[Federal Register: April 8, 1998 (Volume 63, Number 67)]
[Rules and Regulations]               
[Page 17090-17092]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr08ap98-4]

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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.

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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 (V<INF>MCG</INF>).
    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