[Federal Register Volume 63, Number 67 (Wednesday, April 8, 1998)]
[Rules and Regulations]
[Pages 17090-17092]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-9211]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM145; Special Conditions No. 25-137-SC]
Special Conditions: Lockheed-Martin Model 382J, Automatic Thrust
Control System
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
-----------------------------------------------------------------------
SUMMARY: These special conditions are issued for the Lockheed-Martin
Model 382J airplane. This airplane will have a novel or unusual design
feature associated with an automatic thrust control system. The
applicable airworthiness regulations do not contain adequate or
appropriate safety standards for this design feature. These 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.
EFFECTIVE DATE: May 8, 1998.
FOR FURTHER INFORMATION CONTACT: Connie Beane, FAA, Standardization
Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue SW, Renton, Washington 98055-4056; telephone
(425) 227-2796.
SUPPLEMENTARY INFORMATION:
Background
On August 28, 1992, Lockheed-Martin applied for an amendment to
Type Certificate No. A1S0 to include the new Model 382J. The Model
382J, which is a derivative of the Model 382G currently approved under
Type Certificate No. A1S0, is a high wing/low tail configured four-
engine turboprop airplane derived from the Lockheed C-130 Hercules
military transport. The Model 382J incorporates a new Full Authority
Digital Engine Control (FADEC), Allison engines with six blade
composite propellers, a modernized cockpit including Electronic Flight
Instrument Systems (EFIS), Engine Indication and Crew Alerting Systems
(EICAS), and a Head Up Display (HUD) of primary flight information.
The increased thrust provided by the new engine/propeller
installation would result in the Model 382J being limited by ground
minimum control speed (VMCG) over a large part of the proposed takeoff
operating envelope, which in turn would result in unbalanced takeoff
field lengths that Lockheed-Martin finds unacceptable. In order to
remedy this situation, Lockheed-Martin has developed an electronically
controlled system that will monitor engine and propeller performance,
and in the event of a failure of an outboard propulsion unit, will
reduce the power setting on the functioning outboard engine to a level
that permits compliance with the requirements of Sec. 25.149(e); the
operation of this system will thus optimize takeoff field lengths for
the Model 382J.
Type Certification Basis
Under the provisions of Sec. 21.101, Lockheed-Martin must show that
the Model 382J meets the applicable provisions of the regulations
incorporated by reference in Type Certificate No. A1SO or the
applicable regulations in effect on the date of application for the
change to the Model 382J. 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. A1SO are as follows:
The certification basis for the present Model 382 series airplanes
is Civil Aviation Regulations (CAR) 9a, which references CAR 4b,
effective December 31, 1953, including Amendments 4b-1 through 4b-11,
SR422B, SR450A, and Amendment 4b-12 as related to CAR 4b.307(a).
[[Page 17091]]
The applicable certification basis for the Model 382J is part 25 of
the Federal Aviation Regulations (FAR) through Amendment 25-80 for all
new or significantly modified portions of the Model 382J (as compared
to the present Model 382) and for unmodified portions of the airplane,
the applicable certification standard will be the rules that were
effective on February 1, 1965 (part 25, Amendment 25-0). In addition,
the certification basis includes certain special conditions that are
not relevant to these proposed 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 Model 382J 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, the Model 382J 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 appropriate, are issued in accordance with
Sec. 11.49 after public notice, as required by Secs. 11.28 and
11.29(b), and become part of the type certification basis in accordance
with Sec. 21.101(b)(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 382J will incorporate the following novel or unusual
design features:
The Lockheed Model 382J has an Automatic Control System which will,
in the event of engine failure on the outboard engine, automatically
feather the propeller on the engine and will automatically modulate the
output torque on the opposite engine to reduce asymmetric thrust. This
system is intended to allow the Model 382J to operate to takeoff
decision speeds that result in balanced field lengths, when the
decision speed would otherwise be constrained by ground minimum control
speed (VMCG).
The system is resident in each of the two outboard mission
computers, which will limit the differential torque between the two
outboard engines by sending torque limit commands to each of the two
Full Authority Digital Engine Controls on each engine. The differential
torque limit is a function of ambient condition and airspeed, so that
in the event of engine failure during takeoff the functional outboard
engine will have its output torque momentarily reduced, and then
gradually increased as the airplane continues to accelerate. At a
certain point in the takeoff, the thrust is restored to its takeoff
rated value. This torque differential limiting acts in a similar
fashion if the power is manually reduced by retarding the power lever
while the airplane is operating in the envelope of atmospheric
conditions and airspeeds where the ATCS is designed to function.
