs of cockpit indicating systems or 
avionics systems to prevent unnecessary airplane diversions.
    (ii) The applicant must define the specific design features used to 
address problems identified in the relevant service experience 
assessment of paragraph (c)(2).
    (4) Test Features. The applicant must define specific new tests, or 
enhanced tests, that will be used to assure engine and airplane system 
design integrity. These test features may be derived from the 
requirements assessment of paragraph (c)(1) and the relevant service 
experience assessment of paragraph (c)(2).
    (5) Analysis Features. The applicant must define specific new 
analyses, or enhanced analyses, that will be used to assure engine and 
airplane system design integrity. These analysis features may be 
derived from the requirements assessment of paragraph (c)(1) and the 
relevant service experience assessment of paragraph (c)(2).
    (6) Manufacturing, Maintenance, or Operational (Other) Features. 
The applicant must define specific new, or enhanced, manufacturing 
processes or procedures, and maintenance or operational procedures that 
are being implemented to assure engine and airplane system integrity. 
These ``other'' features may be derived from the requirements 
assessment of paragraph (c)(1) of this section and the relevant service 
experience assessment of paragraph (c)(2).
    (d) Additional ETOPS Analysis Requirements.
    (1) Performance and Failure Analyses. Engine and airplane 
performance and failure analyses required for certification must be 
expanded to consider ETOPS mission requirements, including exposure 
times associated with a 180-minute single-engine diversion and a 
subsequent 15-minute hold in the terminal airspace at the diversion 
airport. Consideration must be given to crew workload and operational 
implications of continued operation with failure effects for an 
extended period of time. The rationale and all assumptions used in the 
analyses must be documented, justified, and validated, including 
maintenance interval and maintainability assumptions.

[[Page 35344]]

