AC 33.28-3

Advisory circular · Guidance Material For 14 CFR 33.28, Engine Control Systems

Approved
May 23, 2014
Last reviewed
July 31, 2017
Family
AC 33.28-3 · 1 version
14 CFR parts
33
14 CFR sections
§ 33.28

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed October 23, 2026.

Show pages 66–77

Destructive Event. Any malfunction or failure of the EEC system that may result in a condition in which the engine, or any of its components, causes physical damage to the airplane structure or its occupants that may affect continued safe operation of the airplane. Examples include engine separation from its mounts, uncontrolled fire, inability to shutdown the engine, generation of toxic products, or uncontained high-energy debris.

Dispatchable Configuration. All control system configurations approved for flight dispatch.

Electronic Engine Control System (EECS). An engine control system in which the primary functions are provided using electronics. It includes all the components (e.g. electrical, electronic, hydromechanical and pneumatic) necessary for the control of the engine and may incorporate other control functions where desired. Components of the system provided by the installer may be considered part of the system.

Engine Control System (ECS). Any system or device that controls, limits, or monitors active engine operation.

Engine Dedicated Power Source. An electric power source providing electrical power generated and supplied solely for use by a single engine control system.

Engine/Propeller Control System (ECS/PCS). Any system that is an integrated engine and propeller control system. The system then contains elements of both ECS and PCS.

Erroneous data. Data that appears to be valid, but is incorrect.

Error. An omission or incorrect action by a person, a mistake in requirements, in design, or in implementation. An error may result in a failure, but an error is not a failure in and of itself.

Failure. An occurrence that affects the operation of a component, part, or element such that it can no longer function as intended (this includes both loss of function and malfunction). Note:

errors may cause failures, but are not considered to be failures.

Failure Condition. A condition with a direct, consequential engine-level effect caused or contributed to by one or more failures. Examples include any unwanted limitation of thrust to idle or total loss of a signal.

Failure Mode. The cause of the failure or the manner in which an item or function can fail.

Examples include failures due to corrosion or fatigue, opens and shorts in circuits, and malfunctions of electronic components.

Fault. A manifestation of an error in a component, part, element, or system that may lead to a failure.

Fault (or) Failure Accommodation. The capability to mitigate, either wholly or in part, the effects of a fault or failure.

A5-2

Full Authority Digital Engine Control (FADEC). An engine control system in which the primary functions are provided using digital electronics and in which the electronic engine control (EEC) unit has full-range authority over the engine power or thrust.

Full-up Configuration. An EECS that has no known faults or failures present that affect the loss of thrust (or power) control rate.

Local Events. Failures of aircraft systems and components, other than the EECS, that may affect the installed environment of the EEC unit.

Loss of Power Control (LOPC). A ECS failure event resulting in the inability to attain at least 85% of rated power or to modulate power under normal operating conditions.

Loss of Thrust Control (LOTC). An ECS failure event on a turbine engine that results in the inability to attain at least 90% of rated thrust or to modulate thrust under normal operating conditions.

Minor Power Loss (MPL). A reciprocating engine ECS failure event resulting in the ability to attain less than 95%, but still greater than 85%, of rated power.

Primary Mode. The mode for controlling the engine under normal operation; often referred to as the ‘normal mode.

Primary System. The part of the ECS/PCS normally used for controlling the engine/propeller operation.

Programmable Logic Device (PLD). An electronic component that is altered to perform an installation specific function. PLDs include, but are not limited to, Programmable Array Logic (PAL) components, General Array Logic (GAL) components, Field Programmable Gate Array (FPGA) components, and Erasable Programmable Logic Devices (EPLDs). These devices are a subset of AEH.

Propeller Control System (PCS). Any system or device that is part of the propeller type design that controls, limits, or monitors propeller operation.

Redundancy. Multiple independent methods incorporated within a system to accomplish a given function.

Time-Limited Operations (TLO). The duration of reciprocating engine flight operations permitted with the EEC system in a degraded condition.

Uncovered Fault. A fault or failure for which either no detection mechanism exists or, if detected, no accommodation exists.

Unsafe Condition. For the purposes of this AC, any malfunction or failure of a reciprocating engine EECS that could result in a destructive event or EECS LOPC and MPL rate in excess of A5-3

those specified in Tables A3-1 and A3-2 of this AC. This definition is intended to apply to reciprocating engine EECS.

A5-4

J Advbory ~r Feedback Information If you have eemments or recommendations tbr improving this advisory cmmlar (AC). or suggestions for new items or subjects to be added. or if you find an error, you may Jet us know abOUl by using this page as a template. and I) emailing it to 9-A WA-AVS-AIR.SOO-Coord@faa.gov or 2) ming it to the attention of the AIR I>ireetives Management Officer at 202-267-3933.

Subject: (insert AC number and title) Date: (insert date) Pa.mgraph _______ _ Page -- Type of error (check all that iq>ply): Editorial:--- Proeeduml­ Conceptual __ Description/Comnients!'-------------------- In a future change to this advisory ciroular, please include coverage on the following subject:

(briefly describe what you want added attaching separate sheets if necessary) Name: _________ _ AC 33.28-3 5/23/14

A6-1