ED Decision 2003/16/RM
(a) For the purpose of this Code, the powerplant installation includes each part of the rotorcraft (other than the main and auxiliary rotor structures) that:
(1) Is necessary for propulsion;
(2) Affects the control of the major propulsive units; or
(3) Affects the safety of the major propulsive units between normal inspections or overhauls.
(b) For each powerplant installation:
(1) The installation must comply with:
(i) The installation instructions provided under CS-E; and
(ii) The applicable provisions of this Subpart.
(2) Each component of the installation must be constructed, arranged, and installed to ensure its continued safe operation between normal inspections or overhauls for the range of temperature and altitude for which approval is requested.
(3) Accessibility must be provided to allow any inspection and maintenance necessary for continued airworthiness.
(4) Electrical interconnections must be provided to prevent differences of potential between major components of the installation and the rest of the rotorcraft.
(5) Axial and radial expansion of turbine engines may not affect the safety of the installation; and
(6) Design precautions must be taken to minimise the possibility of incorrect assembly of components and equipment essential to safe operation of the rotorcraft, except where operation with the incorrect assembly can be shown to be extremely improbable.
(c) For each powerplant and auxiliary power unit installation, it must be established that no single failure or malfunction or probable combination of failures will jeopardise the safe operation of the rotorcraft except that the failure of structural elements need not be considered if the probability of any such failure is extremely remote.
(d) Each auxiliary power unit installation must meet the applicable provisions of this Subpart.
ED Decision 2003/16/RM
(a) (Reserved)
(b) Category A; engine isolation. For each Category A rotorcraft, the powerplants must be arranged and isolated from each other to allow operation, in at least one configuration, so that the failure or malfunction of any engine, or the failure of any system that can affect any engine, will not –
(1) Prevent the continued safe operation of the remaining engines; or
(2) Require immediate action, other than normal pilot action with primary flight controls, by any crew member to maintain safe operation.
(c) Category A; control of engine rotation. For each Category A rotorcraft, there must be a means for stopping the rotation of any engine individually in flight, except that, for turbine engine installations, the means for stopping the engine need be provided only where necessary for safety. In addition –
(1) Each component of the engine stopping system that is located on the engine side of the firewall, and that might be exposed to fire, must be at least fire resistant; or
(2) Duplicate means must be available for stopping the engine and the controls must be where all are not likely to be damaged at the same time in case of fire.
(d) Turbine engine installation. For turbine engine installations,
(1) Design precautions must be taken to minimise the hazards to the rotorcraft in the event of an engine rotor failure; and,
(2) The powerplant systems associated with engine control devices, systems, and instrumentation must be designed to give reasonable assurance that those engine operating limitations that adversely affect engine rotor structural integrity will not be exceeded in service.
(e) Restart capability:
(1) A means to restart any engine in flight must be provided.
(2) Except for the in-flight shutdown of all engines, engine restart capability must be demonstrated throughout a flight envelope for the rotorcraft.
(3) Following the in-flight shutdown of all engines, in-flight engine restart capability must be provided.
AMC1 29.903(d)(1) Turbine engine installation
ED Decision 2023/001/R
FRAGMENT CONTAINMENT
This AMC supplements FAA AC 29.903 with regard to the credit that can be taken from engine manufacturer data substantiating the capability of the engine to contain fragments.
(a) Blade containment
Single blade radial containment is a CS-E / CS-APU requirement. Full credit is given to engine certification for blade containment, and no specific certification activity is required at helicopter level for blade failure. This approach is supported by the in-service experience.
(b) Small debris containment at engine level
Some engine designs feature the capability to retain radially small debris, featuring, for instance, a reinforced casing or blade shedding capability.
The engine uncontained model features a small debris over a ±15° spread angle. Small fragments can be a collateral effect of either large or intermediate fragment release, but are released over larger spread angles, typically ±15°. Therefore, from a CS 29.903(d) point of view, no credit can be given to engine radial containment for small debris, which might however have other safety benefits.
