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Federal Register / Vol. 86, No. 184 / Monday, September 27, 2021 / Rules and Regulations analysis as described in Special Condition no. 17, the cooling system monitoring features and usage must be documented in the engine installation manual.
7. Engine-Mounting Attachments and Structure The engine-mounting attachments and related engine structures must comply with 14 CFR 33.23.
8. Accessory Attachments The engine must comply with 14 CFR
33.25.
9. Overspeed a A rotor overspeed must not result in a burst, rotor growth, or damage that results in a hazardous engine effect, as defined in Special Condition no.
17d2. Compliance with this paragraph must be shown by test, validated analysis, or a combination of both. Applicable assumed rotor speeds must be declared and justified.
b Rotors must possess sufficient strength with a margin to burst above certified operating conditions and above failure conditions leading to rotor overspeed. The margin to burst must be shown by test, validated analysis, or a combination thereof.
c The engine must not exceed the rotor speed operational limitations that could affect rotor structural integrity.

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10. Engine Control Systems a Applicability.
The requirements of this special condition apply to any system or device that is part of the engine type design, that controls, limits, monitors, or protects engine operation and is necessary for the continued airworthiness of the engine.
b Engine control.
The engine control system must ensure the engine does not experience any unacceptable operating characteristics or exceed its operating limits, including in failure conditions where the fault or failure results in a change from one control mode to another, from one channel to another, or from the primary system to the back-up system, if applicable.
c Design assurance.
The software and complex electronic hardware, including programmable logic devices, must be 1 Designed and developed using a structured and systematic approach that provides a level of assurance for the logic commensurate with the hazard associated with the failure or malfunction of the systems in which the devices are located; and
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2 Substantiated by a verification methodology acceptable to the Administrator.
d Validation.
All functional aspects of the control system must be substantiated by test, analysis, or a combination thereof, to show that the engine control system performs the intended functions throughout the declared operational envelope.
e Environmental limits.
Environmental limits that cannot be adequately substantiated by endurance demonstration, validated analysis, or a combination thereof must be demonstrated by the system and component tests in Special Condition no. 27.
f Engine control system failures.
The engine control system must 1 Have a maximum rate of Loss of Power Control LOPC that is suitable for the intended aircraft application;
2 When in the full-up configuration, be single fault tolerant, as determined by the Administrator, for electrical, electrically detectable, and electronic failures involving LOPC events;
3 Not have any single failure that results in hazardous engine effects; and 4 Not have any likely failure or malfunction that lead to local events in the intended aircraft application.
g System safety assessment.
The applicant must perform a system safety assessment. This assessment must identify faults or failures that affect normal operation, together with the predicted frequency of occurrence of these faults or failures. The intended aircraft application must be taken into account to assure the assessment of the engine control system safety is valid.
h Protection systems.
The engine control devices and systems design and function, together with engine instruments, operating instructions, and maintenance instructions, must ensure that engine operating limits will not be exceeded inservice.
i Aircraft-supplied data.
Any single failure leading to loss, interruption, or corruption of aircraftsupplied data other than power command signals from the aircraft, or aircraft-supplied data shared between engine systems within a single engine or between fully independent engine systems, must 1 Not result in a hazardous engine effect, as defined in Special Condition no. 17d2, for any engine installed on the aircraft; and 2 Be able to be detected and accommodated by the control system.
j Engine control system electrical power.

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1 The engine control system must be designed such that the loss, malfunction, or interruption of the control system electrical power source will not result in a hazardous engine effect, as defined in Special Condition no. 17d2, the unacceptable transmission of erroneous data, or continued engine operation in the absence of the control function. The engine control system must be capable of resuming normal operation when aircraft-supplied power returns to within the declared limits.
2 The applicant must identify and declare, in the engine installation manual, the characteristics of any electrical power supplied from the aircraft to the engine control system for starting and operating the engine, including transient and steady-state voltage limits, and any other characteristics necessary for safe operation of the engine.
11. Instrument Connection The applicant must comply with 14
CFR 33.29a, e, and g.
a In addition, as part of the system safety assessment of Special Condition no. 10g, the applicant must assess the possibility and subsequent effect of incorrect fit of instruments, sensors, or connectors. Where practicable, the applicant must take design precautions to prevent incorrect configuration of the system.
b The applicant must provide instrumentation enabling the flight crew to monitor the functioning of the engine cooling system unless evidence shows that:
1 Other existing instrumentation provides adequate warning of failure or impending failure;
2 Failure of the cooling system would not lead to hazardous engine effects before detection; or 3 The probability of failure of the cooling system is extremely remote.
12. Stress Analysis a A mechanical, thermal, and electromagnetic stress analysis must show a sufficient design margin to prevent unacceptable operating characteristics and hazardous engine effects.
b Maximum stresses in the engine must be determined by test, validated analysis, or a combination thereof and must be shown not to exceed minimum material properties.
13. Critical and Life-Limited Parts a The applicant must show, by a safety analysis or means acceptable to the Administrator, whether rotating or moving components, bearings, shafts,
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