Special Conditions: Dassault Aviation Model Falcon 2000 Airplane; Automatic Takeoff Thrust Control System

SUMMARY: This notice proposes special conditions for the Dassault

Aviation Model Falcon 2000 airplane. This new airplane will have an

unusual design feature associated with an Automatic Takeoff Thrust

Control System (ATTCS), for which the applicable airworthiness

regulations do not contain appropriate safety standards for approach

climb performance using an ATTCS. These proposed special conditions

contain the additional safety standards that the Administrator

considers necessary to establish a level of safety equivalent to that

established by the existing airworthiness standards.

DATES: Comments must be received on or before January 17, 1995.

ADDRESSES: Comments on these proposed special conditions may be mailed

in duplicate to: Federal Aviation Administration, Office of the

Assistant Chief Counsel, Attn.: Rules Docket (ANM-7), Docket No. NM-

103, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; or delivered

in duplicate to the Office of the Assistant Chief Counsel at the above

address. Comments must be marked ``Docket No. NM-103.'' 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:

Stephen Slotte, FAA, Standardization Branch, ANM-113, Transport

Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue

SW., Renton, Washington, 98055-4056, telephone (206) 227-2797.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of

these proposed special conditions by submitting such written data,

views, or arguments as they may desire. Communications should identify

the regulatory docket or notice number and be submitted in duplicate to

the address specified above. All communications received on or before

the closing date for comments will be considered by the Administrator

before further rulemaking action is taken on these proposals. The

proposals contained in this notice may be changed in light of the

comments received. All comments submitted will be available in the

Rules Docket for examination by interested persons, both before and

after the closing date for comments. A report summarizing each

substantive public contact with FAA personnel concerning this

rulemaking will be filed in the docket. Persons wishing the FAA to

acknowledge receipt of their comments submitted in response to this

request must submit with those comments a self-addressed, stamped

postcard on which the following statement is made: ``Comments to Docket

No. NM-103.'' The postcard will be date stamped and returned to the

commenter.

Background

On September 13, 1989, Dassault Aviation, B.P. 24, 33701

Merignac, Cedex, France, applied for a new type certificate

in the transport airplane category for the Model Falcon 2000 airplane.

The Dassault Aviation Model Falcon 2000 is a medium-sized

transcontinental business jet powered by two General Electric/Garrett

CFE 738 turbofan engines mounted on pylons extending from the aft

fuselage. Each engine will be capable of delivering 5,600 lbs. thrust.

The airplane will be capable of operation with two flight crewmembers

and eight passengers.

The Model Falcon 2000 will incorporate an unusual design feature,

the Automatic Takeoff Thrust Control System (ATTCS), referred to by

Dassault as Automatic Power Reserve or APR, to show compliance with the

approach climb requirements of Sec. 25.121(d). Appendix I to part 25

limits the application of performance credit for ATTCS to takeoff only.

Since the airworthiness regulations do not contain appropriate safety

standards for approach climb performance using ATTCS, special

conditions are required to ensure a level of safety equivalent to that

established in the regulations.

Type Certification Basis

Under the provisions of Sec. 21.17 of the FAR, Dassault Aviation

must show that the Falcon 2000 meets the applicable provisions of part

25, effective February 1, 1965, as amended by Amendments 25-1 through

25-69. The certification basis may also include later amendments to

part 25 that are not relevant to these special conditions. In addition,

the certification basis for the Falcon 2000 includes part 34, effective

September 10, 1990, plus any amendments in effect at the time of

certification; and part 36, effective December 1, 1969, as amended by

Amendments 36-1 through the amendment in effect at the time of

certification. These special conditions form an additional part of the

type certification basis. In addition, the certification basis may

include other special conditions that are not relevant to these special

conditions.

If the Administrator finds that the applicable airworthiness

regulations (i.e., part 25, as amended) do not contain adequate or

appropriate safety standards for the Dassault Aviation Model Falcon

2000 because of a novel or unusual design feature, special conditions

are prescribed under the provisions of Sec. 21.16 to establish a level

of safety equivalent to that established in the regulations.

Special conditions, as appropriate, are issued in accordance with

Sec. 11.49 of the FAR after public notice, as required by Secs. 11.28

and 11.29, and become part of the type certification basis in

accordance with Sec. 21.17(a)(2).

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).

