ED Decision 2003/2/RM
(a) Each engine must have an independent oil system that can supply it with an appropriate quantity of oil at a temperature not above that safe for continuous operation.
(b) The usable oil capacity may not be less than the product of the endurance of the aeroplane under critical operating conditions and the approved maximum allowable oil consumption of the engine under the same conditions, plus a suitable margin to ensure system circulation.
ED Decision 2003/2/RM
(a) Installation. Each oil tank installation must meet the requirements of CS 25.967.
(b) Expansion space. Oil tank expansion space must be provided as follows:
(1) Each oil tank must have an expansion space of not less than 10% of the tank capacity.
(2) Each reserve oil tank not directly connected to any engine may have an expansion space of not less than 2% of the tank capacity.
(3) It must be impossible to fill the expansion space inadvertently with the aeroplane in the normal ground attitude.
(c) Filler connection. Each recessed oil tank filler connection that can retain any appreciable quantity of oil must have a drain that discharges clear of each part of the aeroplane. In addition each oil tank filler cap must provide an oil-tight seal.
(d) Vent. Oil tanks must be vented as follows:
(1) Each oil tank must be vented from the top part of the expansion space so that venting is effective under any normal flight condition.
(2) Oil tank vents must be arranged so that condensed water vapour that might freeze and obstruct the line cannot accumulate at any point.
(e) Outlet. There must be means to prevent entrance into the tank itself, or into the tank outlet, of any object that might obstruct the flow of oil through the system. No oil tank outlet may be enclosed by any screen or guard that would reduce the flow of oil below a safe value at any operating temperature. There must be a shut-off valve at the outlet of each oil tank, unless the external portion of the oil system (including the oil tank supports) is fireproof.
(f) Flexible oil tank liners. Each flexible oil tank liner must be approved or must be shown to be suitable for the particular application.
ED Decision 2003/2/RM
Each oil tank must be designed and installed so that –
(a) It can withstand, without failure, each vibration, inertia, and fluid load that it may be subjected to in operation; and
(b) It meets the provisions of CS 25.965, except –
(1) The test pressure –
(i) For pressurised tanks used with a turbine engine, may not be less than 34 kPa (5 psi) plus the maximum operating pressure of the tank instead of the pressure specified in CS 25.965(a); and
(ii) For all other tanks, may not be less than 34 kPa (5 psi) instead of the pressure specified in CS 25.965(a); and
(2) The test fluid must be oil at 121°C (250°F) instead of the fluid specified in CS 25.965(c).
CS 25.1017 Oil lines and fittings
ED Decision 2003/2/RM
(a) Each oil line must meet the requirements of CS 25.993 and each oil line and fitting in any designated fire zone must meet the requirements of CS 25.1183.
(b) Breather lines must be arranged so that –
(1) Condensed water vapour that might freeze and obstruct the line cannot accumulate at any point;
(2) The breather discharge does not constitute a fire hazard if foaming occurs or causes emitted oil to strike the pilot’s windshield; and
(3) The breather does not discharge into the engine air induction system.
CS 25.1019 Oil strainer or filter
ED Decision 2003/2/RM
(a) Each turbine engine installation must incorporate an oil strainer or filter through which all of the engine oil flows and which meets the following requirements:
(1) Each oil strainer or filter that has a bypass, must be constructed and installed so that oil will flow at the normal rate through the rest of the system with the strainer or filter completely blocked.
(2) The oil strainer or filter must have the capacity (with respect to operating limitations established for the engine) to ensure that engine oil system functioning is not impaired when the oil is contaminated to a degree (with respect to particle size and density) that is greater than that established for the engine under CS-E.
(3) The oil strainer or filter, unless it is installed at an oil tank outlet, must incorporate an indicator that will indicate contamination before it reaches the capacity established in accordance with sub-paragraph (a)(2) of this paragraph.
(4) The bypass of a strainer or filter must be constructed and installed so that the release of collected contaminants is minimised by appropriate location of the bypass to ensure that collected contaminants are not in the bypass flow path.
(5) An oil strainer or filter that has no bypass, except one that is installed at an oil tank outlet, must have a means to connect it to the warning system required in CS 25.1305(c)(7).
ED Decision 2003/2/RM
A drain (or drains) must be provided to allow safe drainage of the oil system. Each drain must –
(a) Be accessible; and
(b) Have manual or automatic means for positive locking in the closed position.
ED Decision 2003/2/RM
(a) Each oil radiator must be able to withstand, without failure, any vibration, inertia, and oil pressure load to which it would be subjected in operation.
(b) Each oil radiator air duct must be located so that, in case of fire, flames coming from normal openings of the engine nacelle cannot impinge directly upon the radiator.
ED Decision 2003/2/RM
(a) Each oil shut-off must meet the requirements of CS 25.1189.
(b) The closing of oil shut-off means may not prevent propeller feathering.
(c) Each oil valve must have positive stops or suitable index provisions in the ‘on’ and ‘off’ positions and must be supported so that no loads resulting from its operation or from accelerated flight conditions are transmitted to the lines attached to the valve.
CS 25.1027 Propeller feathering system
ED Decision 2003/2/RM
(See AMC 25.1027.)
(a) If the propeller feathering system depends on engine oil, there must be means to trap an amount of oil in the tank if the supply becomes depleted due to failure of any part of the lubricating system other than the tank itself.
(b) The amount of trapped oil must be enough to accomplish the feathering operation and must be available only to the feathering pump. (See AMC 25.1027(b).)
(c) The ability of the system to accomplish feathering with the trapped oil must be shown. This may be done on the ground using an auxiliary source of oil for lubricating the engine during operation.
(d) Provision must be made to prevent sludge or other foreign matter from affecting the safe operation of the propeller feathering system.
AMC 25.1027 Inadvertent Propeller Feathering
ED Decision 2003/002/RM
The design of the propeller feathering system should be such that it is possible to complete the feathering and the unfeathering operation under all normal operating conditions.
AMC 25.1027(b) Propeller Feathering
ED Decision 2003/002/RM
The amount of trapped oil should be sufficient to cover one feathering operation; taking into account the maximum oil leakage in the feathering system due to wear and deterioration in service.