[Federal Register Volume 68, Number 109 (Friday, June 6, 2003)]
[Rules and Regulations]
[Pages 33836-33840]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-14337]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM255; Special Conditions No. 25-03-04-SC]


Special Conditions: Bombardier Model BD-100-1A10 Airplane; 
Automatic Takeoff Thrust Control System

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the Bombardier Model 
BD-100-1A10 airplane. This airplane will have a novel or unusual design 
feature when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. This design 
feature is associated with an Automatic Takeoff Thrust Control System 
(ATTCS). The applicable airworthiness regulations do not contain 
adequate or appropriate safety standards for approach climb performance 
using an ATTCS. These special conditions contain the additional safety 
standards the Administrator considers necessary to establish a level of 
safety equivalent to that established by the existing airworthiness 
standards.

DATES: The effective date of these special conditions is May 28, 2003.
    Comments must be received on or before July 7, 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. NM255, 1601 Lind Avenue 
SW., Renton, Washington 98055-4056; or delivered in duplicate to the 
Transport Airplane Directorate at that address. You must mark your 
comments: Docket No. NM255. Comments may be inspected in the Rules 
Docket at that address on weekdays, except Federal holidays, between 
7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Larry Reising, FAA, Propulsion/ 
Mechanical Systems Branch, Transport Airplane Directorate, Aircraft 
Certification Office, ANM-112, 1601 Lind Avenue SW., Renton, 
Washington, telephone (425) 227-2683; fax (425) 227-2683.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice and 
opportunity for prior public comment hereon are impracticable, because 
those procedures would significantly delay issuance of the approval 
design and thus delivery of the affected aircraft. In addition, the 
substance of these special conditions has been subject to the public 
comment process in several prior instances with no substantive comments 
received. The FAA, therefore, finds that good cause exists for making 
these special conditions effective upon issuance.

Comments Invited

    The FAA has determined that notice and opportunity for public 
comment in accordance with 14 CFR 11.38 are unnecessary, because the 
FAA has provided previous opportunities to comment on substantially 
identical special conditions and has fully considered and addressed all 
the substantive comments received. Based on a review of the comment 
history and the comment resolution, the FAA is satisfied that new 
comments are unlikely. The FAA, therefore, finds that good cause exists 
for making these special conditions effective upon issuance.
    However, the FAA invites interested persons to participate in this 
rulemaking by submitting written comments, data, and 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 the FAA 
personnel concerning these proposed 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 notice 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 the 
special conditions based on the comments we receive.
    If you want the FAA to acknowledge receipt of your comments on 
these special conditions, 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

    On March 26, 1999, Bombardier Aerospace submitted an application to

[[Page 33837]]

Transport Canada for type certification of the Bombardier Model BD-100-
1A10. On June 28, 1999, Transport Canada made application on behalf of 
Bombardier for type certification of the Model BD-100-1A10 by the FAA. 
The Bombardier Model BD-100-1A10 will be type certificated in Canada 
and in the United States. The Model BD-100-1A10 is a medium-sized 
transport category airplane, powered by two Allied Signal high bypass 
turbofan engines mounted on the aft fuselage. Each engine can deliver 
up to 6,500 pounds of thrust at takeoff. The airplane will be capable 
of operating with two flight crewmembers and up to 16 passengers.
    The Bombardier Model BD-100-1A10 airplane will incorporate an 
unusual design feature to show compliance with the approach climb 
requirements of Sec.  25.121(d) (``Climb: One-engine-inoperative''). 
This design feature is the Automatic Takeoff Thrust Control System 
(ATTCS). Appendix I to Title 14, Code of Federal Regulations (CFR), 
part 25, limits the application of performance credit for ATTCS to 
takeoff. 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, Bombardier must show that 
Bombardier Model BD-100-1A10 meets the applicable provisions of 14 CFR 
part 25, effective February 1, 1965, including amendments 25-1 through 
25-98.
    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 Bombardier Model BD-100-1A10 
airplane because of novel or unusual design features, special 
conditions are prescribed under the provisions of Sec.  21.16.
    The certification basis also may include later amendments to part 
25 that are not relevant to these special conditions. In addition, the 
certification basis for the Bombardier Model BD-100-1A10 airplane 
includes the following:
    [sbull] 14 CFR part 34, effective September 10, 1990, including 
amendment 34, effective February 3, 1999, and
    [sbull] 14 CFR part 36, effective December 1, 1969, including 
amendments 36-1 through 36-23 or through 36-24, as elected by the 
applicant.
    These special conditions form an additional part of the type 
certification basis. The certification basis also may include other 
special conditions that are not relevant to these specific special 
conditions.
    If the Administrator finds that the applicable airworthiness 
regulations (in this case, part 25) do not contain adequate or 
appropriate safety standards for the Bombardier Model because of a 
novel or unusual design feature, the FAA may prescribe special 
conditions under the provisions of Sec.  21.16 (``Special 
conditions''). The special conditions become part of the type 
certification basis in accordance with Sec.  21.101(b)(2) 
(``Designation of applicable regulations'').
    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