Novel or Unusual Design Features

The Model Falcon 2000 will incorporate an unusual design feature,

the ATTCS (referred to by Dassault as the Automatic Power Reserve or

APR), to show compliance with the approach climb requirements of

Sec. 25.121(d). The FALCON 2000 is a twin-turbofan-powered airplane

equipped with Full Authority Digital Engine Controls (FADECs) that, in

part, protect against exceeding engine limits. Further, the FALCON 2000

incorporates a non-moving throttle system that functions by placing the

throttle levers in detents for the takeoff and climb phases of flight,

allowing the FADEC to schedule power setting based on flight phase.

With the throttle levers placed in either of the two forward detents

(takeoff/go-around and climb), if an engine failure (RPM (N1))

difference of greater than 10 percent between engines is sensed, power

is automatically advanced on the remaining engine to the APR power

level associated with the detent. The system is permanently armed and

will function any time the throttle levers are in either of the two

forward detents and an engine failure is sensed. Additionally, as in

the case of an APR failure, or in an all-engines mode, the crew can

select APR by placing the throttle levers in either of the two forward

detents and manually activating the system using an instrument panel-

mounted override switch.

APR power levels manifest themselves as an increase in the engine

flat-rating temperature for the operating altitude, and, in general,

result in higher thrust levels than those associated with the throttle

detents alone. Dassault also makes reference in the APR logic

description to thrust increase being armed for a throttle lever angle

above 27 degrees (max cruise position), but does not make it clear in

the system description if the APR system functions when the throttle is

not in a detent. Further discussions with Dassault make it clear that

when the throttle is between two detents, the FADEC makes a linear

intepolation between the related tables of corrected N1; i.e., an

almost linear thrust change. As function outside of a detent is

possible, then a throttle angle of 28 degrees (arming angle + 1 degree)

would produce almost no additional thrust when APR is activated, while

1 degree before the next detent (max cruise/max continuous) would

produce almost the same thrust increase as when the throttle is in that

detent. Logic for the max climb/max continuous detents is the same.

From a practical point of view, throttle positions between the detents

are not used.

The part 25 standards for ATTCS, contained in Sec. 25.904 and

Appendix I, specifically restrict performance credit for ATTCS to

takeoff. Expanding the scope of the standards to include other phases

of flight, including go-around, was considered at the time the

standards were issued, but flightcrew workload issues precluded further

consideration. As stated in the preamble to Amendment 25-62:

In regard to ATTCS credit for approach climb and go-around

maneuvers, current regulations preclude a higher thrust for the

approach climb (Sec. 25.121(d)) than for the landing climb

(Sec. 25.119). The workload required for the flightcrew to monitor

and select from multiple in-flight thrust settings in the event of

an engine failure during a critical point in the approach, landing,

or go-around operations is excessive. Therefore, the FAA does not

agree that the scope of the amendment should be changed to include

the use of ATTCS for anything except the takeoff phase. (52 FR

43153, November 9, 1987)

The ATTCS incorporated on the FALCON 2000 allows the pilot to use

the same power setting procedure during a go-around, regardless of

whether or not an engine fails. In either case, the pilot obtains go-

around power by moving the throttles into the forward (takeoff/go-

around) throttle detent. Since the ATTCS is permanently armed, it will

function automatically following an engine failure, and advance the

remaining engine to the ATTCS thrust level. Therefore, this design

adequately addresses the pilot workload concerns identified in the

preamble to Amendment 25-62. Accordingly, these proposed special

conditions would require a showing of compliance with those provisions

of Sec. 25.904 and Appendix I that are applicable to the approach climb

and go-around maneuvers.

The definition of a critical time interval for the approach climb

case, during which time it must be extremely improbable to violate a

flight path based on the Sec. 25.121(d) gradient requirement, is of

primary importance. The Sec. 25.121(d) gradient requirement implies a

minimum one-engine-inoperative flight path capability with the airplane

in the approach configuration. The engine may have been inoperative

before initiating the go-around, or it may become inoperative during

the go-around. The definition of the critical time interval must

consider both possibilities.

As discussed above, these proposed special conditions would be

applicable to the Dassault Aviation Model Falcon 2000. Should Dassault

Aviation apply at a later date for a change to the type certificate to

include another model incorporating the same novel or unusual design

feature, these special conditions would apply to that model as well

under the provisions of Sec. 21.101(a)(1).

Conclusion

This action affects only certain design features on the Dassault

Aviation Model Falcon 2000 airplane. It is not a rule of general

applicability and affects only the manufacturer who applied to the FAA

for approval of these features on the airplane.

List of Subjects in 14 CFR Part 25

Aircraft, Aviation safety, Reporting and recordkeeping

requirements.