(c) Rotor containment at engine or APU level
CS-APU has provisions to demonstrate rotor containment. For engines, while not required by CS-E, engine manufacturers might decide to design their engines featuring rotor containment systems, for all or specific rotating stages.
— For engines, the containment capability is not required by CS-E and the corresponding data is not covered by the engine type certificate; the helicopter manufacturer should propose a mechanism to ensure that the data is valid, under their DOA or by validation through the engine type certificate whereas for an APU, CS-ETSO requirements are in place, and it can be expected that the data is covered by the ETSO issuance.
— In-service experience has shown that such containment features successfully perform their intended purpose of retaining the biggest debris (large fragments). However, small debris can defeat the containment system, either by missing it or by exiting through damages caused by the large fragments. Rotor containment systems, as explained in paragraph f.(1) of AC 29.903C, still require some activity at helicopter level to ensure that the risks associated with uncontained engine or APU uncontained failure are adequately mitigated.
Note: For APUs, AMC 20.128A defines an acceptable model based upon debris exiting the containment system with a 1 % residual energy.
[Amdt No: 29/11]
ED Decision 2023/001/R
This AMC replaces FAA AC 29-2C, § AC 29.903B and should be used when showing compliance with CS 29.903(e).
(a) Explanation
CS 29.903(e) requires that any engine must have a restart capability that has been demonstrated throughout a flight envelope to be certificated for the rotorcraft.
(b) Procedures
Compliance is usually shown by conducting actual in-flight restarts during flight tests or other tests in accordance with an approved test plan. However, CS 29.903(e)(2) does not require in-flight demonstration of restart capability for single-engine rotorcraft or for all-engine shutdown of multi-engine rotorcraft. In the past, engine restart capability for single-engine rotorcraft has been demonstrated on the ground taking into account altitude effects, warm engine characteristics, depleted battery, etc. However, latest-technology engines embody electronic engine controls (EEC or FADEC) that may have sophisticated starting or restarting laws. For these designs the engine restart capability demonstrated on ground may not provide the level of representativeness required and therefore applicants are encouraged to demonstrate the capability in flight. The minimum restart envelope for category A rotorcraft is discussed in AC 29.903A. The restart capability can consider windmilling of the engine as part of this restart capability; however, most rotorcraft airspeeds and the locations of the engines do not support engine windmilling up to start speeds. Only electrical power requirements were considered for restarting; however, other factors that may affect this capability are permitted to be considered. Engine restart capability following an in-flight shutdown of the engine in single-engine rotorcraft, or all engines in a multi-engine rotorcraft, is the primary requirement, and the means of providing this capability is left to the applicant. To minimise any potential altitude loss following the failure of one or more engines, engine restart should be available at the earliest opportunity. The engine certification should be checked to ensure that the flight manual instructions for in-flight restart are consistent with any specific engine restart requirements. If the procedure was only demonstrated on ground, this should be stated in the RFM.
[Amdt No: 29/11]
ED Decision 2003/16/RM
(a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft.
(b) The addition of the rotor and the rotor drive system to the engine may not subject the principal rotating parts of the engine to excessive vibration stresses. This must be shown by a vibration investigation.
ED Decision 2003/16/RM
For cooling fans that are a part of a powerplant installation the following apply:
(a) Category A. For cooling fans installed in Category A rotorcraft, it must be shown that a fan blade failure will not prevent continued safe flight either because of damage caused by the failed blade or loss of cooling air.
(b) Category B. For cooling fans installed in Category B rotorcraft, there must be means to protect the rotorcraft and allow a safe landing if a fan blade fails. It must be shown that :
(1) The fan blade would be contained in the case of a failure;
(2) Each fan is located so that a fan blade failure will not jeopardise safety; or
(3) Each fan blade can withstand an ultimate load of 1.5 times the centrifugal force expected in service, limited by either:
(i) The highest rotational speeds achievable under uncontrolled conditions; or
(ii) An overspeed limiting device.
(c) Fatigue evaluation. Unless a fatigue evaluation under CS 29.571 is conducted, it must be shown that cooling fan blades are not operating at resonant conditions within the operating limits of the rotorcraft.