    As stated previously, the Bombardier Model BD-100-1A10 airplane 
will incorporate an unusual design feature--ATTCS--to show compliance 
with the approach climb requirements of Sec.  25.121(d). This airplane 
is powered by two Allied Signal turbofan engines mounted on the aft 
fuselage and equipped with Full Authority Digital Engine Controls 
(FADEC) that, in part, protect against exceeding engine limits.
    The airplane also incorporates a non-moving throttle system that 
functions by placing the throttle levers in detents for the takeoff and 
climb phases of flight or for a go-around; this throttle system allows 
the FADEC to schedule the power setting, based on the phase of flight. 
With the ATTCS and associated systems functioning as designed, all 
applicable requirements of part 25 will be met without requiring any 
action by the flight crew to increase power.
    Automatic takeoff power control on the Bombardier Model BD-100-1A10 
airplane involves uptrimming the operating engine to maximum takeoff 
power. This action will be controlled by the FADEC. At takeoff, when 
the power levers are set to the Takeoff Go-Around (TOGA) detent, if 
there are no FADEC fault or failure messages displayed, the system is 
armed, and ATTCS uptrim will occur without any further action by the 
crew if an engine fails. During a go-around, the uptrim is 
automatically armed.
    For a go-around, the thrust levers are placed in the TOGA detent. 
The value of TOGA for the current ambient conditions will be calculated 
and set by the FADEC. If an engine fails, the ATTCS will change the 
power reference on the operating engine to achieve the maximum go-
around power for the ambient conditions. The propulsive thrust used to 
determine compliance with the approach climb requirements of Sec.  
25.121(d) is limited to the lesser of (i) the thrust provided by the 
ATTCS system, and (ii) 111 percent of the thrust resulting from the 
initial thrust setting with the ATTCS system failing to perform its 
uptrim function and without action by the crew to reset thrust. This 
requirement serves to limit the performance effects of an ATTCS system 
failure and ensures that all-engines-operating go-around performance is 
not significantly degraded.
    The engine operating limits (turbine temperature and N1) for TOGA 
are set and displayed to the pilot when that rating is selected. These 
limits are set in such a way that the engine redline limits are not 
exceeded when an ATTCS is engaged. When the maximum takeoff power 
rating is selected or triggered, the engine limits are reset 
automatically to reflect the uptrimmed engine redline limits.
    The system is armed during all phases of the flight. The power 
levers will continue to function normally if the ATTCS should fail. 
Maximum takeoff/go-around power is available if the pilot elects to 
push the power levers past the takeoff/go-around power detent into the 
overtravel range.
    Operations of all systems and equipment will be designed to 
function within the engine power range. Thrust increase from the 
initial to the maximum approved takeoff/go-around power level will be 
free of hazardous engine response characteristics.
    The ATTCS function, as described above, is part of the powerplant 
control system. The ATTCS is always armed whenever power levers are 
above the idle detent. The system is verified before each flight via 
the FADEC built-in test feature. When the ATTCS is triggered following 
an engine failure, an ``APR'' message will appear on the engine 
display.
    The FADEC installed on the Bombardier Model BD-100-1A10 airplane 
will ensure that inherent flight characteristics of the airplane do 
provide adequate warning, if an engine failure occurs during takeoff. 
The natural yawing tendency of the airplane, coupled with flashing 
master warning and master caution lights, will provide

[[Page 33838]]

the pilot with a clear indication of any engine failure during takeoff.
    The part 25 standards for ATTCS, contained in Sec.  25.904 
(Automatic takeoff thrust control system (ATTCS)'') and Appendix I, 
specifically restrict performance credit for ATTCS to takeoff. 
Expanding the scope of the standards to include other phases of flight, 
such as go-around, was considered at the time the standards were 
issued, but flight crew 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.'' (Refer to 52 FR 
43153, November 9, 1987.)