The authority citation for these proposed special conditions is as

follows:

Authority: 49 U.S.C. app. 1344, 1348(c), 1352, 1354(a), 1355,

1421 through 1431, 1502, 1651(b)(2), 42 U.S.C. 1857f-10, 4321 et

seq.; E.O. 11514; and 49 U.S.C. 106(g).

The Proposed Special Conditions

Accordingly, the Federal Aviation Administration (FAA) proposes the

following special conditions as part of the type certification basis

for the Dassault Aviation Model Falcon 2000 airplane.

(a) General: An ATTCS is defined as the entire automatic system,

including all devices, both mechanical and electrical, that sense

engine failure, transmit signals, actuate fuel controls or power

levers, or increase engine power by other means on operating engines to

achieve scheduled thrust or power increases and furnish cockpit

information on system operation.

(b) Automatic takeoff thrust control system (ATTCS). The engine

power control system that automatically resets the power or thrust on

the operating engine (following engine failure during the approach for

landing) must comply with the following requirements:

(1) Performance and System Reliability Requirements. The

probability analysis must include consideration of ATTCS failure

occurring after the time at which the fightcrew last verifies that the

ATTCS is in a condition to operate until the beginning of the critical

time interval.

(2) Thrust Setting. The initial takeoff thrust set on each engine

at the beginning of the takeoff roll or go-around may not be less than:

(i) Ninety (90) percent of the thrust level set by the ATTCS (the

maximum takeoff thrust or power approved for the airplane under

existing ambient conditions);

(ii) That required to permit normal operating of all safety-related

systems and equipment dependent upon engine thrust or power lever

position; or

(iii) That shown to be free of hazardous engine response

characteristics when thrust is advanced from the initial takeoff thrust

or power to the maximum approved takeoff thrust or power.

(3) Powerplant Controls. In addition to the requirements of

Sec. 25.1141, no single failure or malfunction, or probable combination

thereof, of the ATTCS, including associated systems, may cause the

failure of any powerplant function necessary for safety. The ATTCS must

be designed to:

(i) Apply thrust or power on the operating engine(s), following any

one engine failure during takeoff or go-around, to achieve the maximum

approved takeoff thrust or power without exceeding engine operating

limits; and

(ii) Provide a means to verify to the flightcrew before takeoff and

before beginning an approach for landing that the ATTCS is in a

condition to operate.

(c) Critical Time Interval. The definition of the Critical Time

Interval in Appendix I, Section 125.2(b) shall be expanded to include

the following:

(1) When conducting an approach for landing using ATTCS, the

critical time interval is defined as follows:

(i) The critical time interval begins at a point on a 2.5 degree

approach glide path from which, assuming a simultaneous engine and

ATTCS failure, the resulting approach climb flight path intersects a

flight path originating at a later point on the same approach path

corresponding to the Part 25 one-engine-inoperative approach climb

gradient. The period of time from the point of simultaneous engine and

ATTCS failure to the intersection of these flight paths must be no

shorter than the time interval used in evaluating the critical time

interval for takeoff beginning from the point of simultaneous engine

and ATTCS failure and ending upon reaching a height of 400 feet.

(ii) The critical time interval ends at the point on a minimum

performance, all-engines-operating go-around flight path from which,

assuming a simultaneous engine and ATTCS failure, the resulting minimum

approach climb flight path intersects a flight path corresponding to

the Part 25 minimum one-engine-inoperative approach climb gradient. The

all-engines-operating go-around flight path and the Part 25 one-engine-

inoperative approach climb gradient flight path originate from a common

point on a 2.5 degree approach path. The period of time from the point

of simultaneous engine and ATTCS failure to the intersection of these

flight paths must be no shorter than the time interval used in

evaluating the critical time interval for the takeoff beginning from

the point of simultaneous engine and ATTCS failure and ending upon

reaching a height of 400 feet.

(2) The critical time interval must be determined at the altitude

resulting in the longest critical time interval for which one-engine-

inoperative approach climb performance data are presented in the

Airplane Flight Manual.

(3) The critical time interval is illustrated in the following

figure:

BILLING CODE 4910-13-M

TP16DE94.070

BILLING CODE 4910-13-C

*The engine and ATTCS failed time interval must be no shorter

than the time interval from the point of simultaneous engine and

ATTCS failure to a height of 400 feet used to comply with I25.2(b)

for ATTCS use during takeoff.

Issued in Renton, Washington, on December 2, 1994.

Darrell M. Pederson,

Acting Manager Transport Airplane Directorate Aircraft Certification

Service, ANM-100.

[FR Doc. 94-30955 Filed 12-15-94; 8:45 am]

BILLING CODE 4910-13-M