Discussion of Comments
Notice of Proposed Special Conditions No. 25-98-01-SC for the
Lockheed-Martin L382J airplane, was published in the Federal Register
on January 14, 1998 (63 FR 2186). Two commenters responded to the
notice. One commenter supports the notice. The other commenter
questions the need for an override of the ATCS (Special Condition No.
3), stating this would only be of use to disable the system if it
operated when not required and this should, by definition, be
nonhazardous. The commenter likens the inadvertent power reduction on
an outboard engine, without a failure of the opposite outboard engine,
to a very mild engine failure. The commenter states this should be no
more hazardous than a normal engine failure, for which the requirements
of part 25 apply. The FAA does not disagree that the specific scenario
presented by the commenter has a benign effect compared to the critical
engine failure that is assumed in all of the part 25 takeoff
performance determinations. There are other circumstances where a
failure of the ATCS system that would partially reduce the power on a
single engine might pose a hazard, for instance, a balked landing climb
where the required gradient would not be achievable without obtaining
rated power from all four engines. The FAA believes that requiring the
installation of an override is necessary to achieve an adequate level
of safety. The special condition also requires provisions to prevent
inadvertent operation with the ATCS disabled by requiring clear
annunciation of ATCS armed state (Special Condition No. 2.) and by
incorporation into the takeoff configuration warning system.
Applicability
As discussed above, these special conditions are applicable to the
Model 382J. Should Lockheed-Martin apply at a later date for a change
to the type certificate to include another model incorporating the same
novel or unusual design feature, the special conditions would apply to
that model as well under the provision of Sec. 25.101(a)(1).
Conclusion
This action affects only certain novel or unusual design features
on one model of 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 14 CFR Part 25
Air transportation, Aircraft safety, Safety.
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Special Conditions
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 Lockheed-Martin Model 382J
airplane.
1. The Automatic Thrust Control System (ATCS) shall be designed so
that the combined probability of engine failure and ATCS failure is
extremely improbable (on the order of 1 X 10-9 per flight hour).
Inadvertent operation of the ATCS shall be improbable (on the order of
1 X 10-5 per flight hour). These requirements may drive the necessity
for automatic fault detection and annunciation and/or periodic
functional checks. For the purposes of this requirement, the ATCS is
intended to include but is not limited to, all engine failure detection
means, all sensor inputs used to compute thrust modulation
requirements, all communication provisions between system components
(Mil-Std-1553 bus, for example), and actuation mechanisms for the
propeller feathering and outboard engine thrust control.
2. Flight deck annunciation of the armed state of the ATCS shall be
provided. ATCS failed or not armed must be incorporated into the
takeoff configuration warning system, or alternatively, a visual
annunciation can be incorporated if the annunciation lies within the
primary field of view of both pilots.
3. Provisions for flightcrew override of the ATCS must be provided.
The
[[Page 17092]]
provisions must be through power level actuation, or alternatively,
through other means provided the means (1) is located on or forward of
the power levers, (2) is easily identified and operated under all
operating conditions by either pilot with the hand that is normally
used to actuate the power levers, and (3) meets the location, sense of
motion, and accessibility requirements of Sec. 25.777(a), (b), and (c).
4. The critical engine must be identified for the performance
requirements of paragraphs 5 and 6 below, i.e., the performance must
account for failure of a critical outboard engine with the ATCS
(including autofeather) operating, or failure of the critical inboard
engine to a feathered propeller condition, whichever is more adverse.
5. The performance must conservatively account for the failure of
the critical engine at the critical point in the takeoff path. The
effect of the ATCS thrust modulation on the gross and net takeoff paths
must be modeled into the published performance data. The approved
takeoff distance established in accordance with Sec. 25.113 must
account for the adverse effect of ATCS on thrust-to-weight ratio.
6. The one-engine-inoperative climb gradient requirements of
Sec. 25.121 must be met at the critical power operating condition for
each climb segment. The most critical adverse effect of the ATCS on the
thrust-to-weight ratio must be accounted for in establishing the climb
limited weights for all ambient conditions within the approved
envelope.
7. The determination of minimum control speeds must account for the
critical failure mode (ATCS controlled outboard engine failure versus
feathered propeller inboard engine failure) for directional
controllability.
8. Any reduced takeoff power procedures must be shown compatible
with operation of the ATCS and must not result in any reduction in the
level of safety established for operation of the airplane with normal
takeoff power settings and ATCS operating.
9. The ATCS must clearly indicate to the crew when it has been
activated, and indicate that the output torque from the modulated
engine is being adequately controlled by the ATCS.
Issued in Renton, Washington, on March 31, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 98-9211 Filed 4-7-98; 8:45 am]
BILLING CODE 4910-13-P