    The ATTCS incorporated on the Bombardier Model BD-100-1A10 airplane 
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 special conditions will 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 gradient requirement of Sec.  25.121(d), is of 
primary importance. That 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.

Applicability

    As discussed above, these special conditions are applicable to the 
Bombardier Model BD-100-1A10 airplane. Should Bombardier apply later 
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), Amendment 21-69, effective September 16, 1991.

Conclusion

    This action affects only certain novel or unusual design features 
on the Bombardier Model BD-100-1A10 airplane. It is not a rule of 
general applicability and affects only the applicant that applied to 
the FAA for approval of these features on the airplane.
    The substance of these special conditions has been subjected to the 
notice and public comment process in several prior instances, and has 
been derived without substantive change from those special conditions 
previously issued. It is unlikely that prior public comment on this 
action would result in a significant change from the substance 
contained in this document. For this reason, and because a delay would 
significantly affect the certification of the airplane, which is 
imminent, the FAA has determined that prior public notice and comment 
are unnecessary and impracticable. The FAA is requesting comments to 
allow interested persons to submit views that may not have been 
submitted in response to the prior opportunities for comment described 
above.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

0
The authority citation for these special conditions is as follows:

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

The Special Conditions

0
Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for the Bombardier Model BD-100-1A10 
airplane.
    1. General. An Automatic Takeoff Thrust Control System (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.
    2. 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 stated in paragraphs 2.a, 2.b, and 2.c:
    a. Performance and System Reliability Requirements.
    (1) The probability analysis must include consideration of ATTCS 
failure occurring after the time at which the flightcrew last verifies 
that the ATTCS is in a condition to operate until the beginning of the 
critical time interval.
    (2) The propulsive thrust obtained from the operating engine after 
failure of the critical engine during a go-around used to show 
compliance with the one-engine-inoperative climb requirements of Sec.  
25.12(d) may not be greater than the lesser of:
    (i) The actual propulsive thrust resulting from the initial setting 
of power or thrust controls with the ATTCS system functioning; or
    (ii) 111 percent of the propulsive thrust resulting from the 
initial setting of power or thrust controls with the ATTCS system 
failing to reset thrust or power and without any action by the crew to 
reset thrust or power.
    b. Thrust or Power Setting.
    (1) The initial thrust or power setting on each engine at the 
beginning of the takeoff roll or go-around may not be less than any of 
the following:
    (i) That required to permit normal operation of all safety-related 
systems and equipment dependent upon engine thrust or power lever 
position; and
    (ii) That shown to be free of hazardous engine response 
characteristics and not to result in any unsafe aircraft operating or 
handling characteristics when thrust or power is increased from the 
initial takeoff or go-around thrust or power to the maximum approved 
takeoff thrust or power.
    (2) For approval of an ATTCS system for go-around, the thrust or 
power setting procedure must be the same for go-arounds initiated with 
all engines operating as for go-arounds initiated with one engine 
inoperative.
    c. 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:
    (1) Apply thrust or power on the operating engine(s), following any 
one engine failure during takeoff or go-around, to achieve the maximum

[[Page 33839]]

approved takeoff thrust or power without exceeding engine operating 
limits; and
    (2) 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.
    3. Critical Time Interval. The definition of the Critical Time 
Interval in appendix I, Sec.  I25.2(b) shall be expanded to include the 
following:
    a. When conducting an approach for landing using ATTCS, the 
critical time interval is defined as follows:
    (1) 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.
    (2) 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.
    b. 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 (AFM).
    c. The critical time interval is illustrated in the following 
figure:
[GRAPHIC] [TIFF OMITTED] TR06JN03.035



[[Page 33840]]


    Issued in Renton, Washington, on May 28, 2003.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-14337 Filed 6-5-03; 8:45 am]
BILLING CODE 4910-13-P