    (2) Maintenance and Flight Operations Evaluation. The Type Design 
Assessment Plan must contain a program to systematically detect and 
correct problems occurring as a result of improper execution of 
maintenance or flight operations. Corrective actions for any problems 
found must be identified and implemented through the Problem Tracking 
and Resolution System required by paragraph (f).
    (3) Manufacturing Variability. The Type Design Assessment Plan must 
contain a program to minimize potential manufacturing problems. The 
plan should address early validation of tooling and procedures, as well 
as any related problems, as identified in paragraph (c)(2). Corrective 
actions for problems that impact the safe operation of the airplane 
must be identified and implemented through the problem tracking and 
resolution system required by paragraph (f).
    (e) Additional ETOPS Test Requirements. As part of, or in addition 
to, the testing identified in paragraph (c)(4), the following specific 
test requirements apply:
    (1) Configuration Requirements. All testing defined in paragraph 
(e) must be conducted with the configuration proposed for 
certification, and must include sufficient interfacing system hardware 
and software to simulate the actual airplane installation.
    (2) Completion of Applicable Failure Analyses. Failure analyses 
required for ETOPS type design approval must be submitted to the FAA 
prior to the start of the testing defined in paragraph (e).
    (3) Vibration Testing. Vibration testing must be conducted on the 
complete installed engine configuration to demonstrate that no damaging 
resonances exist within the operating envelope of the engine that could 
lead to component, part, or fluid line failures. The complete installed 
engine configuration includes the engine, nacelle, engine mounted 
components, and engine mounting structure up the strut to wing 
interface.
    (4) New Technology Demonstration Testing. Testing must be conducted 
to substantiate the suitability of any technology new to the applicant, 
including substantially new manufacturing techniques.
    (5) Auxiliary Power Unit Demonstration Test. If requesting credit 
for APU backup electrical power generation, one auxiliary power unit 
(APU), of the type to be certificated with the airplane, must complete 
3000 equivalent airplane operational cycles.
    (6) Engine Demonstration Test. One engine of each type to be 
certificated with the airplane must complete 3000 equivalent airplane 
operational cycles. The engine must be configured with a complete 
airplane nacelle package for this demonstration, including engine-
mounted equipment except for any configuration differences necessary to 
accommodate test instrumentation and test stand interfaces with the 
engine nacelle package. At completion of the engine demonstration test, 
the engine and airplane nacelle test hardware must undergo a complete 
teardown inspection. This inspection must be conducted in a manner to 
identify abnormal conditions that could become potential sources of 
engine inflight shutdown. An analysis of any abnormal conditions found 
must consider the possible consequences of similar occurrences in 
service to determine if they may become sources of engine inflight 
shutdowns, power loss, or inability to control engine thrust. Any 
potential sources of engine inflight shutdown identified must be 
corrected in accordance with paragraph (g)(2).
    (7) Airplane Demonstration Test. In addition to the function and 
reliability testing required by 14 CFR 21.35(b)(2), for each engine 
type to be certificated with the airplane, one or more airplanes must 
complete flight testing which demonstrates that the aircraft, its 
components, and equipment, are capable of and function properly during 
long range operations and airplane diversions, including engine-
inoperative diversions.
    (i) The flight conditions must expose the airplane to 
representative operational variations based on the airplane's system 
and equipment design and the intended use of the airplane including:
    (A) Engine inoperative maximum length diversions to demonstrate the 
airplane and propulsion system's capability to safely conduct a 
diversion.
    (B) Non-normal conditions to demonstrate the airplane's capability 
to safely divert under worst case probable system failure conditions.
    (C) Simulated airline operations including normal cruise altitudes, 
step climbs, and maximum expected flight durations out of and into a 
variety of departure and arrival airports.
    (D) Diversions to worldwide airports representative of those 
intended as operational alternates.
    (E) Repeated exposure to humid and inclement weather on the ground 
followed by long-range operation at normal cruise altitude.
    (ii) The flight testing must validate expected airplane flying 
qualities and performance considering engine failure, electrical power 
losses, etc. The testing must demonstrate the adequacy of remaining 
airplane systems and performance and flightcrew ability to deal with an 
emergency considering remaining flight deck information following 
expected failure conditions.
    (iii) The engine-inoperative diversions must be evenly distributed 
among the number of engines in the applicant's flight test program.
    (iv) The test airplane(s) must be operated and maintained using the 
recommended operations and maintenance manual procedures during the 
airplane demonstration test.
    (v) At completion of the airplane demonstration test, the test 
engines and engine-mounted equipment must undergo a complete external 
on-wing visual inspection. The engines must also undergo a complete 
internal visual inspection. These inspections must be conducted in a 
manner to identify abnormal conditions that could become potential 
sources of engine inflight shutdowns. An analysis of any abnormal 
conditions found must consider the possible consequences of similar 
occurrences in service to determine if they may become sources of 
engine inflight shutdowns. Any potential sources of engine inflight 
shutdown that are identified must be corrected in accordance with 
paragraph (g)(2).
    (f) Problem Tracking System. An FAA-approved problem tracking 
system must be established to address problems encountered on the 
engine and airplane systems that could affect the safety of ETOPS 
operations.
    (1) The system must contain a means for the prompt identification 
of those problems that could impact the safety of ETOPS operations in 
order that they may be resolved in a timely manner.
    (2) The system must contain the process for the timely notification 
to the responsible FAA office of all relevant problems encountered, and 
corrective actions deemed necessary, in a manner that allows for 
appropriate FAA review of all planned corrective actions.
    (3) The system must be in effect during the phases of airplane 
development that will be used to assess early ETOPS eligibility, and 
for at least the first 250,000 engine-hours of fleet operating 
experience after the airplane enters revenue service. For the revenue 
service period, this system must define the sources and content of in-
service data that will be made available to the manufacturers in 
support of the problem tracking system. The content of the data 
provided must include, as a minimum, the data necessary to evaluate the 
specific cause of all service incidents reportable under Sec.  21.3(c) 
of part 21, in addition to any other failure or

[[Page 35345]]

malfunction that could prevent safe flight and landing of the airplane, 
or affect the ability of the crew to cope with adverse operating 
conditions.
    (4) Corrective actions for all problems discovered during the 
development and certification test program that could affect the safety 
of ETOPS operations, or the intended function of systems whose use is 
relied upon to accomplish the ETOPS mission, must be identified and 
implemented in accordance with paragraph (g)(2). If, during the 
certification program, it is discovered that a fault has developed that 
requires significant rework of manufacturing, maintenance, and/or 
operational procedures, the FAA will review the ETOPS suitability of 
the affected system and interfacing hardware and identify any 
additional actions to be accomplished to substantiate the corrective 
actions.
    (5) For each engine type to be certificated with the airplane, the 
system must include provisions for an accelerated engine cyclic 
endurance test program that will accumulate cycles on one 
representative production-equivalent propulsion system in advance of 
the high-cycle revenue fleet engine. This test program will assist the 
applicant and the FAA in identifying and correcting problems before 
they occur in revenue service. This program must be in place for, at a 
minimum, the first 250,000 engine-hours of fleet operating experience 
after the airplane enters revenue service. The representative 
production-equivalent propulsion system may, at the manufacturer's 
discretion, be used for other fleet support activities.
    (g) Reliability Assessment Board.
    (1) An FAA Reliability Assessment Board will be formed to evaluate 
the suitability of the airplane for ETOPS approval and make a 
recommendation to the Manager, Transport Airplane Directorate, 
regarding the adequacy of the type design for 180-minute ETOPS 
operation. The purpose of this board will be:
    (i) To periodically review the development and certification flight 
test program accomplishments from both type design and operational 
perspectives;
    (ii) To ensure that all specific problems, as well as their 
implications on the effectiveness of the Early ETOPS process, are 
resolved; and
    (iii) To assess the design suitability for ETOPS. The board will 
consider design, maintenance, manufacturing, and operational aspects of 
the type design when finding suitability for ETOPS approval.
    (2) The FAA Reliability Assessment Board will review and evaluate 
the data from the problem tracking and resolution system to establish 
compliance with the requirements of paragraph (h). The board will 
evaluate the overall type design for ETOPS suitability as demonstrated 
in flight test, and the Airplane Demonstration Test, considering all 
resolutions of problems. The following suitability criteria will be 
applied:
    (i) Sources of engine shutdown/thrust loss, engine anomalies, or 
airplane system problems that have a potential significant adverse 
effect on in-service safety will be resolved.
    (ii) Resolutions are identified for all items in paragraph (i) with 
analysis and/or testing to show all resolutions are effective. These 
resolutions may be accomplished through one or more of the following 
categories: Design change, Operating procedure revision, Maintenance 
procedure revision, Manufacturing change.
    (iii) The resolutions of paragraphs (i) and (ii) will be 
incorporated prior to entry into service.
    (iv) The engine shutdown history of the test program indicates that 
the engine reliability of the configuration is suitable for the ETOPS 
approval being considered.
    (v) Where interim resolutions having operational impact are 
defined, the cumulative effect must be determined to be acceptable.
    (vi) System or component failures experienced during the program 
are consistent with the assumptions made in the failure analyses.
    (h) Reliability Demonstration Acceptance Criteria.
    (1) For the engine and airplane systems, the type and frequency of 
failures that occur during the airplane flight test program and the 
Airplane Demonstration Test must be consistent with the type and 
frequency of failures or malfunctions that would be expected to occur 
on presently certified 180-minute ETOPS airplanes. The failures to be 
considered are those associated with system components that conform to 
the type design requested for certification. The Reliability Assessment 
Board will determine compliance with this requirement based on an 
evaluation of the problem reporting system data, considering system 
redundancies, failure significance, problem resolution, and engineering 
judgment.
    (2) Corrective action for any of the following classes of problems 
occurring during the testing identified in paragraph (h)(1) that 
requires a major system redesign would delay ETOPS type design 
approval, or result in approval of a reduced single-engine diversion 
time, unless corrective action has been substantiated to, and accepted 
by, the FAA Reliability Assessment Board:
    (i) Any source of unplanned inflight shutdown or loss of thrust.
    (ii) Any problem that jeopardizes the safety of an airplane 
diversion.
    (3) The FAA Reliability Assessment Board must determine that the 
suitability criteria of paragraph (g)(2) have been met.
    (i) Demonstration of Compliance. In order to be eligible for 180-
minute ETOPS type design approval, the following conditions apply:
    (1) The engine assessment has been completed and eligibility for 
ETOPS operation has been approved by the FAA Engine Certification 
Office.
    (2) All design, manufacturing, maintenance, operational, and other 
features necessary to meet the ETOPS requirements of paragraph (c)(1), 
and to resolve the problems identified in paragraph (c)(2), have been 
successfully implemented.
    (3) The identified test and analysis features in paragraph (c)(4) 
and (c)(5) have been shown to be effective in validating the successful 
implementation of the features in paragraph (i)(2).
    (4) The additional analysis requirements of paragraph (d) have been 
completed and the results have been approved.
    (5) The additional test requirements of paragraph (e) have been 
successfully completed.
    (6) All significant problems identified in accordance with 
paragraph (f) have been resolved, and fixes substantiated to be 
effective have been implemented.
    (7) The accelerated engine cyclic endurance test program of 
paragraph (f)(5) must be in place.
    (8) Compliance with the reliability demonstration acceptance 
criteria of paragraph (h) has been found by the Reliability Assessment 
Board.

    Issued in Renton, Washington on June 4, 2003.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-14992 Filed 6-12-03; 8:45 am]
BILLING CODE 4910-13-P